Release 7.2

* Remove deprecated dump1090-fa/ html files and update dump1090-fa.install accordingly

* Remove deprecated lighttpd files and update paths/readmes

* SkyAware readme update

* More SkyAware readme updates

* Bump html/css script cache bust versions

.gitattributes

@@ -0,0 +1,4 @@
+*.xz binary
+dsp/generated/* merge=binary linguist-generated
+cpu_features/** linguist-vendored
+starch/** linguist-vendored

.gitignore

@@ -7,4 +7,13 @@ frames.js
 *~
 *.rej
 *.orig
-untrackedDeveloperSettings.js
+untrackedDeveloperSettings.js
+view1090
+faup1090
+package-wheezy
+oneoff/convert_benchmark
+oneoff/uc8_capture_stats
+oneoff/dsp_error_measurement
+oneoff/decode_comm_b
+starch-benchmark
+wisdom.local

.travis.yml

@@ -0,0 +1,31 @@
+language: c
+
+sudo: required
+
+matrix:
+    include:
+        - os: linux
+          dist: trusty
+        - os: osx
+          osx_image: xcode7.3
+        - os: osx
+          osx_image: xcode7.1
+        - os: osx
+          osx_image: beta-xcode6.2
+
+before_install:
+    - if [ `uname` = "Linux" ]; then
+          sudo apt-get update -qq;
+          sudo apt-get install -y build-essential debhelper librtlsdr-dev libusb-1.0-0-dev pkg-config fakeroot libbladerf-dev dh-systemd;
+      elif [ `uname` = "Darwin" ]; then
+          brew update;
+          brew install -v librtlsdr;
+      fi
+
+script:
+    - if [ `uname` = "Linux" ]; then
+          dpkg-buildpackage -b -us -uc;
+      elif [ `uname` = "Darwin" ]; then
+          make;
+         make test;
+      fi

COPYING

@@ -0,0 +1,339 @@
+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+			    Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+  Finally, any free program is threatened constantly by software
+patents.  We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary.  To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+		    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The "Program", below,
+refers to any such program or work, and a "work based on the Program"
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+  1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+  2. You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+    a) You must cause the modified files to carry prominent notices
+    stating that you changed the files and the date of any change.
+
+    b) You must cause any work that you distribute or publish, that in
+    whole or in part contains or is derived from the Program or any
+    part thereof, to be licensed as a whole at no charge to all third
+    parties under the terms of this License.
+
+    c) If the modified program normally reads commands interactively
+    when run, you must cause it, when started running for such
+    interactive use in the most ordinary way, to print or display an
+    announcement including an appropriate copyright notice and a
+    notice that there is no warranty (or else, saying that you provide
+    a warranty) and that users may redistribute the program under
+    these conditions, and telling the user how to view a copy of this
+    License.  (Exception: if the Program itself is interactive but
+    does not normally print such an announcement, your work based on
+    the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+    a) Accompany it with the complete corresponding machine-readable
+    source code, which must be distributed under the terms of Sections
+    1 and 2 above on a medium customarily used for software interchange; or,
+
+    b) Accompany it with a written offer, valid for at least three
+    years, to give any third party, for a charge no more than your
+    cost of physically performing source distribution, a complete
+    machine-readable copy of the corresponding source code, to be
+    distributed under the terms of Sections 1 and 2 above on a medium
+    customarily used for software interchange; or,
+
+    c) Accompany it with the information you received as to the offer
+    to distribute corresponding source code.  (This alternative is
+    allowed only for noncommercial distribution and only if you
+    received the program in object code or executable form with such
+    an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+  5. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+			    NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+		     END OF TERMS AND CONDITIONS
+
+	    How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.

Jenkinsfile

@@ -0,0 +1,53 @@
+node(label: 'raspberrypi') {
+    properties([
+        pipelineTriggers([
+            upstream(threshold: 'SUCCESS',
+                     upstreamProjects: "bladeRF/${env.BRANCH_NAME}")
+        ]),
+        disableConcurrentBuilds(),
+        durabilityHint(hint: 'PERFORMANCE_OPTIMIZED')
+    ])
+
+    def dists = ["bullseye", "buster", "stretch"]
+    def srcdir = "${WORKSPACE}/src"
+
+    stage('Checkout') {
+        sh "rm -fr ${srcdir}"
+        sh "mkdir ${srcdir}"
+        dir(srcdir) {
+            checkout scm
+        }
+    }
+
+    for (int i = 0; i < dists.size(); ++i) {
+        def dist = dists[i]
+        def pkgdir = "package-${dist}"
+        def results = "results-${dist}"
+
+        stage("Prepare source for ${dist}") {
+            sh "rm -fr ${pkgdir}"
+            sh "${srcdir}/prepare-build.sh ${dist} ${pkgdir}"
+        }
+
+        stage("Build for ${dist}") {
+            sh "rm -fr ${results}"
+            sh "mkdir -p ${results}"
+            dir(pkgdir) {
+                sh "DIST=${dist} BRANCH=${env.BRANCH_NAME} pdebuild --use-pdebuild-internal --debbuildopts -b --buildresult ${WORKSPACE}/${results} -- --override-config"
+            }
+            archiveArtifacts artifacts: "${results}/*.deb", fingerprint: true
+        }
+
+        stage("Test install on ${dist}") {
+            sh "BRANCH=${env.BRANCH_NAME} /build/pi-builder/scripts/validate-packages.sh ${dist} ${results}/dump1090-fa_*.deb"
+        }
+    }
+
+    stage('Deploy to internal repository') {
+        for (int i = 0; i < dists.size(); ++i) {
+            def dist = dists[i]
+            def results = "results-${dist}"
+            sh "/build/pi-builder/scripts/deploy.sh -distribution ${dist} -branch ${env.BRANCH_NAME} ${results}/*.deb"
+        }
+    }
+}

LICENSE

@@ -0,0 +1,41 @@
+This version of dump1090 is licensed under the GPL, v2 or later.
+
+Please see the individual source files and the file COPYING
+for full copyright and license details.
+
+If you need to use dump1090 in a way that is incompatible with
+the GPL, please contact Oliver Jowett <oliver@mutability.co.uk>
+to discuss your requirements.
+
+The source code incorporates work that was released under a
+BSD-style license, reproduced below. For unmodified versions
+of the original work that may be used under the terms of that
+license, please see https://github.com/antirez/dump1090 and
+https://github.com/MalcolmRobb/dump1090.
+
+// Copyright (C) 2012 by Salvatore Sanfilippo <antirez@gmail.com>
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//  *  Redistributions of source code must retain the above copyright
+//     notice, this list of conditions and the following disclaimer.
+//
+//  *  Redistributions in binary form must reproduce the above copyright
+//     notice, this list of conditions and the following disclaimer in the
+//     documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Makefile

@@ -1,31 +1,250 @@
-#
-# When building a package or installing otherwise in the system, make
-# sure that the variable PREFIX is defined, e.g. make PREFIX=/usr/local
-#
 PROGNAME=dump1090
 
-ifdef PREFIX
-BINDIR=$(PREFIX)/bin
-SHAREDIR=$(PREFIX)/share/$(PROGNAME)
-EXTRACFLAGS=-DHTMLPATH=\"$(SHAREDIR)\"
+DUMP1090_VERSION ?= unknown
+
+CFLAGS ?= -O3 -g
+DUMP1090_CFLAGS := -std=c11 -fno-common -Wall -Wmissing-declarations -Werror -W
+DUMP1090_CPPFLAGS := -I. -D_POSIX_C_SOURCE=200112L -DMODES_DUMP1090_VERSION=\"$(DUMP1090_VERSION)\" -DMODES_DUMP1090_VARIANT=\"dump1090-fa\"
+
+LIBS = -lpthread -lm
+SDR_OBJ = cpu.o sdr.o fifo.o sdr_ifile.o dsp/helpers/tables.o
+
+# Try to autodetect available libraries via pkg-config if no explicit setting was used
+PKGCONFIG=$(shell pkg-config --version >/dev/null 2>&1 && echo "yes" || echo "no")
+ifeq ($(PKGCONFIG), yes)
+  ifndef RTLSDR
+    ifdef RTLSDR_PREFIX
+      RTLSDR := yes
+    else
+      RTLSDR := $(shell pkg-config --exists librtlsdr && echo "yes" || echo "no")
+    endif
+  endif
+
+  ifndef BLADERF
+    BLADERF := $(shell pkg-config --exists libbladeRF && echo "yes" || echo "no")
+  endif
+
+  ifndef HACKRF
+    HACKRF := $(shell pkg-config --exists libhackrf && echo "yes" || echo "no")
+  endif
+
+  ifndef LIMESDR
+    LIMESDR := $(shell pkg-config --exists LimeSuite && echo "yes" || echo "no")
+  endif
+else
+  # pkg-config not available. Only use explicitly enabled libraries.
+  RTLSDR ?= no
+  BLADERF ?= no
+  HACKRF ?= no
+  LIMESDR ?= no
 endif
 
-CFLAGS+=-O2 -g -Wall -W `pkg-config --cflags librtlsdr`
-LIBS=-lpthread -lm -lrt
-LIBS_RTL=`pkg-config --libs librtlsdr`
-CC=gcc
+HOST_UNAME := $(shell uname)
+HOST_ARCH := $(shell uname -m)
+
+UNAME ?= $(HOST_UNAME)
+ARCH ?= $(HOST_ARCH)
+
+ifeq ($(UNAME), Linux)
+  DUMP1090_CPPFLAGS += -D_DEFAULT_SOURCE
+  LIBS += -lrt
+  LIBS_USB += -lusb-1.0
+  LIBS_CURSES := -lncurses
+  CPUFEATURES ?= yes
+endif
+
+ifeq ($(UNAME), Darwin)
+  ifneq ($(shell sw_vers -productVersion | egrep '^10\.([0-9]|1[01])\.'),) # Mac OS X ver <= 10.11
+    DUMP1090_CPPFLAGS += -DMISSING_GETTIME
+    COMPAT += compat/clock_gettime/clock_gettime.o
+  endif
+  DUMP1090_CPPFLAGS += -DMISSING_NANOSLEEP
+  COMPAT += compat/clock_nanosleep/clock_nanosleep.o
+  LIBS_USB += -lusb-1.0
+  LIBS_CURSES := -lncurses
+  # cpufeatures reportedly does not work (yet) on darwin arm64
+  ifneq ($(ARCH),arm64)
+    CPUFEATURES ?= yes
+  endif
+endif
+
+ifeq ($(UNAME), OpenBSD)
+  DUMP1090_CPPFLAGS += -DMISSING_NANOSLEEP
+  COMPAT += compat/clock_nanosleep/clock_nanosleep.o
+  LIBS_USB += -lusb-1.0
+  LIBS_CURSES := -lncurses
+endif
+
+ifeq ($(UNAME), FreeBSD)
+  DUMP1090_CPPFLAGS += -D_DEFAULT_SOURCE
+  LIBS += -lrt
+  LIBS_USB += -lusb
+  LIBS_CURSES := -lncurses
+endif
+
+ifeq ($(UNAME), NetBSD)
+  DUMP1090_CPPFLAGS += -D_DEFAULT_SOURCE
+  LIBS += -lrt
+  LIBS_USB += -lusb-1.0
+  LIBS_CURSES := -lcurses
+endif
+
+CPUFEATURES ?= no
+
+ifeq ($(CPUFEATURES),yes)
+  include Makefile.cpufeatures
+  DUMP1090_CPPFLAGS += -DENABLE_CPUFEATURES -Icpu_features/include
+endif
+
+RTLSDR ?= yes
+BLADERF ?= yes
+
+ifeq ($(RTLSDR), yes)
+  SDR_OBJ += sdr_rtlsdr.o
+  DUMP1090_CPPFLAGS += -DENABLE_RTLSDR
+
+  ifdef RTLSDR_PREFIX
+    DUMP1090_CPPFLAGS += -I$(RTLSDR_PREFIX)/include
+    ifeq ($(STATIC), yes)
+      LIBS_SDR += -L$(RTLSDR_PREFIX)/lib -Wl,-Bstatic -lrtlsdr -Wl,-Bdynamic $(LIBS_USB)
+    else
+      LIBS_SDR += -L$(RTLSDR_PREFIX)/lib -lrtlsdr $(LIBS_USB)
+    endif
+  else
+    # some packaged .pc files are massively broken, try to handle it
+
+    # FreeBSD's librtlsdr.pc includes -std=gnu89 in cflags
+    # some linux librtlsdr packages return a bare -I/ with no path in --cflags
+    RTLSDR_CFLAGS := $(shell pkg-config --cflags librtlsdr)
+    RTLSDR_CFLAGS := $(filter-out -std=%,$(RTLSDR_CFLAGS))
+    RTLSDR_CFLAGS := $(filter-out -I/,$(RTLSDR_CFLAGS))
+    DUMP1090_CFLAGS += $(RTLSDR_CFLAGS)
+
+    # some linux librtlsdr packages return a bare -L with no path in --libs
+    # which horribly confuses things because it eats the next option on the command line
+    RTLSDR_LFLAGS := $(shell pkg-config --libs-only-L librtlsdr)
+    ifeq ($(RTLSDR_LFLAGS),-L)
+      LIBS_SDR += $(shell pkg-config --libs-only-l --libs-only-other librtlsdr)
+    else
+      LIBS_SDR += $(shell pkg-config --libs librtlsdr)
+    endif
+  endif
+endif
+
+ifeq ($(BLADERF), yes)
+  SDR_OBJ += sdr_bladerf.o
+  DUMP1090_CPPFLAGS += -DENABLE_BLADERF
+  DUMP1090_CFLAGS += $(shell pkg-config --cflags libbladeRF)
+  LIBS_SDR += $(shell pkg-config --libs libbladeRF)
+endif
+
+ifeq ($(HACKRF), yes)
+  SDR_OBJ += sdr_hackrf.o
+  DUMP1090_CPPFLAGS += -DENABLE_HACKRF
+  DUMP1090_CFLAGS += $(shell pkg-config --cflags libhackrf)
+  LIBS_SDR += $(shell pkg-config --libs libhackrf)
+endif
+
+ifeq ($(LIMESDR), yes)
+  SDR_OBJ += sdr_limesdr.o
+  DUMP1090_CPPFLAGS += -DENABLE_LIMESDR
+  DUMP1090_CFLAGS += $(shell pkg-config --cflags LimeSuite)
+  LIBS_SDR += $(shell pkg-config --libs LimeSuite)
+endif
 
 
-all: dump1090 view1090
+##
+## starch (runtime DSP code selection) mix, architecture-specific
+##
 
-%.o: %.c
-	$(CC) $(CPPFLAGS) $(CFLAGS) $(EXTRACFLAGS) -c $<
+ifneq ($(CPUFEATURES),yes)
+  # need to be able to detect CPU features at runtime to enable any non-standard compiler flags
+  STARCH_MIX := generic
+  DUMP1090_CPPFLAGS += -DSTARCH_MIX_GENERIC
+else
+  ifeq ($(ARCH),x86_64)
+    # AVX, AVX2
+    STARCH_MIX := x86
+    DUMP1090_CPPFLAGS += -DSTARCH_MIX_X86
+  else ifeq ($(findstring aarch,$(ARCH)),aarch)
+    STARCH_MIX := aarch64
+    DUMP1090_CPPFLAGS += -DSTARCH_MIX_AARCH64
+  else ifeq ($(findstring arm64,$(ARCH)),arm64)
+    # Apple calls this arm64, not aarch64
+    STARCH_MIX := aarch64
+    DUMP1090_CPPFLAGS += -DSTARCH_MIX_AARCH64
+  else ifeq ($(findstring arm,$(ARCH)),arm)
+    # ARMv7 NEON
+    STARCH_MIX := arm
+    DUMP1090_CPPFLAGS += -DSTARCH_MIX_ARM
+  else
+    STARCH_MIX := generic
+    DUMP1090_CPPFLAGS += -DSTARCH_MIX_GENERIC
+  endif
+endif
+all: showconfig dump1090 view1090 starch-benchmark
 
-dump1090: dump1090.o anet.o interactive.o mode_ac.o mode_s.o net_io.o
-	$(CC) -g -o dump1090 dump1090.o anet.o interactive.o mode_ac.o mode_s.o net_io.o $(LIBS) $(LIBS_RTL) $(LDFLAGS)
+ALL_CCFLAGS := $(CPPFLAGS) $(DUMP1090_CPPFLAGS) $(CFLAGS) $(DUMP1090_CFLAGS)
 
-view1090: view1090.o anet.o interactive.o mode_ac.o mode_s.o net_io.o
-	$(CC) -g -o view1090 view1090.o anet.o interactive.o mode_ac.o mode_s.o net_io.o $(LIBS) $(LDFLAGS)
+STARCH_COMPILE := $(CC) $(ALL_CCFLAGS) -c
+include dsp/generated/makefile.$(STARCH_MIX)
+
+showconfig:
+	@echo "Building with:" >&2
+	@echo "  Version string:  $(DUMP1090_VERSION)" >&2
+	@echo "  Architecture:    $(ARCH)" >&2
+	@echo "  DSP mix:         $(STARCH_MIX)" >&2
+	@echo "  RTLSDR support:  $(RTLSDR)" >&2
+	@echo "  BladeRF support: $(BLADERF)" >&2
+	@echo "  HackRF support:  $(HACKRF)" >&2
+	@echo "  LimeSDR support: $(LIMESDR)" >&2
+
+%.o: %.c *.h
+	$(CC) $(ALL_CCFLAGS) -c $< -o $@
+
+dump1090: dump1090.o anet.o interactive.o mode_ac.o mode_s.o comm_b.o net_io.o crc.o demod_2400.o stats.o cpr.o icao_filter.o track.o util.o convert.o ais_charset.o adaptive.o $(SDR_OBJ) $(COMPAT) $(CPUFEATURES_OBJS) $(STARCH_OBJS)
+	$(CC) -g -o $@ $^ $(LDFLAGS) $(LIBS) $(LIBS_SDR) $(LIBS_CURSES)
+
+view1090: view1090.o anet.o interactive.o mode_ac.o mode_s.o comm_b.o net_io.o crc.o stats.o cpr.o icao_filter.o track.o util.o ais_charset.o sdr_stub.o $(COMPAT)
+	$(CC) -g -o $@ $^ $(LDFLAGS) $(LIBS) $(LIBS_CURSES)
+
+faup1090: faup1090.o anet.o mode_ac.o mode_s.o comm_b.o net_io.o crc.o stats.o cpr.o icao_filter.o track.o util.o ais_charset.o sdr_stub.o $(COMPAT)
+	$(CC) -g -o $@ $^ $(LDFLAGS) $(LIBS)
+
+starch-benchmark: cpu.o dsp/helpers/tables.o $(CPUFEATURES_OBJS) $(STARCH_OBJS) $(STARCH_BENCHMARK_OBJ)
+	$(CC) -g -o $@ $^ $(LDFLAGS) $(LIBS)
 
 clean:
-	rm -f *.o dump1090 view1090
+	rm -f *.o oneoff/*.o compat/clock_gettime/*.o compat/clock_nanosleep/*.o cpu_features/src/*.o dsp/generated/*.o dsp/helpers/*.o $(CPUFEATURES_OBJS) dump1090 view1090 faup1090 cprtests crctests oneoff/convert_benchmark oneoff/decode_comm_b oneoff/dsp_error_measurement oneoff/uc8_capture_stats starch-benchmark
+
+test: cprtests
+	./cprtests
+
+cprtests: cpr.o cprtests.o
+	$(CC) $(ALL_CCFLAGS) -g -o $@ $^ -lm
+
+crctests: crc.c crc.h
+	$(CC) $(ALL_CCFLAGS) -g -DCRCDEBUG -o $@ $<
+
+benchmarks: oneoff/convert_benchmark
+	oneoff/convert_benchmark
+
+oneoff/convert_benchmark: oneoff/convert_benchmark.o convert.o util.o dsp/helpers/tables.o cpu.o $(CPUFEATURES_OBJS) $(STARCH_OBJS)
+	$(CC) $(ALL_CCFLAGS) -g -o $@ $^ -lm -lpthread
+
+oneoff/decode_comm_b: oneoff/decode_comm_b.o comm_b.o ais_charset.o
+	$(CC) $(ALL_CCFLAGS) -g -o $@ $^ -lm
+
+oneoff/dsp_error_measurement: oneoff/dsp_error_measurement.o dsp/helpers/tables.o cpu.o $(CPUFEATURES_OBJS) $(STARCH_OBJS)
+	$(CC) $(ALL_CCFLAGS) -g -o $@ $^ -lm
+
+oneoff/uc8_capture_stats: oneoff/uc8_capture_stats.o
+	$(CC) $(ALL_CCFLAGS) -g -o $@ $^ -lm
+
+starchgen:
+	dsp/starchgen.py .
+
+.PHONY: wisdom.local
+wisdom.local: starch-benchmark
+	./starch-benchmark -i 5 -o wisdom.local mean_power_u16 mean_power_u16_aligned magnitude_uc8 magnitude_uc8_aligned
+	./starch-benchmark -i 5 -r wisdom.local -o wisdom.local

Makefile.cpufeatures

@@ -0,0 +1,38 @@
+# -*- makefile -*-
+
+# cmake integration is a little tricky, so let's do this by hand for now
+
+CPUFEATURES_UNAME ?= $(UNAME)
+CPUFEATURES_ARCH ?= $(ARCH)
+CPUFEATURES_CFLAGS ?= $(CFLAGS)
+
+CPUFEATURES_OBJS := cpu_features/src/filesystem.o cpu_features/src/stack_line_reader.o cpu_features/src/string_view.o
+CPUFEATURES_EXTRA_CFLAGS := -std=c99
+CPUFEATURES_EXTRA_CPPFLAGS := -DSTACK_LINE_READER_BUFFER_SIZE=1024 -DNDEBUG -Icpu_features/include
+
+ifeq ($(CPUFEATURES_UNAME),Linux)
+  CPUFEATURES_OBJS += cpu_features/src/hwcaps.o
+  CPUFEATURES_EXTRA_CPPFLAGS += -DHAVE_STRONG_GETAUXVAL
+endif
+
+ifeq ($(CPUFEATURES_UNAME),Darwin)
+  CPUFEATURES_EXTRA_CPPFLAGS += -DHAVE_SYSCTLBYNAME
+endif
+
+ifeq ($(CPUFEATURES_ARCH),x86_64)
+  CPUFEATURES_OBJS += cpu_features/src/cpuinfo_x86.o
+endif
+
+ifneq (,$(filter i%86,$(CPUFEATURES_ARCH)))
+  CPUFEATURES_OBJS += cpu_features/src/cpuinfo_x86.o
+endif
+
+ifneq (,$(findstring arm,$(CPUFEATURES_ARCH)))
+  CPUFEATURES_OBJS += cpu_features/src/cpuinfo_arm.o
+endif
+
+ifneq (,$(findstring aarch64,$(CPUFEATURES_ARCH)))
+  CPUFEATURES_OBJS += cpu_features/src/cpuinfo_aarch64.o
+endif
+
+$(CPUFEATURES_OBJS): override ALL_CCFLAGS := $(CPUFEATURES_CPPFLAGS) $(CPUFEATURES_EXTRA_CPPFLAGS) $(CPUFEATURES_CFLAGS) $(CPUFEATURES_EXTRA_CFLAGS)

README-json.md

@@ -0,0 +1,167 @@
+# JSON output formats
+
+dump1090 generates several json files with informaton about the receiver itself, currently known aircraft,
+and general statistics. These are used by the webmap, but could also be used by other things
+e.g. [this collectd plugin](https://github.com/mutability/dump1090-tools/tree/master/collectd) feeds stats
+about dump1090's operation to collectd for later graphing.
+
+## Reading the json files
+
+dump1090-fa writes json files periodically to the location specified by the `--write-json` command line option.
+These json files can then be exposed via a separate standalone webserver e.g. lighttpd.
+
+The files are written periodically; for aircraft, typically once a second, for stats, once a minute.
+The interval between file updates can be controlled by the `--write-json-every` and `--json-stats-every` options.
+As these files are frequently updated, it's a good idea to put them in RAM rather than on disk. Package installs
+default to putting the file under `/run`, which is in RAM.
+
+New versions of each file are written to a temporary file, then atomically renamed to the right path, so you should never see partial copies.
+
+Each file contains a single JSON object. The file formats are:
+
+## receiver.json
+
+This file has general metadata about dump1090. It does not change often and you probably just want to read it once at startup.
+The keys are:
+
+ * version: the version of dump1090 in use
+ * refresh: how often aircraft.json is updated (for the file version), in milliseconds. the webmap uses this to control its refresh interval.
+ * history: the current number of valid history files (see below)
+ * lat: the latitude of the receiver in decimal degrees. Optional, may not be present.
+ * lon: the longitude of the receiver in decimal degrees. Optional, may not be present.
+
+## aircraft.json
+
+This file contains dump1090's list of recently seen aircraft. The keys are:
+
+ * now: the time this file was generated, in seconds since Jan 1 1970 00:00:00 GMT (the Unix epoch).
+ * messages: the total number of Mode S messages processed since dump1090 started.
+ * aircraft: an array of JSON objects, one per known aircraft. Each aircraft has the following keys. Keys will be omitted if data is not available.
+   * hex: the 24-bit ICAO identifier of the aircraft, as 6 hex digits. The identifier may start with '~', this means that the address is a non-ICAO address (e.g. from TIS-B).
+   * type: type of underlying message, one of:
+     * adsb_icao: messages from a Mode S or ADS-B transponder, using a 24-bit ICAO address
+     * adsb_icao_nt: messages from an ADS-B equipped "non-transponder" emitter e.g. a ground vehicle, using a 24-bit ICAO address
+     * adsr_icao: rebroadcast of ADS-B messages originally sent via another data link e.g. UAT, using a 24-bit ICAO address
+     * tisb_icao: traffic information about a non-ADS-B target identified by a 24-bit ICAO address, e.g. a Mode S target tracked by secondary radar
+     * adsb_other: messages from an ADS-B transponder using a non-ICAO address, e.g. anonymized address
+     * adsr_other: rebroadcast of ADS-B messages originally sent via another data link e.g. UAT, using a non-ICAO address
+     * tisb_other: traffic information about a non-ADS-B target using a non-ICAO address
+     * tisb_trackfile: traffic information about a non-ADS-B target using a track/file identifier, typically from primary or Mode A/C radar
+   * flight: callsign, the flight name or aircraft registration as 8 chars (2.2.8.2.6)
+   * alt_baro: the aircraft barometric altitude in feet
+   * alt_geom: geometric (GNSS / INS) altitude in feet referenced to the WGS84 ellipsoid
+   * gs: ground speed in knots
+   * ias: indicated air speed in knots
+   * tas: true air speed in knots
+   * mach: Mach number
+   * track: true track over ground in degrees (0-359)
+   * track_rate: Rate of change of track, degrees/second
+   * roll: Roll, degrees, negative is left roll
+   * mag_heading: Heading, degrees clockwise from magnetic north
+   * true_heading: Heading, degrees clockwise from true north
+   * baro_rate: Rate of change of barometric altitude, feet/minute
+   * geom_rate: Rate of change of geometric (GNSS / INS) altitude, feet/minute
+   * squawk: Mode A code (Squawk), encoded as 4 octal digits
+   * emergency: ADS-B emergency/priority status, a superset of the 7x00 squawks (2.2.3.2.7.8.1.1)
+   * category: emitter category to identify particular aircraft or vehicle classes (values A0 - D7) (2.2.3.2.5.2)
+   * nav_qnh: altimeter setting (QFE or QNH/QNE), hPa
+   * nav_altitude_mcp: selected altitude from the Mode Control Panel / Flight Control Unit (MCP/FCU) or equivalent equipment
+   * nav_altitude_fms: selected altitude from the Flight Manaagement System (FMS) (2.2.3.2.7.1.3.3)
+   * nav_heading: selected heading (True or Magnetic is not defined in DO-260B, mostly Magnetic as that is the de facto standard) (2.2.3.2.7.1.3.7)
+   * nav_modes: set of engaged automation modes: 'autopilot', 'vnav', 'althold', 'approach', 'lnav', 'tcas'
+   * lat, lon: the aircraft position in decimal degrees
+   * nic: Navigation Integrity Category (2.2.3.2.7.2.6)
+   * rc: Radius of Containment, meters; a measure of position integrity derived from NIC & supplementary bits. (2.2.3.2.7.2.6, Table 2-69)
+   * seen_pos: how long ago (in seconds before "now") the position was last updated
+   * version: ADS-B Version Number 0, 1, 2 (3-7 are reserved) (2.2.3.2.7.5)
+   * nic_baro: Navigation Integrity Category for Barometric Altitude (2.2.5.1.35)
+   * nac_p: Navigation Accuracy for Position (2.2.5.1.35)
+   * nac_v: Navigation Accuracy for Velocity (2.2.5.1.19)
+   * sil: Source Integity Level (2.2.5.1.40)
+   * sil_type: interpretation of SIL: unknown, perhour, persample
+   * gva: Geometric Vertical Accuracy  (2.2.3.2.7.2.8)
+   * sda: System Design Assurance (2.2.3.2.7.2.4.6)
+   * modea: true if we seem to be also receiving Mode A responses from this aircraft
+   * modec: true if we seem to be also receiving Mode C responses from this aircraft
+   * mlat: list of fields derived from MLAT data
+   * tisb: list of fields derived from TIS-B data
+   * messages: total number of Mode S messages received from this aircraft
+   * seen: how long ago (in seconds before "now") a message was last received from this aircraft
+   * rssi: recent average RSSI (signal power), in dbFS; this will always be negative.
+
+Section references (2.2.xyz) refer to DO-260B.
+
+## history_0.json, history_1.json, ..., history_119.json
+
+These files are historical copies of aircraft.json at (by default) 30 second intervals. They follow exactly the
+same format as aircraft.json. To know how many are valid, see receiver.json ("history" value). They are written in
+a cycle, with history_0 being overwritten after history_119 is generated, so history_0.json is not necessarily the
+oldest history entry. To load history, you should:
+
+ * read "history" from receiver.json.
+ * load that many history_N.json files
+ * sort the resulting files by their "now" values
+ * process the files in order
+ 
+## stats.json
+
+This file contains statistics about dump1090's operations.
+
+There are 5 top level keys: "latest", "last1min", "last5min", "last15min", "total". Each key has statistics for a different period, defined by the "start" and "end" subkeys:
+
+ * "total" covers the entire period from when dump1090 was started up to the current time
+ * "last1min" covers a recent 1-minute period. This may be up to 1 minute out of date (i.e. "end" may be up to 1 minute old).
+ * "last5min" covers a recent 5-minute period. As above, this may be up to 1 minute out of date.
+ * "last15min" covers a recent 15-minute period. As above, this may be up to 1 minute out of date.
+ * "latest" covers the time between the end of the "last1min" period and the current time.
+
+Internally, live stats are collected into "latest". Once a minute, "latest" is copied to "last1min" and "latest" is reset. Then "last5min" and "last15min" are recalculated from a history of the last 5 or 15 1-minute periods.
+
+Each period has the following subkeys:
+
+ * start: the start time (in seconds-since-1-Jan-1970) of this statistics collection period.
+ * end: the end time (in seconds-since-1-Jan-1970) of this statistics collection period.
+ * local: statistics about messages received from a local SDR dongle. Not present in --net-only mode. Has subkeys:
+   * blocks_processed: number of sample blocks processed
+   * blocks_dropped: number of sample blocks dropped before processing. A nonzero value means CPU overload.
+   * modeac: number of Mode A / C messages decoded
+   * modes: number of Mode S preambles received. This is *not* the number of valid messages!
+   * bad: number of Mode S preambles that didn't result in a valid message
+   * unknown_icao: number of Mode S preambles which looked like they might be valid but we didn't recognize the ICAO address and it was one of the message types where we can't be sure it's valid in this case.
+   * accepted: array. Index N has the number of valid Mode S messages accepted with N-bit errors corrected.
+   * signal: mean signal power of successfully received messages, in dbFS; always negative.
+   * peak_signal: peak signal power of a successfully received message, in dbFS; always negative.
+   * strong_signals: number of messages received that had a signal power above -3dBFS.
+ * remote: statistics about messages received from remote clients. Only present in --net or --net-only mode. Has subkeys:
+   * modeac: number of Mode A / C messages received.
+   * modes: number of Mode S messages received.
+   * bad: number of Mode S messages that had bad CRC or were otherwise invalid.
+   * unknown_icao: number of Mode S messages which looked like they might be valid but we didn't recognize the ICAO address and it was one of the message types where we can't be sure it's valid in this case.
+   * accepted: array. Index N has the number of valid Mode S messages accepted with N-bit errors corrected.
+   * http_requests: number of HTTP requests handled.
+ * cpu: statistics about CPU use. Has subkeys:
+   * demod: milliseconds spent doing demodulation and decoding in response to data from a SDR dongle
+   * reader: milliseconds spent reading sample data over USB from a SDR dongle
+   * background: milliseconds spent doing network I/O, processing received network messages, and periodic tasks.
+ * cpr: statistics about Compact Position Report message decoding. Has subkeys:
+   * surface: total number of surface CPR messages received
+   * airborne: total number of airborne CPR messages received
+   * global_ok: global positions successfuly derived
+   * global_bad: global positions that were rejected because they were inconsistent
+     * global_range: global positions that were rejected because they exceeded the receiver max range
+     * global_speed: global positions that were rejected because they failed the inter-position speed check
+   * global_skipped: global position attempts skipped because we did not have the right data (e.g. even/odd messages crossed a zone boundary)
+   * local_ok: local (relative) positions successfully found
+     * local_aircraft_relative: local positions found relative to a previous aircraft position
+     * local_receiver_relative: local positions found relative to the receiver position
+   * local_skipped: local (relative) positions not used because we did not have the right data
+     * local_range: local positions not used because they exceeded the receiver max range or fell into the ambiguous part of the receiver range
+     * local_speed: local positions not used because they failed the inter-position speed check
+   * filtered: number of CPR messages ignored because they matched one of the heuristics for faulty transponder output
+ * tracks: statistics on aircraft tracks. Each track represents a unique aircraft and persists for up to 5 minutes after the last message
+   from the aircraft is heard. If messages from the same aircraft are subsequently heard after the 5 minute period, this will be counted
+   as a new track.
+   * all: total tracks created
+   * single_message: tracks consisting of only a single message. These are usually due to message decoding errors that produce a bad aircraft address.
+ * messages: total number of messages accepted by dump1090 from any source
+ * messages_by_df: an array of integers where entry N (0..31) is the total number of messages accepted with downlink format (DF) = N.

README.adaptive-gain.md

@@ -0,0 +1,191 @@
+# Adaptive gain configuration
+
+dump1090-fa can optionally tune the receiver gain automatically to try to
+pick a gain value for the particular hardware and RF environment without
+manual tuning. This README covers some of the background for why this is
+useful, and how to configure dump1090 to enable this feature.
+
+## Background
+
+In general, more receiver gain means better reception. Most ADS-B transmitters
+within line of sight transmit with enough power that their messages can
+potentially be decoded, but if the receiver gain setting is too low then very
+weak signals may still be too weak to be decoded even after amplification.
+Adding extra receiver gain helps in this case.
+
+However, there are two problems with just adding more gain to a wideband SDR.
+First, _everything_ is amplified, not only the signals of interest. Noise and
+RF interference is also amplified. At high gain settings or in noisy RF
+environments, this can interfere with receiving the ADS-B signals themselves.
+
+Second, there is a wide range of possible ADS-B signal strengths. There can be
+a 60dB or more difference between the weakest signals (a distant aircraft at
+the limit of receiver range) and the strongest signals (a nearby aircraft on
+the ramp 100m from the receiver). Increasing the receiver gain to handle the
+weakest signals can mean that the strongest signals overload the receiver.
+A rtlsdr receiver only has about 30-35dB of dynamic range available at a
+particular gain setting, so there is no single gain setting that can
+simultaneously handle both the weakest and strongest signals.
+
+Adaptive gain tries to deal with these cases by changing the receiver gain
+on the fly to handle the signal and noise levels that are currently being seen
+without human intervention. It is not perfect and it's not a substitute for
+hand-tuning of gain settings, but it aims at picking a reasonable setting for
+cases where individual hand-tuning isn't possible.
+
+## Where to configure adaptive gain options
+
+How to configure adaptive gain varies depending on how you have installed
+dump1090.
+
+If you are using a PiAware sdcard image, adaptive gain can be configured by
+editing `/boot/piaware-config.txt` or by using the `piaware-config` command.
+
+If you are using the Debian package, adaptive gain can be configured by editing
+`/etc/default/dump1090-fa`.
+
+If running dump1090 directly, adaptive gain options are set directly by
+command-line options.
+
+## Default settings
+
+For new PiAware or Debian package installations, adaptive dynamic range mode
+is enabled by default and adaptive burst mode is disabled by default.
+
+For _upgrades_ of PiAware or the Debian package from versions older than 6.0,
+both adaptive gain modes are disabled by default.
+
+These defaults can be overridden as described below.
+
+## Adaptive gain in dynamic range mode
+
+The dynamic range adaptive gain mode attempts to set the receiver gain to
+maintain a given dynamic range - that is, it tries to set the gain so that
+general noise is at or below a given level. This takes into account different
+or changing RF environments and different receiver hardware (antenna,
+preamplifiers, etc) that affects the overall gain of the system, and usually
+will pick a reasonable gain setting without intervention.
+
+To enable this mode:
+
+* Set `adaptive-dynamic-range yes` in piaware-config; or
+* Set `ADAPTIVE_DYNAMIC_RANGE=yes` in `/etc/default/dump1090-fa`; or
+* Pass the `--adaptive-range` option on the command line.
+
+The default settings for dynamic range will use a dynamic range target chosen
+based on SDR type (e.g. 30dB for rtlsdr receivers). This is usually a good
+default. To override this target:
+
+* Set `adaptive-dynamic-range-target` in piaware-config; or
+* Set `ADAPTIVE_DYNAMIC_RANGE_TARGET` in `/etc/default/dump1090-fa`; or
+* Pass the `--adaptive-range-target` option on the command line.
+
+## Adaptive gain in "burst" / loud signal mode
+
+The "burst" adaptive gain mode listens for loud bursts of signal that were
+_not_ successfully decoded as ADS-B messages, but which have approximately
+the right timing to be possible messages that were lost due to receiver
+overloading. When enough overly-loud signals are heard in a short period of
+time, dump1090 will _reduce_ the receiver gain to try to allow them to be
+received.
+
+This is a more situational setting. It may allow reception of loud nearby
+aircraft (e.g. if you are close to an airport). The tradeoff is that when
+there are nearby aircraft, overall receiver range may be reduced. Whether
+this is a good tradeoff depends on the aircraft you're interested in.
+By default, adaptive gain burst mode is disabled.
+
+To enable burst mode:
+
+* Set `adaptive-burst yes` in piaware-config; or
+* Set `ADAPTIVE_BURST=yes` in `/etc/default/dump1090-fa`; or
+* Pass the `--adaptive-burst` option on the command line.
+
+This mode is more experimental than the dynamic range mode and tweaking of
+the advanced burst options may be needed depending on your local installation.
+In particular, `--adaptive-burst-loud-rate` and `adaptive-burst-quiet-rate`
+may need adjusting. Feedback on what works for you and what doesn't would
+be appreciated!
+
+Burst mode and dynamic range mode can be enabled at the same time.
+
+## Limiting the gain range
+
+If you know in advance approximately what the gain setting should be, so
+you want to allow adaptive gain to change the gain only within a certain range,
+you can set minimum and maximum gain settings in dB. Adaptive gain will only
+adjust the gain within this range. To set this:
+
+* Set `adaptive-min-gain` and `adaptive-max-gain` in piaware-config; or
+* Set `ADAPTIVE_MIN_GAIN` and `ADAPTIVE_MAX_GAIN` in `/etc/default/dump1090-fa`; or
+* Pass the `--adaptive-min-gain` and `--adaptive-max-gain` options on the command line.
+
+If you know approximately where the gain should be, then a good starting point would be
+to set the max and min adaptive gain to +/- 10dB around your gain setting.
+
+## Reducing the CPU cost of adaptive gain
+
+The measurements needed to adjust gain have a CPU cost, and on slower
+devices it may be useful to reduce the amount of work that adaptive gain does.
+This can be done by adjusting the adaptive gain duty cycle. This is a
+percentage that controls what fraction of incoming data adaptive gain inspects.
+100% means that every sample is inspected. Lower values reduce CPU use, with
+a tradeoff that adaptive gain has a less accurate picture of the RF
+environment. The default duty cycle is 50% on "fast" CPUs and 10% on "slow"
+CPUs (where currently "slow" means "armv6 architecture", for example the
+Pi Zero or Pi 1). To reduce the duty cycle further:
+
+* Set `slow-cpu yes` in piaware-config; or
+* Set `SLOW_CPU=yes` in `/etc/default/dump1090-fa`; or
+* Pass the `--adaptive-duty-cycle` option on the command line
+
+## Advanced options
+
+There are a number of advanced options that are only supported as
+command-line options or via the EXTRA_OPTIONS setting in
+`/etc/default/dump1090-fa`. They tweak settings that require some knowledge of
+dump1090 internals to make sense of, so YMMV.
+
+For a complete list of options, run `dump1090-fa --help` and look at the
+adaptive gain section.
+
+## Device support
+
+Currently, adaptive gain is only supported on rtlsdr devices. Support for other
+SDRs is planned for the future.
+
+If you're a developer and want to add support for your SDR, you'll need
+to implement the gain control API used in `sdr.[ch]`. See `sdr_rtlsdr.c`
+(`rtlsdrGetGain`, `rtlsdrSetGain`, etc) for examples.
+
+## Comparison with wiedehopf's auto-gain scripts
+
+There is an [auto-gain script](https://github.com/wiedehopf/adsb-scripts/wiki/Automatic-gain-optimization-for-readsb-and-dump1090-fa)
+written by [wiedehopf](https://github.com/wiedehopf) that aims to solve similar
+problems. The implementation approaches are quite different, and which one works best
+for you will depend on the problem you're trying to solve.
+
+The major differences between adaptive gain and the auto-gain script are:
+
+ * Adaptive gain works on short-term data (seconds or minutes) and can react to
+   changes in a similar timeframe. It tries to set an appropriate gain for the
+   _current_ environment without much regard for longer-term trends. The auto-gain
+   script looks at data over longer timeframes (1+ days) and reacts more slowly,
+   but takes into account data across that whole period.
+
+ * Adaptive gain in dynamic range mode looks at an estimate of the noise floor
+   to decide whether to increase gain. Adaptive gain in burst mode looks at the
+   signal strength of samples that were _not_ successfully decoded to decide when
+   to reduce gain. The auto-gain scripts look at the signal strength of _successfully_
+   decoded messages to decide when to increase or decrease gain. These are each measuring
+   something different, and which is most effective will depend on the exact RF
+   environment.
+
+ * Adaptive gain burst mode and the auto-gain script superfically measure similar things,
+   but the difference in measurement timeframe mean they react quite differently. Burst mode
+   tries to react to transient loud signals i.e. temporarily nearby aircraft. The auto-gain
+   script uses the loud-messages fraction as an estimate for messages lost to excessive
+   gain over the long term, not only the transient case.
+
+ * Adaptive gain has a few less moving parts (i.e. no external scripts, no config changes over
+   time) as it's built directly into dump1090 itself.

README.md

@@ -1,284 +1,122 @@
-Dump1090 README
-===
+# dump1090-fa Debian/Raspbian packages
 
-Dump 1090 is a Mode S decoder specifically designed for RTLSDR devices.
+dump1090-fa is a ADS-B, Mode S, and Mode 3A/3C demodulator and decoder that
+will receive and decode aircraft transponder messages received via
+a directly connected software defined radio, or from data provided over a
+network connection.
 
-The main features are:
+It is the successor to
+[dump1090-mutability](https://github.com/mutability/dump1090) and is
+maintained by [FlightAware](http://flightaware.com/).
 
-* Robust decoding of weak messages, with mode1090 many users observed
-  improved range compared to other popular decoders.
-* Network support: TCP30003 stream (MSG5...), Raw packets, HTTP.
-* Embedded HTTP server that displays the currently detected aircrafts on
-  Google Map.
-* Single bit errors correction using the 24 bit CRC.
-* Ability to decode DF11, DF17 messages.
-* Ability to decode DF formats like DF0, DF4, DF5, DF16, DF20 and DF21
-  where the checksum is xored with the ICAO address by brute forcing the
-  checksum field using recently seen ICAO addresses.
-* Decode raw IQ samples from file (using --ifile command line switch).
-* Interactive command-line-interfae mode where aircrafts currently detected
-  are shown as a list refreshing as more data arrives.
-* CPR coordinates decoding and track calculation from velocity.
-* TCP server streaming and recceiving raw data to/from connected clients
-  (using --net).
+It can provide a display of locally received aircraft data in a terminal or
+via a browser map. Together with [PiAware](http://flightaware.com/adsb/piaware)
+it can be used to contribute crowd-sourced flight tracking data to FlightAware.
 
-Installation
----
+It is designed to build as a Debian package, but should also be buildable on
+many other Linux or Unix-like systems.
 
-Type "make".
+## Building under bullseye, buster, or stretch
 
-Normal usage
----
+```bash
+$ sudo apt-get install build-essential fakeroot debhelper librtlsdr-dev pkg-config libncurses5-dev libbladerf-dev libhackrf-dev liblimesuite-dev
+$ ./prepare-build.sh bullseye    # or buster, or stretch
+$ cd package-bullseye            # or buster, or stretch
+$ dpkg-buildpackage -b --no-sign
+```
 
-To capture traffic directly from your RTL device and show the captured traffic
-on standard output, just run the program without options at all:
+## Building with limited dependencies
 
-    ./dump1090
+(Supported for bullseye and buster builds only)
 
-To just output hexadecimal messages:
+The package supports some build profiles to allow building without all
+required SDR libraries being present. This will produce a package with
+limited SDR support only.
 
-    ./dump1090 --raw
+Pass `--build-profiles` to `dpkg-buildpackage` with a comma-separated list of
+profiles. The list of profiles should include `custom` and zero or more of
+`rtlsdr`, `bladerf`, `hackrf`, `limesdr` depending on what you want:
 
-To run the program in interactive mode:
+```bash
+$ dpkg-buildpackage -b --no-sign --build-profiles=custom,rtlsdr          # builds with rtlsdr support only
+$ dpkg-buildpackage -b --no-sign --build-profiles=custom,rtlsdr,bladerf  # builds with rtlsdr and bladeRF support
+$ dpkg-buildpackage -b --no-sign --build-profiles=custom                 # builds with _no_ SDR support (network support only)
+```
 
-    ./dump1090 --interactive
+## Building manually
 
-To run the program in interactive mode, with networking support, and connect
-with your browser to http://localhost:8080 to see live traffic:
+You can probably just run "make" after installing the required dependencies.
+Binaries are built in the source directory; you will need to arrange to
+install them (and a method for starting them) yourself.
 
-    ./dump1090 --interactive --net
+``make BLADERF=no`` will disable bladeRF support and remove the dependency on
+libbladeRF.
 
-In iteractive mode it is possible to have a less information dense but more
-"arcade style" output, where the screen is refreshed every second displaying
-all the recently seen aircrafts with some additional information such as
-altitude and flight number, extracted from the received Mode S packets.
+``make RTLSDR=no`` will disable rtl-sdr support and remove the dependency on
+librtlsdr.
 
-Using files as source of data
----
+``make HACKRF=no`` will disable HackRF support and remove the dependency on 
+libhackrf.
 
-To decode data from file, use:
+``make LIMESDR=no`` will disable LimeSDR support and remove the dependency on
+libLimeSuite.
 
-    ./dump1090 --ifile /path/to/binfile
+## Building on OSX
 
-The binary file should be created using `rtl_sdr` like this (or with any other
-program that is able to output 8-bit unsigned IQ samples at 2Mhz sample rate).
+Minimal testing on Mojave 10.14.6, YMMV.
 
-    rtl_sdr -f 1090000000 -s 2000000 -g 50 output.bin
+```
+$ brew install librtlsdr
+$ brew install libbladerf
+$ brew install hackrf
+$ brew install pkg-config
+$ make
+```
 
-In the example `rtl_sdr` a gain of 50 is used, simply you should use the highest
-gain availabe for your tuner. This is not needed when calling Dump1090 itself
-as it is able to select the highest gain supported automatically.
+## Building on FreeBSD
 
-It is possible to feed the program with data via standard input using
-the --ifile option with "-" as argument.
+Minimal testing on 12.1-RELEASE, YMMV.
 
-Additional options
----
+```
+# pkg install gmake
+# pkg install pkgconf
+# pkg install rtl-sdr
+# pkg install bladerf
+# pkg install hackrf
+$ gmake
+```
 
-Dump1090 can be called with other command line options to set a different
-gain, frequency, and so forth. For a list of options use:
+## Generating wisdom files
 
-    ./dump1090 --help
+dump1090-fa uses [starch](https://github.com/flightaware/starch) to build
+multiple versions of the DSP code and choose the fastest supported by the
+hardware at runtime. The implementations chosen can been seen by running
+`dump1090-fa --version`.
 
-Everything is not documented here should be obvious, and for most users calling
-it without arguments at all is the best thing to do.
+The implementations used are controlled by "wisdom files", a list of
+implementations to use in order of priority. For each DSP function, the first
+implementation listed that's supported by the current hardware is used.
+By default dump1090-fa provides compiled-in wisdom for [x86](wisdom.x86),
+[ARM 32-bit](wisdom.arm), and [ARM 64-bit](wisdom.aarch64). If the defaults
+are not suitable for your hardware or if you're building on a different
+architecture, you may want to generate your own external wisdom file.
 
-Reliability
----
+Ideally, to get stable results, you want to do this on an idle system
+with CPU frequency scaling disabled. Running the benchmarks will take
+some time (10s of minutes).
 
-By default Dump1090 checks for decoding errors using the 24-bit CRC checksum,
-where available. Messages with errors are discarded.
+### Package installs
 
-The --fix command line switch enables fixing single bit error correction
-based on the CRC checksum. Technically, it uses a table of precomputed
-checksum differences resulting from single bit errors to look up the
-wrong bit position.
+Run `/usr/share/dump1090-fa/generate-wisdom`. Wait.
 
-This is indeed able to fix errors and works reliably in my experience,
-however if you are interested in very reliable data I suggest to use
-the --no-fix command line switch in order to disable error fixing.
+Follow the instructions to copy the resulting wisdom file to `/etc/dump1090-fa/wisdom.local`.
 
-Performances and sensibility of detection
----
+Restart dump1090.
 
-In my limited experience Dump1090 was able to decode a big number of messages
-even in conditions where I encountered problems using other programs, however
-no formal test was performed so I can't really claim that this program is
-better or worse compared to other similar programs.
+### Manual installs
 
-If you can capture traffic that Dump1090 is not able to decode properly, drop
-me an email with a download link. I may try to improve the detection during
-my free time (this is just an hobby project).
+Run `make wisdom.local`. Wait.
 
-Network server features
----
+Copy the resulting `wisdom.local` file somewhere appropriate.
 
-By enabling the networking support with --net Dump1090 starts listening
-for clients connections on port 30002 and 30001 (you can change both the
-ports if you want, see --help output).
-
-Port 30002
----
-
-Connected clients are served with data ASAP as they arrive from the device
-(or from file if --ifile is used) in the raw format similar to the following:
-
-    *8D451E8B99019699C00B0A81F36E;
-
-Every entry is separated by a simple newline (LF character, hex 0x0A).
-
-Port 30001
----
-
-Port 30001 is the raw input port, and can be used to feed Dump1090 with
-data in the same format as specified above, with hex messages starting with
-a `*` and ending with a `;` character.
-
-So for instance if there is another remote Dump1090 instance collecting data
-it is possible to sum the output to a local Dump1090 instance doing something
-like this:
-
-    nc remote-dump1090.example.net 30002 | nc localhost 30001
-
-It is important to note that what is received via port 30001 is also
-broadcasted to clients listening to port 30002.
-
-In general everything received from port 30001 is handled exactly like the
-normal traffic from RTL devices or from file when --ifile is used.
-
-It is possible to use Dump1090 just as an hub using --ifile with /dev/zero
-as argument as in the following example:
-
-    ./dump1090 --net-only
-
-Or alternatively to see what's happening on the screen:
-
-    ./dump1090 --net-only --interactive
-
-Then you can feed it from different data sources from the internet.
-
-Port 30003
----
-
-Connected clients are served with messages in SBS1 (BaseStation) format,
-similar to:
-
-    MSG,4,,,738065,,,,,,,,420,179,,,0,,0,0,0,0
-    MSG,3,,,738065,,,,,,,35000,,,34.81609,34.07810,,,0,0,0,0
-
-This can be used to feed data to various sharing sites without the need to use another decoder.
-
-Antenna
----
-
-Mode S messages are transmitted in the 1090 Mhz frequency. If you have a decent
-antenna you'll be able to pick up signals from aircrafts pretty far from your
-position, especially if you are outdoor and in a position with a good sky view.
-
-You can easily build a very cheap antenna following the istructions at:
-
-    http://antirez.com/news/46
-
-With this trivial antenna I was able to pick up signals of aircrafts 200+ Km
-away from me.
-
-If you are interested in a more serious antenna check the following
-resources:
-
-* http://gnuradio.org/redmine/attachments/download/246/06-foster-adsb.pdf
-* http://www.lll.lu/~edward/edward/adsb/antenna/ADSBantenna.html
-* http://modesbeast.com/pix/adsb-ant-drawing.gif
-
-Aggressive mode
----
-
-With --aggressive it is possible to activate the *aggressive mode* that is a
-modified version of the Mode S packet detection and decoding.
-The aggresive mode uses more CPU usually (especially if there are many planes
-sending DF17 packets), but can detect a few more messages.
-
-The algorithm in aggressive mode is modified in the following ways:
-
-* Up to two demodulation errors are tolerated (adjacent entires in the
-  magnitude vector with the same eight). Normally only messages without
-  errors are checked.
-* It tries to fix DF17 messages with CRC errors resulting from any two bit
-  errors.
-
-The use of aggressive mdoe is only advised in places where there is
-low traffic in order to have a chance to capture some more messages.
-
-Debug mode
----
-
-The Debug mode is a visual help to improve the detection algorithm or to
-understand why the program is not working for a given input.
-
-In this mode messages are displayed in an ASCII-art style graphical
-representation, where the individial magnitude bars sampled at 2Mhz are
-displayed.
-
-An index shows the sample number, where 0 is the sample where the first
-Mode S peak was found. Some additional background noise is also added
-before the first peak to provide some context.
-
-To enable debug mode and check what combinations of packets you can
-log, use `mode1090 --help` to obtain a list of available debug flags.
-
-Debug mode includes an optional javascript output that is used to visualize
-packets using a web browser, you can use the file debug.html under the
-'tools' directory to load the generated frames.js file.
-
-How this program works?
----
-
-The code is very documented and written in order to be easy to understand.
-For the diligent programmer with a Mode S specification on his hands it
-should be trivial to understand how it works.
-
-The algorithms I used were obtained basically looking at many messages
-as displayed using a trow-away SDL program, and trying to model the algorithm
-based on how the messages look graphically.
-
-How to test the program?
----
-
-If you have an RTLSDR device and you happen to be in an area where there
-are aircrafts flying over your head, just run the program and check for signals.
-
-However if you don't have an RTLSDR device, or if in your area the presence
-of aircrafts is very limited, you may want to try the sample file distributed
-with the Dump1090 distribution under the "testfiles" directory.
-
-Just run it like this:
-
-    ./dump1090 --ifile testfiles/modes1.bin
-
-What is --strip mode?
----
-
-It is just a simple filter that will get raw IQ 8 bit samples in input
-and will output a file missing all the parts of the file where I and Q
-are lower than the specified <level> for more than 32 samples.
-
-Use it like this:
-
-    cat big.bin | ./dump1090 --snip 25 > small.bin
-
-I used it in order to create a small test file to include inside this
-program source code distribution.
-
-Contributing
----
-
-Dump1090 was written during some free time during xmas 2012, it is an hobby
-project so I'll be able to address issues and improve it only during
-free time, however you are incouraged to send pull requests in order to
-improve the program. A good starting point can be the TODO list included in
-the source distribution.
-
-Credits
----
-
-Dump1090 was written by Salvatore Sanfilippo <antirez@gmail.com> and is
-released under the BSD three clause license.
+Update the dump1090-fa command-line options to include `--wisdom /path/to/wisdom.local`

TODO

@@ -1,5 +0,0 @@
-TODO
-
-* Extract more information from captured Mode S messages.
-* Improve the web interface gmap.html.
-* Enhance the algorithm to reliably decode more messages.

adaptive.c

@@ -0,0 +1,645 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// adaptive.c: adaptive gain control
+//
+// Copyright (c) 2021 FlightAware, LLC
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "dump1090.h"
+#include "adaptive.h"
+
+//
+// gain limits
+//
+static int adaptive_gain_min;
+static int adaptive_gain_max;
+
+// gain steps relative to current gain
+static float adaptive_gain_up_db;
+static float adaptive_gain_down_db;
+
+//
+// block handling
+//
+// 1 block = approx 1 second of samples. Control updates are done at the end of each block only.
+// Each block is made up of an integer number of subblocks (currently 20)
+//
+// 1 subblock = approx 50ms of samples. Duty cycle decisions are made at the subblock level;
+// either the whole subblock is processed, or the whole subblock is skipped.
+// Each subblock is made up of an integer number of windows (currently 1250)
+//
+// 1 window = approx 40us of samples. Burst measurements are made by counting samples within each window.
+//
+// All three levels are aligned, i.e. every block boundary is also a subblock boundary;
+// every subblock boundary is also a window boundary.
+
+
+static const unsigned adaptive_subblocks_per_block = 20;   // subblocks per block
+static unsigned adaptive_subblocks_remaining;              // subblocks remaining in the current block
+
+// Duty cycle is expressed as N/D
+// where N = adaptive_subblbock_dutycycle_N = adaptive_subblocks_per_block * Modes.adaptive_duty_cycle
+//   and D = adaptive_subblocks_dutycycle_D = adaptive_subblocks_per_block
+//
+// i.e. within each block, there are exactly N active subblocks out of D total subblocks
+//
+// The active subblocks are distributed evenly across the block by increasing a counter by N on each
+// subblock, modulo D, and marking the subblock as active each time the counter rolls over.
+
+static unsigned adaptive_subblock_dutycycle_N;                                        // subblock duty cycle numerator N
+
+// stretch gcc doesn't like this as a separate const
+#define adaptive_subblock_dutycycle_D adaptive_subblocks_per_block
+
+static unsigned adaptive_subblock_dutycycle_counter;   // subblock duty cycle counter (modulo D)
+static bool adaptive_subblock_active;                  // is the current subblock active i.e. samples should be processed, not skipped?
+
+static unsigned adaptive_samples_per_subblock;         // samples per subblock
+static unsigned adaptive_subblock_samples_remaining;   // samples remaining in the current subblock
+
+static unsigned adaptive_samples_per_window;           // samples per window
+
+void adaptive_init();
+void adaptive_update(uint16_t *buf, unsigned length, struct modesMessage *decoded);
+static void adaptive_update_subblock(uint16_t *buf, unsigned length, struct modesMessage *decoded);
+static void adaptive_end_of_block();
+static void adaptive_control_update();
+
+//
+// burst handling
+//
+
+static unsigned adaptive_burst_window_remaining;       // samples remaining in the current burst window
+static unsigned adaptive_burst_window_counter;         // loud samples seen in current burst window
+static unsigned adaptive_burst_runlength;              // consecutive loud burst windows seen
+static unsigned adaptive_burst_block_loud_undecoded;   // loud undecoded bursts seen in this block so far
+static unsigned adaptive_burst_block_loud_decoded;     // loud decoded messages seen in this block so far
+static double adaptive_burst_loud_undecoded_smoothed;  // smoothed rate of loud misdecodes per block
+static double adaptive_burst_loud_decoded_smoothed;    // smoothed rate of loud successful decodes per block
+static unsigned adaptive_burst_change_timer;           // countdown inhibiting control after changing gain
+static double adaptive_burst_loud_threshold;           // current signal level threshold for a "loud decode"
+static unsigned adaptive_burst_loud_blocks = 0;        // consecutive blocks with loud rate
+static unsigned adaptive_burst_quiet_blocks = 0;       // consecutive blocks with quiet rate
+
+static void adaptive_burst_update(uint16_t *buf, unsigned length);
+static void adaptive_burst_skip(unsigned length);
+static unsigned adaptive_burst_count_samples(uint16_t *buf, unsigned n);
+static void adaptive_burst_scan_windows(uint16_t *buf, unsigned windows);
+static void adaptive_burst_end_of_window(unsigned counter);
+static void adaptive_burst_end_of_block();
+
+//
+// noise floor measurement (adaptive dynamic range)
+//
+
+static unsigned *adaptive_range_radix;                 // radix-sort buckets for current block
+static unsigned adaptive_range_radix_counter;          // sum of all radix-sort buckets (= number of samples sorted)
+static double adaptive_range_smoothed;                 // smoothed noise floor estimate, dBFS
+static enum { RANGE_SCAN_IDLE, RANGE_SCAN_UP, RANGE_SCAN_DOWN, RANGE_RESCAN_UP, RANGE_RESCAN_DOWN } adaptive_range_state = RANGE_SCAN_UP;
+static unsigned adaptive_range_change_timer;           // countdown inhibiting control after changing gain
+static unsigned adaptive_range_rescan_timer;           // countdown to next upwards gain reprobe
+static int adaptive_range_gain_limit;                  // probed maximum gain step with acceptable dynamic range
+
+static void adaptive_range_update(uint16_t *buf, unsigned length);
+static void adaptive_range_end_of_block();
+
+// Try to change the SDR gain to 'step' and tell the user about it,
+// with 'why' as the reason to show. Return true if the gain actually changed.
+static bool adaptive_set_gain(int step, const char *why)
+{
+    if (step < adaptive_gain_min)
+        step = adaptive_gain_min;
+    if (step > adaptive_gain_max)
+        step = adaptive_gain_max;
+
+    int current_gain = sdrGetGain();
+    if (current_gain == step)
+        return false;
+
+    fprintf(stderr, "adaptive: changing gain from %.1fdB (step %d) to %.1fdB (step %d) because: %s\n",
+            sdrGetGainDb(current_gain), current_gain, sdrGetGainDb(step), step, why);
+
+    int new_gain = sdrSetGain(step);
+    bool changed = (current_gain != new_gain);
+    if (changed)
+        ++Modes.stats_current.adaptive_gain_changes;
+    return changed;
+}
+
+// Update internal state to reflect a gain change
+// (usually after adaptive_set_gain returns true, but also called during init)
+static void adaptive_gain_changed()
+{
+    int new_gain = sdrGetGain();
+    adaptive_gain_up_db = sdrGetGainDb(new_gain + 1) - sdrGetGainDb(new_gain);
+    adaptive_gain_down_db = sdrGetGainDb(new_gain) - sdrGetGainDb(new_gain - 1);
+    
+    double loud_threshold_dbfs = 0 - adaptive_gain_up_db - 3.0;
+    adaptive_burst_loud_threshold = pow(10, loud_threshold_dbfs / 10.0);
+
+    adaptive_range_change_timer = Modes.adaptive_range_change_delay;
+    adaptive_burst_change_timer = Modes.adaptive_burst_change_delay;
+    adaptive_burst_loud_blocks = 0;
+    adaptive_burst_quiet_blocks = 0;
+}
+
+// External init entry point
+void adaptive_init()
+{
+    int maxgain = sdrGetMaxGain();
+
+    // If the SDR doesn't support gain control, disable ourselves
+    if (maxgain < 0) {
+        if (Modes.adaptive_burst_control || Modes.adaptive_range_control) {
+            fprintf(stderr, "warning: adaptive gain control requested, but SDR gain control not available, ignored.\n");
+        }
+        Modes.adaptive_burst_control = false;
+        Modes.adaptive_range_control = false;
+    }        
+
+    // If we're disabled, do nothing
+    if (!Modes.adaptive_burst_control && !Modes.adaptive_range_control)
+        return;
+
+    // Set up window, subblock, and block sizes
+    // Look for 40us bursts
+    adaptive_samples_per_window = Modes.sample_rate / 25000;
+
+    // Use ~50ms subblocks; ensure it's an exact multiple of window size
+    adaptive_samples_per_subblock = adaptive_samples_per_window * 1250;
+
+    adaptive_subblocks_remaining = adaptive_subblocks_per_block;
+    adaptive_subblock_samples_remaining = adaptive_samples_per_subblock;
+    adaptive_subblock_active = false;
+
+    float N = roundf(adaptive_subblock_dutycycle_D * Modes.adaptive_duty_cycle);
+    if (N <= 0)
+        N = 1;
+    if (N > adaptive_subblock_dutycycle_D)
+        N = adaptive_subblock_dutycycle_D;
+    fprintf(stderr, "adaptive: using %.0f%% duty cycle\n", 100.0 * N / adaptive_subblock_dutycycle_D);
+    adaptive_subblock_dutycycle_N = (unsigned)N;
+
+    adaptive_burst_window_remaining = adaptive_samples_per_window;
+    adaptive_burst_window_counter = 0;
+
+    adaptive_range_radix = calloc(sizeof(unsigned), 65536);
+    adaptive_range_state = RANGE_RESCAN_UP;
+
+    // select and enforce gain limits
+    for (adaptive_gain_min = 0; adaptive_gain_min < maxgain; ++adaptive_gain_min) {
+        if (sdrGetGainDb(adaptive_gain_min) >= Modes.adaptive_min_gain_db)
+            break;
+    }
+
+    for (adaptive_gain_max = maxgain; adaptive_gain_max > adaptive_gain_min; --adaptive_gain_max) {
+        if (sdrGetGainDb(adaptive_gain_max) <= Modes.adaptive_max_gain_db)
+            break;
+    }
+
+    fprintf(stderr, "adaptive: enabled adaptive gain control with gain limits %.1fdB (step %d) .. %.1fdB (step %d)\n",
+            sdrGetGainDb(adaptive_gain_min), adaptive_gain_min, sdrGetGainDb(adaptive_gain_max), adaptive_gain_max);
+    if (Modes.adaptive_range_control)
+        fprintf(stderr, "adaptive: enabled dynamic range control, target dynamic range %.1fdB\n", Modes.adaptive_range_target);
+    if (Modes.adaptive_burst_control)
+        fprintf(stderr, "adaptive: enabled burst control\n");
+    adaptive_set_gain(sdrGetGain(), "constraining gain to adaptive gain limits");
+    adaptive_gain_changed();
+
+    adaptive_range_gain_limit = sdrGetGain();
+}
+
+// Feed some samples into the adaptive system. Any number of samples might be passed in.
+void adaptive_update(uint16_t *buf, unsigned length, struct modesMessage *decoded)
+{
+    if (!Modes.adaptive_burst_control && !Modes.adaptive_range_control)
+        return;
+
+    // process complete subblocks
+    while (length >= adaptive_subblock_samples_remaining) {
+        if (adaptive_subblock_active)
+            adaptive_update_subblock(buf, adaptive_subblock_samples_remaining, decoded);
+
+        buf += adaptive_subblock_samples_remaining;
+        length -= adaptive_subblock_samples_remaining;
+        adaptive_subblock_samples_remaining = adaptive_samples_per_subblock;
+
+        adaptive_subblock_dutycycle_counter += adaptive_subblock_dutycycle_N;
+        if (adaptive_subblock_dutycycle_counter >= adaptive_subblock_dutycycle_D) {
+            adaptive_subblock_dutycycle_counter -= adaptive_subblock_dutycycle_D;
+            adaptive_subblock_active = true;
+        } else {
+            adaptive_subblock_active = false;
+            // fake a quiet window to reset any existing run
+            adaptive_burst_end_of_window(0);
+        }
+
+        if (!--adaptive_subblocks_remaining) {
+            // Block completed, do a control update
+            adaptive_subblocks_remaining = adaptive_subblocks_per_block;
+            adaptive_end_of_block();
+        }
+    }
+
+    // process final samples that don't complete a subblock
+    if (length > 0) {
+        if (adaptive_subblock_active)
+            adaptive_update_subblock(buf, length, decoded);
+        adaptive_subblock_samples_remaining -= length;
+    }
+}
+
+// Feed some samples into the adaptive system. The samples are guaranteed to not cross a subblock boundary.
+// The samples should be processsed (i.e. duty cycle is in the active part)
+static void adaptive_update_subblock(uint16_t *buf, unsigned length, struct modesMessage *decoded)
+{
+    if (decoded) {
+        if (/* decoded->msgbits == 112 && */ decoded->signalLevel >= adaptive_burst_loud_threshold)
+            ++adaptive_burst_block_loud_decoded;
+        adaptive_burst_skip(length);
+    } else {
+        adaptive_burst_update(buf, length);
+        adaptive_range_update(buf, length);
+    }
+}
+
+// Burst measurement: ignore the next 'length' samples (they are a successfully decoded message)
+static void adaptive_burst_skip(unsigned length)
+{
+    if (!Modes.adaptive_burst_control)
+        return;
+
+    // first window
+    if (length < adaptive_burst_window_remaining) {
+        // partial fill
+        adaptive_burst_window_remaining -= length;
+        return;
+    }
+
+    // skip remainder of first window, dispatch it
+    adaptive_burst_end_of_window(adaptive_burst_window_counter);
+    length -= adaptive_burst_window_remaining;
+
+    // skip remaining windows, dispatch them
+    unsigned windows = length / adaptive_samples_per_window;
+    unsigned samples = windows * adaptive_samples_per_window;
+    while (windows--)
+        adaptive_burst_end_of_window(0);
+
+    length -= samples;
+
+    // final partial window
+    adaptive_burst_window_counter = 0;
+    adaptive_burst_window_remaining = adaptive_samples_per_window - length;
+}
+
+// Burst measurement: process 'length' samples from 'buf', look for loud bursts;
+// the samples might cross burst window boundaries;
+// the samples will not cross a block boundary.
+static void adaptive_burst_update(uint16_t *buf, unsigned length)
+{
+    if (!Modes.adaptive_burst_control)
+        return;
+
+    // first window
+    if (length < adaptive_burst_window_remaining) {
+        // partial fill
+        adaptive_burst_window_counter += adaptive_burst_count_samples(buf, length);
+        adaptive_burst_window_remaining -= length;
+        return;
+    }
+
+    // complete fill of first partial window
+    unsigned n = adaptive_burst_window_remaining;
+    unsigned counter = adaptive_burst_window_counter + adaptive_burst_count_samples(buf, n);
+    adaptive_burst_end_of_window(counter);
+    buf += n;
+    length -= n;
+
+    // remaining windows
+    unsigned windows = length / adaptive_samples_per_window;
+    unsigned samples = windows * adaptive_samples_per_window;
+    adaptive_burst_scan_windows(buf, windows);
+    buf += samples;
+    length -= samples;
+
+    // final partial window
+    adaptive_burst_window_counter = adaptive_burst_count_samples(buf, length);
+    adaptive_burst_window_remaining = adaptive_samples_per_window - length;
+}
+
+// Burst measurement: process 'windows' complete burst windows starting at 'buf';
+// 'buf' is aligned to the start of a burst window
+static void adaptive_burst_scan_windows(uint16_t *buf, unsigned windows)
+{
+    while (windows--) {
+        unsigned counter = adaptive_burst_count_samples(buf, adaptive_samples_per_window);
+        buf += adaptive_samples_per_window;
+        adaptive_burst_end_of_window(counter);
+    }
+}
+
+// Burst measurement: process 'n' samples from 'buf', look for loud samples;
+// the samples are guaranteed not to cross window boundaries;
+// return the number of loud samples seen
+static inline unsigned adaptive_burst_count_samples(uint16_t *buf, unsigned n)
+{
+    unsigned counter;
+    starch_count_above_u16(buf, n, 46395 /* -3dBFS */, &counter);
+    return counter;
+}
+
+// Burst measurement: we reached the end of a burst window with 'counter'
+// loud samples seen, handle that window.
+static void adaptive_burst_end_of_window(unsigned counter)
+{
+    if (counter > adaptive_samples_per_window / 4) {
+        // This window is loud, extend any existing run of loud windows
+        ++adaptive_burst_runlength;
+    } else {
+        // Quiet window. If we saw a run of loud windows >= 80us long, count
+        // that as a candidate for an over-amplified message that was
+        // not decoded.
+        if (adaptive_burst_runlength >= 2 && adaptive_burst_runlength <= 5)
+            ++adaptive_burst_block_loud_undecoded;
+        adaptive_burst_runlength = 0;
+    }
+}
+
+// Noise measurement: process 'length' samples from 'buf'.
+// The samples will not cross a block boundary.
+static void adaptive_range_update(uint16_t *buf, unsigned length)
+{
+    if (!Modes.adaptive_range_control)
+        return;
+
+    adaptive_range_radix_counter += length;
+    while (length--) {
+        // do a very simple radix sort of sample magnitudes
+        // so we can later find the Nth percentile value
+        ++adaptive_range_radix[buf[0]];
+        ++buf;
+    }
+}
+
+// Noise measurement: we reached the end of a block, update
+// our noise estimate
+static void adaptive_range_end_of_block()
+{
+    if (!Modes.adaptive_range_control)
+        return;
+
+    unsigned n = 0, i = 0;
+
+    // measure Nth percentile magnitude
+    unsigned count_n = adaptive_range_radix_counter * Modes.adaptive_range_percentile / 100;
+    while (i < 65536 && n <= count_n)
+        n += adaptive_range_radix[i++];
+    uint16_t percentile_n = i - 1;
+
+    // maintain an EMA of the Nth percentile
+    adaptive_range_smoothed = adaptive_range_smoothed * (1 - Modes.adaptive_range_alpha) + percentile_n * Modes.adaptive_range_alpha;
+    // .. report to stats in dBFS
+    if (adaptive_range_smoothed > 0) {
+        Modes.stats_current.adaptive_noise_dbfs = 20 * log10(adaptive_range_smoothed / 65536.0);
+    } else {
+        Modes.stats_current.adaptive_noise_dbfs = 0;
+    }
+
+    // reset radix sort for the next block
+    memset(adaptive_range_radix, 0, 65536 * sizeof(unsigned));
+    adaptive_range_radix_counter = 0;
+}
+
+// Burst measurement: we reached the end of a block, update our burst rate estimate
+static void adaptive_burst_end_of_block()
+{
+    if (!Modes.adaptive_burst_control)
+        return;
+
+    // scale rates based on the actual duty cycle fraction
+    //  (e.g. if we are only inspecting 2/5 of samples, then scale the rate by 5/2)
+    double scale = (double)adaptive_subblock_dutycycle_D / adaptive_subblock_dutycycle_N;
+
+    // maintain an EMA of the number of undecoded loud bursts seen per block
+    Modes.stats_current.adaptive_loud_undecoded += adaptive_burst_block_loud_undecoded;
+    adaptive_burst_loud_undecoded_smoothed = adaptive_burst_loud_undecoded_smoothed * (1 - Modes.adaptive_burst_alpha) + scale * adaptive_burst_block_loud_undecoded * Modes.adaptive_burst_alpha;
+    adaptive_burst_block_loud_undecoded = 0;
+
+    // maintain an EMA of the number of decoded, but loud, messages seen per block
+    Modes.stats_current.adaptive_loud_decoded += adaptive_burst_block_loud_decoded;
+    adaptive_burst_loud_decoded_smoothed = adaptive_burst_loud_decoded_smoothed * (1 - Modes.adaptive_burst_alpha) + scale * adaptive_burst_block_loud_decoded * Modes.adaptive_burst_alpha;
+    adaptive_burst_block_loud_decoded = 0;
+}
+
+
+void flush_stats(uint64_t now);
+
+static void adaptive_increase_gain(const char *why)
+{
+    if (adaptive_set_gain(sdrGetGain() + 1, why))
+        adaptive_gain_changed();
+}
+
+static void adaptive_decrease_gain(const char *why)
+{
+    if (adaptive_set_gain(sdrGetGain() - 1, why))
+        adaptive_gain_changed();
+}
+
+// Adaptive gain: we reached a block boundary. Update measurements and act on them.
+static void adaptive_end_of_block()
+{
+    adaptive_range_end_of_block();
+    adaptive_burst_end_of_block();
+
+    adaptive_control_update();
+
+    Modes.stats_current.adaptive_valid = true;
+    unsigned current = Modes.stats_current.adaptive_gain = sdrGetGain();
+    Modes.stats_current.adaptive_range_gain_limit = adaptive_range_gain_limit;
+    ++Modes.stats_current.adaptive_gain_seconds[current < STATS_GAIN_COUNT ? current : STATS_GAIN_COUNT-1];
+}
+
+static void adaptive_control_update()
+{
+    // votes for what to do with the gain
+    // "gain_not_up" overlaps somewhat with "gain_down", but they are not identical;
+    // burst control may want to prevent gain from increasing, but not necessarily
+    // decrease gain.
+
+    bool gain_up = false;
+    const char *gain_up_reason = NULL;
+    bool gain_down = false;
+    const char *gain_down_reason = NULL;
+    bool gain_not_up = false;
+
+    int current_gain = sdrGetGain();
+
+    if (adaptive_burst_change_timer)
+        --adaptive_burst_change_timer;
+    if (adaptive_range_change_timer > 0)
+        --adaptive_range_change_timer;
+    if (adaptive_range_rescan_timer > 0)
+        --adaptive_range_rescan_timer;
+
+    if (Modes.adaptive_burst_control && !adaptive_burst_change_timer) {
+        if (adaptive_burst_loud_undecoded_smoothed > Modes.adaptive_burst_loud_rate) {
+            adaptive_burst_quiet_blocks = 0;
+            ++adaptive_burst_loud_blocks;
+        } else if (adaptive_burst_loud_decoded_smoothed < Modes.adaptive_burst_quiet_rate) {
+            adaptive_burst_loud_blocks = 0;
+            ++adaptive_burst_quiet_blocks;
+        } else {
+            adaptive_burst_loud_blocks = 0;
+            adaptive_burst_quiet_blocks = 0;
+        }
+
+        if (adaptive_burst_loud_blocks >= Modes.adaptive_burst_loud_runlength) {
+            // we need to reduce gain (further)
+            gain_down = gain_not_up = true;
+            gain_down_reason = "high rate of loud undecoded messages";
+
+            // if we're currently doing a downward scan, reducing gain further may confuse it;
+            // stop that scan and restart it once we are no longer in a reduced-gain state
+            if (adaptive_range_state == RANGE_SCAN_DOWN || adaptive_range_state == RANGE_RESCAN_DOWN) {
+                adaptive_range_state = RANGE_SCAN_IDLE;
+                adaptive_range_rescan_timer = 0;
+            }
+        } else if (adaptive_burst_quiet_blocks < Modes.adaptive_burst_quiet_runlength) {
+            // we're OK at the current gain, but should not increase it
+            gain_not_up = true;
+        } else if (current_gain < adaptive_range_gain_limit) {
+            // we're OK at the current gain, and can increase gain to the previously discovered
+            // dynamic range limit
+            gain_up = true;
+            gain_up_reason = "low loud message rate and gain below dynamic range limit";
+        }
+    }
+
+    if (Modes.adaptive_range_control && !adaptive_range_change_timer) {
+        float available_range = -20 * log10(adaptive_range_smoothed / 65536.0);
+        // allow the gain limit to increase if this gain setting is acceptable
+        // (decreasing the limit is done separately depending on the current state as we make slightly different decisions in IDLE
+        // to provide hysteresis)
+        if (available_range >= Modes.adaptive_range_target && current_gain > adaptive_range_gain_limit) {
+            adaptive_range_gain_limit = current_gain;
+        }
+        switch (adaptive_range_state) {
+        case RANGE_SCAN_UP:
+        case RANGE_RESCAN_UP:
+            if (available_range < Modes.adaptive_range_target) {
+                // Current gain fails to meet our target. Switch to downward scanning.
+                fprintf(stderr, "adaptive: available dynamic range (%.1fdB) < required dynamic range (%.1fdB), switching to downward scan\n", available_range, Modes.adaptive_range_target);
+                gain_down = gain_not_up = true;
+                gain_down_reason = "probing dynamic range gain lower bound";
+                adaptive_range_state = (adaptive_range_state == RANGE_RESCAN_UP ? RANGE_RESCAN_DOWN : RANGE_SCAN_DOWN);
+                if (adaptive_range_gain_limit >= current_gain) {
+                    adaptive_range_gain_limit = current_gain - 1;
+                }
+                break;
+            }
+
+            if (sdrGetGain() >= adaptive_gain_max) {
+                // We have reached our upper gain limit
+                fprintf(stderr, "adaptive: reached upper gain limit, halting dynamic range scan here\n");
+                adaptive_range_state = RANGE_SCAN_IDLE;
+                adaptive_range_rescan_timer = Modes.adaptive_range_rescan_delay;
+                break;
+            }
+
+            // This gain step is OK and we have more to try, try the next gain step up.
+            // (But if burst detection has inhibited increasing gain, don't do anything yet, just try again next block)
+            if (!gain_not_up) {
+                fprintf(stderr, "adaptive: available dynamic range (%.1fdB) >= required dynamic range (%.1fdB), continuing upward scan\n", available_range, Modes.adaptive_range_target);
+                gain_up = true;
+                gain_up_reason = "probing dynamic range gain upper bound";
+            }
+            break;
+
+        case RANGE_SCAN_DOWN:
+        case RANGE_RESCAN_DOWN:
+            if (available_range >= Modes.adaptive_range_target) {
+                // Current gain meets our target; we are done with the scan.
+                fprintf(stderr, "adaptive: available dynamic range (%.1fdB) >= required dynamic range (%.1fdB), stopping downwards scan here\n", available_range, Modes.adaptive_range_target);
+                adaptive_range_state = RANGE_SCAN_IDLE;
+                adaptive_range_rescan_timer = (adaptive_range_state == RANGE_SCAN_DOWN ? Modes.adaptive_range_scan_delay : Modes.adaptive_range_rescan_delay);
+                break;
+            }
+
+            if (adaptive_range_gain_limit >= current_gain) {
+                adaptive_range_gain_limit = current_gain - 1;
+            }
+
+            if (sdrGetGain() <= adaptive_gain_min) {
+                fprintf(stderr, "adaptive: reached lower gain limit, halting dynamic range scan here\n");
+                adaptive_range_state = RANGE_SCAN_IDLE;
+                adaptive_range_rescan_timer = Modes.adaptive_range_rescan_delay;
+                break;
+            }
+
+            // This gain step is too loud and we have more to try, try the next gain step down
+            fprintf(stderr, "adaptive: available dynamic range (%.1fdB) < required dynamic range (%.1fdB), continuing downwards scan\n", available_range, Modes.adaptive_range_target);
+            gain_down = gain_not_up = true;
+            gain_down_reason = "probing dynamic range gain lower bound";
+            break;
+
+        case RANGE_SCAN_IDLE:
+            // Look for increased noise that could be compensated for by decreasing gain.
+            // Do this even if we're waiting to rescan or if burst control is also active
+            if (available_range + adaptive_gain_down_db / 2 < Modes.adaptive_range_target && sdrGetGain() > adaptive_gain_min) {
+                fprintf(stderr, "adaptive: available dynamic range (%.1fdB) + half gain step down (%.1fdB) < required dynamic range (%.1fdB), starting downward scan\n",
+                        available_range, Modes.adaptive_range_target, adaptive_gain_down_db);
+                if (adaptive_range_gain_limit >= current_gain) {
+                    adaptive_range_gain_limit = current_gain - 1;
+                }
+                adaptive_range_state = RANGE_SCAN_DOWN;
+                gain_down = gain_not_up = true;
+                gain_down_reason = "dynamic range fell below target value";
+                break;
+            }
+
+            // Infrequently consider increasing gain to handle the case where we've selected a too-low gain where the noise floor is dominated by noise unrelated to the gain setting.
+            // But don't do this while burst control is preventing gain increases.
+            if (!adaptive_range_rescan_timer && !gain_not_up) {
+                if (available_range >= Modes.adaptive_range_target && sdrGetGain() < adaptive_gain_max) {
+                    fprintf(stderr, "adaptive: start periodic scan for acceptable dynamic range at increased gain\n");
+                    gain_up = true;
+                    gain_up_reason = "periodic re-probing of dynamic range gain upper bound";
+                    adaptive_range_state = RANGE_RESCAN_UP;
+                    break;
+                }
+
+                // Nothing to do for a while.
+                adaptive_range_rescan_timer = Modes.adaptive_range_rescan_delay;
+            }
+
+            break;
+
+        default:
+            fprintf(stderr, "adaptive: in a weird state (%d), trying to fix it\n", adaptive_range_state);
+            adaptive_range_state = RANGE_SCAN_IDLE;
+            adaptive_range_rescan_timer = Modes.adaptive_range_rescan_delay;
+            break;
+        }
+    }
+
+    // now actually perform any gain changes
+
+    if (gain_down)
+        adaptive_decrease_gain(gain_down_reason);
+    else if (gain_up && !gain_not_up)
+        adaptive_increase_gain(gain_up_reason);
+}

adaptive.h

@@ -0,0 +1,30 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// adaptive.h: adaptive gain control prototypes
+//
+// Copyright (c) 2021 FlightAware, LLC
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef ADAPTIVE_H
+#define ADAPTIVE_H
+
+#include <inttypes.h>
+
+struct modesMessage;
+
+void adaptive_init();
+void adaptive_update(uint16_t *buf, unsigned length, struct modesMessage *decoded);
+
+#endif

ais_charset.c

@@ -0,0 +1,3 @@
+#include "ais_charset.h"
+
+char ais_charset[64] = "@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_ !\"#$%&'()*+,-./0123456789:;<=>?";

ais_charset.h

@@ -0,0 +1,6 @@
+#ifndef AIS_CHARSET_H
+#define AIS_CHARSET_H
+
+extern char ais_charset[64];
+
+#endif

anet.c

@@ -1,3 +1,26 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// anet.c: Basic TCP socket stuff made a bit less boring
+//
+// Copyright (c) 2016 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// This file incorporates work covered by the following copyright and
+// permission notice:
+//
+
 /* anet.c -- Basic TCP socket stuff made a bit less boring
  *
  * Copyright (c) 2006-2012, Salvatore Sanfilippo <antirez at gmail dot com>
@@ -28,25 +51,20 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef _WIN32
-  #include <sys/types.h>
-  #include <sys/socket.h>
-  #include <sys/stat.h>
-  #include <sys/un.h>
-  #include <netinet/in.h>
-  #include <netinet/tcp.h>
-  #include <arpa/inet.h>
-  #include <unistd.h>
-  #include <fcntl.h>
-  #include <string.h>
-  #include <netdb.h>
-  #include <errno.h>
-  #include <stdarg.h>
-  #include <stdio.h>
-#else
-  #include "winstubs.h" //Put everything Windows specific in here
-  #include "dump1090.h"
-#endif
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/un.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <netdb.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
 
 #include "anet.h"
 
@@ -63,7 +81,7 @@ static void anetSetError(char *err, const char *fmt, ...)
 int anetNonBlock(char *err, int fd)
 {
     int flags;
-#ifndef _WIN32
+
     /* Set the socket nonblocking.
      * Note that fcntl(2) for F_GETFL and F_SETFL can't be
      * interrupted by a signal. */
@@ -75,14 +93,7 @@ int anetNonBlock(char *err, int fd)
         anetSetError(err, "fcntl(F_SETFL,O_NONBLOCK): %s", strerror(errno));
         return ANET_ERR;
     }
-#else
-    flags = 1;
-    if (ioctlsocket(fd, FIONBIO, &flags)) {
-        errno = WSAGetLastError();
-        anetSetError(err, "ioctlsocket(FIONBIO): %s", strerror(errno));
-        return ANET_ERR;
-    }
-#endif
+
     return ANET_OK;
 }
 
@@ -117,31 +128,10 @@ int anetTcpKeepAlive(char *err, int fd)
     return ANET_OK;
 }
 
-int anetResolve(char *err, char *host, char *ipbuf)
+static int anetCreateSocket(char *err, int domain)
 {
-    struct sockaddr_in sa;
-
-    sa.sin_family = AF_INET;
-    if (inet_aton(host, (void*)&sa.sin_addr) == 0) {
-        struct hostent *he;
-
-        he = gethostbyname(host);
-        if (he == NULL) {
-            anetSetError(err, "can't resolve: %s", host);
-            return ANET_ERR;
-        }
-        memcpy(&sa.sin_addr, he->h_addr, sizeof(struct in_addr));
-    }
-    strcpy(ipbuf,inet_ntoa(sa.sin_addr));
-    return ANET_OK;
-}
-
-static int anetCreateSocket(char *err, int domain) {
     int s, on = 1;
     if ((s = socket(domain, SOCK_STREAM, 0)) == -1) {
-#ifdef _WIN32
-        errno = WSAGetLastError();
-#endif
         anetSetError(err, "creating socket: %s", strerror(errno));
         return ANET_ERR;
     }
@@ -157,52 +147,63 @@ static int anetCreateSocket(char *err, int domain) {
 
 #define ANET_CONNECT_NONE 0
 #define ANET_CONNECT_NONBLOCK 1
-static int anetTcpGenericConnect(char *err, char *addr, int port, int flags)
+static int anetTcpGenericConnect(char *err, char *addr, char *service, int flags)
 {
     int s;
-    struct sockaddr_in sa;
+    struct addrinfo gai_hints;
+    struct addrinfo *gai_result, *p;
+    int gai_error;
 
-    if ((s = anetCreateSocket(err,AF_INET)) == ANET_ERR)
+    gai_hints.ai_family = AF_UNSPEC;
+    gai_hints.ai_socktype = SOCK_STREAM;
+    gai_hints.ai_protocol = 0;
+    gai_hints.ai_flags = 0;
+    gai_hints.ai_addrlen = 0;
+    gai_hints.ai_addr = NULL;
+    gai_hints.ai_canonname = NULL;
+    gai_hints.ai_next = NULL;
+
+    gai_error = getaddrinfo(addr, service, &gai_hints, &gai_result);
+    if (gai_error != 0) {
+        anetSetError(err, "can't resolve %s: %s", addr, gai_strerror(gai_error));
         return ANET_ERR;
+    }
 
-    memset(&sa,0,sizeof(sa));
-    sa.sin_family = AF_INET;
-    sa.sin_port = htons((uint16_t)port);
-    if (inet_aton(addr, (void*)&sa.sin_addr) == 0) {
-        struct hostent *he;
+    for (p = gai_result; p != NULL; p = p->ai_next) {
+        if ((s = anetCreateSocket(err, p->ai_family)) == ANET_ERR)
+            continue;
 
-        he = gethostbyname(addr);
-        if (he == NULL) {
-            anetSetError(err, "can't resolve: %s", addr);
-            close(s);
-            return ANET_ERR;
+        if (flags & ANET_CONNECT_NONBLOCK) {
+            if (anetNonBlock(err,s) != ANET_OK)
+                return ANET_ERR;
         }
-        memcpy(&sa.sin_addr, he->h_addr, sizeof(struct in_addr));
-    }
-    if (flags & ANET_CONNECT_NONBLOCK) {
-        if (anetNonBlock(err,s) != ANET_OK)
-            return ANET_ERR;
-    }
-    if (connect(s, (struct sockaddr*)&sa, sizeof(sa)) == -1) {
-        if (errno == EINPROGRESS &&
-            flags & ANET_CONNECT_NONBLOCK)
+
+        if (connect(s, p->ai_addr, p->ai_addrlen) >= 0) {
+            freeaddrinfo(gai_result);
             return s;
+        }
+
+        if (errno == EINPROGRESS && (flags & ANET_CONNECT_NONBLOCK)) {
+            freeaddrinfo(gai_result);
+            return s;
+        }
 
         anetSetError(err, "connect: %s", strerror(errno));
         close(s);
-        return ANET_ERR;
     }
-    return s;
+
+    freeaddrinfo(gai_result);
+    return ANET_ERR;
 }
 
-int anetTcpConnect(char *err, char *addr, int port)
+int anetTcpConnect(char *err, char *addr, char *service)
 {
-    return anetTcpGenericConnect(err,addr,port,ANET_CONNECT_NONE);
+    return anetTcpGenericConnect(err,addr,service,ANET_CONNECT_NONE);
 }
 
-int anetTcpNonBlockConnect(char *err, char *addr, int port)
+int anetTcpNonBlockConnect(char *err, char *addr, char *service)
 {
-    return anetTcpGenericConnect(err,addr,port,ANET_CONNECT_NONBLOCK);
+    return anetTcpGenericConnect(err,addr,service,ANET_CONNECT_NONBLOCK);
 }
 
 /* Like read(2) but make sure 'count' is read before to return
@@ -236,10 +237,12 @@ int anetWrite(int fd, char *buf, int count)
 }
 
 static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len) {
+    if (sa->sa_family == AF_INET6) {
+        int on = 1;
+        setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on));
+    }
+
     if (bind(s,sa,len) == -1) {
-#ifdef _WIN32
-        errno = WSAGetLastError();
-#endif
         anetSetError(err, "bind: %s", strerror(errno));
         close(s);
         return ANET_ERR;
@@ -249,9 +252,6 @@ static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len) {
      * the kernel does: backlogsize = roundup_pow_of_two(backlogsize + 1);
      * which will thus give us a backlog of 512 entries */
     if (listen(s, 511) == -1) {
-#ifdef _WIN32
-        errno = WSAGetLastError();
-#endif
         anetSetError(err, "listen: %s", strerror(errno));
         close(s);
         return ANET_ERR;
@@ -259,40 +259,52 @@ static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len) {
     return ANET_OK;
 }
 
-int anetTcpServer(char *err, int port, char *bindaddr)
+int anetTcpServer(char *err, char *service, char *bindaddr, int *fds, int nfds)
 {
     int s;
-    struct sockaddr_in sa;
+    int i = 0;
+    struct addrinfo gai_hints;
+    struct addrinfo *gai_result, *p;
+    int gai_error;
 
-    if ((s = anetCreateSocket(err,AF_INET)) == ANET_ERR)
-        return ANET_ERR;
+    gai_hints.ai_family = AF_UNSPEC;
+    gai_hints.ai_socktype = SOCK_STREAM;
+    gai_hints.ai_protocol = 0;
+    gai_hints.ai_flags = AI_PASSIVE;
+    gai_hints.ai_addrlen = 0;
+    gai_hints.ai_addr = NULL;
+    gai_hints.ai_canonname = NULL;
+    gai_hints.ai_next = NULL;
 
-    memset(&sa,0,sizeof(sa));
-    sa.sin_family = AF_INET;
-    sa.sin_port = htons((uint16_t)port);
-    sa.sin_addr.s_addr = htonl(INADDR_ANY);
-    if (bindaddr && inet_aton(bindaddr, (void*)&sa.sin_addr) == 0) {
-        anetSetError(err, "invalid bind address");
-        close(s);
+    gai_error = getaddrinfo(bindaddr, service, &gai_hints, &gai_result);
+    if (gai_error != 0) {
+        anetSetError(err, "can't resolve %s: %s", bindaddr, gai_strerror(gai_error));
         return ANET_ERR;
     }
-    if (anetListen(err,s,(struct sockaddr*)&sa,sizeof(sa)) == ANET_ERR)
-        return ANET_ERR;
-    return s;
+
+    for (p = gai_result; p != NULL && i < nfds; p = p->ai_next) {
+        if ((s = anetCreateSocket(err, p->ai_family)) == ANET_ERR)
+            continue;
+
+        if (anetListen(err, s, p->ai_addr, p->ai_addrlen) == ANET_ERR) {
+            continue;
+        }
+
+        fds[i++] = s;
+    }
+
+    freeaddrinfo(gai_result);
+    return (i > 0 ? i : ANET_ERR);
 }
 
-static int anetGenericAccept(char *err, int s, struct sockaddr *sa, socklen_t *len) {
+static int anetGenericAccept(char *err, int s, struct sockaddr *sa, socklen_t *len)
+{
     int fd;
     while(1) {
         fd = accept(s,sa,len);
         if (fd == -1) {
-#ifndef _WIN32
             if (errno == EINTR) {
                 continue;
-#else
-            errno = WSAGetLastError();
-            if (errno == WSAEWOULDBLOCK) {
-#endif
             } else {
                 anetSetError(err, "accept: %s", strerror(errno));
             }
@@ -302,44 +314,13 @@ static int anetGenericAccept(char *err, int s, struct sockaddr *sa, socklen_t *l
     return fd;
 }
 
-int anetTcpAccept(char *err, int s, char *ip, int *port) {
+int anetTcpAccept(char *err, int s) {
     int fd;
-    struct sockaddr_in sa;
-    socklen_t salen = sizeof(sa);
-    if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == ANET_ERR)
+    struct sockaddr_storage ss;
+    socklen_t sslen = sizeof(ss);
+
+    if ((fd = anetGenericAccept(err, s, (struct sockaddr*)&ss, &sslen)) == ANET_ERR)
         return ANET_ERR;
 
-    if (ip) strcpy(ip,inet_ntoa(sa.sin_addr));
-    if (port) *port = ntohs(sa.sin_port);
     return fd;
 }
-
-int anetPeerToString(int fd, char *ip, int *port) {
-    struct sockaddr_in sa;
-    socklen_t salen = sizeof(sa);
-
-    if (getpeername(fd,(struct sockaddr*)&sa,&salen) == -1) {
-        *port = 0;
-        ip[0] = '?';
-        ip[1] = '\0';
-        return -1;
-    }
-    if (ip) strcpy(ip,inet_ntoa(sa.sin_addr));
-    if (port) *port = ntohs(sa.sin_port);
-    return 0;
-}
-
-int anetSockName(int fd, char *ip, int *port) {
-    struct sockaddr_in sa;
-    socklen_t salen = sizeof(sa);
-
-    if (getsockname(fd,(struct sockaddr*)&sa,&salen) == -1) {
-        *port = 0;
-        ip[0] = '?';
-        ip[1] = '\0';
-        return -1;
-    }
-    if (ip) strcpy(ip,inet_ntoa(sa.sin_addr));
-    if (port) *port = ntohs(sa.sin_port);
-    return 0;
-}

anet.h

@@ -1,3 +1,26 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// anet.h: Basic TCP socket stuff made a bit less boring
+//
+// Copyright (c) 2016 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// This file incorporates work covered by the following copyright and
+// permission notice:
+//
+
 /* anet.c -- Basic TCP socket stuff made a bit less boring
  *
  * Copyright (c) 2006-2012, Salvatore Sanfilippo <antirez at gmail dot com>
@@ -39,21 +62,15 @@
 #define AF_LOCAL AF_UNIX
 #endif
 
-int anetTcpConnect(char *err, char *addr, int port);
-int anetTcpNonBlockConnect(char *err, char *addr, int port);
-int anetUnixConnect(char *err, char *path);
-int anetUnixNonBlockConnect(char *err, char *path);
+int anetTcpConnect(char *err, char *addr, char *service);
+int anetTcpNonBlockConnect(char *err, char *addr, char *service);
 int anetRead(int fd, char *buf, int count);
-int anetResolve(char *err, char *host, char *ipbuf);
-int anetTcpServer(char *err, int port, char *bindaddr);
-int anetUnixServer(char *err, char *path, mode_t perm);
-int anetTcpAccept(char *err, int serversock, char *ip, int *port);
-int anetUnixAccept(char *err, int serversock);
+int anetTcpServer(char *err, char *service, char *bindaddr, int *fds, int nfds);
+int anetTcpAccept(char *err, int serversock);
 int anetWrite(int fd, char *buf, int count);
 int anetNonBlock(char *err, int fd);
 int anetTcpNoDelay(char *err, int fd);
 int anetTcpKeepAlive(char *err, int fd);
-int anetPeerToString(int fd, char *ip, int *port);
 int anetSetSendBuffer(char *err, int fd, int buffsize);
 
 #endif

bladerf/README

@@ -0,0 +1,43 @@
+bladeRF support
+---------------
+
+There is basic support for the bladeRF included in dump1090-fa.
+It uses the same demodulator as the regular rtlsdr version and it does not
+take advantage of the bladeRF's improved sampling rate or FPGA (but see below)
+
+To use it:
+
+$ dump1090-fa --device-type bladerf --gain 66 (.. other options ..)
+
+The bladeRF has sensitivity problems when receiving ADS-B and will benefit
+from all the gain you can give it. 66dB is the maximum configurable gain on
+the board itself, you may want to add an external LNA too.
+
+
+bladeRF custom FPGA bitstream
+-----------------------------
+
+The package includes a custom FPGA bitstream for the bladeRF which can
+improve ADS-B reception with dump1090.
+
+It adds a Fs/4 mixer step to avoid the DC offset of the bladeRF, and
+decimate-by-8 downsampling step to improve sensitivity. Some of the bladeRF
+parameters need to be adjusted so that it produces correctly tuned/downsampled
+data in the form that dump1090 is expecting.
+
+To use it:
+
+$ dump1090-fa --device-type bladerf --gain 66 \
+   --bladerf-fpga /usr/share/dump1090-fa/bladerf/decimate8-x40.rbf \
+   --bladerf-decimation 8 \
+   --bladerf-bandwidth 14000000 \
+   --freq 1085200000 \
+   (other options ...)
+
+The bladeRF will be configured for a 19.2MHz sampling rate and will tune to
+1085.2MHz so that the 1090MHz signal appears around 4.8MHz in the baseband
+samples. The FPGA Fs/4 mixing step shifts the baseband signal so that it is centered
+around 0, and the FPGA downsampling step produces samples at 2.4MHz, which is what
+dump1090 is expecting.
+
+This FPGA bitstream is built for the 40kLE bladeRF.

coaa.h

@@ -1,6 +0,0 @@
-// coaa.h configuration file for Plane Plotter Uploader
-//
-// You MUST apply via the COAA website for your own personal version of this file
-// Do not disclose the contents of this file to anyone thereafter as it uniquely
-// identifies you to the PlanePlotter system 
-//

comm_b.c

@@ -0,0 +1,985 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// comm_b.c: Comm-B message decoding
+//
+// Copyright (c) 2017 FlightAware, LLC
+// Copyright (c) 2017 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "dump1090.h"
+#include "ais_charset.h"
+
+typedef int (*CommBDecoderFn)(struct modesMessage *,bool);
+
+static int decodeEmptyResponse(struct modesMessage *mm, bool store);
+static int decodeBDS10(struct modesMessage *mm, bool store);
+static int decodeBDS17(struct modesMessage *mm, bool store);
+static int decodeBDS20(struct modesMessage *mm, bool store);
+static int decodeBDS30(struct modesMessage *mm, bool store);
+static int decodeBDS40(struct modesMessage *mm, bool store);
+static int decodeBDS44(struct modesMessage *mm, bool store);
+static int decodeBDS50(struct modesMessage *mm, bool store);
+static int decodeBDS60(struct modesMessage *mm, bool store);
+static int decodeBDS05(struct modesMessage *mm, bool store);
+
+static CommBDecoderFn comm_b_decoders[] = {
+    &decodeEmptyResponse,
+    &decodeBDS10,
+    &decodeBDS20,
+    &decodeBDS30,
+    &decodeBDS17,
+    &decodeBDS40,
+    &decodeBDS50,
+    &decodeBDS60,
+    &decodeBDS44,
+    &decodeBDS05
+};
+
+void decodeCommB(struct modesMessage *mm)
+{
+    // If DR or UM are set, this message is _probably_ noise
+    // as nothing really seems to use the multisite broadcast stuff?
+    // Also skip anything that had errors corrected
+    if (mm->DR != 0 || mm->UM != 0 || mm->correctedbits > 0) {
+        mm->commb_format = COMMB_NOT_DECODED;
+        return;
+    }
+
+    // This is a bit hairy as we don't know what the requested register was
+    int bestScore = 0;
+    CommBDecoderFn bestDecoder = NULL;
+    int ambiguous = 0;
+
+    for (unsigned i = 0; i < (sizeof(comm_b_decoders) / sizeof(comm_b_decoders[0])); ++i) {
+        int score = comm_b_decoders[i](mm, false);
+        if (score > bestScore) {
+            bestScore = score;
+            bestDecoder = comm_b_decoders[i];
+            ambiguous = 0;
+        } else if (score == bestScore) {
+            ambiguous = 1;
+        }
+    }
+
+    if (bestDecoder) {
+        if (ambiguous) {
+            mm->commb_format = COMMB_AMBIGUOUS;
+        } else {
+            // decode it
+            bestDecoder(mm, true);
+        }
+    } else {
+        mm->commb_format = COMMB_UNKNOWN;
+    }
+}
+
+static int decodeEmptyResponse(struct modesMessage *mm, bool store)
+{
+    // 00000000000000 is a common response. Ignore it.
+    //
+    // Also, it's common to see responses that look like this:
+    //    40000000000000
+    //    50000000000000
+    //    60000000000000
+    // typically in grouped bursts (one of each message) from
+    // the same aircraft.
+    //
+    // I speculate that these are response to interrogations for
+    // BDS 4,0 5,0 and 6,0 respectively where the transponder
+    // doesn't support the register or has no data loaded for it.
+    // Treat them like empty responses.
+
+    switch (mm->MB[0]) {
+    case 0x00:
+    case 0x40:
+    case 0x50:
+    case 0x60:
+        break;
+
+    default:
+        return 0;
+    }
+
+    for (unsigned i = 1; i < 7; ++i) {
+        if (mm->MB[i] != 0) {
+            return 0;
+        }
+    }
+
+    if (store) {
+        mm->commb_format = COMMB_EMPTY_RESPONSE;
+    }
+
+    return 56;
+}
+
+// BDS1,0 Datalink capabilities
+static int decodeBDS10(struct modesMessage *mm, bool store)
+{
+    unsigned char *msg = mm->MB;
+
+    // BDS identifier
+    if (msg[0] != 0x10) {
+        return 0;
+    }
+
+    // Reserved bits
+    if (getbits(msg, 10, 14) != 0) {
+        return 0;
+    }
+
+    // Looks plausible.
+
+    if (store) {
+        mm->commb_format = COMMB_DATALINK_CAPS;
+    }
+
+    return 56;
+}
+
+// BDS1,7 Common usage GICB capability report
+static int decodeBDS17(struct modesMessage *mm, bool store)
+{
+    unsigned char *msg = mm->MB;
+
+    // reserved bits
+    if (getbits(msg, 25, 56) != 0) {
+        return 0;
+    }
+
+    int score = 0;
+    if (getbit(msg, 7)) {
+        score += 1;  // 2,0 aircraft identification
+    } else {
+        // BDS2,0 is on almost everything
+        score -= 2;
+    }
+
+    // unlikely bits
+    if (getbit(msg, 10)) { // 4,1 next waypoint identifier
+        score -= 2;
+    }
+    if (getbit(msg, 11)) { // 4,2 next waypoint position
+        score -= 2;
+    }
+    if (getbit(msg, 12)) { // 4,3 next waypoint information
+        score -= 2;
+    }
+    if (getbit(msg, 13)) { // 4,4 meterological routine report
+        score -= 1;
+    }
+    if (getbit(msg, 14)) { // 4,4 meterological hazard report
+        score -= 1;
+    }
+    if (getbit(msg, 20)) { // 5,4 waypoint 1
+        score -= 2;
+    }
+    if (getbit(msg, 21)) { // 5,5 waypoint 2
+        score -= 2;
+    }
+    if (getbit(msg, 22)) { // 5,6 waypoint 3
+        score -= 2;
+    }
+
+    if (getbit(msg, 1) && getbit(msg, 2) && getbit(msg, 3) && getbit(msg, 4) && getbit(msg, 5)) {
+        // looks like ES capable
+        score += 5;
+        if (getbit(msg, 6)) {
+            // ES EDI
+            score += 1;
+        }
+    } else if (!getbit(msg, 1) && !getbit(msg, 2) && !getbit(msg, 3) && !getbit(msg, 4) && !getbit(msg, 5) && !getbit(msg, 6)) {
+        // not ES capable
+        score += 1;
+    } else if (!getbit(msg, 1) && !getbit(msg, 2) && getbit(msg, 3) && getbit(msg, 4) && getbit(msg, 5)) {
+        // ES with no position data
+        score += 3;
+    } else {
+        // other combinations, unlikely
+        score -= 12;
+    }
+
+    if (getbit(msg, 16) && getbit(msg, 24)) {
+        // track/turn, heading/speed
+        score += 2;
+        if (getbit(msg, 9)) {
+            // vertical intent
+            score += 1;
+        }
+    } else if (!getbit(msg, 16) && !getbit(msg, 24) && !getbit(msg, 9)) {
+        // neither
+        score += 1;
+    } else {
+        // unlikely
+        score -= 6;
+    }
+
+    if (store) {
+        mm->commb_format = COMMB_GICB_CAPS;
+    }
+
+    return score;
+}
+
+// BDS2,0 Aircraft identification
+static int decodeBDS20(struct modesMessage *mm, bool store)
+{
+    char callsign[9];
+    unsigned char *msg = mm->MB;
+
+    // BDS identifier
+    if (msg[0] != 0x20) {
+        return 0;
+    }
+
+    callsign[0] = ais_charset[getbits(msg, 9, 14)];
+    callsign[1] = ais_charset[getbits(msg, 15, 20)];
+    callsign[2] = ais_charset[getbits(msg, 21, 26)];
+    callsign[3] = ais_charset[getbits(msg, 27, 32)];
+    callsign[4] = ais_charset[getbits(msg, 33, 38)];
+    callsign[5] = ais_charset[getbits(msg, 39, 44)];
+    callsign[6] = ais_charset[getbits(msg, 45, 50)];
+    callsign[7] = ais_charset[getbits(msg, 51, 56)];
+    callsign[8] = 0;
+
+    // score based on number of valid characters
+    int score = 8;
+    int valid = 1;
+    for (unsigned i = 0; i < 8; ++i) {
+        if ((callsign[i] >= 'A' && callsign[i] <= 'Z') || (callsign[i] >= '0' && callsign[i] <= '9') || callsign[i] == ' ') {
+            score += 6;
+        } else if (callsign[i] == '@') {
+            // Padding (sometimes we get @@@@@@@@, i.e. BDS2,0 with all zeros - we do want to accept this as a BDS2,0 but not actually use the callsign)
+            valid = 0;
+        } else {
+            // Invalid
+            return 0;
+        }
+    }
+
+    if (store) {
+        mm->commb_format = COMMB_AIRCRAFT_IDENT;
+        if (valid) {
+            memcpy(mm->callsign, callsign, sizeof(mm->callsign));
+            mm->callsign_valid = 1;
+        }
+    }
+
+    return score;
+}
+
+// BDS3,0 ACAS RA
+static int decodeBDS30(struct modesMessage *mm, bool store)
+{
+    unsigned char *msg = mm->MB;
+
+    // BDS identifier
+    if (msg[0] != 0x30) {
+        return 0;
+    }
+
+    if (store) {
+        mm->commb_format = COMMB_ACAS_RA;
+    }
+
+    // just accept it.
+    return 56;
+}
+
+// BDS4,0 Selected vertical intention
+static int decodeBDS40(struct modesMessage *mm, bool store)
+{
+    unsigned char *msg = mm->MB;
+
+    unsigned mcp_valid = getbit(msg, 1);
+    unsigned mcp_raw = getbits(msg, 2, 13);
+    unsigned fms_valid = getbit(msg, 14);
+    unsigned fms_raw = getbits(msg, 15, 26);
+    unsigned baro_valid = getbit(msg, 27);
+    unsigned baro_raw = getbits(msg, 28, 39);
+    unsigned reserved_1 = getbits(msg, 40, 47);
+    unsigned mode_valid = getbit(msg, 48);
+    unsigned mode_raw = getbits(msg, 49, 51);
+    unsigned reserved_2 = getbits(msg, 52, 53);
+    unsigned source_valid = getbit(msg, 54);
+    unsigned source_raw = getbits(msg, 55, 56);
+
+    if (!mcp_valid && !fms_valid && !baro_valid && !mode_valid && !source_valid) {
+        return 0;
+    }
+
+    int score = 0;
+
+    unsigned mcp_alt = 0;
+    if (mcp_valid && mcp_raw != 0) {
+        mcp_alt = mcp_raw * 16;
+        if (mcp_alt >= 1000 && mcp_alt <= 50000) {
+            score += 13;
+        } else {
+            // unlikely altitude
+            return 0;
+        }
+    } else if (!mcp_valid && mcp_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    unsigned fms_alt = 0;
+    if (fms_valid && fms_raw != 0) {
+        fms_alt = fms_raw * 16;
+        if (fms_alt >= 1000 && fms_alt <= 50000) {
+            score += 13;
+        } else {
+            // unlikely altitude
+            return 0;
+        }
+    } else if (!fms_valid && fms_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    float baro_setting = 0;
+    if (baro_valid && baro_raw != 0) {
+        baro_setting = 800 + baro_raw * 0.1;
+        if (baro_setting >= 900 && baro_setting <= 1100) {
+            score += 13;
+        } else {
+            // unlikely pressure setting
+            return 0;
+        }
+    } else if (!baro_valid && baro_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    if (reserved_1 != 0) {
+        return 0;
+    }
+
+    if (mode_valid) {
+        score += 4;
+    } else if (!mode_valid && mode_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    if (reserved_2 != 0) {
+        return 0;
+    }
+
+    if (source_valid) {
+        score += 3;
+    } else if (!source_valid && source_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    // small penalty for inconsistent data
+    if (mcp_valid && fms_valid && mcp_alt != fms_alt) {
+        score -= 4;
+    }
+
+    if (mcp_valid) {
+        unsigned remainder = mcp_alt % 500;
+        if (!(remainder < 16 || remainder > 484)) {
+            // mcp altitude is not a multiple of 500
+            score -= 4;
+        }
+    }
+
+    if (fms_valid) {
+        unsigned remainder = fms_alt % 500;
+        if (!(remainder < 16 || remainder > 484)) {
+            // fms altitude is not a multiple of 500
+            score -= 4;
+        }
+    }
+
+    if (store) {
+        mm->commb_format = COMMB_VERTICAL_INTENT;
+
+        if (mcp_valid) {
+            mm->nav.mcp_altitude_valid = 1;
+            mm->nav.mcp_altitude = mcp_alt;
+        }
+
+        if (fms_valid) {
+            mm->nav.fms_altitude_valid = 1;
+            mm->nav.fms_altitude = fms_alt;
+        }
+
+        if (baro_valid) {
+            mm->nav.qnh_valid = 1;
+            mm->nav.qnh = baro_setting;
+        }
+
+        if (mode_valid) {
+            mm->nav.modes_valid = 1;
+            mm->nav.modes =
+                ((mode_raw & 4) ? NAV_MODE_VNAV : 0) |
+                ((mode_raw & 2) ? NAV_MODE_ALT_HOLD : 0) |
+                ((mode_raw & 1) ? NAV_MODE_APPROACH : 0);
+        }
+
+        if (source_valid) {
+            switch (source_raw) {
+            case 0:
+                mm->nav.altitude_source = NAV_ALT_UNKNOWN;
+                break;
+            case 1:
+                mm->nav.altitude_source = NAV_ALT_AIRCRAFT;
+                break;
+            case 2:
+                mm->nav.altitude_source = NAV_ALT_MCP;
+                break;
+            case 3:
+                mm->nav.altitude_source = NAV_ALT_FMS;
+                break;
+            default:
+                mm->nav.altitude_source = NAV_ALT_INVALID;
+                break;
+            }
+        } else {
+            mm->nav.altitude_source = NAV_ALT_INVALID;
+        }
+    }
+
+    return score;
+}
+
+// BDS5,0 Track and turn report
+static int decodeBDS50(struct modesMessage *mm, bool store)
+{
+    unsigned char *msg = mm->MB;
+
+    unsigned roll_valid = getbit(msg, 1);
+    unsigned roll_sign = getbit(msg, 2);
+    unsigned roll_raw = getbits(msg, 3, 11);
+
+    unsigned track_valid = getbit(msg, 12);
+    unsigned track_sign = getbit(msg, 13);
+    unsigned track_raw = getbits(msg, 14, 23);
+
+    unsigned gs_valid = getbit(msg, 24);
+    unsigned gs_raw = getbits(msg, 25, 34);
+
+    unsigned track_rate_valid = getbit(msg, 35);
+    unsigned track_rate_sign = getbit(msg, 36);
+    unsigned track_rate_raw = getbits(msg, 37, 45);
+
+    unsigned tas_valid = getbit(msg, 46);
+    unsigned tas_raw = getbits(msg, 47, 56);
+
+    if (!roll_valid || !track_valid || !gs_valid || !tas_valid) {
+        return 0;
+    }
+
+    int score = 0;
+
+    float roll = 0;
+    if (roll_valid) {
+        roll = roll_raw * 45.0 / 256.0;
+        if (roll_sign) {
+            roll -= 90.0;
+        }
+
+        if (roll >= -40 && roll < 40) {
+            score += 11;
+        } else {
+            return 0;
+        }
+    } else if (!roll_valid && roll_raw == 0 && !roll_sign) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    float track = 0;
+    if (track_valid) {
+        score += 12;
+        track = track_raw * 90.0 / 512.0;
+        if (track_sign) {
+            track += 180.0;
+        }
+    } else if (!track_valid && track_raw == 0 && !track_sign) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    unsigned gs = 0;
+    if (gs_valid && gs_raw != 0) {
+        gs = gs_raw * 2;
+
+        if (gs >= 50 && gs <= 700) {
+            score += 11;
+        } else {
+            return 0;
+        }
+    } else if (!gs_valid && gs_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    float track_rate = 0;
+    if (track_rate_valid) {
+        track_rate = track_rate_raw * 8.0 / 256.0;
+        if (track_rate_sign) {
+            track_rate -= 16;
+        }
+
+        if (track_rate >= -10.0 && track_rate <= 10.0) {
+            score += 11;
+        } else {
+            return 0;
+        }
+    } else if (!track_rate_valid && track_rate_raw == 0 && !track_rate_sign) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    unsigned tas = 0;
+    if (tas_valid && tas_raw != 0) {
+        tas = tas_raw * 2;
+
+        if (tas >= 50 && tas <= 700) {
+            score += 11;
+        } else {
+            return 0;
+        }
+    } else if (!tas_valid && tas_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    // small penalty for inconsistent data
+    if (gs_valid && tas_valid) {
+        int delta = abs((int)gs_valid - (int)tas_valid);
+        if (delta > 150) {
+            score -= 6;
+        }
+    }
+
+    // compute the theoretical turn rate and compare to track angle rate
+    if (roll_valid && tas_valid && tas > 0 && track_rate_valid) {
+        double turn_rate = 68625 * tan(roll * M_PI / 180.0) / (tas * 20 * M_PI);
+        double delta = fabs(turn_rate - track_rate);
+        if (delta > 2.0) {
+            score -= 6;
+        }
+    }
+
+    if (store) {
+        mm->commb_format = COMMB_TRACK_TURN;
+
+        if (roll_valid) {
+            mm->roll_valid = 1;
+            mm->roll = roll;
+        }
+
+        if (track_valid) {
+            mm->heading_valid = 1;
+            mm->heading = track;
+            mm->heading_type = HEADING_GROUND_TRACK;
+        }
+
+        if (gs_valid) {
+            mm->gs_valid = 1;
+            mm->gs.v0 = mm->gs.v2 = mm->gs.selected = gs;
+        }
+
+        if (track_rate_valid) {
+            mm->track_rate_valid = 1;
+            mm->track_rate = track_rate;
+        }
+
+        if (tas_valid) {
+            mm->tas_valid = 1;
+            mm->tas = tas;
+        }
+    }
+
+    return score;
+}
+
+// BDS6,0 Heading and speed report
+static int decodeBDS60(struct modesMessage *mm, bool store)
+{
+    unsigned char *msg = mm->MB;
+
+    unsigned heading_valid = getbit(msg, 1);
+    unsigned heading_sign = getbit(msg, 2);
+    unsigned heading_raw = getbits(msg, 3, 12);
+
+    unsigned ias_valid = getbit(msg, 13);
+    unsigned ias_raw = getbits(msg, 14, 23);
+
+    unsigned mach_valid = getbit(msg, 24);
+    unsigned mach_raw = getbits(msg, 25, 34);
+
+    unsigned baro_rate_valid = getbit(msg, 35);
+    unsigned baro_rate_sign = getbit(msg, 36);
+    unsigned baro_rate_raw = getbits(msg, 37, 45);
+
+    unsigned inertial_rate_valid = getbit(msg, 46);
+    unsigned inertial_rate_sign = getbit(msg, 47);
+    unsigned inertial_rate_raw = getbits(msg, 48, 56);
+
+    if (!heading_valid || !ias_valid || !mach_valid || (!baro_rate_valid && !inertial_rate_valid)) {
+        return 0;
+    }
+
+    int score = 0;
+
+    float heading = 0;
+    if (heading_valid) {
+        heading = heading_raw * 90.0 / 512.0;
+        if (heading_sign) {
+            heading += 180.0;
+        }
+        score += 12;
+    } else if (!heading_valid && heading_raw == 0 && !heading_sign) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    unsigned ias = 0;
+    if (ias_valid && ias_raw != 0) {
+        ias = ias_raw;
+        if (ias >= 50 && ias <= 700) {
+            score += 11;
+        } else {
+            return 0;
+        }
+    } else if (!ias_valid && ias_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    float mach = 0;
+    if (mach_valid && mach_raw != 0) {
+        mach = mach_raw * 2.048 / 512;
+        if (mach >= 0.1 && mach <= 0.9) {
+            score += 11;
+        } else {
+            return 0;
+        }
+    } else if (!mach_valid && mach_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    int baro_rate = 0;
+    if (baro_rate_valid) {
+        baro_rate = baro_rate_raw * 32;
+        if (baro_rate_sign) {
+            baro_rate -= 16384;
+        }
+
+        if (baro_rate >= -6000 && baro_rate <= 6000) {
+            score += 11;
+        } else {
+            return 0;
+        }
+    } else if (!baro_rate_valid && baro_rate_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    int inertial_rate = 0;
+    if (inertial_rate_valid) {
+        inertial_rate = inertial_rate_raw * 32;
+        if (inertial_rate_sign) {
+            inertial_rate -= 16384;
+        }
+
+        if (inertial_rate >= -6000 && inertial_rate <= 6000) {
+            score += 11;
+        } else {
+            return 0;
+        }
+    } else if (!inertial_rate_valid && inertial_rate_raw == 0) {
+        score += 1;
+    } else {
+        return 0;
+    }
+
+    // small penalty for inconsistent data
+
+    // Should check IAS vs Mach at given altitude, but the maths is a little involved
+
+    if (baro_rate_valid && inertial_rate_valid) {
+        int delta = abs(baro_rate - inertial_rate);
+        if (delta > 2000) {
+            score -= 12;
+        }
+    }
+
+    if (store) {
+        mm->commb_format = COMMB_HEADING_SPEED;
+
+        if (heading_valid) {
+            mm->heading_valid = 1;
+            mm->heading = heading;
+            mm->heading_type = HEADING_MAGNETIC;
+        }
+
+        if (ias_valid) {
+            mm->ias_valid = 1;
+            mm->ias = ias;
+        }
+
+        if (mach_valid) {
+            mm->mach_valid = 1;
+            mm->mach = mach;
+        }
+
+        if (baro_rate_valid) {
+            mm->baro_rate_valid = 1;
+            mm->baro_rate = baro_rate;
+        }
+
+        if (inertial_rate_valid) {
+            // INS-derived data is treated as a "geometric rate" / "geometric altitude"
+            // elsewhere, so do the same here.
+            mm->geom_rate_valid = 1;
+            mm->geom_rate = inertial_rate;
+        }
+    }
+
+    return score;
+}
+
+// BDS4,4 Meterological routine air report
+static int decodeBDS44(struct modesMessage *mm, bool store)
+{
+    unsigned char *msg = mm->MB;
+
+    unsigned source = getbits(msg, 1, 4);
+
+    unsigned wind_valid = getbit(msg, 5);
+    unsigned windspeed_raw = getbits(msg, 6, 14);
+    unsigned winddir_raw = getbits(msg, 15, 23);
+
+    // ICAO 9871 is inconsistent, it claims:
+    //  bit 24       sign
+    //  bits 25..34  static air temperature, MSB = 64C, LSB=0.25C, range -128C..+128C
+    //
+    // .. but this does not actually work, there is one too many bits in the bitfield
+    // for the claimed values.
+    //
+    // Based on observed data, the most plausible actual layout is:
+    //
+    //   bit 24       status
+    //   bit 25       sign
+    //   bits 26..34  static air temperature, MSB=64C, LSB=0.25C, range -128C..+128C
+
+    unsigned sat_valid = getbit(msg, 24);
+    unsigned sat_sign = getbit(msg, 25);
+    unsigned sat_raw = getbits(msg, 26, 34);
+
+    unsigned asp_valid = getbit(msg, 35);
+    unsigned asp_raw = getbits(msg, 36, 46);
+
+    unsigned turbulence_valid = getbit(msg, 47);
+    unsigned turbulence_raw = getbits(msg, 48, 49);
+
+    unsigned humidity_valid = getbit(msg, 50);
+    unsigned humidity_raw = getbits(msg, 51, 56);
+
+    if (source == MRAR_SOURCE_INVALID || source >= MRAR_SOURCE_RESERVED)
+        return 0; // invalid or reserved source
+
+    if (!wind_valid || !sat_valid)
+        return 0; // all valid messages seen in the wild have at least temp + wind
+
+    if (!asp_valid && asp_raw != 0)
+        return 0; // ASP not valid, but non-zero values in the ASP field
+
+    if (!turbulence_valid && turbulence_raw != 0)
+        return 0; // turbulence not valid, but non-zero values in the turbulence field
+
+    if (!humidity_valid && humidity_raw != 0)
+        return 0; // humidity not valid, but non-zero values in the humidity field
+
+    int score = 0;
+
+    float wind_speed = 0;
+    float wind_dir = 0;
+    if (wind_valid) {
+        wind_dir = winddir_raw * (180.0 / 256.0);
+        wind_speed = windspeed_raw;
+
+        if (windspeed_raw == 0) // possible but uncommon
+            score += 2;
+        else if (wind_speed <= 250)
+            score += 19;
+        else
+            return 0;
+    } else {
+        score += 1;
+    }
+
+    float sat = 0;
+    if (sat_valid) {
+        sat = sat_raw * 0.25;
+        if (sat_sign)
+            sat -= 128;
+        if (sat == 0) // possible but uncommon
+            score += 2;
+        else if (sat >= -80 && sat <= 60)
+            score += 11;
+        else
+            return 0;
+    } else {
+        score += 1;
+    }
+
+    float asp = 0;
+    if (asp_valid) {
+        asp = asp_raw;
+        if (asp >= 25 && asp <= 1100)
+            score += 12;
+        else
+            return 0;
+    } else {
+        score += 1;
+    }
+
+    hazard_t turbulence = HAZARD_NIL;
+    if (turbulence_valid) {
+        turbulence = (hazard_t) turbulence_raw;
+        score += 3;
+    } else {
+        score += 1;
+    }
+
+    float humidity = 0;
+    if (humidity_valid) {
+        humidity = humidity_raw * (100.0 / 64.0);
+        score += 7;
+    } else {
+        score += 1;
+    }
+
+    if (source == MRAR_SOURCE_DMEDME && wind_valid && sat_valid && score > 0) {
+        // Some GICB messages can be easily mistaken for a MRAR:
+        //
+        //   GICB bit 1: BDS 0,5 ES airborne position      = 0 ]
+        //   GICB bit 2: BDS 0,6 ES surface position       = 0 ]
+        //   GICB bit 3: BDS 0,7 ES status                 = 1 ]
+        //   GICB bit 4: BDS 0,8 ES type & identification  = 1 ] -> MRAR source = 3
+        //   GICB bit 5: BDS 0,9 ES airborne velocity      = 1   -> MRAR wind valid bit
+        //   GICB bit 24: BDS 6,0 heading and speed report = 1   -> MRAR temp valid bit
+        //   most trailing bits = 0
+        //
+        // so only treat this as MRAR as a last resort
+        score = 1;
+    }
+
+    if (store) {
+        mm->commb_format = COMMB_MRAR;
+        mm->mrar_source_valid = 1;
+        mm->mrar_source = (mrar_source_t) source;
+
+        if (wind_valid) {
+            mm->wind_valid = 1;
+            mm->wind_speed = wind_speed;
+            mm->wind_dir = wind_dir;
+        }
+
+        if (sat_valid) {
+            mm->temperature_valid = 1;
+            mm->temperature = sat;
+        }
+
+        if (asp_valid) {
+            mm->pressure_valid = 1;
+            mm->pressure = asp;
+        }
+
+        if (turbulence_valid) {
+            mm->turbulence_valid = 1;
+            mm->turbulence = turbulence;
+        }
+
+        if (humidity_valid) {
+            mm->humidity_valid = 1;
+            mm->humidity = humidity;
+        }
+    }
+
+    return score;
+}
+
+// BDS0,5 extended squitter airborne position
+// (apparently this gets queried via comm-b sometimes??)
+// We don't try to _use_ this as a position, but we can
+// at least try to recognize it, to exclude other
+// comm-b types (in particular they can be mistaken for MRAR)
+static int decodeBDS05(struct modesMessage *mm, bool store)
+{
+    // We recognize these by matching the position altitude against
+    // the altitude in the surrounding message, so we need a
+    // DF20 not a DF21
+    if (mm->msgtype != 20)
+        return 0;
+
+    unsigned char *msg = mm->MB;
+
+    unsigned typecode = getbits(msg, 1, 5);
+    if (typecode < 9 || typecode > 18)
+        return 0; // only consider typecodes that could be an airborne position with baro altitude
+
+    unsigned t_bit = getbit(msg, 21);
+    if (t_bit)  // unlikely
+        return 0;
+
+    unsigned ac12 = getbits(msg, 9, 20);
+    if (!ac12)
+        return 0;
+
+    // Insert M=0 to make an AC13 value, match against the
+    // AC13 value in the surrounding message
+    unsigned ac13 = ((ac12 & 0x0FC0) << 1) | (ac12 & 0x003F);
+    if (mm->AC != ac13)
+        return 0; // no altitude match
+
+    unsigned lat = getbits(msg, 23, 39);
+    unsigned lon = getbits(msg, 40, 56);
+    if (lat == 0 || lon == 0) // unlikely position
+        return 0;
+
+    if (store) {
+        mm->commb_format = COMMB_AIRBORNE_POSITION;
+        // No further decoding done, we don't really trust this
+        // enough to use as real input to CPR
+    }
+
+    // Score this high enough to override everything else
+    return 100;
+}

comm_b.h

@@ -0,0 +1,26 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// comm_b.h: Comm-B message decoding (prototypes)
+//
+// Copyright (c) 2017 FlightAware, LLC
+// Copyright (c) 2017 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef COMM_B_H
+#define COMM_B_H
+
+void decodeCommB(struct modesMessage *mm);
+
+#endif

compat/clock_gettime/LICENSE

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c), MM Weiss
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *     1. Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *
+ *     2. Redistributions in binary form must reproduce the above copyright notice,
+ *     this list of conditions and the following disclaimer in the documentation
+ *     and/or other materials provided with the distribution.
+ *
+ *     3. Neither the name of the MM Weiss nor the names of its contributors
+ *     may be used to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
+ * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */

compat/clock_gettime/clock_gettime.c

@@ -0,0 +1,138 @@
+/*
+ * Copyright (c), MM Weiss
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ *     1. Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *
+ *     2. Redistributions in binary form must reproduce the above copyright notice,
+ *     this list of conditions and the following disclaimer in the documentation
+ *     and/or other materials provided with the distribution.
+ *
+ *     3. Neither the name of the MM Weiss nor the names of its contributors
+ *     may be used to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
+ * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ *  clock_gettime_stub.c
+ *  gcc -Wall -c clock_gettime_stub.c
+ *  posix realtime functions; MacOS user space glue
+ */
+
+/*  @comment
+ *  other possible implementation using intel builtin rdtsc
+ *  rdtsc-workaround: http://www.mcs.anl.gov/~kazutomo/rdtsc.html
+ *
+ *  we could get the ticks by doing this
+ *
+ *  __asm __volatile("mov %%ebx, %%esi\n\t"
+ *  		"cpuid\n\t"
+ *  		"xchg %%esi, %%ebx\n\t"
+ *  		"rdtsc"
+ *  		: "=a" (a),
+ *  		  "=d" (d)
+ * 	);
+ *  we could even replace our tricky sched_yield call by assembly code to get a better accurency,
+ *  anyway the following C stub will satisfy 99% of apps using posix clock_gettime call,
+ *  moreover, the setter version (clock_settime) could be easly written using mach primitives:
+ *  http://www.opensource.apple.com/source/xnu/xnu-${VERSION}/osfmk/man/ (clock_[set|get]_time)
+ *
+ *  hackers don't be crackers, don't you use a flush toilet?
+ *
+ *
+ *  @see draft: ./posix-realtime-stub/posix-realtime-stub.c
+ *
+ */
+
+#include "../compat.h"
+#include <mach/mach_time.h>
+#include <mach/clock.h>             // for clock_get_time
+#include <mach/clock_types.h>       // for mach_timespec_t, CALENDAR_CLOCK, etc
+#include <mach/kern_return.h>       // for KERN_SUCCESS, kern_return_t
+#include <mach/mach_host.h>         // for host_get_clock_service
+#include <mach/mach_init.h>         // for mach_host_self
+#include <mach/mach_types.h>        // for clock_serv_t
+#include <sched.h>                  // for sched_yield
+#include <errno.h>                  // for EINVAL, errno
+#include <unistd.h>                 // for getpid
+
+static mach_timebase_info_data_t __clock_gettime_inf;
+
+int clock_gettime(clockid_t clk_id, struct timespec *tp)
+{
+    kern_return_t   ret;
+    clock_serv_t    clk;
+    clock_id_t clk_serv_id;
+    mach_timespec_t tm;
+
+    uint64_t start, end, delta, nano;
+
+    /*
+    task_basic_info_data_t tinfo;
+    task_thread_times_info_data_t ttinfo;
+    mach_msg_type_number_t tflag;
+    */
+
+    int retval = -1;
+    switch (clk_id)
+    {
+    case CLOCK_REALTIME:
+    case CLOCK_MONOTONIC:
+        clk_serv_id = clk_id == CLOCK_REALTIME ? CALENDAR_CLOCK : SYSTEM_CLOCK;
+        if (KERN_SUCCESS == (ret = host_get_clock_service(mach_host_self(), clk_serv_id, &clk)))
+        {
+            if (KERN_SUCCESS == (ret = clock_get_time(clk, &tm)))
+            {
+                tp->tv_sec  = tm.tv_sec;
+                tp->tv_nsec = tm.tv_nsec;
+                retval = 0;
+            }
+        }
+        if (KERN_SUCCESS != ret)
+        {
+            errno = EINVAL;
+            retval = -1;
+        }
+        break;
+    case CLOCK_PROCESS_CPUTIME_ID:
+    case CLOCK_THREAD_CPUTIME_ID:
+        start = mach_absolute_time();
+        if (clk_id == CLOCK_PROCESS_CPUTIME_ID)
+        {
+            getpid();
+        }
+        else
+        {
+            sched_yield();
+        }
+        end = mach_absolute_time();
+        delta = end - start;
+        if (0 == __clock_gettime_inf.denom)
+        {
+            mach_timebase_info(&__clock_gettime_inf);
+        }
+        nano = delta * __clock_gettime_inf.numer / __clock_gettime_inf.denom;
+        tp->tv_sec = nano * 1e-9;
+        tp->tv_nsec = nano - (tp->tv_sec * 1e9);
+        retval = 0;
+        break;
+    default:
+        errno = EINVAL;
+        retval = -1;
+    }
+    return retval;
+}

compat/clock_gettime/clock_gettime.h

@@ -0,0 +1,6 @@
+#ifndef CLOCK_GETTIME_H
+#define CLOCK_GETTIME_H
+
+int clock_gettime(clockid_t clk_id, struct timespec *tp);
+
+#endif // CLOCK_GETTIME_H

compat/clock_nanosleep/LICENSE

@@ -0,0 +1,16 @@
+/***********************************************************************
+ *  Copyright © 2006 Rémi Denis-Courmont.                              *
+ *  This program is free software; you can redistribute and/or modify  *
+ *  it under the terms of the GNU General Public License as published  *
+ *  by the Free Software Foundation; version 2 of the license, or (at  *
+ *  your option) any later version.                                    *
+ *                                                                     *
+ *  This program is distributed in the hope that it will be useful,    *
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of     *
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.               *
+ *  See the GNU General Public License for more details.               *
+ *                                                                     *
+ *  You should have received a copy of the GNU General Public License  *
+ *  along with this program; if not, you can get it from:              *
+ *  http://www.gnu.org/copyleft/gpl.html                               *
+ ***********************************************************************/

compat/clock_nanosleep/clock_nanosleep.c

@@ -0,0 +1,62 @@
+/*
+ * clock_nanosleep.c - clock_nanosleep() replacement
+ */
+
+/***********************************************************************
+ *  Copyright © 2006 Rémi Denis-Courmont.                              *
+ *  This program is free software; you can redistribute and/or modify  *
+ *  it under the terms of the GNU General Public License as published  *
+ *  by the Free Software Foundation; version 2 of the license, or (at  *
+ *  your option) any later version.                                    *
+ *                                                                     *
+ *  This program is distributed in the hope that it will be useful,    *
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of     *
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.               *
+ *  See the GNU General Public License for more details.               *
+ *                                                                     *
+ *  You should have received a copy of the GNU General Public License  *
+ *  along with this program; if not, you can get it from:              *
+ *  http://www.gnu.org/copyleft/gpl.html                               *
+ ***********************************************************************/
+
+#include <errno.h>                           // for errno, EINVAL
+#include <time.h>                            // for nanosleep, NULL
+
+#include "../compat.h"
+
+int clock_nanosleep(clockid_t id, int flags, const struct timespec *ts,
+                    struct timespec *ots) {
+    int ret;
+
+    if (id != CLOCK_REALTIME)
+        return EINVAL;
+
+    if (flags & TIMER_ABSTIME) {
+        struct timespec mine;
+
+        if (clock_gettime(id, &mine))
+            return errno;
+
+        if (mine.tv_sec > ts->tv_sec)
+            return 0; // behind schedule
+
+        if (mine.tv_nsec > ts->tv_nsec) {
+            if (mine.tv_sec == ts->tv_sec)
+                return 0; // behind schedule too
+
+            mine.tv_nsec = 1000000000 + ts->tv_nsec - mine.tv_nsec;
+            mine.tv_sec++;
+        }
+        else
+            mine.tv_nsec = ts->tv_nsec - mine.tv_nsec;
+
+        mine.tv_sec = ts->tv_sec - mine.tv_sec;
+
+        /* With TIMER_ABSTIME, clock_nanosleep ignores <ots> */
+        ret = nanosleep(&mine, NULL);
+    }
+    else
+        ret = nanosleep(ts, ots);
+
+    return ret ? errno : 0;
+}

compat/clock_nanosleep/clock_nanosleep.h

@@ -0,0 +1,7 @@
+#ifndef CLOCK_NANOSLEEP_H
+#define CLOCK_NANOSLEEP_H
+
+int clock_nanosleep (clockid_t id, int flags, const struct timespec *ts,
+                     struct timespec *ots);
+
+#endif //CLOCK_NANOSLEEP_H

compat/compat.h

@@ -0,0 +1,63 @@
+#ifndef COMPAT_UTIL_H
+#define COMPAT_UTIL_H
+
+/*
+ * Platform-specific bits
+ */
+
+#if defined(__APPLE__)
+
+/*
+ * Mach endian conversion
+ */
+# include <libkern/OSByteOrder.h>
+# define bswap_16 OSSwapInt16
+# define bswap_32 OSSwapInt32
+# define bswap_64 OSSwapInt64
+# include <machine/endian.h>
+# define le16toh(x) OSSwapLittleToHostInt16(x)
+# define le32toh(x) OSSwapLittleToHostInt32(x)
+# define le64toh(x) OSSwapLittleToHostInt64(x)
+
+#elif defined(__FreeBSD__)
+#include <sys/endian.h>
+
+#else // other platforms
+
+# include <endian.h>
+
+#endif
+
+/* clock_* and time-related types */
+
+#include <time.h>
+
+#if defined(CLOCK_REALTIME)
+#  define HAVE_CLOCKID_T
+#endif
+
+#ifndef HAVE_CLOCKID_T
+typedef enum
+{
+    CLOCK_REALTIME,
+    CLOCK_MONOTONIC,
+    CLOCK_PROCESS_CPUTIME_ID,
+    CLOCK_THREAD_CPUTIME_ID
+} clockid_t;
+#endif // !HAVE_CLOCKID_T
+
+#ifndef TIMER_ABSTIME
+#define TIMER_ABSTIME 1
+#endif // !TIMER_ABSTIME
+
+struct timespec;
+
+#ifdef MISSING_NANOSLEEP
+#include "clock_nanosleep/clock_nanosleep.h"
+#endif
+
+#ifdef MISSING_GETTIME
+#include "clock_gettime/clock_gettime.h"
+#endif
+
+#endif //COMPAT_UTIL_H

convert.c

@@ -0,0 +1,123 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// convert.c: support for various IQ -> magnitude conversions
+//
+// Copyright (c) 2015 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "dump1090.h"
+
+static void convert_uc8(void *iq_data,
+                        uint16_t *mag_data,
+                        unsigned nsamples,
+                        struct converter_state *state,
+                        double *out_mean_level,
+                        double *out_mean_power)
+{
+    MODES_NOTUSED(state);
+
+    const uc8_t *in = (const uc8_t *) iq_data;
+
+    if (out_mean_level && out_mean_power) {
+        if (STARCH_IS_ALIGNED(in) && STARCH_IS_ALIGNED(mag_data))
+            starch_magnitude_power_uc8_aligned(in, mag_data, nsamples, out_mean_level, out_mean_power);
+        else
+            starch_magnitude_power_uc8(in, mag_data, nsamples, out_mean_level, out_mean_power);
+    } else {
+        if (STARCH_IS_ALIGNED(in) && STARCH_IS_ALIGNED(mag_data))
+            starch_magnitude_uc8_aligned(in, mag_data, nsamples);
+        else
+            starch_magnitude_uc8(in, mag_data, nsamples);
+    }
+}
+
+static void convert_sc16(void *iq_data,
+                         uint16_t *mag_data,
+                         unsigned nsamples,
+                         struct converter_state *state,
+                         double *out_mean_level,
+                         double *out_mean_power)
+{
+    MODES_NOTUSED(state);
+
+    const sc16_t *in = (const sc16_t *) iq_data;
+
+    if (STARCH_IS_ALIGNED(in) && STARCH_IS_ALIGNED(mag_data))
+        starch_magnitude_sc16_aligned(in, mag_data, nsamples);
+    else
+        starch_magnitude_sc16(in, mag_data, nsamples);
+
+    if (out_mean_level && out_mean_power) {
+        if (STARCH_IS_ALIGNED(mag_data))
+            starch_mean_power_u16_aligned(mag_data, nsamples, out_mean_level, out_mean_power);
+        else
+            starch_mean_power_u16(mag_data, nsamples, out_mean_level, out_mean_power);
+    }
+}
+
+static void convert_sc16q11(void *iq_data,
+                            uint16_t *mag_data,
+                            unsigned nsamples,
+                            struct converter_state *state,
+                            double *out_mean_level,
+                            double *out_mean_power)
+{
+    MODES_NOTUSED(state);
+
+    const sc16_t *in = (const sc16_t *) iq_data;
+
+    if (STARCH_IS_ALIGNED(in) && STARCH_IS_ALIGNED(mag_data))
+        starch_magnitude_sc16q11_aligned(in, mag_data, nsamples);
+    else
+        starch_magnitude_sc16q11(in, mag_data, nsamples);
+
+    if (out_mean_level && out_mean_power) {
+        if (STARCH_IS_ALIGNED(mag_data))
+            starch_mean_power_u16_aligned(mag_data, nsamples, out_mean_level, out_mean_power);
+        else
+            starch_mean_power_u16(mag_data, nsamples, out_mean_level, out_mean_power);
+    }
+}
+
+iq_convert_fn init_converter(input_format_t format,
+                             double sample_rate,
+                             int filter_dc,
+                             struct converter_state **out_state)
+{
+    MODES_NOTUSED(sample_rate);
+    MODES_NOTUSED(out_state);
+
+    if (filter_dc) {
+        fprintf(stderr, "DC filtering not supported (yet)\n");
+        return NULL;
+    }
+
+    switch (format) {
+    case INPUT_UC8:
+        return convert_uc8;
+    case INPUT_SC16:
+        return convert_sc16;
+    case INPUT_SC16Q11:
+        return convert_sc16q11;
+    default:
+        fprintf(stderr, "no suitable converter for format=%d\n", format);
+        return NULL;
+    }
+}
+
+void cleanup_converter(struct converter_state *state)
+{
+    MODES_NOTUSED(state);
+}

convert.h

@@ -0,0 +1,40 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// convert.h: support for various IQ -> magnitude conversions
+//
+// Copyright (c) 2015 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef DUMP1090_CONVERT_H
+#define DUMP1090_CONVERT_H
+
+struct converter_state;
+typedef enum { INPUT_UC8=0, INPUT_SC16, INPUT_SC16Q11 } input_format_t;
+
+typedef void (*iq_convert_fn)(void *iq_data,
+                              uint16_t *mag_data,
+                              unsigned nsamples,
+                              struct converter_state *state,
+                              double *out_mean_level,
+                              double *out_mean_power);
+
+iq_convert_fn init_converter(input_format_t format,
+                             double sample_rate,
+                             int filter_dc,
+                             struct converter_state **out_state);
+
+void cleanup_converter(struct converter_state *state);
+
+#endif

cpr.c

@@ -0,0 +1,369 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// cpr.c - Compact Position Reporting decoder and tests
+//
+// Copyright (c) 2014,2015 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// This file incorporates work covered by the following copyright and
+// permission notice:
+//
+//   Copyright (C) 2012 by Salvatore Sanfilippo <antirez@gmail.com>
+//
+//   All rights reserved.
+//
+//   Redistribution and use in source and binary forms, with or without
+//   modification, are permitted provided that the following conditions are
+//   met:
+//
+//    *  Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//
+//    *  Redistributions in binary form must reproduce the above copyright
+//       notice, this list of conditions and the following disclaimer in the
+//       documentation and/or other materials provided with the distribution.
+//
+//   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+//   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+//   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+//   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+//   HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+//   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+//   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+//   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+//   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+//   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+//   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "cpr.h"
+
+#include <math.h>
+#include <stdio.h>
+
+//
+//=========================================================================
+//
+// Always positive MOD operation, used for CPR decoding.
+//
+static int cprModInt(int a, int b) {
+    int res = a % b;
+    if (res < 0) res += b;
+    return res;
+}
+
+static double cprModDouble(double a, double b) {
+    double res = fmod(a, b);
+    if (res < 0) res += b;
+    return res;
+}
+
+//
+//=========================================================================
+//
+// The NL function uses the precomputed table from 1090-WP-9-14
+//
+static int cprNLFunction(double lat) {
+    if (lat < 0) lat = -lat; // Table is simmetric about the equator
+    if (lat < 10.47047130) return 59;
+    if (lat < 14.82817437) return 58;
+    if (lat < 18.18626357) return 57;
+    if (lat < 21.02939493) return 56;
+    if (lat < 23.54504487) return 55;
+    if (lat < 25.82924707) return 54;
+    if (lat < 27.93898710) return 53;
+    if (lat < 29.91135686) return 52;
+    if (lat < 31.77209708) return 51;
+    if (lat < 33.53993436) return 50;
+    if (lat < 35.22899598) return 49;
+    if (lat < 36.85025108) return 48;
+    if (lat < 38.41241892) return 47;
+    if (lat < 39.92256684) return 46;
+    if (lat < 41.38651832) return 45;
+    if (lat < 42.80914012) return 44;
+    if (lat < 44.19454951) return 43;
+    if (lat < 45.54626723) return 42;
+    if (lat < 46.86733252) return 41;
+    if (lat < 48.16039128) return 40;
+    if (lat < 49.42776439) return 39;
+    if (lat < 50.67150166) return 38;
+    if (lat < 51.89342469) return 37;
+    if (lat < 53.09516153) return 36;
+    if (lat < 54.27817472) return 35;
+    if (lat < 55.44378444) return 34;
+    if (lat < 56.59318756) return 33;
+    if (lat < 57.72747354) return 32;
+    if (lat < 58.84763776) return 31;
+    if (lat < 59.95459277) return 30;
+    if (lat < 61.04917774) return 29;
+    if (lat < 62.13216659) return 28;
+    if (lat < 63.20427479) return 27;
+    if (lat < 64.26616523) return 26;
+    if (lat < 65.31845310) return 25;
+    if (lat < 66.36171008) return 24;
+    if (lat < 67.39646774) return 23;
+    if (lat < 68.42322022) return 22;
+    if (lat < 69.44242631) return 21;
+    if (lat < 70.45451075) return 20;
+    if (lat < 71.45986473) return 19;
+    if (lat < 72.45884545) return 18;
+    if (lat < 73.45177442) return 17;
+    if (lat < 74.43893416) return 16;
+    if (lat < 75.42056257) return 15;
+    if (lat < 76.39684391) return 14;
+    if (lat < 77.36789461) return 13;
+    if (lat < 78.33374083) return 12;
+    if (lat < 79.29428225) return 11;
+    if (lat < 80.24923213) return 10;
+    if (lat < 81.19801349) return 9;
+    if (lat < 82.13956981) return 8;
+    if (lat < 83.07199445) return 7;
+    if (lat < 83.99173563) return 6;
+    if (lat < 84.89166191) return 5;
+    if (lat < 85.75541621) return 4;
+    if (lat < 86.53536998) return 3;
+    if (lat < 87.00000000) return 2;
+    else return 1;
+}
+//
+//=========================================================================
+//
+static int cprNFunction(double lat, int fflag) {
+    int nl = cprNLFunction(lat) - (fflag ? 1 : 0);
+    if (nl < 1) nl = 1;
+    return nl;
+}
+//
+//=========================================================================
+//
+static double cprDlonFunction(double lat, int fflag, int surface) {
+    return (surface ? 90.0 : 360.0) / cprNFunction(lat, fflag);
+}
+//
+//=========================================================================
+//
+// This algorithm comes from:
+// http://www.lll.lu/~edward/edward/adsb/DecodingADSBposition.html.
+//
+// A few remarks:
+// 1) 131072 is 2^17 since CPR latitude and longitude are encoded in 17 bits.
+//
+int decodeCPRairborne(int even_cprlat, int even_cprlon,
+                      int odd_cprlat, int odd_cprlon,
+                      int fflag,
+                      double *out_lat, double *out_lon)
+{
+    double AirDlat0 = 360.0 / 60.0;
+    double AirDlat1 = 360.0 / 59.0;
+    double lat0 = even_cprlat;
+    double lat1 = odd_cprlat;
+    double lon0 = even_cprlon;
+    double lon1 = odd_cprlon;
+
+    double rlat, rlon;
+
+    // Compute the Latitude Index "j"
+    int    j     = (int) floor(((59*lat0 - 60*lat1) / 131072) + 0.5);
+    double rlat0 = AirDlat0 * (cprModInt(j,60) + lat0 / 131072);
+    double rlat1 = AirDlat1 * (cprModInt(j,59) + lat1 / 131072);
+
+    if (rlat0 >= 270) rlat0 -= 360;
+    if (rlat1 >= 270) rlat1 -= 360;
+
+    // Check to see that the latitude is in range: -90 .. +90
+    if (rlat0 < -90 || rlat0 > 90 || rlat1 < -90 || rlat1 > 90)
+        return (-2); // bad data
+
+    // Check that both are in the same latitude zone, or abort.
+    if (cprNLFunction(rlat0) != cprNLFunction(rlat1))
+        return (-1); // positions crossed a latitude zone, try again later
+
+    // Compute ni and the Longitude Index "m"
+    if (fflag) { // Use odd packet.
+        int ni = cprNFunction(rlat1,1);
+        int m = (int) floor((((lon0 * (cprNLFunction(rlat1)-1)) -
+                              (lon1 * cprNLFunction(rlat1))) / 131072.0) + 0.5);
+        rlon = cprDlonFunction(rlat1, 1, 0) * (cprModInt(m, ni)+lon1/131072);
+        rlat = rlat1;
+    } else {     // Use even packet.
+        int ni = cprNFunction(rlat0,0);
+        int m = (int) floor((((lon0 * (cprNLFunction(rlat0)-1)) -
+                              (lon1 * cprNLFunction(rlat0))) / 131072) + 0.5);
+        rlon = cprDlonFunction(rlat0, 0, 0) * (cprModInt(m, ni)+lon0/131072);
+        rlat = rlat0;
+    }
+
+    // Renormalize to -180 .. +180
+    rlon -= floor( (rlon + 180) / 360 ) * 360;
+
+    *out_lat = rlat;
+    *out_lon = rlon;
+
+    return 0;
+}
+
+int decodeCPRsurface(double reflat, double reflon,
+                     int even_cprlat, int even_cprlon,
+                     int odd_cprlat, int odd_cprlon,
+                     int fflag,
+                     double *out_lat, double *out_lon)
+{
+    double AirDlat0 = 90.0 / 60.0;
+    double AirDlat1 = 90.0 / 59.0;
+    double lat0 = even_cprlat;
+    double lat1 = odd_cprlat;
+    double lon0 = even_cprlon;
+    double lon1 = odd_cprlon;
+    double rlon, rlat;
+
+    // Compute the Latitude Index "j"
+    int    j     = (int) floor(((59*lat0 - 60*lat1) / 131072) + 0.5);
+    double rlat0 = AirDlat0 * (cprModInt(j,60) + lat0 / 131072);
+    double rlat1 = AirDlat1 * (cprModInt(j,59) + lat1 / 131072);
+
+    // Pick the quadrant that's closest to the reference location -
+    // this is not necessarily the same quadrant that contains the
+    // reference location.
+    //
+    // There are also only two valid quadrants: -90..0 and 0..90;
+    // no correct message would try to encoding a latitude in the
+    // ranges -180..-90 and 90..180.
+    //
+    // If the computed latitude is more than 45 degrees north of
+    // the reference latitude (using the northern hemisphere
+    // solution), then the southern hemisphere solution will be
+    // closer to the refernce latitude.
+    //
+    // e.g. reflat=0, rlat=44, use rlat=44
+    //      reflat=0, rlat=46, use rlat=46-90 = -44
+    //      reflat=40, rlat=84, use rlat=84
+    //      reflat=40, rlat=86, use rlat=86-90 = -4
+    //      reflat=-40, rlat=4, use rlat=4
+    //      reflat=-40, rlat=6, use rlat=6-90 = -84
+
+    // As a special case, -90, 0 and +90 all encode to zero, so
+    // there's a little extra work to do there.
+
+    if (rlat0 == 0) {
+        if (reflat < -45)
+            rlat0 = -90;
+        else if (reflat > 45)
+            rlat0 = 90;
+    } else if ((rlat0 - reflat) > 45) {
+        rlat0 -= 90;
+    }
+
+    if (rlat1 == 0) {
+        if (reflat < -45)
+            rlat1 = -90;
+        else if (reflat > 45)
+            rlat1 = 90;
+    } else if ((rlat1 - reflat) > 45) {
+        rlat1 -= 90;
+    }
+
+    // Check to see that the latitude is in range: -90 .. +90
+    if (rlat0 < -90 || rlat0 > 90 || rlat1 < -90 || rlat1 > 90)
+        return (-2); // bad data
+
+    // Check that both are in the same latitude zone, or abort.
+    if (cprNLFunction(rlat0) != cprNLFunction(rlat1))
+        return (-1); // positions crossed a latitude zone, try again later
+
+    // Compute ni and the Longitude Index "m"
+    if (fflag) { // Use odd packet.
+        int ni = cprNFunction(rlat1,1);
+        int m = (int) floor((((lon0 * (cprNLFunction(rlat1)-1)) -
+                              (lon1 * cprNLFunction(rlat1))) / 131072.0) + 0.5);
+        rlon = cprDlonFunction(rlat1, 1, 1) * (cprModInt(m, ni)+lon1/131072);
+        rlat = rlat1;
+    } else {     // Use even packet.
+        int ni = cprNFunction(rlat0,0);
+        int m = (int) floor((((lon0 * (cprNLFunction(rlat0)-1)) -
+                              (lon1 * cprNLFunction(rlat0))) / 131072) + 0.5);
+        rlon = cprDlonFunction(rlat0, 0, 1) * (cprModInt(m, ni)+lon0/131072);
+        rlat = rlat0;
+    }
+
+    // Pick the quadrant that's closest to the reference location -
+    // this is not necessarily the same quadrant that contains the
+    // reference location. Unlike the latitude case, all four
+    // quadrants are valid.
+
+    // if reflon is more than 45 degrees away, move some multiple of 90 degrees towards it
+    rlon += floor( (reflon - rlon + 45) / 90 ) * 90;  // this might move us outside (-180..+180), we fix this below
+
+    // Renormalize to -180 .. +180
+    rlon -= floor( (rlon + 180) / 360 ) * 360;
+
+    *out_lat = rlat;
+    *out_lon = rlon;
+    return 0;
+}
+
+//
+//=========================================================================
+//
+// This algorithm comes from:
+// 1090-WP29-07-Draft_CPR101 (which also defines decodeCPR() )
+//
+// Despite what the earlier comment here said, we should *not* be using trunc().
+// See Figure 5-5 / 5-6 and note that floor is applied to (0.5 + fRP - fEP), not
+// directly to (fRP - fEP). Eq 38 is correct.
+//
+int decodeCPRrelative(double reflat, double reflon,
+                      int cprlat, int cprlon,
+                      int fflag, int surface,
+                      double *out_lat, double *out_lon)
+{
+    double AirDlat;
+    double AirDlon;
+    double fractional_lat = cprlat / 131072.0;
+    double fractional_lon = cprlon / 131072.0;
+    double rlon, rlat;
+    int j,m;
+
+    AirDlat = (surface ? 90.0 : 360.0) / (fflag ? 59.0 : 60.0);
+
+    // Compute the Latitude Index "j"
+    j = (int) (floor(reflat/AirDlat) +
+               floor(0.5 + cprModDouble(reflat, AirDlat)/AirDlat - fractional_lat));
+    rlat = AirDlat * (j + fractional_lat);
+    if (rlat >= 270) rlat -= 360;
+
+    // Check to see that the latitude is in range: -90 .. +90
+    if (rlat < -90 || rlat > 90) {
+        return (-1);                               // Time to give up - Latitude error
+    }
+
+    // Check to see that answer is reasonable - ie no more than 1/2 cell away
+    if (fabs(rlat - reflat) > (AirDlat/2)) {
+        return (-1);                               // Time to give up - Latitude error
+    }
+
+    // Compute the Longitude Index "m"
+    AirDlon = cprDlonFunction(rlat, fflag, surface);
+    m = (int) (floor(reflon/AirDlon) +
+               floor(0.5 + cprModDouble(reflon, AirDlon)/AirDlon - fractional_lon));
+    rlon = AirDlon * (m + fractional_lon);
+    if (rlon > 180) rlon -= 360;
+
+    // Check to see that answer is reasonable - ie no more than 1/2 cell away
+    if (fabs(rlon - reflon) > (AirDlon/2))
+        return (-1);                               // Time to give up - Longitude error
+
+    *out_lat = rlat;
+    *out_lon = rlon;
+    return (0);
+}

cpr.h

@@ -0,0 +1,39 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// cpr.h - Compact Position Reporting prototypes
+//
+// Copyright (c) 2014,2015 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef DUMP1090_CPR_H
+#define DUMP1090_CPR_H
+
+int decodeCPRairborne(int even_cprlat, int even_cprlon,
+                      int odd_cprlat, int odd_cprlon,
+                      int fflag,
+                      double *out_lat, double *out_lon);
+
+int decodeCPRsurface(double reflat, double reflon,
+                     int even_cprlat, int even_cprlon,
+                     int odd_cprlat, int odd_cprlon,
+                     int fflag,
+                     double *out_lat, double *out_lon);
+
+int decodeCPRrelative(double reflat, double reflon,
+                      int cprlat, int cprlon,
+                      int fflag, int surface,
+                      double *out_lat, double *out_lon);
+
+#endif

cprtests.c

@@ -0,0 +1,309 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// cprtests.c - tests for CPR decoder
+//
+// Copyright (c) 2014,2015 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+#include <math.h>
+#include <stdio.h>
+
+#include "cpr.h"
+
+// Global, airborne CPR test data:
+static const struct {
+    int even_cprlat, even_cprlon;   // input: raw CPR values, even message
+    int odd_cprlat, odd_cprlon;     // input: raw CPR values, odd message
+    int even_result;                // verify: expected result from decoding with fflag=0 (even message is latest)
+    double even_rlat, even_rlon;    // verify: expected position from decoding with fflag=0 (even message is latest)
+    int odd_result;                 // verify: expected result from decoding with fflag=1 (odd message is latest)
+    double odd_rlat, odd_rlon;      // verify: expected position from decoding with fflag=1 (odd message is latest)
+} cprGlobalAirborneTests[] = {
+    { 80536, 9432, 61720, 9192, 0, 51.686646, 0.700156, 0, 51.686763, 0.701294 },
+    { 80534, 9413, 61714, 9144, 0, 51.686554, 0.698745, 0, 51.686484, 0.697632 },
+
+    // todo: more positions, bad data
+};
+
+// Global, surface CPR test data:
+static const struct {
+    double reflat, reflon;          // input: reference location for decoding
+    int even_cprlat, even_cprlon;   // input: raw CPR values, even message
+    int odd_cprlat, odd_cprlon;     // input: raw CPR values, odd message
+    int even_result;                // verify: expected result from decoding with fflag=0 (even message is latest)
+    double even_rlat, even_rlon;    // verify: expected position from decoding with fflag=0 (even message is latest)
+    int odd_result;                 // verify: expected result from decoding with fflag=1 (odd message is latest)
+    double odd_rlat, odd_rlon;      // verify: expected position from decoding with fflag=1 (odd message is latest)
+} cprGlobalSurfaceTests[] = {
+    // The real position received here was on the Cambridge (UK) airport apron at 52.21N 0.177E
+    // We mess with the reference location to check that the right quadrant is used.
+
+    // longitude quadrants:
+    { 52.00, -180.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601 - 180.0, 0, 52.209976, 0.176507 - 180.0 },
+    { 52.00, -140.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601 - 180.0, 0, 52.209976, 0.176507 - 180.0 },
+    { 52.00, -130.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601 - 90.0,  0, 52.209976, 0.176507 - 90.0 },
+    { 52.00,  -50.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601 - 90.0,  0, 52.209976, 0.176507 - 90.0 },
+    { 52.00,  -40.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601,         0, 52.209976, 0.176507 },
+    { 52.00,  -10.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601,         0, 52.209976, 0.176507 },
+    { 52.00,    0.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601,         0, 52.209976, 0.176507 },
+    { 52.00,   10.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601,         0, 52.209976, 0.176507 },
+    { 52.00,   40.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601,         0, 52.209976, 0.176507 },
+    { 52.00,   50.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601 + 90.0,  0, 52.209976, 0.176507 + 90.0 },
+    { 52.00,  130.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601 + 90.0,  0, 52.209976, 0.176507 + 90.0 },
+    { 52.00,  140.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601 - 180.0, 0, 52.209976, 0.176507 - 180.0 },
+    { 52.00,  180.00, 105730, 9259, 29693, 8997, 0, 52.209984, 0.176601 - 180.0, 0, 52.209976, 0.176507 - 180.0 },
+
+    // latitude quadrants (but only 2). The decoded longitude also changes because the cell size changes with latitude
+    {  90.00,   0.00, 105730, 9259, 29693, 8997, 0, 52.209984,        0.176601,  0, 52.209976,        0.176507 },
+    {  52.00,   0.00, 105730, 9259, 29693, 8997, 0, 52.209984,        0.176601,  0, 52.209976,        0.176507 },
+    {   8.00,   0.00, 105730, 9259, 29693, 8997, 0, 52.209984,        0.176601,  0, 52.209976,        0.176507 },
+    {   7.00,   0.00, 105730, 9259, 29693, 8997, 0, 52.209984 - 90.0, 0.135269,  0, 52.209976 - 90.0, 0.134299 },
+    { -52.00,   0.00, 105730, 9259, 29693, 8997, 0, 52.209984 - 90.0, 0.135269,  0, 52.209976 - 90.0, 0.134299 },
+    { -90.00,   0.00, 105730, 9259, 29693, 8997, 0, 52.209984 - 90.0, 0.135269,  0, 52.209976 - 90.0, 0.134299 },
+
+    // poles/equator cases
+    { -46.00, -180.00,  0, 0,  0, 0,  0, -90.0, -180.000000,  0, -90.0, -180.0 },   // south pole
+    { -44.00, -180.00,  0, 0,  0, 0,  0,   0.0, -180.000000,  0,   0.0, -180.0 },   // equator
+    {  44.00, -180.00,  0, 0,  0, 0,  0,   0.0, -180.000000,  0,   0.0, -180.0 },   // equator
+    {  46.00, -180.00,  0, 0,  0, 0,  0,  90.0, -180.000000,  0,  90.0, -180.0 },   // north pole
+
+};
+
+// Relative CPR test data:
+static const struct {
+    double reflat, reflon;          // input: reference location for decoding
+    int cprlat, cprlon;             // input: raw CPR values, even or odd message
+    int fflag;                      // input: fflag in raw message
+    int surface;                    // input: decode as air (0) or surface (1) position
+    int result;                     // verify: expected result
+    double rlat, rlon;              // verify: expected position
+} cprRelativeTests[] = {
+    //
+    // AIRBORNE
+    //
+
+    { 52.00, 0.00, 80536, 9432, 0, 0, 0, 51.686646, 0.700156 },  // even, airborne
+    { 52.00, 0.00, 61720, 9192, 1, 0, 0, 51.686763, 0.701294 },  // odd, airborne
+    { 52.00, 0.00, 80534, 9413, 0, 0, 0, 51.686554, 0.698745 },  // even, airborne
+    { 52.00, 0.00, 61714, 9144, 1, 0, 0, 51.686484, 0.697632 },  // odd, airborne
+
+    // test moving the receiver around a bit
+    // We cannot move it more than 1/2 cell away before ambiguity happens.
+
+    // latitude must be within about 3 degrees (cell size is 360/60 = 6 degrees)
+    { 48.70, 0.00, 80536, 9432, 0, 0, 0, 51.686646, 0.700156 },  // even, airborne
+    { 48.70, 0.00, 61720, 9192, 1, 0, 0, 51.686763, 0.701294 },  // odd, airborne
+    { 48.70, 0.00, 80534, 9413, 0, 0, 0, 51.686554, 0.698745 },  // even, airborne
+    { 48.70, 0.00, 61714, 9144, 1, 0, 0, 51.686484, 0.697632 },  // odd, airborne
+    { 54.60, 0.00, 80536, 9432, 0, 0, 0, 51.686646, 0.700156 },  // even, airborne
+    { 54.60, 0.00, 61720, 9192, 1, 0, 0, 51.686763, 0.701294 },  // odd, airborne
+    { 54.60, 0.00, 80534, 9413, 0, 0, 0, 51.686554, 0.698745 },  // even, airborne
+    { 54.60, 0.00, 61714, 9144, 1, 0, 0, 51.686484, 0.697632 },  // odd, airborne
+
+    // longitude must be within about 4.8 degrees at this latitude
+    { 52.00, 5.40, 80536, 9432, 0, 0, 0, 51.686646, 0.700156 },  // even, airborne
+    { 52.00, 5.40, 61720, 9192, 1, 0, 0, 51.686763, 0.701294 },  // odd, airborne
+    { 52.00, 5.40, 80534, 9413, 0, 0, 0, 51.686554, 0.698745 },  // even, airborne
+    { 52.00, 5.40, 61714, 9144, 1, 0, 0, 51.686484, 0.697632 },  // odd, airborne
+    { 52.00, -4.10, 80536, 9432, 0, 0, 0, 51.686646, 0.700156 },  // even, airborne
+    { 52.00, -4.10, 61720, 9192, 1, 0, 0, 51.686763, 0.701294 },  // odd, airborne
+    { 52.00, -4.10, 80534, 9413, 0, 0, 0, 51.686554, 0.698745 },  // even, airborne
+    { 52.00, -4.10, 61714, 9144, 1, 0, 0, 51.686484, 0.697632 },  // odd, airborne
+
+    //
+    // SURFACE
+    //
+
+    // Surface position on the Cambridge (UK) airport apron at 52.21N 0.18E
+    { 52.00,    0.00, 105730, 9259, 0, 1, 0, 52.209984, 0.176601 },   // even, surface
+    { 52.00,    0.00,  29693, 8997, 1, 1, 0, 52.209976, 0.176507 },   // odd, surface
+
+    // test moving the receiver around a bit
+    // We cannot move it more than 1/2 cell away before ambiguity happens.
+
+    // latitude must be within about 0.75 degrees (cell size is 90/60 = 1.5 degrees)
+    { 51.46,    0.00, 105730, 9259, 0, 1, 0, 52.209984, 0.176601 },   // even, surface
+    { 51.46,    0.00,  29693, 8997, 1, 1, 0, 52.209976, 0.176507 },   // odd, surface
+    { 52.95,    0.00, 105730, 9259, 0, 1, 0, 52.209984, 0.176601 },   // even, surface
+    { 52.95,    0.00,  29693, 8997, 1, 1, 0, 52.209976, 0.176507 },   // odd, surface
+
+    // longitude must be within about 1.25 degrees at this latitude
+    { 52.00,    1.40, 105730, 9259, 0, 1, 0, 52.209984, 0.176601 },   // even, surface
+    { 52.00,    1.40,  29693, 8997, 1, 1, 0, 52.209976, 0.176507 },   // odd, surface
+    { 52.00,   -1.05, 105730, 9259, 0, 1, 0, 52.209984, 0.176601 },   // even, surface
+    { 52.00,   -1.05,  29693, 8997, 1, 1, 0, 52.209976, 0.176507 },   // odd, surface
+};
+
+static int testCPRGlobalAirborne() {
+    int ok = 1;
+    unsigned i;
+    for (i = 0; i < sizeof(cprGlobalAirborneTests)/sizeof(cprGlobalAirborneTests[0]); ++i) {
+        double rlat = 0, rlon = 0;
+        int res;
+
+        res = decodeCPRairborne(cprGlobalAirborneTests[i].even_cprlat, cprGlobalAirborneTests[i].even_cprlon,
+                                cprGlobalAirborneTests[i].odd_cprlat, cprGlobalAirborneTests[i].odd_cprlon,
+                                0,
+                                &rlat, &rlon);
+        if (res != cprGlobalAirborneTests[i].even_result
+            || fabs(rlat - cprGlobalAirborneTests[i].even_rlat) > 1e-6
+            || fabs(rlon - cprGlobalAirborneTests[i].even_rlon) > 1e-6) {
+            ok = 0;
+            fprintf(stderr,
+                    "testCPRGlobalAirborne[%u,EVEN]: FAIL: decodeCPRairborne(%d,%d,%d,%d,EVEN) failed:\n"
+                    " result %d  (expected %d)\n"
+                    " lat %.6f   (expected %.6f)\n"
+                    " lon %.6f   (expected %.6f)\n",
+                    i,
+                    cprGlobalAirborneTests[i].even_cprlat, cprGlobalAirborneTests[i].even_cprlon,
+                    cprGlobalAirborneTests[i].odd_cprlat, cprGlobalAirborneTests[i].odd_cprlon,
+                    res, cprGlobalAirborneTests[i].even_result,
+                    rlat, cprGlobalAirborneTests[i].even_rlat,
+                    rlon, cprGlobalAirborneTests[i].even_rlon);
+        } else {
+            fprintf(stderr, "testCPRGlobalAirborne[%u,EVEN]: PASS\n", i);
+        }
+
+        res = decodeCPRairborne(cprGlobalAirborneTests[i].even_cprlat, cprGlobalAirborneTests[i].even_cprlon,
+                                cprGlobalAirborneTests[i].odd_cprlat, cprGlobalAirborneTests[i].odd_cprlon,
+                                1,
+                                &rlat, &rlon);
+        if (res != cprGlobalAirborneTests[i].odd_result
+            || fabs(rlat - cprGlobalAirborneTests[i].odd_rlat) > 1e-6
+            || fabs(rlon - cprGlobalAirborneTests[i].odd_rlon) > 1e-6) {
+            ok = 0;
+            fprintf(stderr,
+                    "testCPRGlobalAirborne[%u,ODD]:  FAIL: decodeCPRairborne(%d,%d,%d,%d,ODD) failed:\n"
+                    " result %d  (expected %d)\n"
+                    " lat %.6f   (expected %.6f)\n"
+                    " lon %.6f   (expected %.6f)\n",
+                    i,
+                    cprGlobalAirborneTests[i].even_cprlat, cprGlobalAirborneTests[i].even_cprlon,
+                    cprGlobalAirborneTests[i].odd_cprlat, cprGlobalAirborneTests[i].odd_cprlon,
+                    res, cprGlobalAirborneTests[i].odd_result,
+                    rlat, cprGlobalAirborneTests[i].odd_rlat,
+                    rlon, cprGlobalAirborneTests[i].odd_rlon);
+        } else {
+            fprintf(stderr, "testCPRGlobalAirborne[%u,ODD]:  PASS\n", i);
+        }
+    }
+
+    return ok;
+}
+
+static int testCPRGlobalSurface() {
+    int ok = 1;
+    unsigned i;
+    for (i = 0; i < sizeof(cprGlobalSurfaceTests)/sizeof(cprGlobalSurfaceTests[0]); ++i) {
+        double rlat = 0, rlon = 0;
+        int res;
+
+        res = decodeCPRsurface(cprGlobalSurfaceTests[i].reflat, cprGlobalSurfaceTests[i].reflon,
+                               cprGlobalSurfaceTests[i].even_cprlat, cprGlobalSurfaceTests[i].even_cprlon,
+                               cprGlobalSurfaceTests[i].odd_cprlat, cprGlobalSurfaceTests[i].odd_cprlon,
+                               0,
+                               &rlat, &rlon);
+        if (res != cprGlobalSurfaceTests[i].even_result
+            || fabs(rlat - cprGlobalSurfaceTests[i].even_rlat) > 1e-6
+            || fabs(rlon - cprGlobalSurfaceTests[i].even_rlon) > 1e-6) {
+            ok = 0;
+            fprintf(stderr,
+                    "testCPRGlobalSurface[%u,EVEN]:  FAIL: decodeCPRsurface(%.6f,%.6f,%d,%d,%d,%d,EVEN) failed:\n"
+                    " result %d  (expected %d)\n"
+                    " lat %.6f   (expected %.6f)\n"
+                    " lon %.6f   (expected %.6f)\n",
+                    i,
+                    cprGlobalSurfaceTests[i].reflat, cprGlobalSurfaceTests[i].reflon,
+                    cprGlobalSurfaceTests[i].even_cprlat, cprGlobalSurfaceTests[i].even_cprlon,
+                    cprGlobalSurfaceTests[i].odd_cprlat, cprGlobalSurfaceTests[i].odd_cprlon,
+                    res, cprGlobalSurfaceTests[i].even_result,
+                    rlat, cprGlobalSurfaceTests[i].even_rlat,
+                    rlon, cprGlobalSurfaceTests[i].even_rlon);
+        } else {
+            fprintf(stderr, "testCPRGlobalSurface[%u,EVEN]:  PASS\n", i);
+        }
+
+        res = decodeCPRsurface(cprGlobalSurfaceTests[i].reflat, cprGlobalSurfaceTests[i].reflon,
+                               cprGlobalSurfaceTests[i].even_cprlat, cprGlobalSurfaceTests[i].even_cprlon,
+                               cprGlobalSurfaceTests[i].odd_cprlat, cprGlobalSurfaceTests[i].odd_cprlon,
+                               1,
+                               &rlat, &rlon);
+        if (res != cprGlobalSurfaceTests[i].odd_result
+            || fabs(rlat - cprGlobalSurfaceTests[i].odd_rlat) > 1e-6
+            || fabs(rlon - cprGlobalSurfaceTests[i].odd_rlon) > 1e-6) {
+            ok = 0;
+            fprintf(stderr,
+                    "testCPRGlobalSurface[%u,ODD]:   FAIL: decodeCPRsurface(%.6f,%.6f,%d,%d,%d,%d,ODD) failed:\n"
+                    " result %d  (expected %d)\n"
+                    " lat %.6f   (expected %.6f)\n"
+                    " lon %.6f   (expected %.6f)\n",
+                    i,
+                    cprGlobalSurfaceTests[i].reflat, cprGlobalSurfaceTests[i].reflon,
+                    cprGlobalSurfaceTests[i].even_cprlat, cprGlobalSurfaceTests[i].even_cprlon,
+                    cprGlobalSurfaceTests[i].odd_cprlat, cprGlobalSurfaceTests[i].odd_cprlon,
+                    res, cprGlobalSurfaceTests[i].odd_result,
+                    rlat, cprGlobalSurfaceTests[i].odd_rlat,
+                    rlon, cprGlobalSurfaceTests[i].odd_rlon);
+        } else {
+            fprintf(stderr, "testCPRGlobalSurface[%u,ODD]:   PASS\n", i);
+        }
+    }
+
+    return ok;
+}
+
+static int testCPRRelative() {
+    int ok = 1;
+    unsigned i;
+    for (i = 0; i < sizeof(cprRelativeTests)/sizeof(cprRelativeTests[0]); ++i) {
+        double rlat = 0, rlon = 0;
+        int res;
+
+        res = decodeCPRrelative(cprRelativeTests[i].reflat, cprRelativeTests[i].reflon,
+                                cprRelativeTests[i].cprlat, cprRelativeTests[i].cprlon,
+                                cprRelativeTests[i].fflag, cprRelativeTests[i].surface,
+                                &rlat, &rlon);
+        if (res != cprRelativeTests[i].result
+            || fabs(rlat - cprRelativeTests[i].rlat) > 1e-6
+            || fabs(rlon - cprRelativeTests[i].rlon) > 1e-6) {
+            ok = 0;
+            fprintf(stderr,
+                    "testCPRRelative[%u]:  FAIL: decodeCPRrelative(%.6f,%.6f,%d,%d,%d,%d) failed:\n"
+                    " result %d  (expected %d)\n"
+                    " lat %.6f   (expected %.6f)\n"
+                    " lon %.6f   (expected %.6f)\n",
+                    i,
+                    cprRelativeTests[i].reflat, cprRelativeTests[i].reflon,
+                    cprRelativeTests[i].cprlat, cprRelativeTests[i].cprlon,
+                    cprRelativeTests[i].fflag, cprRelativeTests[i].surface,
+                    res, cprRelativeTests[i].result,
+                    rlat, cprRelativeTests[i].rlat,
+                    rlon, cprRelativeTests[i].rlon);
+        } else {
+            fprintf(stderr, "testCPRRelative[%u]:  PASS\n", i);
+        }
+    }
+
+    return ok;
+}
+
+int main(int __attribute__ ((unused)) argc, char __attribute__ ((unused)) **argv) {
+    int ok = 1;
+    ok = testCPRGlobalAirborne() && ok;
+    ok = testCPRGlobalSurface() && ok;
+    ok = testCPRRelative() && ok;
+    return ok ? 0 : 1;
+}

cpu.c

@@ -0,0 +1,109 @@
+#include "cpu.h"
+
+#include <stdbool.h>
+
+#ifdef ENABLE_CPUFEATURES
+#include "cpu_features_macros.h"
+#endif
+
+//
+// x86
+//
+
+#ifdef CPU_FEATURES_ARCH_X86
+#include "cpuinfo_x86.h"
+
+static X86Info *x86_info()
+{
+    static bool valid = false;
+    static X86Info cache;
+
+    if (!valid) {
+        cache = GetX86Info();
+        valid = true;
+    }
+
+    return &cache;
+}
+
+#endif
+
+int cpu_supports_avx(void)
+{
+#ifdef CPU_FEATURES_ARCH_X86
+    return x86_info()->features.avx;
+#else
+    return 0;
+#endif
+}
+
+int cpu_supports_avx2(void)
+{
+#ifdef CPU_FEATURES_ARCH_X86
+    return x86_info()->features.avx2;
+#else
+    return 0;
+#endif
+}
+
+//
+// ARM
+//
+
+#ifdef CPU_FEATURES_ARCH_ARM
+#include "cpuinfo_arm.h"
+
+static ArmInfo *arm_info()
+{
+    static bool valid = false;
+    static ArmInfo cache;
+
+    if (!valid) {
+        cache = GetArmInfo();
+        valid = true;
+    }
+
+    return &cache;
+}
+
+#endif
+
+int cpu_supports_armv7_neon_vfpv4(void)
+{
+#ifdef CPU_FEATURES_ARCH_ARM
+    return arm_info()->architecture >= 7 && arm_info()->features.neon && arm_info()->features.vfpv4 && arm_info()->features.vfpd32;
+#else
+    return 0;
+#endif
+}
+
+//
+// AARCH64
+//
+
+#ifdef CPU_FEATURES_ARCH_AARCH64
+#include "cpuinfo_aarch64.h"
+
+static Aarch64Info *aarch64_info()
+{
+    static bool valid = false;
+    static Aarch64Info cache;
+
+    if (!valid) {
+        cache = GetAarch64Info();
+        valid = true;
+    }
+
+    return &cache;
+}
+
+#endif
+
+int cpu_supports_armv8_simd(void)
+{
+#ifdef CPU_FEATURES_ARCH_AARCH64
+    return aarch64_info()->features.asimd;
+#else
+    return 0;
+#endif
+}

cpu.h

@@ -0,0 +1,15 @@
+#ifndef DUMP1090_CPU_H
+#define DUMP1090_CPU_H
+
+// x86
+int cpu_supports_avx(void);
+int cpu_supports_avx2(void);
+
+// ARM
+int cpu_supports_armv7_neon_vfpv4(void);
+
+// AARCH64
+int cpu_supports_armv8_simd(void);
+int cpu_supports_armv8_simd_sve(void);
+
+#endif

cpu_features/.clang-format

@@ -0,0 +1,4 @@
+---
+Language:        Cpp
+BasedOnStyle:  Google
+...

cpu_features/.gitignore

@@ -0,0 +1,4 @@
+cmake_build/
+build/
+
+*.swp

cpu_features/.travis.yml

@@ -0,0 +1,121 @@
+language: c
+
+sudo: false
+
+cache:
+  timeout: 1000
+  directories:
+    - $HOME/cpu_features_archives
+
+addons:
+  apt_packages:
+    - ninja-build
+
+env:
+  global:
+    TOOLCHAIN=NATIVE
+    CMAKE_GENERATOR=Ninja
+
+matrix:
+  include:
+  - os: linux
+    compiler: gcc
+    env:
+      TARGET=x86_64-linux-gnu
+  - os: linux
+    compiler: clang
+    env:
+      TARGET=x86_64-linux-gnu
+  - os: osx
+    compiler: gcc
+    env:
+      TARGET=x86_64-osx
+      CMAKE_GENERATOR="Unix Makefiles"
+  - os: osx
+    compiler: clang
+    env:
+      TARGET=x86_64-osx
+      CMAKE_GENERATOR="Unix Makefiles"
+  - os: windows
+    env:
+      TARGET=x86_64-windows
+      CMAKE_GENERATOR="Visual Studio 15 2017 Win64"
+
+  # see: https://docs.travis-ci.com/user/multi-cpu-architectures/
+  - os: linux
+    arch: ppc64le
+    compiler: gcc
+    env:
+      TARGET=ppc64le-linux-gnu
+  - os: linux
+    arch: ppc64le
+    compiler: clang
+    env:
+      TARGET=ppc64le-linux-gnu
+
+  # Toolchains for little-endian, 64-bit ARMv8 for GNU/Linux systems
+  - os: linux
+    env:
+      TOOLCHAIN=LINARO
+      TARGET=aarch64-linux-gnu
+      QEMU_ARCH=aarch64
+  # Toolchains for little-endian, hard-float, 32-bit ARMv7 (and earlier) for GNU/Linux systems
+  - os: linux
+    env:
+      TOOLCHAIN=LINARO
+      TARGET=arm-linux-gnueabihf
+      QEMU_ARCH=arm
+  # Toolchains for little-endian, 32-bit ARMv8 for GNU/Linux systems
+  - os: linux
+    env:
+      TOOLCHAIN=LINARO
+      TARGET=armv8l-linux-gnueabihf
+      QEMU_ARCH=arm
+  # Toolchains for little-endian, soft-float, 32-bit ARMv7 (and earlier) for GNU/Linux systems
+  - os: linux
+    env:
+      TOOLCHAIN=LINARO
+      TARGET=arm-linux-gnueabi
+      QEMU_ARCH=arm
+  # Toolchains for big-endian, 64-bit ARMv8 for GNU/Linux systems
+  - os: linux
+    env:
+      TOOLCHAIN=LINARO
+      TARGET=aarch64_be-linux-gnu
+      QEMU_ARCH=DISABLED
+  # Toolchains for big-endian, hard-float, 32-bit ARMv7 (and earlier) for GNU/Linux systems
+  - os: linux
+    env:
+      TOOLCHAIN=LINARO
+      TARGET=armeb-linux-gnueabihf
+      QEMU_ARCH=DISABLED
+  # Toolchains for big-endian, soft-float, 32-bit ARMv7 (and earlier) for GNU/Linux systems
+  - os: linux
+    env:
+      TOOLCHAIN=LINARO
+      TARGET=armeb-linux-gnueabi
+      QEMU_ARCH=DISABLED
+  - os: linux
+    env:
+      TOOLCHAIN=CODESCAPE
+      TARGET=mips32
+      QEMU_ARCH=mips
+  - os: linux
+    env:
+      TOOLCHAIN=CODESCAPE
+      TARGET=mips32el
+      QEMU_ARCH=mipsel
+  - os: linux
+    env:
+      TOOLCHAIN=CODESCAPE
+      TARGET=mips64
+      QEMU_ARCH=mips64
+  - os: linux
+    env:
+      TOOLCHAIN=CODESCAPE
+      TARGET=mips64el
+      QEMU_ARCH=mips64el
+
+script:
+  - cmake --version
+  - bash -e -x ./scripts/run_integration.sh

cpu_features/CMakeLists.txt

@@ -0,0 +1,259 @@
+cmake_minimum_required(VERSION 3.0)
+
+# option() honors normal variables.
+# see: https://cmake.org/cmake/help/git-stage/policy/CMP0077.html
+if(POLICY CMP0077)
+  cmake_policy(SET CMP0077 NEW)
+endif()
+
+project(CpuFeatures VERSION 0.6.0 LANGUAGES C)
+
+set(CMAKE_C_STANDARD 99)
+
+# Default Build Type to be Release
+if(NOT CMAKE_BUILD_TYPE)
+  set(CMAKE_BUILD_TYPE "Release" CACHE STRING
+      "Choose the type of build, options are: Debug Release RelWithDebInfo MinSizeRel."
+      FORCE)
+endif(NOT CMAKE_BUILD_TYPE)
+
+# BUILD_TESTING is a standard CMake variable, but we declare it here to make it
+# prominent in the GUI.
+option(BUILD_TESTING "Enable test (depends on googletest)." OFF)
+# BUILD_SHARED_LIBS is a standard CMake variable, but we declare it here to make
+# it prominent in the GUI.
+# cpu_features uses bit-fields which are - to some extends - implementation-defined (see https://en.cppreference.com/w/c/language/bit_field).
+# As a consequence it is discouraged to use cpu_features as a shared library because different compilers may interpret the code in different ways.
+# Prefer static linking from source whenever possible.
+option(BUILD_SHARED_LIBS "Build library as shared." OFF)
+# PIC
+option(BUILD_PIC "Build with Position Independant Code." OFF) # Default is off at least for GCC
+
+# Force PIC on unix when building shared libs
+# see: https://en.wikipedia.org/wiki/Position-independent_code
+if(BUILD_SHARED_LIBS AND UNIX)
+  set(BUILD_PIC ON)
+endif()
+
+include(CheckIncludeFile)
+include(CheckSymbolExists)
+include(GNUInstallDirs)
+
+macro(setup_include_and_definitions TARGET_NAME)
+  target_include_directories(${TARGET_NAME}
+    PUBLIC  $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
+    PRIVATE $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include/internal>
+  )
+  target_compile_definitions(${TARGET_NAME}
+    PUBLIC STACK_LINE_READER_BUFFER_SIZE=1024
+  )
+endmacro()
+
+set(PROCESSOR_IS_MIPS FALSE)
+set(PROCESSOR_IS_ARM FALSE)
+set(PROCESSOR_IS_AARCH64 FALSE)
+set(PROCESSOR_IS_X86 FALSE)
+set(PROCESSOR_IS_POWER FALSE)
+
+if(CMAKE_SYSTEM_PROCESSOR MATCHES "^mips")
+  set(PROCESSOR_IS_MIPS TRUE)
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm")
+  set(PROCESSOR_IS_ARM TRUE)
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^aarch64")
+  set(PROCESSOR_IS_AARCH64 TRUE)
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "(x86_64)|(AMD64|amd64)|(^i.86$)")
+  set(PROCESSOR_IS_X86 TRUE)
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "^(powerpc|ppc)")
+  set(PROCESSOR_IS_POWER TRUE)
+endif()
+
+macro(add_cpu_features_headers_and_sources HDRS_LIST_NAME SRCS_LIST_NAME)
+  list(APPEND ${HDRS_LIST_NAME} ${PROJECT_SOURCE_DIR}/include/cpu_features_macros.h)
+  list(APPEND ${HDRS_LIST_NAME} ${PROJECT_SOURCE_DIR}/include/cpu_features_cache_info.h)
+  if(PROCESSOR_IS_MIPS)
+      list(APPEND ${HDRS_LIST_NAME} ${PROJECT_SOURCE_DIR}/include/cpuinfo_mips.h)
+      list(APPEND ${SRCS_LIST_NAME} ${PROJECT_SOURCE_DIR}/src/cpuinfo_mips.c)
+  elseif(PROCESSOR_IS_ARM)
+      list(APPEND ${HDRS_LIST_NAME} ${PROJECT_SOURCE_DIR}/include/cpuinfo_arm.h)
+      list(APPEND ${SRCS_LIST_NAME} ${PROJECT_SOURCE_DIR}/src/cpuinfo_arm.c)
+  elseif(PROCESSOR_IS_AARCH64)
+      list(APPEND ${HDRS_LIST_NAME} ${PROJECT_SOURCE_DIR}/include/cpuinfo_aarch64.h)
+      list(APPEND ${SRCS_LIST_NAME} ${PROJECT_SOURCE_DIR}/src/cpuinfo_aarch64.c)
+  elseif(PROCESSOR_IS_X86)
+      list(APPEND ${HDRS_LIST_NAME} ${PROJECT_SOURCE_DIR}/include/cpuinfo_x86.h)
+      list(APPEND ${SRCS_LIST_NAME} ${PROJECT_SOURCE_DIR}/include/internal/cpuid_x86.h)
+      list(APPEND ${SRCS_LIST_NAME} ${PROJECT_SOURCE_DIR}/src/cpuinfo_x86.c)
+  elseif(PROCESSOR_IS_POWER)
+      list(APPEND ${HDRS_LIST_NAME} ${PROJECT_SOURCE_DIR}/include/cpuinfo_ppc.h)
+      list(APPEND ${SRCS_LIST_NAME} ${PROJECT_SOURCE_DIR}/src/cpuinfo_ppc.c)
+  else()
+    message(FATAL_ERROR "Unsupported architectures ${CMAKE_SYSTEM_PROCESSOR}")
+  endif()
+endmacro()
+
+#
+# library : utils
+#
+
+add_library(utils OBJECT
+  ${PROJECT_SOURCE_DIR}/include/internal/bit_utils.h
+  ${PROJECT_SOURCE_DIR}/include/internal/filesystem.h
+  ${PROJECT_SOURCE_DIR}/include/internal/stack_line_reader.h
+  ${PROJECT_SOURCE_DIR}/include/internal/string_view.h
+  ${PROJECT_SOURCE_DIR}/src/filesystem.c
+  ${PROJECT_SOURCE_DIR}/src/stack_line_reader.c
+  ${PROJECT_SOURCE_DIR}/src/string_view.c
+)
+set_property(TARGET utils PROPERTY POSITION_INDEPENDENT_CODE ${BUILD_PIC})
+setup_include_and_definitions(utils)
+
+#
+# library : unix_based_hardware_detection
+#
+
+if(UNIX)
+  add_library(unix_based_hardware_detection OBJECT
+    ${PROJECT_SOURCE_DIR}/include/internal/hwcaps.h
+    ${PROJECT_SOURCE_DIR}/src/hwcaps.c
+  )
+  setup_include_and_definitions(unix_based_hardware_detection)
+  check_include_file(dlfcn.h HAVE_DLFCN_H)
+  if(HAVE_DLFCN_H)
+    target_compile_definitions(unix_based_hardware_detection PRIVATE HAVE_DLFCN_H)
+  endif()
+  check_symbol_exists(getauxval "sys/auxv.h" HAVE_STRONG_GETAUXVAL)
+  if(HAVE_STRONG_GETAUXVAL)
+    target_compile_definitions(unix_based_hardware_detection PRIVATE HAVE_STRONG_GETAUXVAL)
+  endif()
+  set_property(TARGET unix_based_hardware_detection PROPERTY POSITION_INDEPENDENT_CODE ${BUILD_PIC})
+endif()
+
+#
+# library : cpu_features
+#
+set (CPU_FEATURES_HDRS)
+set (CPU_FEATURES_SRCS)
+add_cpu_features_headers_and_sources(CPU_FEATURES_HDRS CPU_FEATURES_SRCS)
+list(APPEND CPU_FEATURES_SRCS $<TARGET_OBJECTS:utils>)
+if(NOT PROCESSOR_IS_X86 AND UNIX)
+  list(APPEND CPU_FEATURES_SRCS $<TARGET_OBJECTS:unix_based_hardware_detection>)
+endif()
+add_library(cpu_features ${CPU_FEATURES_HDRS} ${CPU_FEATURES_SRCS})
+set_target_properties(cpu_features PROPERTIES PUBLIC_HEADER "${CPU_FEATURES_HDRS}")
+setup_include_and_definitions(cpu_features)
+target_link_libraries(cpu_features PUBLIC ${CMAKE_DL_LIBS})
+set_property(TARGET cpu_features PROPERTY POSITION_INDEPENDENT_CODE ${BUILD_PIC})
+target_include_directories(cpu_features
+  PUBLIC $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/cpu_features>
+)
+if(PROCESSOR_IS_X86)
+  if(APPLE)
+    target_compile_definitions(cpu_features PRIVATE HAVE_SYSCTLBYNAME)
+  endif()
+endif()
+add_library(CpuFeature::cpu_features ALIAS cpu_features)
+
+#
+# program : list_cpu_features
+#
+
+add_executable(list_cpu_features ${PROJECT_SOURCE_DIR}/src/utils/list_cpu_features.c)
+target_link_libraries(list_cpu_features PRIVATE cpu_features)
+add_executable(CpuFeature::list_cpu_features ALIAS list_cpu_features)
+
+#
+# ndk_compat
+#
+
+if(ANDROID)
+add_subdirectory(ndk_compat)
+endif()
+
+#
+# tests
+#
+
+include(CTest)
+if(BUILD_TESTING)
+  # Automatically incorporate googletest into the CMake Project if target not
+  # found.
+  enable_language(CXX)
+
+  set(CMAKE_CXX_STANDARD 11)
+  set(CMAKE_CXX_STANDARD_REQUIRED ON)
+  set(CMAKE_CXX_EXTENSIONS OFF) # prefer use of -std11 instead of -gnustd11
+
+  if(NOT TARGET gtest OR NOT TARGET gmock_main)
+    # Download and unpack googletest at configure time.
+    configure_file(
+      cmake/googletest.CMakeLists.txt.in
+      googletest-download/CMakeLists.txt
+    )
+
+    execute_process(
+      COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
+      RESULT_VARIABLE result
+      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/googletest-download)
+
+    if(result)
+      message(FATAL_ERROR "CMake step for googletest failed: ${result}")
+    endif()
+
+    execute_process(
+      COMMAND ${CMAKE_COMMAND} --build .
+      RESULT_VARIABLE result
+      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/googletest-download)
+
+    if(result)
+      message(FATAL_ERROR "Build step for googletest failed: ${result}")
+    endif()
+
+    # Prevent overriding the parent project's compiler/linker settings on
+    # Windows.
+    set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+
+    # Add googletest directly to our build. This defines the gtest and
+    # gtest_main targets.
+    add_subdirectory(${CMAKE_BINARY_DIR}/googletest-src
+                     ${CMAKE_BINARY_DIR}/googletest-build
+                     EXCLUDE_FROM_ALL)
+  endif()
+
+  add_subdirectory(test)
+endif()
+
+#
+# Install cpu_features and list_cpu_features
+#
+
+include(GNUInstallDirs)
+install(TARGETS cpu_features list_cpu_features
+  EXPORT CpuFeaturesTargets
+  PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/cpu_features
+  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+)
+install(EXPORT CpuFeaturesTargets
+  NAMESPACE CpuFeatures::
+  DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/CpuFeatures
+  COMPONENT Devel
+)
+include(CMakePackageConfigHelpers)
+configure_package_config_file(cmake/CpuFeaturesConfig.cmake.in
+  "${PROJECT_BINARY_DIR}/CpuFeaturesConfig.cmake"
+  INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/CpuFeatures"
+  NO_SET_AND_CHECK_MACRO
+  NO_CHECK_REQUIRED_COMPONENTS_MACRO
+)
+write_basic_package_version_file(
+  "${PROJECT_BINARY_DIR}/CpuFeaturesConfigVersion.cmake"
+  COMPATIBILITY SameMajorVersion
+)
+install(
+  FILES
+    "${PROJECT_BINARY_DIR}/CpuFeaturesConfig.cmake"
+    "${PROJECT_BINARY_DIR}/CpuFeaturesConfigVersion.cmake"
+  DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/CpuFeatures"
+  COMPONENT Devel
+)

cpu_features/CONTRIBUTING.md

@@ -0,0 +1,23 @@
+# How to Contribute
+
+We'd love to accept your patches and contributions to this project. There are
+just a few small guidelines you need to follow.
+
+## Contributor License Agreement
+
+Contributions to this project must be accompanied by a Contributor License
+Agreement. You (or your employer) retain the copyright to your contribution;
+this simply gives us permission to use and redistribute your contributions as
+part of the project. Head over to <https://cla.developers.google.com/> to see
+your current agreements on file or to sign a new one.
+
+You generally only need to submit a CLA once, so if you've already submitted one
+(even if it was for a different project), you probably don't need to do it
+again.
+
+## Code reviews
+
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.

cpu_features/LICENSE

@@ -0,0 +1,230 @@
+
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+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
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+
+   Unless required by applicable law or agreed to in writing, software
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+--------------------------------------------------------------------------------
+For files in the `ndk_compat` folder:
+--------------------------------------------------------------------------------
+
+Copyright (C) 2010 The Android Open Source Project
+All rights reserved.
+Redistribution and use in source and binary forms, with or without
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+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.

cpu_features/README.md

@@ -0,0 +1,199 @@
+# cpu_features [![Build Status](https://travis-ci.org/google/cpu_features.svg?branch=master)](https://travis-ci.org/google/cpu_features) [![Build status](https://ci.appveyor.com/api/projects/status/46d1owsj7n8dsylq/branch/master?svg=true)](https://ci.appveyor.com/project/gchatelet/cpu-features/branch/master)
+
+A cross-platform C library to retrieve CPU features (such as available
+instructions) at runtime.
+
+## Table of Contents
+
+- [Design Rationale](#rationale)
+- [Code samples](#codesample)
+- [Running sample code](#usagesample)
+- [What's supported](#support)
+- [Android NDK's drop in replacement](#ndk)
+- [License](#license)
+- [Build with cmake](#cmake)
+
+<a name="rationale"></a>
+## Design Rationale
+
+-   **Simple to use.** See the snippets below for examples.
+-   **Extensible.** Easy to add missing features or architectures.
+-   **Compatible with old compilers** and available on many architectures so it
+    can be used widely. To ensure that cpu_features works on as many platforms
+    as possible, we implemented it in a highly portable version of C: C99.
+-   **Sandbox-compatible.** The library uses a variety of strategies to cope
+    with sandboxed environments or when `cpuid` is unavailable. This is useful
+    when running integration tests in hermetic environments.
+-   **Thread safe, no memory allocation, and raises no exceptions.**
+    cpu_features is suitable for implementing fundamental libc functions like
+    `malloc`, `memcpy`, and `memcmp`.
+-   **Unit tested.**
+
+<a name="codesample"></a>
+## Code samples
+
+**Note:** For C++ code, the library functions are defined in the `CpuFeatures` namespace.
+
+### Checking features at runtime
+
+Here's a simple example that executes a codepath if the CPU supports both the
+AES and the SSE4.2 instruction sets:
+
+```c
+#include "cpuinfo_x86.h"
+
+// For C++, add `using namespace CpuFeatures;`
+static const X86Features features = GetX86Info().features;
+
+void Compute(void) {
+  if (features.aes && features.sse4_2) {
+    // Run optimized code.
+  } else {
+    // Run standard code.
+  }
+}
+```
+
+### Caching for faster evaluation of complex checks
+
+If you wish, you can read all the features at once into a global variable, and
+then query for the specific features you care about. Below, we store all the ARM
+features and then check whether AES and NEON are supported.
+
+```c
+#include <stdbool.h>
+#include "cpuinfo_arm.h"
+
+// For C++, add `using namespace CpuFeatures;`
+static const ArmFeatures features = GetArmInfo().features;
+static const bool has_aes_and_neon = features.aes && features.neon;
+
+// use has_aes_and_neon.
+```
+
+This is a good approach to take if you're checking for combinations of features
+when using a compiler that is slow to extract individual bits from bit-packed
+structures.
+
+### Checking compile time flags
+
+The following code determines whether the compiler was told to use the AVX
+instruction set (e.g., `g++ -mavx`) and sets `has_avx` accordingly.
+
+```c
+#include <stdbool.h>
+#include "cpuinfo_x86.h"
+
+// For C++, add `using namespace CpuFeatures;`
+static const X86Features features = GetX86Info().features;
+static const bool has_avx = CPU_FEATURES_COMPILED_X86_AVX || features.avx;
+
+// use has_avx.
+```
+
+`CPU_FEATURES_COMPILED_X86_AVX` is set to 1 if the compiler was instructed to
+use AVX and 0 otherwise, combining compile time and runtime knowledge.
+
+### Rejecting poor hardware implementations based on microarchitecture
+
+On x86, the first incarnation of a feature in a microarchitecture might not be
+the most efficient (e.g. AVX on Sandy Bridge). We provide a function to retrieve
+the underlying microarchitecture so you can decide whether to use it.
+
+Below, `has_fast_avx` is set to 1 if the CPU supports the AVX instruction
+set&mdash;but only if it's not Sandy Bridge.
+
+```c
+#include <stdbool.h>
+#include "cpuinfo_x86.h"
+
+// For C++, add `using namespace CpuFeatures;`
+static const X86Info info = GetX86Info();
+static const X86Microarchitecture uarch = GetX86Microarchitecture(&info);
+static const bool has_fast_avx = info.features.avx && uarch != INTEL_SNB;
+
+// use has_fast_avx.
+```
+
+This feature is currently available only for x86 microarchitectures.
+
+<a name="usagesample"></a>
+### Running sample code
+
+Building `cpu_features` (check [quickstart](#quickstart) below) brings a small executable to test the library.
+
+```shell
+ % ./build/list_cpu_features
+arch            : x86
+brand           :        Intel(R) Xeon(R) CPU E5-1650 0 @ 3.20GHz
+family          :   6 (0x06)
+model           :  45 (0x2D)
+stepping        :   7 (0x07)
+uarch           : INTEL_SNB
+flags           : aes,avx,cx16,smx,sse4_1,sse4_2,ssse3
+```
+
+```shell
+% ./build/list_cpu_features --json
+{"arch":"x86","brand":"       Intel(R) Xeon(R) CPU E5-1650 0 @ 3.20GHz","family":6,"model":45,"stepping":7,"uarch":"INTEL_SNB","flags":["aes","avx","cx16","smx","sse4_1","sse4_2","ssse3"]}
+```
+
+<a name="support"></a>
+## What's supported
+
+|         | x86³ |   ARM   | AArch64 |  MIPS⁴ |  POWER  |
+|---------|:----:|:-------:|:-------:|:------:|:-------:|
+| Android | yes² |   yes¹  |   yes¹  |  yes¹  |   N/A   |
+| iOS     |  N/A | not yet | not yet |   N/A  |   N/A   |
+| Linux   | yes² |   yes¹  |   yes¹  |  yes¹  |   yes¹  |
+| MacOs   | yes² |   N/A   | not yet |   N/A  |    no   |
+| Windows | yes² | not yet | not yet |   N/A  |   N/A   |
+
+1.  **Features revealed from Linux.** We gather data from several sources
+    depending on availability:
+    +   from glibc's
+        [getauxval](https://www.gnu.org/software/libc/manual/html_node/Auxiliary-Vector.html)
+    +   by parsing `/proc/self/auxv`
+    +   by parsing `/proc/cpuinfo`
+2.  **Features revealed from CPU.** features are retrieved by using the `cpuid`
+    instruction.
+3.  **Microarchitecture detection.** On x86 some features are not always
+    implemented efficiently in hardware (e.g. AVX on Sandybridge). Exposing the
+    microarchitecture allows the client to reject particular microarchitectures.
+4.  All flavors of Mips are supported, little and big endian as well as 32/64
+    bits.
+
+<a name="ndk"></a>
+## Android NDK's drop in replacement
+
+[cpu_features](https://github.com/google/cpu_features) is now officially
+supporting Android and offers a drop in replacement of for the NDK's [cpu-features.h](https://android.googlesource.com/platform/ndk/+/master/sources/android/cpufeatures/cpu-features.h)
+, see [ndk_compat](ndk_compat) folder for details.
+
+<a name="license"></a>
+## License
+
+The cpu_features library is licensed under the terms of the Apache license.
+See [LICENSE](LICENSE) for more information.
+
+<a name="cmake"></a>
+## Build with CMake
+
+Please check the [CMake build instructions](cmake/README.md).
+
+<a name="quickstart"></a>
+### Quickstart with `Ninja`
+
+ - build `list_cpu_features`
+```
+    cmake -B/tmp/cpu_features -H. -GNinja -DCMAKE_BUILD_TYPE=Release
+    ninja -C/tmp/cpu_features
+    /tmp/cpu_features/list_cpu_features --json
+```
+
+ - run tests
+```
+    cmake -B/tmp/cpu_features -H. -GNinja -DBUILD_TESTING=ON
+    ninja -C/tmp/cpu_features
+    ninja -C/tmp/cpu_features test
+```

cpu_features/WORKSPACE

@@ -0,0 +1,7 @@
+# ===== googletest =====
+
+git_repository(
+    name = "com_google_googletest",
+    remote = "https://github.com/google/googletest.git",
+    commit = "c3f65335b79f47b05629e79a54685d899bc53b93",
+)

cpu_features/appveyor.yml

@@ -0,0 +1,24 @@
+version: '{build}'
+shallow_clone: true
+
+platform: x64
+
+environment:
+  matrix:
+  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+    CMAKE_GENERATOR: "Visual Studio 15 2017 Win64"
+  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    CMAKE_GENERATOR: "Visual Studio 14 2015 Win64"
+
+matrix:
+  fast_finish: true
+
+before_build:
+  - cmake --version
+  - cmake -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTING=ON -H. -Bcmake_build -G "%CMAKE_GENERATOR%"
+
+build_script:
+  - cmake --build cmake_build --config Debug --target ALL_BUILD
+
+test_script:
+  - cmake --build cmake_build --config Debug --target RUN_TESTS

cpu_features/cmake/CpuFeaturesConfig.cmake.in

@@ -0,0 +1,3 @@
+# CpuFeatures CMake configuration file
+
+include("${CMAKE_CURRENT_LIST_DIR}/CpuFeaturesTargets.cmake")

cpu_features/cmake/CpuFeaturesNdkCompatConfig.cmake.in

@@ -0,0 +1,3 @@
+# CpuFeaturesNdkCompat CMake configuration file
+
+include("${CMAKE_CURRENT_LIST_DIR}/CpuFeaturesNdkCompatTargets.cmake")

cpu_features/cmake/README.md

@@ -0,0 +1,28 @@
+# CMake build instructions
+
+## Recommended usage : Incorporating cpu_features into a CMake project
+
+  For API / ABI compatibility reasons, it is recommended to build and use
+  cpu_features in a subdirectory of your project or as an embedded dependency.
+
+  This is similar to the recommended usage of the googletest framework
+  ( https://github.com/google/googletest/blob/master/googletest/README.md )
+
+  Build and use step-by-step
+
+
+  1- Download cpu_features and copy it in a sub-directory in your project.
+      or add cpu_features as a git-submodule in your project
+
+  2- You can then use the cmake command `add_subdirectory()` to include
+     cpu_features directly and use the `cpu_features` target in your project.
+
+  3- Add the `cpu_features` target to the `target_link_libraries()` section of
+     your executable or of your library.
+
+## Enabling tests
+
+  CMake default options for cpu_features is Release built type with tests
+  disabled. To enable testing set cmake `BUILD_TESTING` variable to `ON`,
+  [.travis.yml](../.travis.yml) and [appveyor.yml](../appveyor.yml) have up to
+  date examples.

cpu_features/cmake/googletest.CMakeLists.txt.in

@@ -0,0 +1,15 @@
+cmake_minimum_required(VERSION 2.8.2)
+
+project(googletest-download NONE)
+
+include(ExternalProject)
+ExternalProject_Add(googletest
+  GIT_REPOSITORY    https://github.com/google/googletest.git
+  GIT_TAG           master
+  SOURCE_DIR        "${CMAKE_BINARY_DIR}/googletest-src"
+  BINARY_DIR        "${CMAKE_BINARY_DIR}/googletest-build"
+  CONFIGURE_COMMAND ""
+  BUILD_COMMAND     ""
+  INSTALL_COMMAND   ""
+  TEST_COMMAND      ""
+)

cpu_features/include/cpu_features_cache_info.h

@@ -0,0 +1,54 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_INCLUDE_CPUINFO_COMMON_H_
+#define CPU_FEATURES_INCLUDE_CPUINFO_COMMON_H_
+
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+typedef enum {
+  CPU_FEATURE_CACHE_NULL = 0,
+  CPU_FEATURE_CACHE_DATA = 1,
+  CPU_FEATURE_CACHE_INSTRUCTION = 2,
+  CPU_FEATURE_CACHE_UNIFIED = 3,
+  CPU_FEATURE_CACHE_TLB = 4,
+  CPU_FEATURE_CACHE_DTLB = 5,
+  CPU_FEATURE_CACHE_STLB = 6,
+  CPU_FEATURE_CACHE_PREFETCH = 7
+} CacheType;
+
+typedef struct {
+  int level;
+  CacheType cache_type;
+  int cache_size;    // Cache size in bytes
+  int ways;          // Associativity, 0 undefined, 0xFF fully associative
+  int line_size;     // Cache line size in bytes
+  int tlb_entries;   // number of entries for TLB
+  int partitioning;  // number of lines per sector
+} CacheLevelInfo;
+
+// Increase this value if more cache levels are needed.
+#ifndef CPU_FEATURES_MAX_CACHE_LEVEL
+#define CPU_FEATURES_MAX_CACHE_LEVEL 10
+#endif
+typedef struct {
+  int size;
+  CacheLevelInfo levels[CPU_FEATURES_MAX_CACHE_LEVEL];
+} CacheInfo;
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#endif  // CPU_FEATURES_INCLUDE_CPUINFO_COMMON_H_

cpu_features/include/cpu_features_macros.h

@@ -0,0 +1,216 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_INCLUDE_CPU_FEATURES_MACROS_H_
+#define CPU_FEATURES_INCLUDE_CPU_FEATURES_MACROS_H_
+
+////////////////////////////////////////////////////////////////////////////////
+// Architectures
+////////////////////////////////////////////////////////////////////////////////
+
+#if defined(__pnacl__) || defined(__CLR_VER)
+#define CPU_FEATURES_ARCH_VM
+#endif
+
+#if (defined(_M_IX86) || defined(__i386__)) && !defined(CPU_FEATURES_ARCH_VM)
+#define CPU_FEATURES_ARCH_X86_32
+#endif
+
+#if (defined(_M_X64) || defined(__x86_64__)) && !defined(CPU_FEATURES_ARCH_VM)
+#define CPU_FEATURES_ARCH_X86_64
+#endif
+
+#if defined(CPU_FEATURES_ARCH_X86_32) || defined(CPU_FEATURES_ARCH_X86_64)
+#define CPU_FEATURES_ARCH_X86
+#endif
+
+#if (defined(__arm__) || defined(_M_ARM))
+#define CPU_FEATURES_ARCH_ARM
+#endif
+
+#if defined(__aarch64__)
+#define CPU_FEATURES_ARCH_AARCH64
+#endif
+
+#if (defined(CPU_FEATURES_ARCH_AARCH64) || defined(CPU_FEATURES_ARCH_ARM))
+#define CPU_FEATURES_ARCH_ANY_ARM
+#endif
+
+#if defined(__mips64)
+#define CPU_FEATURES_ARCH_MIPS64
+#endif
+
+#if defined(__mips__) && !defined(__mips64)  // mips64 also declares __mips__
+#define CPU_FEATURES_ARCH_MIPS32
+#endif
+
+#if defined(CPU_FEATURES_ARCH_MIPS32) || defined(CPU_FEATURES_ARCH_MIPS64)
+#define CPU_FEATURES_ARCH_MIPS
+#endif
+
+#if defined(__powerpc__)
+#define CPU_FEATURES_ARCH_PPC
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+// Os
+////////////////////////////////////////////////////////////////////////////////
+
+#if defined(__linux__)
+#define CPU_FEATURES_OS_LINUX_OR_ANDROID
+#endif
+
+#if defined(__ANDROID__)
+#define CPU_FEATURES_OS_ANDROID
+#endif
+
+#if (defined(_WIN64) || defined(_WIN32))
+#define CPU_FEATURES_OS_WINDOWS
+#endif
+
+#if (defined(__apple__) || defined(__APPLE__) || defined(__MACH__))
+#define CPU_FEATURES_OS_DARWIN
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+// Compilers
+////////////////////////////////////////////////////////////////////////////////
+
+#if defined(__clang__)
+#define CPU_FEATURES_COMPILER_CLANG
+#endif
+
+#if defined(__GNUC__) && !defined(__clang__)
+#define CPU_FEATURES_COMPILER_GCC
+#endif
+
+#if defined(_MSC_VER)
+#define CPU_FEATURES_COMPILER_MSC
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+// Cpp
+////////////////////////////////////////////////////////////////////////////////
+
+#if defined(__cplusplus)
+#define CPU_FEATURES_START_CPP_NAMESPACE \
+  namespace cpu_features {               \
+  extern "C" {
+#define CPU_FEATURES_END_CPP_NAMESPACE \
+  }                                    \
+  }
+#else
+#define CPU_FEATURES_START_CPP_NAMESPACE
+#define CPU_FEATURES_END_CPP_NAMESPACE
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+// Compiler flags
+////////////////////////////////////////////////////////////////////////////////
+
+// Use the following to check if a feature is known to be available at
+// compile time. See README.md for an example.
+#if defined(CPU_FEATURES_ARCH_X86)
+
+#if defined(__AES__)
+#define CPU_FEATURES_COMPILED_X86_AES 1
+#else
+#define CPU_FEATURES_COMPILED_X86_AES 0
+#endif  //  defined(__AES__)
+
+#if defined(__F16C__)
+#define CPU_FEATURES_COMPILED_X86_F16C 1
+#else
+#define CPU_FEATURES_COMPILED_X86_F16C 0
+#endif  //  defined(__F16C__)
+
+#if defined(__BMI__)
+#define CPU_FEATURES_COMPILED_X86_BMI 1
+#else
+#define CPU_FEATURES_COMPILED_X86_BMI 0
+#endif  //  defined(__BMI__)
+
+#if defined(__BMI2__)
+#define CPU_FEATURES_COMPILED_X86_BMI2 1
+#else
+#define CPU_FEATURES_COMPILED_X86_BMI2 0
+#endif  //  defined(__BMI2__)
+
+#if (defined(__SSE__) || (_M_IX86_FP >= 1))
+#define CPU_FEATURES_COMPILED_X86_SSE 1
+#else
+#define CPU_FEATURES_COMPILED_X86_SSE 0
+#endif
+
+#if (defined(__SSE2__) || (_M_IX86_FP >= 2))
+#define CPU_FEATURES_COMPILED_X86_SSE2 1
+#else
+#define CPU_FEATURES_COMPILED_X86_SSE2 0
+#endif
+
+#if defined(__SSE3__)
+#define CPU_FEATURES_COMPILED_X86_SSE3 1
+#else
+#define CPU_FEATURES_COMPILED_X86_SSE3 0
+#endif  //  defined(__SSE3__)
+
+#if defined(__SSSE3__)
+#define CPU_FEATURES_COMPILED_X86_SSSE3 1
+#else
+#define CPU_FEATURES_COMPILED_X86_SSSE3 0
+#endif  //  defined(__SSSE3__)
+
+#if defined(__SSE4_1__)
+#define CPU_FEATURES_COMPILED_X86_SSE4_1 1
+#else
+#define CPU_FEATURES_COMPILED_X86_SSE4_1 0
+#endif  //  defined(__SSE4_1__)
+
+#if defined(__SSE4_2__)
+#define CPU_FEATURES_COMPILED_X86_SSE4_2 1
+#else
+#define CPU_FEATURES_COMPILED_X86_SSE4_2 0
+#endif  //  defined(__SSE4_2__)
+
+#if defined(__AVX__)
+#define CPU_FEATURES_COMPILED_X86_AVX 1
+#else
+#define CPU_FEATURES_COMPILED_X86_AVX 0
+#endif  //  defined(__AVX__)
+
+#if defined(__AVX2__)
+#define CPU_FEATURES_COMPILED_X86_AVX2 1
+#else
+#define CPU_FEATURES_COMPILED_X86_AVX2 0
+#endif  //  defined(__AVX2__)
+
+#endif  // defined(CPU_FEATURES_ARCH_X86)
+
+#if defined(CPU_FEATURES_ARCH_ANY_ARM)
+#if defined(__ARM_NEON__)
+#define CPU_FEATURES_COMPILED_ANY_ARM_NEON 1
+#else
+#define CPU_FEATURES_COMPILED_ANY_ARM_NEON 0
+#endif  //  defined(__ARM_NEON__)
+#endif  //  defined(CPU_FEATURES_ARCH_ANY_ARM)
+
+#if defined(CPU_FEATURES_ARCH_MIPS)
+#if defined(__mips_msa)
+#define CPU_FEATURES_COMPILED_MIPS_MSA 1
+#else
+#define CPU_FEATURES_COMPILED_MIPS_MSA 0
+#endif  //  defined(__mips_msa)
+#endif  //  defined(CPU_FEATURES_ARCH_MIPS)
+
+#endif  // CPU_FEATURES_INCLUDE_CPU_FEATURES_MACROS_H_

cpu_features/include/cpuinfo_aarch64.h

@@ -0,0 +1,156 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_INCLUDE_CPUINFO_AARCH64_H_
+#define CPU_FEATURES_INCLUDE_CPUINFO_AARCH64_H_
+
+#include "cpu_features_cache_info.h"
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+typedef struct {
+  int fp : 1;          // Floating-point.
+  int asimd : 1;       // Advanced SIMD.
+  int evtstrm : 1;     // Generic timer generated events.
+  int aes : 1;         // Hardware-accelerated Advanced Encryption Standard.
+  int pmull : 1;       // Polynomial multiply long.
+  int sha1 : 1;        // Hardware-accelerated SHA1.
+  int sha2 : 1;        // Hardware-accelerated SHA2-256.
+  int crc32 : 1;       // Hardware-accelerated CRC-32.
+  int atomics : 1;     // Armv8.1 atomic instructions.
+  int fphp : 1;        // Half-precision floating point support.
+  int asimdhp : 1;     // Advanced SIMD half-precision support.
+  int cpuid : 1;       // Access to certain ID registers.
+  int asimdrdm : 1;    // Rounding Double Multiply Accumulate/Subtract.
+  int jscvt : 1;       // Support for JavaScript conversion.
+  int fcma : 1;        // Floating point complex numbers.
+  int lrcpc : 1;       // Support for weaker release consistency.
+  int dcpop : 1;       // Data persistence writeback.
+  int sha3 : 1;        // Hardware-accelerated SHA3.
+  int sm3 : 1;         // Hardware-accelerated SM3.
+  int sm4 : 1;         // Hardware-accelerated SM4.
+  int asimddp : 1;     // Dot product instruction.
+  int sha512 : 1;      // Hardware-accelerated SHA512.
+  int sve : 1;         // Scalable Vector Extension.
+  int asimdfhm : 1;    // Additional half-precision instructions.
+  int dit : 1;         // Data independent timing.
+  int uscat : 1;       // Unaligned atomics support.
+  int ilrcpc : 1;      // Additional support for weaker release consistency.
+  int flagm : 1;       // Flag manipulation instructions.
+  int ssbs : 1;        // Speculative Store Bypass Safe PSTATE bit.
+  int sb : 1;          // Speculation barrier.
+  int paca : 1;        // Address authentication.
+  int pacg : 1;        // Generic authentication.
+  int dcpodp : 1;      // Data cache clean to point of persistence.
+  int sve2 : 1;        // Scalable Vector Extension (version 2).
+  int sveaes : 1;      // SVE AES instructions.
+  int svepmull : 1;    // SVE polynomial multiply long instructions.
+  int svebitperm : 1;  // SVE bit permute instructions.
+  int svesha3 : 1;     // SVE SHA3 instructions.
+  int svesm4 : 1;      // SVE SM4 instructions.
+  int flagm2 : 1;      // Additional flag manipulation instructions.
+  int frint : 1;       // Floating point to integer rounding.
+  int svei8mm : 1;     // SVE Int8 matrix multiplication instructions.
+  int svef32mm : 1;    // SVE FP32 matrix multiplication instruction.
+  int svef64mm : 1;    // SVE FP64 matrix multiplication instructions.
+  int svebf16 : 1;     // SVE BFloat16 instructions.
+  int i8mm : 1;        // Int8 matrix multiplication instructions.
+  int bf16 : 1;        // BFloat16 instructions.
+  int dgh : 1;         // Data Gathering Hint instruction.
+  int rng : 1;         // True random number generator support.
+  int bti : 1;         // Branch target identification.
+
+  // Make sure to update Aarch64FeaturesEnum below if you add a field here.
+} Aarch64Features;
+
+typedef struct {
+  Aarch64Features features;
+  int implementer;
+  int variant;
+  int part;
+  int revision;
+} Aarch64Info;
+
+Aarch64Info GetAarch64Info(void);
+
+////////////////////////////////////////////////////////////////////////////////
+// Introspection functions
+
+typedef enum {
+  AARCH64_FP,
+  AARCH64_ASIMD,
+  AARCH64_EVTSTRM,
+  AARCH64_AES,
+  AARCH64_PMULL,
+  AARCH64_SHA1,
+  AARCH64_SHA2,
+  AARCH64_CRC32,
+  AARCH64_ATOMICS,
+  AARCH64_FPHP,
+  AARCH64_ASIMDHP,
+  AARCH64_CPUID,
+  AARCH64_ASIMDRDM,
+  AARCH64_JSCVT,
+  AARCH64_FCMA,
+  AARCH64_LRCPC,
+  AARCH64_DCPOP,
+  AARCH64_SHA3,
+  AARCH64_SM3,
+  AARCH64_SM4,
+  AARCH64_ASIMDDP,
+  AARCH64_SHA512,
+  AARCH64_SVE,
+  AARCH64_ASIMDFHM,
+  AARCH64_DIT,
+  AARCH64_USCAT,
+  AARCH64_ILRCPC,
+  AARCH64_FLAGM,
+  AARCH64_SSBS,
+  AARCH64_SB,
+  AARCH64_PACA,
+  AARCH64_PACG,
+  AARCH64_DCPODP,
+  AARCH64_SVE2,
+  AARCH64_SVEAES,
+  AARCH64_SVEPMULL,
+  AARCH64_SVEBITPERM,
+  AARCH64_SVESHA3,
+  AARCH64_SVESM4,
+  AARCH64_FLAGM2,
+  AARCH64_FRINT,
+  AARCH64_SVEI8MM,
+  AARCH64_SVEF32MM,
+  AARCH64_SVEF64MM,
+  AARCH64_SVEBF16,
+  AARCH64_I8MM,
+  AARCH64_BF16,
+  AARCH64_DGH,
+  AARCH64_RNG,
+  AARCH64_BTI,
+  AARCH64_LAST_,
+} Aarch64FeaturesEnum;
+
+int GetAarch64FeaturesEnumValue(const Aarch64Features* features,
+                                Aarch64FeaturesEnum value);
+
+const char* GetAarch64FeaturesEnumName(Aarch64FeaturesEnum);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#if !defined(CPU_FEATURES_ARCH_AARCH64)
+#error "Including cpuinfo_aarch64.h from a non-aarch64 target."
+#endif
+
+#endif  // CPU_FEATURES_INCLUDE_CPUINFO_AARCH64_H_

cpu_features/include/cpuinfo_arm.h

@@ -0,0 +1,121 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_INCLUDE_CPUINFO_ARM_H_
+#define CPU_FEATURES_INCLUDE_CPUINFO_ARM_H_
+
+#include <stdint.h>  // uint32_t
+
+#include "cpu_features_cache_info.h"
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+typedef struct {
+  int swp : 1;       // SWP instruction (atomic read-modify-write)
+  int half : 1;      // Half-word loads and stores
+  int thumb : 1;     // Thumb (16-bit instruction set)
+  int _26bit : 1;    // "26 Bit" Model (Processor status register folded into
+                     // program counter)
+  int fastmult : 1;  // 32x32->64-bit multiplication
+  int fpa : 1;       // Floating point accelerator
+  int vfp : 1;       // Vector Floating Point.
+  int edsp : 1;     // DSP extensions (the 'e' variant of the ARM9 CPUs, and all
+                    // others above)
+  int java : 1;     // Jazelle (Java bytecode accelerator)
+  int iwmmxt : 1;   // Intel Wireless MMX Technology.
+  int crunch : 1;   // MaverickCrunch coprocessor
+  int thumbee : 1;  // ThumbEE
+  int neon : 1;     // Advanced SIMD.
+  int vfpv3 : 1;    // VFP version 3
+  int vfpv3d16 : 1;  // VFP version 3 with 16 D-registers
+  int tls : 1;       // TLS register
+  int vfpv4 : 1;     // VFP version 4 with fast context switching
+  int idiva : 1;     // SDIV and UDIV hardware division in ARM mode.
+  int idivt : 1;     // SDIV and UDIV hardware division in Thumb mode.
+  int vfpd32 : 1;    // VFP with 32 D-registers
+  int lpae : 1;     // Large Physical Address Extension (>4GB physical memory on
+                    // 32-bit architecture)
+  int evtstrm : 1;  // kernel event stream using generic architected timer
+  int aes : 1;      // Hardware-accelerated Advanced Encryption Standard.
+  int pmull : 1;    // Polynomial multiply long.
+  int sha1 : 1;     // Hardware-accelerated SHA1.
+  int sha2 : 1;     // Hardware-accelerated SHA2-256.
+  int crc32 : 1;    // Hardware-accelerated CRC-32.
+
+  // Make sure to update ArmFeaturesEnum below if you add a field here.
+} ArmFeatures;
+
+typedef struct {
+  ArmFeatures features;
+  int implementer;
+  int architecture;
+  int variant;
+  int part;
+  int revision;
+} ArmInfo;
+
+// TODO(user): Add macros to know which features are present at compile
+// time.
+
+ArmInfo GetArmInfo(void);
+
+// Compute CpuId from ArmInfo.
+uint32_t GetArmCpuId(const ArmInfo* const info);
+
+////////////////////////////////////////////////////////////////////////////////
+// Introspection functions
+
+typedef enum {
+  ARM_SWP,
+  ARM_HALF,
+  ARM_THUMB,
+  ARM_26BIT,
+  ARM_FASTMULT,
+  ARM_FPA,
+  ARM_VFP,
+  ARM_EDSP,
+  ARM_JAVA,
+  ARM_IWMMXT,
+  ARM_CRUNCH,
+  ARM_THUMBEE,
+  ARM_NEON,
+  ARM_VFPV3,
+  ARM_VFPV3D16,
+  ARM_TLS,
+  ARM_VFPV4,
+  ARM_IDIVA,
+  ARM_IDIVT,
+  ARM_VFPD32,
+  ARM_LPAE,
+  ARM_EVTSTRM,
+  ARM_AES,
+  ARM_PMULL,
+  ARM_SHA1,
+  ARM_SHA2,
+  ARM_CRC32,
+  ARM_LAST_,
+} ArmFeaturesEnum;
+
+int GetArmFeaturesEnumValue(const ArmFeatures* features, ArmFeaturesEnum value);
+
+const char* GetArmFeaturesEnumName(ArmFeaturesEnum);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#if !defined(CPU_FEATURES_ARCH_ARM)
+#error "Including cpuinfo_arm.h from a non-arm target."
+#endif
+
+#endif  // CPU_FEATURES_INCLUDE_CPUINFO_ARM_H_

cpu_features/include/cpuinfo_mips.h

@@ -0,0 +1,60 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_INCLUDE_CPUINFO_MIPS_H_
+#define CPU_FEATURES_INCLUDE_CPUINFO_MIPS_H_
+
+#include "cpu_features_cache_info.h"
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+typedef struct {
+  int msa : 1;  // MIPS SIMD Architecture
+                // https://www.mips.com/products/architectures/ase/simd/
+  int eva : 1;  // Enhanced Virtual Addressing
+                // https://www.mips.com/products/architectures/mips64/
+  int r6 : 1;   // True if is release 6 of the processor.
+
+  // Make sure to update MipsFeaturesEnum below if you add a field here.
+} MipsFeatures;
+
+typedef struct {
+  MipsFeatures features;
+} MipsInfo;
+
+MipsInfo GetMipsInfo(void);
+
+////////////////////////////////////////////////////////////////////////////////
+// Introspection functions
+
+typedef enum {
+  MIPS_MSA,
+  MIPS_EVA,
+  MIPS_R6,
+  MIPS_LAST_,
+} MipsFeaturesEnum;
+
+int GetMipsFeaturesEnumValue(const MipsFeatures* features,
+                             MipsFeaturesEnum value);
+
+const char* GetMipsFeaturesEnumName(MipsFeaturesEnum);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#if !defined(CPU_FEATURES_ARCH_MIPS)
+#error "Including cpuinfo_mips.h from a non-mips target."
+#endif
+
+#endif  // CPU_FEATURES_INCLUDE_CPUINFO_MIPS_H_

cpu_features/include/cpuinfo_ppc.h

@@ -0,0 +1,146 @@
+// Copyright 2018 IBM
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_INCLUDE_CPUINFO_PPC_H_
+#define CPU_FEATURES_INCLUDE_CPUINFO_PPC_H_
+
+#include "cpu_features_cache_info.h"
+#include "cpu_features_macros.h"
+#include "internal/hwcaps.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+typedef struct {
+  int ppc32 : 1;
+  int ppc64 : 1;
+  int ppc601 : 1;
+  int altivec : 1;
+  int fpu : 1;
+  int mmu : 1;
+  int mac_4xx : 1;
+  int unifiedcache : 1;
+  int spe : 1;
+  int efpsingle : 1;
+  int efpdouble : 1;
+  int no_tb : 1;
+  int power4 : 1;
+  int power5 : 1;
+  int power5plus : 1;
+  int cell : 1;
+  int booke : 1;
+  int smt : 1;
+  int icachesnoop : 1;
+  int arch205 : 1;
+  int pa6t : 1;
+  int dfp : 1;
+  int power6ext : 1;
+  int arch206 : 1;
+  int vsx : 1;
+  int pseries_perfmon_compat : 1;
+  int truele : 1;
+  int ppcle : 1;
+  int arch207 : 1;
+  int htm : 1;
+  int dscr : 1;
+  int ebb : 1;
+  int isel : 1;
+  int tar : 1;
+  int vcrypto : 1;
+  int htm_nosc : 1;
+  int arch300 : 1;
+  int ieee128 : 1;
+  int darn : 1;
+  int scv : 1;
+  int htm_no_suspend : 1;
+
+  // Make sure to update PPCFeaturesEnum below if you add a field here.
+} PPCFeatures;
+
+typedef struct {
+  PPCFeatures features;
+} PPCInfo;
+
+// This function is guaranteed to be malloc, memset and memcpy free.
+PPCInfo GetPPCInfo(void);
+
+typedef struct {
+  char platform[64];  // 0 terminated string
+  char model[64];     // 0 terminated string
+  char machine[64];   // 0 terminated string
+  char cpu[64];       // 0 terminated string
+  PlatformType type;
+} PPCPlatformStrings;
+
+PPCPlatformStrings GetPPCPlatformStrings(void);
+
+////////////////////////////////////////////////////////////////////////////////
+// Introspection functions
+
+typedef enum {
+  PPC_32,          /* 32 bit mode execution */
+  PPC_64,          /* 64 bit mode execution */
+  PPC_601_INSTR,   /* Old POWER ISA */
+  PPC_HAS_ALTIVEC, /* SIMD Unit*/
+  PPC_HAS_FPU,     /* Floating Point Unit */
+  PPC_HAS_MMU,     /* Memory management unit */
+  PPC_HAS_4xxMAC,
+  PPC_UNIFIED_CACHE,  /* Unified instruction and data cache */
+  PPC_HAS_SPE,        /* Signal processing extention unit */
+  PPC_HAS_EFP_SINGLE, /* SPE single precision fpu */
+  PPC_HAS_EFP_DOUBLE, /* SPE double precision fpu */
+  PPC_NO_TB,          /* No timebase */
+  PPC_POWER4,
+  PPC_POWER5,
+  PPC_POWER5_PLUS,
+  PPC_CELL,  /* Cell broadband engine */
+  PPC_BOOKE, /* Embedded ISA */
+  PPC_SMT,   /* Simultaneous multi-threading */
+  PPC_ICACHE_SNOOP,
+  PPC_ARCH_2_05, /* ISA 2.05 - POWER6 */
+  PPC_PA6T,      /* PA Semi 6T core ISA */
+  PPC_HAS_DFP,   /* Decimal floating point unit */
+  PPC_POWER6_EXT,
+  PPC_ARCH_2_06,              /* ISA 2.06 - POWER7 */
+  PPC_HAS_VSX,                /* Vector-scalar extension */
+  PPC_PSERIES_PERFMON_COMPAT, /* Set of backwards compatibile performance
+                                 monitoring events */
+  PPC_TRUE_LE,
+  PPC_PPC_LE,
+  PPC_ARCH_2_07,      /* ISA 2.07 - POWER8 */
+  PPC_HTM,            /* Hardware Transactional Memory */
+  PPC_DSCR,           /* Data stream control register */
+  PPC_EBB,            /* Event base branching */
+  PPC_ISEL,           /* Integer select instructions */
+  PPC_TAR,            /* Target address register */
+  PPC_VEC_CRYPTO,     /* Vector cryptography instructions */
+  PPC_HTM_NOSC,       /* Transactions aborted when syscall made*/
+  PPC_ARCH_3_00,      /* ISA 3.00 - POWER9 */
+  PPC_HAS_IEEE128,    /* VSX IEEE Binary Float 128-bit */
+  PPC_DARN,           /* Deliver a random number instruction */
+  PPC_SCV,            /* scv syscall */
+  PPC_HTM_NO_SUSPEND, /* TM w/out suspended state */
+  PPC_LAST_,
+} PPCFeaturesEnum;
+
+int GetPPCFeaturesEnumValue(const PPCFeatures* features, PPCFeaturesEnum value);
+
+const char* GetPPCFeaturesEnumName(PPCFeaturesEnum);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#if !defined(CPU_FEATURES_ARCH_PPC)
+#error "Including cpuinfo_ppc.h from a non-ppc target."
+#endif
+
+#endif  // CPU_FEATURES_INCLUDE_CPUINFO_PPC_H_

cpu_features/include/cpuinfo_x86.h

@@ -0,0 +1,231 @@
+// Copyright 2017 Google LLC
+// Copyright 2020 Intel Corporation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_INCLUDE_CPUINFO_X86_H_
+#define CPU_FEATURES_INCLUDE_CPUINFO_X86_H_
+
+#include "cpu_features_cache_info.h"
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+// See https://en.wikipedia.org/wiki/CPUID for a list of x86 cpu features.
+// The field names are based on the short name provided in the wikipedia tables.
+typedef struct {
+  int fpu : 1;
+  int tsc : 1;
+  int cx8 : 1;
+  int clfsh : 1;
+  int mmx : 1;
+  int aes : 1;
+  int erms : 1;
+  int f16c : 1;
+  int fma4 : 1;
+  int fma3 : 1;
+  int vaes : 1;
+  int vpclmulqdq : 1;
+  int bmi1 : 1;
+  int hle : 1;
+  int bmi2 : 1;
+  int rtm : 1;
+  int rdseed : 1;
+  int clflushopt : 1;
+  int clwb : 1;
+
+  int sse : 1;
+  int sse2 : 1;
+  int sse3 : 1;
+  int ssse3 : 1;
+  int sse4_1 : 1;
+  int sse4_2 : 1;
+  int sse4a : 1;
+
+  int avx : 1;
+  int avx2 : 1;
+
+  int avx512f : 1;
+  int avx512cd : 1;
+  int avx512er : 1;
+  int avx512pf : 1;
+  int avx512bw : 1;
+  int avx512dq : 1;
+  int avx512vl : 1;
+  int avx512ifma : 1;
+  int avx512vbmi : 1;
+  int avx512vbmi2 : 1;
+  int avx512vnni : 1;
+  int avx512bitalg : 1;
+  int avx512vpopcntdq : 1;
+  int avx512_4vnniw : 1;
+  int avx512_4vbmi2 : 1;
+  int avx512_second_fma : 1;
+  int avx512_4fmaps : 1;
+  int avx512_bf16 : 1;
+  int avx512_vp2intersect : 1;
+  int amx_bf16 : 1;
+  int amx_tile : 1;
+  int amx_int8 : 1;
+
+  int pclmulqdq : 1;
+  int smx : 1;
+  int sgx : 1;
+  int cx16 : 1;  // aka. CMPXCHG16B
+  int sha : 1;
+  int popcnt : 1;
+  int movbe : 1;
+  int rdrnd : 1;
+
+  int dca : 1;
+  int ss : 1;
+  // Make sure to update X86FeaturesEnum below if you add a field here.
+} X86Features;
+
+typedef struct {
+  X86Features features;
+  int family;
+  int model;
+  int stepping;
+  char vendor[13];  // 0 terminated string
+} X86Info;
+
+// Calls cpuid and returns an initialized X86info.
+// This function is guaranteed to be malloc, memset and memcpy free.
+X86Info GetX86Info(void);
+
+// Returns cache hierarchy informations.
+// Can call cpuid multiple times.
+// Only works on Intel CPU at the moment.
+// This function is guaranteed to be malloc, memset and memcpy free.
+CacheInfo GetX86CacheInfo(void);
+
+typedef enum {
+  X86_UNKNOWN,
+  INTEL_CORE,      // CORE
+  INTEL_PNR,       // PENRYN
+  INTEL_NHM,       // NEHALEM
+  INTEL_ATOM_BNL,  // BONNELL
+  INTEL_WSM,       // WESTMERE
+  INTEL_SNB,       // SANDYBRIDGE
+  INTEL_IVB,       // IVYBRIDGE
+  INTEL_ATOM_SMT,  // SILVERMONT
+  INTEL_HSW,       // HASWELL
+  INTEL_BDW,       // BROADWELL
+  INTEL_SKL,       // SKYLAKE
+  INTEL_ATOM_GMT,  // GOLDMONT
+  INTEL_KBL,       // KABY LAKE
+  INTEL_CFL,       // COFFEE LAKE
+  INTEL_WHL,       // WHISKEY LAKE
+  INTEL_CNL,       // CANNON LAKE
+  INTEL_ICL,       // ICE LAKE
+  INTEL_TGL,       // TIGER LAKE
+  INTEL_SPR,       // SAPPHIRE RAPIDS
+  AMD_HAMMER,      // K8
+  AMD_K10,         // K10
+  AMD_BOBCAT,      // K14
+  AMD_BULLDOZER,   // K15
+  AMD_JAGUAR,      // K16
+  AMD_ZEN,         // K17
+} X86Microarchitecture;
+
+// Returns the underlying microarchitecture by looking at X86Info's vendor,
+// family and model.
+X86Microarchitecture GetX86Microarchitecture(const X86Info* info);
+
+// Calls cpuid and fills the brand_string.
+// - brand_string *must* be of size 49 (beware of array decaying).
+// - brand_string will be zero terminated.
+// - This function calls memcpy.
+void FillX86BrandString(char brand_string[49]);
+
+////////////////////////////////////////////////////////////////////////////////
+// Introspection functions
+
+typedef enum {
+  X86_FPU,
+  X86_TSC,
+  X86_CX8,
+  X86_CLFSH,
+  X86_MMX,
+  X86_AES,
+  X86_ERMS,
+  X86_F16C,
+  X86_FMA4,
+  X86_FMA3,
+  X86_VAES,
+  X86_VPCLMULQDQ,
+  X86_BMI1,
+  X86_HLE,
+  X86_BMI2,
+  X86_RTM,
+  X86_RDSEED,
+  X86_CLFLUSHOPT,
+  X86_CLWB,
+  X86_SSE,
+  X86_SSE2,
+  X86_SSE3,
+  X86_SSSE3,
+  X86_SSE4_1,
+  X86_SSE4_2,
+  X86_SSE4A,
+  X86_AVX,
+  X86_AVX2,
+  X86_AVX512F,
+  X86_AVX512CD,
+  X86_AVX512ER,
+  X86_AVX512PF,
+  X86_AVX512BW,
+  X86_AVX512DQ,
+  X86_AVX512VL,
+  X86_AVX512IFMA,
+  X86_AVX512VBMI,
+  X86_AVX512VBMI2,
+  X86_AVX512VNNI,
+  X86_AVX512BITALG,
+  X86_AVX512VPOPCNTDQ,
+  X86_AVX512_4VNNIW,
+  X86_AVX512_4VBMI2,
+  X86_AVX512_SECOND_FMA,
+  X86_AVX512_4FMAPS,
+  X86_AVX512_BF16,
+  X86_AVX512_VP2INTERSECT,
+  X86_AMX_BF16,
+  X86_AMX_TILE,
+  X86_AMX_INT8,
+  X86_PCLMULQDQ,
+  X86_SMX,
+  X86_SGX,
+  X86_CX16,
+  X86_SHA,
+  X86_POPCNT,
+  X86_MOVBE,
+  X86_RDRND,
+  X86_DCA,
+  X86_SS,
+  X86_LAST_,
+} X86FeaturesEnum;
+
+int GetX86FeaturesEnumValue(const X86Features* features, X86FeaturesEnum value);
+
+const char* GetX86FeaturesEnumName(X86FeaturesEnum);
+
+const char* GetX86MicroarchitectureName(X86Microarchitecture);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#if !defined(CPU_FEATURES_ARCH_X86)
+#error "Including cpuinfo_x86.h from a non-x86 target."
+#endif
+
+#endif  // CPU_FEATURES_INCLUDE_CPUINFO_X86_H_

cpu_features/include/internal/bit_utils.h

@@ -0,0 +1,40 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_INCLUDE_INTERNAL_BIT_UTILS_H_
+#define CPU_FEATURES_INCLUDE_INTERNAL_BIT_UTILS_H_
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+inline static bool IsBitSet(uint32_t reg, uint32_t bit) {
+  return (reg >> bit) & 0x1;
+}
+
+inline static uint32_t ExtractBitRange(uint32_t reg, uint32_t msb,
+                                       uint32_t lsb) {
+  const uint64_t bits = msb - lsb + 1ULL;
+  const uint64_t mask = (1ULL << bits) - 1ULL;
+  assert(msb >= lsb);
+  return (reg >> lsb) & mask;
+}
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#endif  // CPU_FEATURES_INCLUDE_INTERNAL_BIT_UTILS_H_

cpu_features/include/internal/cpuid_x86.h

@@ -0,0 +1,37 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_INCLUDE_INTERNAL_CPUID_X86_H_
+#define CPU_FEATURES_INCLUDE_INTERNAL_CPUID_X86_H_
+
+#include <stdint.h>
+
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+// A struct to hold the result of a call to cpuid.
+typedef struct {
+  uint32_t eax, ebx, ecx, edx;
+} Leaf;
+
+// Returns the result of a call to the cpuid instruction.
+Leaf GetCpuidLeaf(uint32_t leaf_id, int ecx);
+
+// Returns the eax value of the XCR0 register.
+uint32_t GetXCR0Eax(void);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#endif  // CPU_FEATURES_INCLUDE_INTERNAL_CPUID_X86_H_

cpu_features/include/internal/filesystem.h

@@ -0,0 +1,39 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// An interface for the filesystem that allows mocking the filesystem in
+// unittests.
+#ifndef CPU_FEATURES_INCLUDE_INTERNAL_FILESYSTEM_H_
+#define CPU_FEATURES_INCLUDE_INTERNAL_FILESYSTEM_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+// Same as linux "open(filename, O_RDONLY)", retries automatically on EINTR.
+int CpuFeatures_OpenFile(const char* filename);
+
+// Same as linux "read(file_descriptor, buffer, buffer_size)", retries
+// automatically on EINTR.
+int CpuFeatures_ReadFile(int file_descriptor, void* buffer, size_t buffer_size);
+
+// Same as linux "close(file_descriptor)".
+void CpuFeatures_CloseFile(int file_descriptor);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#endif  // CPU_FEATURES_INCLUDE_INTERNAL_FILESYSTEM_H_

cpu_features/include/internal/hwcaps.h

@@ -0,0 +1,186 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Interface to retrieve hardware capabilities. It relies on Linux's getauxval
+// or `/proc/self/auxval` under the hood.
+#ifndef CPU_FEATURES_INCLUDE_INTERNAL_HWCAPS_H_
+#define CPU_FEATURES_INCLUDE_INTERNAL_HWCAPS_H_
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+// To avoid depending on the linux kernel we reproduce the architecture specific
+// constants here.
+
+// http://elixir.free-electrons.com/linux/latest/source/arch/arm64/include/uapi/asm/hwcap.h
+#define AARCH64_HWCAP_FP (1UL << 0)
+#define AARCH64_HWCAP_ASIMD (1UL << 1)
+#define AARCH64_HWCAP_EVTSTRM (1UL << 2)
+#define AARCH64_HWCAP_AES (1UL << 3)
+#define AARCH64_HWCAP_PMULL (1UL << 4)
+#define AARCH64_HWCAP_SHA1 (1UL << 5)
+#define AARCH64_HWCAP_SHA2 (1UL << 6)
+#define AARCH64_HWCAP_CRC32 (1UL << 7)
+#define AARCH64_HWCAP_ATOMICS (1UL << 8)
+#define AARCH64_HWCAP_FPHP (1UL << 9)
+#define AARCH64_HWCAP_ASIMDHP (1UL << 10)
+#define AARCH64_HWCAP_CPUID (1UL << 11)
+#define AARCH64_HWCAP_ASIMDRDM (1UL << 12)
+#define AARCH64_HWCAP_JSCVT (1UL << 13)
+#define AARCH64_HWCAP_FCMA (1UL << 14)
+#define AARCH64_HWCAP_LRCPC (1UL << 15)
+#define AARCH64_HWCAP_DCPOP (1UL << 16)
+#define AARCH64_HWCAP_SHA3 (1UL << 17)
+#define AARCH64_HWCAP_SM3 (1UL << 18)
+#define AARCH64_HWCAP_SM4 (1UL << 19)
+#define AARCH64_HWCAP_ASIMDDP (1UL << 20)
+#define AARCH64_HWCAP_SHA512 (1UL << 21)
+#define AARCH64_HWCAP_SVE (1UL << 22)
+#define AARCH64_HWCAP_ASIMDFHM (1UL << 23)
+#define AARCH64_HWCAP_DIT (1UL << 24)
+#define AARCH64_HWCAP_USCAT (1UL << 25)
+#define AARCH64_HWCAP_ILRCPC (1UL << 26)
+#define AARCH64_HWCAP_FLAGM (1UL << 27)
+#define AARCH64_HWCAP_SSBS (1UL << 28)
+#define AARCH64_HWCAP_SB (1UL << 29)
+#define AARCH64_HWCAP_PACA (1UL << 30)
+#define AARCH64_HWCAP_PACG (1UL << 31)
+
+#define AARCH64_HWCAP2_DCPODP (1UL << 0)
+#define AARCH64_HWCAP2_SVE2 (1UL << 1)
+#define AARCH64_HWCAP2_SVEAES (1UL << 2)
+#define AARCH64_HWCAP2_SVEPMULL (1UL << 3)
+#define AARCH64_HWCAP2_SVEBITPERM (1UL << 4)
+#define AARCH64_HWCAP2_SVESHA3 (1UL << 5)
+#define AARCH64_HWCAP2_SVESM4 (1UL << 6)
+#define AARCH64_HWCAP2_FLAGM2 (1UL << 7)
+#define AARCH64_HWCAP2_FRINT (1UL << 8)
+#define AARCH64_HWCAP2_SVEI8MM (1UL << 9)
+#define AARCH64_HWCAP2_SVEF32MM (1UL << 10)
+#define AARCH64_HWCAP2_SVEF64MM (1UL << 11)
+#define AARCH64_HWCAP2_SVEBF16 (1UL << 12)
+#define AARCH64_HWCAP2_I8MM (1UL << 13)
+#define AARCH64_HWCAP2_BF16 (1UL << 14)
+#define AARCH64_HWCAP2_DGH (1UL << 15)
+#define AARCH64_HWCAP2_RNG (1UL << 16)
+#define AARCH64_HWCAP2_BTI (1UL << 17)
+
+// http://elixir.free-electrons.com/linux/latest/source/arch/arm/include/uapi/asm/hwcap.h
+#define ARM_HWCAP_SWP (1UL << 0)
+#define ARM_HWCAP_HALF (1UL << 1)
+#define ARM_HWCAP_THUMB (1UL << 2)
+#define ARM_HWCAP_26BIT (1UL << 3)
+#define ARM_HWCAP_FAST_MULT (1UL << 4)
+#define ARM_HWCAP_FPA (1UL << 5)
+#define ARM_HWCAP_VFP (1UL << 6)
+#define ARM_HWCAP_EDSP (1UL << 7)
+#define ARM_HWCAP_JAVA (1UL << 8)
+#define ARM_HWCAP_IWMMXT (1UL << 9)
+#define ARM_HWCAP_CRUNCH (1UL << 10)
+#define ARM_HWCAP_THUMBEE (1UL << 11)
+#define ARM_HWCAP_NEON (1UL << 12)
+#define ARM_HWCAP_VFPV3 (1UL << 13)
+#define ARM_HWCAP_VFPV3D16 (1UL << 14)
+#define ARM_HWCAP_TLS (1UL << 15)
+#define ARM_HWCAP_VFPV4 (1UL << 16)
+#define ARM_HWCAP_IDIVA (1UL << 17)
+#define ARM_HWCAP_IDIVT (1UL << 18)
+#define ARM_HWCAP_VFPD32 (1UL << 19)
+#define ARM_HWCAP_LPAE (1UL << 20)
+#define ARM_HWCAP_EVTSTRM (1UL << 21)
+#define ARM_HWCAP2_AES (1UL << 0)
+#define ARM_HWCAP2_PMULL (1UL << 1)
+#define ARM_HWCAP2_SHA1 (1UL << 2)
+#define ARM_HWCAP2_SHA2 (1UL << 3)
+#define ARM_HWCAP2_CRC32 (1UL << 4)
+
+// http://elixir.free-electrons.com/linux/latest/source/arch/mips/include/uapi/asm/hwcap.h
+#define MIPS_HWCAP_R6 (1UL << 0)
+#define MIPS_HWCAP_MSA (1UL << 1)
+#define MIPS_HWCAP_CRC32 (1UL << 2)
+
+// http://elixir.free-electrons.com/linux/latest/source/arch/powerpc/include/uapi/asm/cputable.h
+#ifndef _UAPI__ASM_POWERPC_CPUTABLE_H
+/* in AT_HWCAP */
+#define PPC_FEATURE_32 0x80000000
+#define PPC_FEATURE_64 0x40000000
+#define PPC_FEATURE_601_INSTR 0x20000000
+#define PPC_FEATURE_HAS_ALTIVEC 0x10000000
+#define PPC_FEATURE_HAS_FPU 0x08000000
+#define PPC_FEATURE_HAS_MMU 0x04000000
+#define PPC_FEATURE_HAS_4xxMAC 0x02000000
+#define PPC_FEATURE_UNIFIED_CACHE 0x01000000
+#define PPC_FEATURE_HAS_SPE 0x00800000
+#define PPC_FEATURE_HAS_EFP_SINGLE 0x00400000
+#define PPC_FEATURE_HAS_EFP_DOUBLE 0x00200000
+#define PPC_FEATURE_NO_TB 0x00100000
+#define PPC_FEATURE_POWER4 0x00080000
+#define PPC_FEATURE_POWER5 0x00040000
+#define PPC_FEATURE_POWER5_PLUS 0x00020000
+#define PPC_FEATURE_CELL 0x00010000
+#define PPC_FEATURE_BOOKE 0x00008000
+#define PPC_FEATURE_SMT 0x00004000
+#define PPC_FEATURE_ICACHE_SNOOP 0x00002000
+#define PPC_FEATURE_ARCH_2_05 0x00001000
+#define PPC_FEATURE_PA6T 0x00000800
+#define PPC_FEATURE_HAS_DFP 0x00000400
+#define PPC_FEATURE_POWER6_EXT 0x00000200
+#define PPC_FEATURE_ARCH_2_06 0x00000100
+#define PPC_FEATURE_HAS_VSX 0x00000080
+
+#define PPC_FEATURE_PSERIES_PERFMON_COMPAT 0x00000040
+
+/* Reserved - do not use                0x00000004 */
+#define PPC_FEATURE_TRUE_LE 0x00000002
+#define PPC_FEATURE_PPC_LE 0x00000001
+
+/* in AT_HWCAP2 */
+#define PPC_FEATURE2_ARCH_2_07 0x80000000
+#define PPC_FEATURE2_HTM 0x40000000
+#define PPC_FEATURE2_DSCR 0x20000000
+#define PPC_FEATURE2_EBB 0x10000000
+#define PPC_FEATURE2_ISEL 0x08000000
+#define PPC_FEATURE2_TAR 0x04000000
+#define PPC_FEATURE2_VEC_CRYPTO 0x02000000
+#define PPC_FEATURE2_HTM_NOSC 0x01000000
+#define PPC_FEATURE2_ARCH_3_00 0x00800000
+#define PPC_FEATURE2_HAS_IEEE128 0x00400000
+#define PPC_FEATURE2_DARN 0x00200000
+#define PPC_FEATURE2_SCV 0x00100000
+#define PPC_FEATURE2_HTM_NO_SUSPEND 0x00080000
+#endif
+
+typedef struct {
+  unsigned long hwcaps;
+  unsigned long hwcaps2;
+} HardwareCapabilities;
+
+HardwareCapabilities CpuFeatures_GetHardwareCapabilities(void);
+bool CpuFeatures_IsHwCapsSet(const HardwareCapabilities hwcaps_mask,
+                             const HardwareCapabilities hwcaps);
+
+typedef struct {
+  char platform[64];       // 0 terminated string
+  char base_platform[64];  // 0 terminated string
+} PlatformType;
+
+PlatformType CpuFeatures_GetPlatformType(void);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#endif  // CPU_FEATURES_INCLUDE_INTERNAL_HWCAPS_H_

cpu_features/include/internal/stack_line_reader.h

@@ -0,0 +1,49 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Reads a file line by line and stores the data on the stack. This allows
+// parsing files in one go without allocating.
+#ifndef CPU_FEATURES_INCLUDE_INTERNAL_STACK_LINE_READER_H_
+#define CPU_FEATURES_INCLUDE_INTERNAL_STACK_LINE_READER_H_
+
+#include <stdbool.h>
+
+#include "cpu_features_macros.h"
+#include "internal/string_view.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+typedef struct {
+  char buffer[STACK_LINE_READER_BUFFER_SIZE];
+  StringView view;
+  int fd;
+  bool skip_mode;
+} StackLineReader;
+
+// Initializes a StackLineReader.
+void StackLineReader_Initialize(StackLineReader* reader, int fd);
+
+typedef struct {
+  StringView line;  // A view of the line.
+  bool eof;         // Nothing more to read, we reached EOF.
+  bool full_line;   // If false the line was truncated to
+                    // STACK_LINE_READER_BUFFER_SIZE.
+} LineResult;
+
+// Reads the file pointed to by fd and tries to read a full line.
+LineResult StackLineReader_NextLine(StackLineReader* reader);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#endif  // CPU_FEATURES_INCLUDE_INTERNAL_STACK_LINE_READER_H_

cpu_features/include/internal/string_view.h

@@ -0,0 +1,109 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// A view over a piece of string. The view is not 0 terminated.
+#ifndef CPU_FEATURES_INCLUDE_INTERNAL_STRING_VIEW_H_
+#define CPU_FEATURES_INCLUDE_INTERNAL_STRING_VIEW_H_
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+
+#include "cpu_features_macros.h"
+
+CPU_FEATURES_START_CPP_NAMESPACE
+
+typedef struct {
+  const char* ptr;
+  size_t size;
+} StringView;
+
+#ifdef __cplusplus
+static const StringView kEmptyStringView = {NULL, 0};
+#else
+static const StringView kEmptyStringView;
+#endif
+
+// Returns a StringView from the provided string.
+// Passing NULL is valid only if size is 0.
+static inline StringView view(const char* str, const size_t size) {
+  StringView view;
+  view.ptr = str;
+  view.size = size;
+  return view;
+}
+
+static inline StringView str(const char* str) { return view(str, strlen(str)); }
+
+// Returns the index of the first occurrence of c in view or -1 if not found.
+int CpuFeatures_StringView_IndexOfChar(const StringView view, char c);
+
+// Returns the index of the first occurrence of sub_view in view or -1 if not
+// found.
+int CpuFeatures_StringView_IndexOf(const StringView view,
+                                   const StringView sub_view);
+
+// Returns whether a is equal to b (same content).
+bool CpuFeatures_StringView_IsEquals(const StringView a, const StringView b);
+
+// Returns whether a starts with b.
+bool CpuFeatures_StringView_StartsWith(const StringView a, const StringView b);
+
+// Removes count characters from the beginning of view or kEmptyStringView if
+// count if greater than view.size.
+StringView CpuFeatures_StringView_PopFront(const StringView str_view,
+                                           size_t count);
+
+// Removes count characters from the end of view or kEmptyStringView if count if
+// greater than view.size.
+StringView CpuFeatures_StringView_PopBack(const StringView str_view,
+                                          size_t count);
+
+// Keeps the count first characters of view or view if count if greater than
+// view.size.
+StringView CpuFeatures_StringView_KeepFront(const StringView str_view,
+                                            size_t count);
+
+// Retrieves the first character of view. If view is empty the behavior is
+// undefined.
+char CpuFeatures_StringView_Front(const StringView view);
+
+// Retrieves the last character of view. If view is empty the behavior is
+// undefined.
+char CpuFeatures_StringView_Back(const StringView view);
+
+// Removes leading and tailing space characters.
+StringView CpuFeatures_StringView_TrimWhitespace(StringView view);
+
+// Convert StringView to positive integer. e.g. "42", "0x2a".
+// Returns -1 on error.
+int CpuFeatures_StringView_ParsePositiveNumber(const StringView view);
+
+// Copies src StringView to dst buffer.
+void CpuFeatures_StringView_CopyString(const StringView src, char* dst,
+                                       size_t dst_size);
+
+// Checks if line contains the specified whitespace separated word.
+bool CpuFeatures_StringView_HasWord(const StringView line,
+                                    const char* const word);
+
+// Get key/value from line. key and value are separated by ": ".
+// key and value are cleaned up from leading and trailing whitespaces.
+bool CpuFeatures_StringView_GetAttributeKeyValue(const StringView line,
+                                                 StringView* key,
+                                                 StringView* value);
+
+CPU_FEATURES_END_CPP_NAMESPACE
+
+#endif  // CPU_FEATURES_INCLUDE_INTERNAL_STRING_VIEW_H_

cpu_features/ndk_compat/CMakeLists.txt

@@ -0,0 +1,60 @@
+
+#
+# library : NDK compat
+#
+find_package(Threads REQUIRED)
+set (NDK_COMPAT_HDRS cpu-features.h)
+set (NDK_COMPAT_SRCS
+  cpu-features.c
+  $<TARGET_OBJECTS:utils>
+  $<TARGET_OBJECTS:unix_based_hardware_detection>
+)
+# Note that following `add_cpu_features_headers_and_sources` will use
+# NDK_COMPAT_SRCS in lieu of NDK_COMPAT_HDRS because we don't want cpu_features
+# headers to be installed alongside ndk_compat.
+add_cpu_features_headers_and_sources(NDK_COMPAT_SRCS NDK_COMPAT_SRCS)
+add_library(ndk_compat ${NDK_COMPAT_HDRS} ${NDK_COMPAT_SRCS})
+setup_include_and_definitions(ndk_compat)
+target_include_directories(ndk_compat PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+target_link_libraries(ndk_compat PUBLIC ${CMAKE_DL_LIBS} ${CMAKE_THREAD_LIBS_INIT})
+set_target_properties(ndk_compat PROPERTIES PUBLIC_HEADER "${NDK_COMPAT_HDRS}")
+
+include(GNUInstallDirs)
+install(TARGETS ndk_compat
+  EXPORT CpuFeaturesNdkCompatTargets
+  PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/ndk_compat
+  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+)
+install(EXPORT CpuFeaturesNdkCompatTargets
+  NAMESPACE CpuFeatures::
+  DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/CpuFeaturesNdkCompat
+  COMPONENT Devel
+)
+include(CMakePackageConfigHelpers)
+configure_package_config_file(${PROJECT_SOURCE_DIR}/cmake/CpuFeaturesNdkCompatConfig.cmake.in
+  "${PROJECT_BINARY_DIR}/CpuFeaturesNdkCompatConfig.cmake"
+  INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/CpuFeaturesNdkCompat"
+  NO_SET_AND_CHECK_MACRO
+  NO_CHECK_REQUIRED_COMPONENTS_MACRO
+)
+write_basic_package_version_file(
+  "${PROJECT_BINARY_DIR}/CpuFeaturesNdkCompatConfigVersion.cmake"
+  COMPATIBILITY SameMajorVersion
+)
+install(
+  FILES
+    "${PROJECT_BINARY_DIR}/CpuFeaturesNdkCompatConfig.cmake"
+    "${PROJECT_BINARY_DIR}/CpuFeaturesNdkCompatConfigVersion.cmake"
+  DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/CpuFeaturesNdkCompat"
+  COMPONENT Devel
+)
+
+#
+# program : NDK compat test program
+#
+if(ENABLE_TESTING)
+  add_executable(ndk-compat-test ndk-compat-test.c)
+  target_link_libraries(ndk-compat-test PRIVATE ndk_compat)
+endif()

cpu_features/ndk_compat/README.md

@@ -0,0 +1,4 @@
+Provides a header compatible with [android's NDK cpu-features.h](https://android.googlesource.com/platform/ndk/+/master/sources/android/cpufeatures/cpu-features.h).
+
+It is intended to be a drop in replacement for this header and help users
+transition from the NDK to [Google's cpu_features library](https://github.com/google/cpu_features).

cpu_features/ndk_compat/cpu-features.c

@@ -0,0 +1,205 @@
+#include "cpu-features.h"
+
+#include <pthread.h>
+
+#include "cpu_features_macros.h"
+#include "internal/filesystem.h"
+#include "internal/stack_line_reader.h"
+#include "internal/string_view.h"
+
+#if defined(CPU_FEATURES_ARCH_ARM)
+#include "cpuinfo_arm.h"
+#elif defined(CPU_FEATURES_ARCH_X86)
+#include "cpuinfo_x86.h"
+#elif defined(CPU_FEATURES_ARCH_MIPS)
+#include "cpuinfo_mips.h"
+#elif defined(CPU_FEATURES_ARCH_AARCH64)
+#include "cpuinfo_aarch64.h"
+#endif
+
+static pthread_once_t g_once;
+static int g_inited;
+static uint64_t g_cpuFeatures;
+static int g_cpuCount;
+
+#ifdef CPU_FEATURES_ARCH_ARM
+static uint32_t g_cpuIdArm;
+#endif
+
+static void set_cpu_mask_bit(uint32_t index, uint32_t* cpu_mask) {
+  *cpu_mask |= 1UL << index;
+}
+
+// Examples of valid inputs: "31", "4-31"
+static void parse_cpu_mask(const StringView text, uint32_t* cpu_mask) {
+  int separator_index = CpuFeatures_StringView_IndexOfChar(text, '-');
+  if (separator_index < 0) {  // A single cpu index
+    int cpu_index = CpuFeatures_StringView_ParsePositiveNumber(text);
+    if (cpu_index < 0) return;
+    set_cpu_mask_bit(cpu_index, cpu_mask);
+  } else {
+    int cpu_index_a = CpuFeatures_StringView_ParsePositiveNumber(
+        CpuFeatures_StringView_KeepFront(text, separator_index));
+    int cpu_index_b = CpuFeatures_StringView_ParsePositiveNumber(
+        CpuFeatures_StringView_PopFront(text, separator_index + 1));
+    int i;
+    if (cpu_index_a < 0 || cpu_index_b < 0) return;
+    for (i = cpu_index_a; i <= cpu_index_b; ++i) {
+      if (i < 32) {
+        set_cpu_mask_bit(i, cpu_mask);
+      }
+    }
+  }
+}
+
+// Format specification from
+// https://www.kernel.org/doc/Documentation/cputopology.txt
+// Examples of valid inputs: "31", "2,4-31,32-63", "0-1,3"
+static void parse_cpu_mask_line(const LineResult result, uint32_t* cpu_mask) {
+  if (!result.full_line || result.eof) return;
+  StringView line = result.line;
+  for (; line.size > 0;) {
+    int next_entry_index = CpuFeatures_StringView_IndexOfChar(line, ',');
+    if (next_entry_index < 0) {
+      parse_cpu_mask(line, cpu_mask);
+      break;
+    }
+    StringView entry = CpuFeatures_StringView_KeepFront(line, next_entry_index);
+    parse_cpu_mask(entry, cpu_mask);
+    line = CpuFeatures_StringView_PopFront(line, next_entry_index + 1);
+  }
+}
+
+static void update_cpu_mask_from_file(const char* filename,
+                                      uint32_t* cpu_mask) {
+  const int fd = CpuFeatures_OpenFile(filename);
+  if (fd >= 0) {
+    StackLineReader reader;
+    StackLineReader_Initialize(&reader, fd);
+    parse_cpu_mask_line(StackLineReader_NextLine(&reader), cpu_mask);
+    CpuFeatures_CloseFile(fd);
+  }
+}
+
+static int get_cpu_count(void) {
+  uint32_t cpu_mask = 0;
+  update_cpu_mask_from_file("/sys/devices/system/cpu/present", &cpu_mask);
+  update_cpu_mask_from_file("/sys/devices/system/cpu/possible", &cpu_mask);
+  return __builtin_popcount(cpu_mask);
+}
+
+static void android_cpuInit(void) {
+  g_cpuFeatures = 0;
+  g_cpuCount = 1;
+  g_inited = 1;
+
+  g_cpuCount = get_cpu_count();
+  if (g_cpuCount == 0) {
+    g_cpuCount = 1;
+  }
+#if defined(CPU_FEATURES_ARCH_ARM)
+  ArmInfo info = GetArmInfo();
+  if (info.architecture == 7) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_ARMv7;
+  if (info.features.vfpv3) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFPv3;
+  if (info.features.neon) {
+    g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_NEON;
+    g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFP_D32;
+  }
+  if (info.features.vfpv3d16) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFP_FP16;
+  if (info.features.idiva) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_IDIV_ARM;
+  if (info.features.idivt) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_IDIV_THUMB2;
+  if (info.features.iwmmxt) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_iWMMXt;
+  if (info.features.aes) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_AES;
+  if (info.features.pmull) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_PMULL;
+  if (info.features.sha1) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_SHA1;
+  if (info.features.sha2) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_SHA2;
+  if (info.features.crc32) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_CRC32;
+  if (info.architecture >= 6)
+    g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_LDREX_STREX;
+  if (info.features.vfp) g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFPv2;
+  if (info.features.vfpv4) {
+    g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFP_FMA;
+    g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_NEON_FMA;
+  }
+  g_cpuIdArm = GetArmCpuId(&info);
+#elif defined(CPU_FEATURES_ARCH_X86)
+  X86Info info = GetX86Info();
+  if (info.features.ssse3) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_SSSE3;
+  if (info.features.popcnt) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_POPCNT;
+  if (info.features.movbe) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_MOVBE;
+  if (info.features.sse4_1) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_SSE4_1;
+  if (info.features.sse4_2) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_SSE4_2;
+  if (info.features.aes) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_AES_NI;
+  if (info.features.avx) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_AVX;
+  if (info.features.rdrnd) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_RDRAND;
+  if (info.features.avx2) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_AVX2;
+  if (info.features.sha) g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_SHA_NI;
+#elif defined(CPU_FEATURES_ARCH_MIPS)
+  MipsInfo info = GetMipsInfo();
+  if (info.features.r6) g_cpuFeatures |= ANDROID_CPU_MIPS_FEATURE_R6;
+  if (info.features.msa) g_cpuFeatures |= ANDROID_CPU_MIPS_FEATURE_MSA;
+#elif defined(CPU_FEATURES_ARCH_AARCH64)
+  Aarch64Info info = GetAarch64Info();
+  if (info.features.fp) g_cpuFeatures |= ANDROID_CPU_ARM64_FEATURE_FP;
+  if (info.features.asimd) g_cpuFeatures |= ANDROID_CPU_ARM64_FEATURE_ASIMD;
+  if (info.features.aes) g_cpuFeatures |= ANDROID_CPU_ARM64_FEATURE_AES;
+  if (info.features.pmull) g_cpuFeatures |= ANDROID_CPU_ARM64_FEATURE_PMULL;
+  if (info.features.sha1) g_cpuFeatures |= ANDROID_CPU_ARM64_FEATURE_SHA1;
+  if (info.features.sha2) g_cpuFeatures |= ANDROID_CPU_ARM64_FEATURE_SHA2;
+  if (info.features.crc32) g_cpuFeatures |= ANDROID_CPU_ARM64_FEATURE_CRC32;
+#endif
+}
+
+AndroidCpuFamily android_getCpuFamily(void) {
+#if defined(CPU_FEATURES_ARCH_ARM)
+  return ANDROID_CPU_FAMILY_ARM;
+#elif defined(CPU_FEATURES_ARCH_X86_32)
+  return ANDROID_CPU_FAMILY_X86;
+#elif defined(CPU_FEATURES_ARCH_MIPS64)
+  return ANDROID_CPU_FAMILY_MIPS64;
+#elif defined(CPU_FEATURES_ARCH_MIPS32)
+  return ANDROID_CPU_FAMILY_MIPS;
+#elif defined(CPU_FEATURES_ARCH_AARCH64)
+  return ANDROID_CPU_FAMILY_ARM64;
+#elif defined(CPU_FEATURES_ARCH_X86_64)
+  return ANDROID_CPU_FAMILY_X86_64;
+#else
+  return ANDROID_CPU_FAMILY_UNKNOWN;
+#endif
+}
+
+uint64_t android_getCpuFeatures(void) {
+  pthread_once(&g_once, android_cpuInit);
+  return g_cpuFeatures;
+}
+
+int android_getCpuCount(void) {
+  pthread_once(&g_once, android_cpuInit);
+  return g_cpuCount;
+}
+
+static void android_cpuInitDummy(void) { g_inited = 1; }
+
+int android_setCpu(int cpu_count, uint64_t cpu_features) {
+  /* Fail if the library was already initialized. */
+  if (g_inited) return 0;
+  g_cpuCount = (cpu_count <= 0 ? 1 : cpu_count);
+  g_cpuFeatures = cpu_features;
+  pthread_once(&g_once, android_cpuInitDummy);
+  return 1;
+}
+
+#ifdef CPU_FEATURES_ARCH_ARM
+
+uint32_t android_getCpuIdArm(void) {
+  pthread_once(&g_once, android_cpuInit);
+  return g_cpuIdArm;
+}
+
+int android_setCpuArm(int cpu_count, uint64_t cpu_features, uint32_t cpu_id) {
+  if (!android_setCpu(cpu_count, cpu_features)) return 0;
+  g_cpuIdArm = cpu_id;
+  return 1;
+}
+
+#endif  // CPU_FEATURES_ARCH_ARM

cpu_features/ndk_compat/cpu-features.h

@@ -0,0 +1,320 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#ifndef GOOGLE_CPU_FEATURES_H
+#define GOOGLE_CPU_FEATURES_H
+#include <stdint.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* A list of valid values returned by android_getCpuFamily().
+ * They describe the CPU Architecture of the current process.
+ */
+typedef enum {
+  ANDROID_CPU_FAMILY_UNKNOWN = 0,
+  ANDROID_CPU_FAMILY_ARM,
+  ANDROID_CPU_FAMILY_X86,
+  ANDROID_CPU_FAMILY_MIPS,
+  ANDROID_CPU_FAMILY_ARM64,
+  ANDROID_CPU_FAMILY_X86_64,
+  ANDROID_CPU_FAMILY_MIPS64,
+  ANDROID_CPU_FAMILY_MAX /* do not remove */
+} AndroidCpuFamily;
+
+/* Return the CPU family of the current process.
+ *
+ * Note that this matches the bitness of the current process. I.e. when
+ * running a 32-bit binary on a 64-bit capable CPU, this will return the
+ * 32-bit CPU family value.
+ */
+extern AndroidCpuFamily android_getCpuFamily(void);
+
+/* Return a bitmap describing a set of optional CPU features that are
+ * supported by the current device's CPU. The exact bit-flags returned
+ * depend on the value returned by android_getCpuFamily(). See the
+ * documentation for the ANDROID_CPU_*_FEATURE_* flags below for details.
+ */
+extern uint64_t android_getCpuFeatures(void);
+
+/* The list of feature flags for ANDROID_CPU_FAMILY_ARM that can be
+ * recognized by the library (see note below for 64-bit ARM). Value details
+ * are:
+ *
+ *   VFPv2:
+ *     CPU supports the VFPv2 instruction set. Many, but not all, ARMv6 CPUs
+ *     support these instructions. VFPv2 is a subset of VFPv3 so this will
+ *     be set whenever VFPv3 is set too.
+ *
+ *   ARMv7:
+ *     CPU supports the ARMv7-A basic instruction set.
+ *     This feature is mandated by the 'armeabi-v7a' ABI.
+ *
+ *   VFPv3:
+ *     CPU supports the VFPv3-D16 instruction set, providing hardware FPU
+ *     support for single and double precision floating point registers.
+ *     Note that only 16 FPU registers are available by default, unless
+ *     the D32 bit is set too. This feature is also mandated by the
+ *     'armeabi-v7a' ABI.
+ *
+ *   VFP_D32:
+ *     CPU VFP optional extension that provides 32 FPU registers,
+ *     instead of 16. Note that ARM mandates this feature is the 'NEON'
+ *     feature is implemented by the CPU.
+ *
+ *   NEON:
+ *     CPU FPU supports "ARM Advanced SIMD" instructions, also known as
+ *     NEON. Note that this mandates the VFP_D32 feature as well, per the
+ *     ARM Architecture specification.
+ *
+ *   VFP_FP16:
+ *     Half-width floating precision VFP extension. If set, the CPU
+ *     supports instructions to perform floating-point operations on
+ *     16-bit registers. This is part of the VFPv4 specification, but
+ *     not mandated by any Android ABI.
+ *
+ *   VFP_FMA:
+ *     Fused multiply-accumulate VFP instructions extension. Also part of
+ *     the VFPv4 specification, but not mandated by any Android ABI.
+ *
+ *   NEON_FMA:
+ *     Fused multiply-accumulate NEON instructions extension. Optional
+ *     extension from the VFPv4 specification, but not mandated by any
+ *     Android ABI.
+ *
+ *   IDIV_ARM:
+ *     Integer division available in ARM mode. Only available
+ *     on recent CPUs (e.g. Cortex-A15).
+ *
+ *   IDIV_THUMB2:
+ *     Integer division available in Thumb-2 mode. Only available
+ *     on recent CPUs (e.g. Cortex-A15).
+ *
+ *   iWMMXt:
+ *     Optional extension that adds MMX registers and operations to an
+ *     ARM CPU. This is only available on a few XScale-based CPU designs
+ *     sold by Marvell. Pretty rare in practice.
+ *
+ *   AES:
+ *     CPU supports AES instructions. These instructions are only
+ *     available for 32-bit applications running on ARMv8 CPU.
+ *
+ *   CRC32:
+ *     CPU supports CRC32 instructions. These instructions are only
+ *     available for 32-bit applications running on ARMv8 CPU.
+ *
+ *   SHA2:
+ *     CPU supports SHA2 instructions. These instructions are only
+ *     available for 32-bit applications running on ARMv8 CPU.
+ *
+ *   SHA1:
+ *     CPU supports SHA1 instructions. These instructions are only
+ *     available for 32-bit applications running on ARMv8 CPU.
+ *
+ *   PMULL:
+ *     CPU supports 64-bit PMULL and PMULL2 instructions. These
+ *     instructions are only available for 32-bit applications
+ *     running on ARMv8 CPU.
+ *
+ * If you want to tell the compiler to generate code that targets one of
+ * the feature set above, you should probably use one of the following
+ * flags (for more details, see technical note at the end of this file):
+ *
+ *   -mfpu=vfp
+ *   -mfpu=vfpv2
+ *     These are equivalent and tell GCC to use VFPv2 instructions for
+ *     floating-point operations. Use this if you want your code to
+ *     run on *some* ARMv6 devices, and any ARMv7-A device supported
+ *     by Android.
+ *
+ *     Generated code requires VFPv2 feature.
+ *
+ *   -mfpu=vfpv3-d16
+ *     Tell GCC to use VFPv3 instructions (using only 16 FPU registers).
+ *     This should be generic code that runs on any CPU that supports the
+ *     'armeabi-v7a' Android ABI. Note that no ARMv6 CPU supports this.
+ *
+ *     Generated code requires VFPv3 feature.
+ *
+ *   -mfpu=vfpv3
+ *     Tell GCC to use VFPv3 instructions with 32 FPU registers.
+ *     Generated code requires VFPv3|VFP_D32 features.
+ *
+ *   -mfpu=neon
+ *     Tell GCC to use VFPv3 instructions with 32 FPU registers, and
+ *     also support NEON intrinsics (see <arm_neon.h>).
+ *     Generated code requires VFPv3|VFP_D32|NEON features.
+ *
+ *   -mfpu=vfpv4-d16
+ *     Generated code requires VFPv3|VFP_FP16|VFP_FMA features.
+ *
+ *   -mfpu=vfpv4
+ *     Generated code requires VFPv3|VFP_FP16|VFP_FMA|VFP_D32 features.
+ *
+ *   -mfpu=neon-vfpv4
+ *     Generated code requires VFPv3|VFP_FP16|VFP_FMA|VFP_D32|NEON|NEON_FMA
+ *     features.
+ *
+ *   -mcpu=cortex-a7
+ *   -mcpu=cortex-a15
+ *     Generated code requires VFPv3|VFP_FP16|VFP_FMA|VFP_D32|
+ *                             NEON|NEON_FMA|IDIV_ARM|IDIV_THUMB2
+ *     This flag implies -mfpu=neon-vfpv4.
+ *
+ *   -mcpu=iwmmxt
+ *     Allows the use of iWMMXt instrinsics with GCC.
+ *
+ * IMPORTANT NOTE: These flags should only be tested when
+ * android_getCpuFamily() returns ANDROID_CPU_FAMILY_ARM, i.e. this is a
+ * 32-bit process.
+ *
+ * When running a 64-bit ARM process on an ARMv8 CPU,
+ * android_getCpuFeatures() will return a different set of bitflags
+ */
+enum {
+  ANDROID_CPU_ARM_FEATURE_ARMv7 = (1 << 0),
+  ANDROID_CPU_ARM_FEATURE_VFPv3 = (1 << 1),
+  ANDROID_CPU_ARM_FEATURE_NEON = (1 << 2),
+  ANDROID_CPU_ARM_FEATURE_LDREX_STREX = (1 << 3),
+  ANDROID_CPU_ARM_FEATURE_VFPv2 = (1 << 4),
+  ANDROID_CPU_ARM_FEATURE_VFP_D32 = (1 << 5),
+  ANDROID_CPU_ARM_FEATURE_VFP_FP16 = (1 << 6),
+  ANDROID_CPU_ARM_FEATURE_VFP_FMA = (1 << 7),
+  ANDROID_CPU_ARM_FEATURE_NEON_FMA = (1 << 8),
+  ANDROID_CPU_ARM_FEATURE_IDIV_ARM = (1 << 9),
+  ANDROID_CPU_ARM_FEATURE_IDIV_THUMB2 = (1 << 10),
+  ANDROID_CPU_ARM_FEATURE_iWMMXt = (1 << 11),
+  ANDROID_CPU_ARM_FEATURE_AES = (1 << 12),
+  ANDROID_CPU_ARM_FEATURE_PMULL = (1 << 13),
+  ANDROID_CPU_ARM_FEATURE_SHA1 = (1 << 14),
+  ANDROID_CPU_ARM_FEATURE_SHA2 = (1 << 15),
+  ANDROID_CPU_ARM_FEATURE_CRC32 = (1 << 16),
+};
+
+/* The bit flags corresponding to the output of android_getCpuFeatures()
+ * when android_getCpuFamily() returns ANDROID_CPU_FAMILY_ARM64. Value details
+ * are:
+ *
+ *   FP:
+ *     CPU has Floating-point unit.
+ *
+ *   ASIMD:
+ *     CPU has Advanced SIMD unit.
+ *
+ *   AES:
+ *     CPU supports AES instructions.
+ *
+ *   CRC32:
+ *     CPU supports CRC32 instructions.
+ *
+ *   SHA2:
+ *     CPU supports SHA2 instructions.
+ *
+ *   SHA1:
+ *     CPU supports SHA1 instructions.
+ *
+ *   PMULL:
+ *     CPU supports 64-bit PMULL and PMULL2 instructions.
+ */
+enum {
+  ANDROID_CPU_ARM64_FEATURE_FP = (1 << 0),
+  ANDROID_CPU_ARM64_FEATURE_ASIMD = (1 << 1),
+  ANDROID_CPU_ARM64_FEATURE_AES = (1 << 2),
+  ANDROID_CPU_ARM64_FEATURE_PMULL = (1 << 3),
+  ANDROID_CPU_ARM64_FEATURE_SHA1 = (1 << 4),
+  ANDROID_CPU_ARM64_FEATURE_SHA2 = (1 << 5),
+  ANDROID_CPU_ARM64_FEATURE_CRC32 = (1 << 6),
+};
+
+/* The bit flags corresponding to the output of android_getCpuFeatures()
+ * when android_getCpuFamily() returns ANDROID_CPU_FAMILY_X86 or
+ * ANDROID_CPU_FAMILY_X86_64.
+ */
+enum {
+  ANDROID_CPU_X86_FEATURE_SSSE3 = (1 << 0),
+  ANDROID_CPU_X86_FEATURE_POPCNT = (1 << 1),
+  ANDROID_CPU_X86_FEATURE_MOVBE = (1 << 2),
+  ANDROID_CPU_X86_FEATURE_SSE4_1 = (1 << 3),
+  ANDROID_CPU_X86_FEATURE_SSE4_2 = (1 << 4),
+  ANDROID_CPU_X86_FEATURE_AES_NI = (1 << 5),
+  ANDROID_CPU_X86_FEATURE_AVX = (1 << 6),
+  ANDROID_CPU_X86_FEATURE_RDRAND = (1 << 7),
+  ANDROID_CPU_X86_FEATURE_AVX2 = (1 << 8),
+  ANDROID_CPU_X86_FEATURE_SHA_NI = (1 << 9),
+};
+
+/* The bit flags corresponding to the output of android_getCpuFeatures()
+ * when android_getCpuFamily() returns ANDROID_CPU_FAMILY_MIPS
+ * or ANDROID_CPU_FAMILY_MIPS64.  Values are:
+ *
+ *   R6:
+ *     CPU executes MIPS Release 6 instructions natively, and
+ *     supports obsoleted R1..R5 instructions only via kernel traps.
+ *
+ *   MSA:
+ *     CPU supports Mips SIMD Architecture instructions.
+ */
+enum {
+  ANDROID_CPU_MIPS_FEATURE_R6 = (1 << 0),
+  ANDROID_CPU_MIPS_FEATURE_MSA = (1 << 1),
+};
+
+/* Return the number of CPU cores detected on this device.
+ * Please note the current implementation supports up to 32 cpus.
+ */
+extern int android_getCpuCount(void);
+
+/* The following is used to force the CPU count and features
+ * mask in sandboxed processes. Under 4.1 and higher, these processes
+ * cannot access /proc, which is the only way to get information from
+ * the kernel about the current hardware (at least on ARM).
+ *
+ * It _must_ be called only once, and before any android_getCpuXXX
+ * function, any other case will fail.
+ *
+ * This function return 1 on success, and 0 on failure.
+ */
+extern int android_setCpu(int cpu_count, uint64_t cpu_features);
+
+#ifdef __arm__
+
+/* Retrieve the ARM 32-bit CPUID value from the kernel.
+ * Note that this cannot work on sandboxed processes under 4.1 and
+ * higher, unless you called android_setCpuArm() before.
+ */
+extern uint32_t android_getCpuIdArm(void);
+
+/* An ARM-specific variant of android_setCpu() that also allows you
+ * to set the ARM CPUID field.
+ */
+extern int android_setCpuArm(int cpu_count, uint64_t cpu_features,
+                             uint32_t cpu_id);
+
+#endif
+
+__END_DECLS
+#endif /* GOOGLE_CPU_FEATURES_H */

cpu_features/ndk_compat/ndk-compat-test.c

@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+#include "cpu-features.h"
+
+int main() {
+  printf("android_getCpuFamily()=%d\n", android_getCpuFamily());
+  printf("android_getCpuFeatures()=0x%08llx\n", android_getCpuFeatures());
+  printf("android_getCpuCount()=%d\n", android_getCpuCount());
+#ifdef __arm__
+  printf("android_getCpuIdArm()=0x%04x\n", android_getCpuIdArm());
+#endif  //__arm__
+}

cpu_features/scripts/run_integration.sh

@@ -0,0 +1,209 @@
+#!/usr/bin/env bash
+
+readonly SCRIPT_FOLDER=$(cd -P -- "$(dirname -- "$0")" && pwd -P)
+readonly PROJECT_FOLDER="${SCRIPT_FOLDER}/.."
+readonly ARCHIVE_FOLDER=~/cpu_features_archives
+readonly QEMU_INSTALL=${ARCHIVE_FOLDER}/qemu
+readonly DEFAULT_CMAKE_ARGS=" -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTING=ON"
+
+function extract() {
+  case $1 in
+    *.tar.bz2)   tar xjf "$1"    ;;
+    *.tar.xz)    tar xJf "$1"    ;;
+    *.tar.gz)    tar xzf "$1"    ;;
+    *)
+      echo "don't know how to extract '$1'..."
+      exit 1
+  esac
+}
+
+function unpackifnotexists() {
+  mkdir -p "${ARCHIVE_FOLDER}"
+  cd "${ARCHIVE_FOLDER}" || exit
+  local URL=$1
+  local RELATIVE_FOLDER=$2
+  local DESTINATION="${ARCHIVE_FOLDER}/${RELATIVE_FOLDER}"
+  if [[  ! -d "${DESTINATION}" ]] ; then
+    local ARCHIVE_NAME=$(echo ${URL} | sed 's/.*\///')
+    test -f "${ARCHIVE_NAME}" || wget -q "${URL}"
+    extract "${ARCHIVE_NAME}"
+    rm -f "${ARCHIVE_NAME}"
+  fi
+}
+
+function installqemuifneeded() {
+  local VERSION=${QEMU_VERSION:=2.11.1}
+  local ARCHES=${QEMU_ARCHES:=arm aarch64 i386 x86_64 mips mipsel mips64 mips64el}
+  local TARGETS=${QEMU_TARGETS:=$(echo "$ARCHES" | sed 's#$# #;s#\([^ ]*\) #\1-linux-user #g')}
+
+  if echo "${VERSION} ${TARGETS}" | cmp --silent ${QEMU_INSTALL}/.build -; then
+    echo "qemu ${VERSION} up to date!"
+    return 0
+  fi
+
+  echo "VERSION: ${VERSION}"
+  echo "TARGETS: ${TARGETS}"
+
+  rm -rf ${QEMU_INSTALL}
+
+  # Checking for a tarball before downloading makes testing easier :-)
+  local QEMU_URL="http://wiki.qemu-project.org/download/qemu-${VERSION}.tar.xz"
+  local QEMU_FOLDER="qemu-${VERSION}"
+  unpackifnotexists ${QEMU_URL} ${QEMU_FOLDER}
+  cd ${QEMU_FOLDER} || exit
+
+  ./configure \
+    --prefix="${QEMU_INSTALL}" \
+    --target-list="${TARGETS}" \
+    --disable-docs \
+    --disable-sdl \
+    --disable-gtk \
+    --disable-gnutls \
+    --disable-gcrypt \
+    --disable-nettle \
+    --disable-curses \
+    --static
+
+  make -j4
+  make install
+
+  echo "$VERSION $TARGETS" > ${QEMU_INSTALL}/.build
+}
+
+function assert_defined(){
+  local VALUE=${1}
+  : "${VALUE?"${1} needs to be defined"}"
+}
+
+function integrate() {
+  cd "${PROJECT_FOLDER}"
+  case "${OS}" in
+   "Windows_NT") CMAKE_BUILD_ARGS="--config Debug --target ALL_BUILD"
+                 CMAKE_TEST_FILES="${BUILD_DIR}/test/Debug/*_test.exe"
+                 DEMO=${BUILD_DIR}/Debug/list_cpu_features.exe
+                 ;;
+   *)            CMAKE_BUILD_ARGS="--target all"
+                 CMAKE_TEST_FILES="${BUILD_DIR}/test/*_test"
+                 DEMO=${BUILD_DIR}/list_cpu_features
+                 ;;
+  esac
+
+  # Generating CMake configuration
+  cmake -H. -B"${BUILD_DIR}" ${DEFAULT_CMAKE_ARGS} "${CMAKE_ADDITIONAL_ARGS[@]}" -G"${CMAKE_GENERATOR:-Unix Makefiles}"
+
+  # Building
+  cmake --build "${BUILD_DIR}" ${CMAKE_BUILD_ARGS}
+
+  # Running tests if needed
+  if [[ "${QEMU_ARCH}" == "DISABLED" ]]; then
+    return
+  fi
+  RUN_CMD=""
+  if [[ -n "${QEMU_ARCH}" ]]; then
+    installqemuifneeded
+    RUN_CMD="${QEMU_INSTALL}/bin/qemu-${QEMU_ARCH} ${QEMU_ARGS[@]}"
+  fi
+  for test_binary in ${CMAKE_TEST_FILES}; do
+    ${RUN_CMD} ${test_binary}
+  done
+  ${RUN_CMD} ${DEMO}
+}
+
+function expand_linaro_config() {
+  assert_defined TARGET
+  local LINARO_ROOT_URL=https://releases.linaro.org/components/toolchain/binaries/7.2-2017.11
+
+  local GCC_URL=${LINARO_ROOT_URL}/${TARGET}/gcc-linaro-7.2.1-2017.11-x86_64_${TARGET}.tar.xz
+  local GCC_RELATIVE_FOLDER="gcc-linaro-7.2.1-2017.11-x86_64_${TARGET}"
+  unpackifnotexists "${GCC_URL}" "${GCC_RELATIVE_FOLDER}"
+
+  local SYSROOT_URL=${LINARO_ROOT_URL}/${TARGET}/sysroot-glibc-linaro-2.25-2017.11-${TARGET}.tar.xz
+  local SYSROOT_RELATIVE_FOLDER=sysroot-glibc-linaro-2.25-2017.11-${TARGET}
+  unpackifnotexists "${SYSROOT_URL}" "${SYSROOT_RELATIVE_FOLDER}"
+
+  local SYSROOT_FOLDER=${ARCHIVE_FOLDER}/${SYSROOT_RELATIVE_FOLDER}
+  local GCC_FOLDER=${ARCHIVE_FOLDER}/${GCC_RELATIVE_FOLDER}
+
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_SYSTEM_NAME=Linux)
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_SYSTEM_PROCESSOR=${TARGET})
+
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_SYSROOT=${SYSROOT_FOLDER})
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_C_COMPILER=${GCC_FOLDER}/bin/${TARGET}-gcc)
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_CXX_COMPILER=${GCC_FOLDER}/bin/${TARGET}-g++)
+
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_FIND_ROOT_PATH_MODE_PROGRAM=NEVER)
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY)
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ONLY)
+
+  QEMU_ARGS+=(-L ${SYSROOT_FOLDER})
+  QEMU_ARGS+=(-E LD_LIBRARY_PATH=/lib)
+}
+
+function expand_codescape_config() {
+  assert_defined TARGET
+  local DATE=2017.10-08
+  local CODESCAPE_URL=https://codescape.mips.com/components/toolchain/${DATE}/Codescape.GNU.Tools.Package.${DATE}.for.MIPS.MTI.Linux.CentOS-5.x86_64.tar.gz
+  local GCC_URL=${CODESCAPE_URL}
+  local GCC_RELATIVE_FOLDER="mips-mti-linux-gnu/${DATE}"
+  unpackifnotexists "${GCC_URL}" "${GCC_RELATIVE_FOLDER}"
+
+  local GCC_FOLDER=${ARCHIVE_FOLDER}/${GCC_RELATIVE_FOLDER}
+  local MIPS_FLAGS=""
+  local LIBC_FOLDER_SUFFIX=""
+  local FLAVOUR=""
+  case "${TARGET}" in
+    "mips32")    MIPS_FLAGS="-EB -mabi=32"; FLAVOUR="mips-r2-hard"; LIBC_FOLDER_SUFFIX="lib" ;;
+    "mips32el")  MIPS_FLAGS="-EL -mabi=32"; FLAVOUR="mipsel-r2-hard"; LIBC_FOLDER_SUFFIX="lib" ;;
+    "mips64")    MIPS_FLAGS="-EB -mabi=64"; FLAVOUR="mips-r2-hard"; LIBC_FOLDER_SUFFIX="lib64" ;;
+    "mips64el")  MIPS_FLAGS="-EL -mabi=64"; FLAVOUR="mipsel-r2-hard"; LIBC_FOLDER_SUFFIX="lib64" ;;
+    *)           echo 'unknown mips platform'; exit 1;;
+  esac
+
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_FIND_ROOT_PATH=${GCC_FOLDER})
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_SYSTEM_NAME=Linux)
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_SYSTEM_PROCESSOR=${TARGET})
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_C_COMPILER=mips-mti-linux-gnu-gcc)
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_CXX_COMPILER=mips-mti-linux-gnu-g++)
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_C_COMPILER_ARG1="${MIPS_FLAGS}")
+  CMAKE_ADDITIONAL_ARGS+=(-DCMAKE_CXX_COMPILER_ARG1="${MIPS_FLAGS}")
+
+  local SYSROOT_FOLDER=${GCC_FOLDER}/sysroot/${FLAVOUR}
+
+  # Keeping only the sysroot of interest to save on travis cache.
+  if [[ "${CONTINUOUS_INTEGRATION}" = "true" ]]; then
+    for folder in ${GCC_FOLDER}/sysroot/*; do
+      if [[ "${folder}" != "${SYSROOT_FOLDER}" ]]; then
+        rm -rf ${folder}
+      fi
+    done
+  fi
+
+  local LIBC_FOLDER=${GCC_FOLDER}/mips-mti-linux-gnu/lib/${FLAVOUR}/${LIBC_FOLDER_SUFFIX}
+  QEMU_ARGS+=(-L ${SYSROOT_FOLDER})
+  QEMU_ARGS+=(-E LD_PRELOAD=${LIBC_FOLDER}/libstdc++.so.6:${LIBC_FOLDER}/libgcc_s.so.1)
+}
+
+function expand_environment_and_integrate() {
+  assert_defined PROJECT_FOLDER
+  assert_defined TARGET
+
+  BUILD_DIR="${PROJECT_FOLDER}/cmake_build/${TARGET}"
+  mkdir -p "${BUILD_DIR}"
+
+  declare -a CONFIG_NAMES=()
+  declare -a QEMU_ARGS=()
+  declare -a CMAKE_ADDITIONAL_ARGS=()
+
+  case ${TOOLCHAIN} in
+    LINARO)    expand_linaro_config     ;;
+    CODESCAPE) expand_codescape_config  ;;
+    NATIVE)    QEMU_ARCH=""             ;;
+    *)         echo "Unknown toolchain '${TOOLCHAIN}'..."; exit 1;;
+  esac
+  integrate
+}
+
+if [ "${CONTINUOUS_INTEGRATION}" = "true" ]; then
+  QEMU_ARCHES=${QEMU_ARCH}
+  expand_environment_and_integrate
+fi

cpu_features/scripts/test_integration.sh

@@ -0,0 +1,106 @@
+#!/usr/bin/env bash
+
+source "$(dirname -- "$0")"/run_integration.sh
+
+# Toolchains for little-endian, 64-bit ARMv8 for GNU/Linux systems
+function set_aarch64-linux-gnu() {
+  TOOLCHAIN=LINARO
+  TARGET=aarch64-linux-gnu
+  QEMU_ARCH=aarch64
+}
+
+# Toolchains for little-endian, hard-float, 32-bit ARMv7 (and earlier) for GNU/Linux systems
+function set_arm-linux-gnueabihf() {
+  TOOLCHAIN=LINARO
+  TARGET=arm-linux-gnueabihf
+  QEMU_ARCH=arm
+}
+
+# Toolchains for little-endian, 32-bit ARMv8 for GNU/Linux systems
+function set_armv8l-linux-gnueabihf() {
+  TOOLCHAIN=LINARO
+  TARGET=armv8l-linux-gnueabihf
+  QEMU_ARCH=arm
+}
+
+# Toolchains for little-endian, soft-float, 32-bit ARMv7 (and earlier) for GNU/Linux systems
+function set_arm-linux-gnueabi() {
+  TOOLCHAIN=LINARO
+  TARGET=arm-linux-gnueabi
+  QEMU_ARCH=arm
+}
+
+# Toolchains for big-endian, 64-bit ARMv8 for GNU/Linux systems
+function set_aarch64_be-linux-gnu() {
+  TOOLCHAIN=LINARO
+  TARGET=aarch64_be-linux-gnu
+  QEMU_ARCH=DISABLED
+}
+
+# Toolchains for big-endian, hard-float, 32-bit ARMv7 (and earlier) for GNU/Linux systems
+function set_armeb-linux-gnueabihf() {
+  TOOLCHAIN=LINARO
+  TARGET=armeb-linux-gnueabihf
+  QEMU_ARCH=DISABLED
+}
+
+# Toolchains for big-endian, soft-float, 32-bit ARMv7 (and earlier) for GNU/Linux systems
+function set_armeb-linux-gnueabi() {
+  TOOLCHAIN=LINARO
+  TARGET=armeb-linux-gnueabi
+  QEMU_ARCH=DISABLED
+}
+
+function set_mips32() {
+  TOOLCHAIN=CODESCAPE
+  TARGET=mips32
+  QEMU_ARCH=mips
+}
+
+function set_mips32el() {
+  TOOLCHAIN=CODESCAPE
+  TARGET=mips32el
+  QEMU_ARCH=mipsel
+}
+
+function set_mips64() {
+  TOOLCHAIN=CODESCAPE
+  TARGET=mips64
+  QEMU_ARCH=mips64
+}
+
+function set_mips64el() {
+  TOOLCHAIN=CODESCAPE
+  TARGET=mips64el
+  QEMU_ARCH=mips64el
+}
+
+function set_native() {
+  TOOLCHAIN=NATIVE
+  TARGET=native
+  QEMU_ARCH=""
+}
+
+ENVIRONMENTS="
+  set_aarch64-linux-gnu
+  set_arm-linux-gnueabihf
+  set_armv8l-linux-gnueabihf
+  set_arm-linux-gnueabi
+  set_aarch64_be-linux-gnu
+  set_armeb-linux-gnueabihf
+  set_armeb-linux-gnueabi
+  set_mips32
+  set_mips32el
+  set_mips64
+  set_mips64el
+  set_native
+"
+
+set -e
+
+CMAKE_GENERATOR="Ninja"
+
+for SET_ENVIRONMENT in ${ENVIRONMENTS}; do
+  ${SET_ENVIRONMENT}
+  expand_environment_and_integrate
+done

cpu_features/src/cpuinfo_aarch64.c

@@ -0,0 +1,150 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cpuinfo_aarch64.h"
+
+#include <assert.h>
+#include <ctype.h>
+
+#include "internal/filesystem.h"
+#include "internal/hwcaps.h"
+#include "internal/stack_line_reader.h"
+#include "internal/string_view.h"
+
+// Generation of feature's getters/setters functions and kGetters, kSetters,
+// kCpuInfoFlags and kHardwareCapabilities global tables.
+#define DEFINE_TABLE_FEATURES                                                 \
+  FEATURE(AARCH64_FP, fp, "fp", AARCH64_HWCAP_FP, 0)                          \
+  FEATURE(AARCH64_ASIMD, asimd, "asimd", AARCH64_HWCAP_ASIMD, 0)              \
+  FEATURE(AARCH64_EVTSTRM, evtstrm, "evtstrm", AARCH64_HWCAP_EVTSTRM, 0)      \
+  FEATURE(AARCH64_AES, aes, "aes", AARCH64_HWCAP_AES, 0)                      \
+  FEATURE(AARCH64_PMULL, pmull, "pmull", AARCH64_HWCAP_PMULL, 0)              \
+  FEATURE(AARCH64_SHA1, sha1, "sha1", AARCH64_HWCAP_SHA1, 0)                  \
+  FEATURE(AARCH64_SHA2, sha2, "sha2", AARCH64_HWCAP_SHA2, 0)                  \
+  FEATURE(AARCH64_CRC32, crc32, "crc32", AARCH64_HWCAP_CRC32, 0)              \
+  FEATURE(AARCH64_ATOMICS, atomics, "atomics", AARCH64_HWCAP_ATOMICS, 0)      \
+  FEATURE(AARCH64_FPHP, fphp, "fphp", AARCH64_HWCAP_FPHP, 0)                  \
+  FEATURE(AARCH64_ASIMDHP, asimdhp, "asimdhp", AARCH64_HWCAP_ASIMDHP, 0)      \
+  FEATURE(AARCH64_CPUID, cpuid, "cpuid", AARCH64_HWCAP_CPUID, 0)              \
+  FEATURE(AARCH64_ASIMDRDM, asimdrdm, "asimdrdm", AARCH64_HWCAP_ASIMDRDM, 0)  \
+  FEATURE(AARCH64_JSCVT, jscvt, "jscvt", AARCH64_HWCAP_JSCVT, 0)              \
+  FEATURE(AARCH64_FCMA, fcma, "fcma", AARCH64_HWCAP_FCMA, 0)                  \
+  FEATURE(AARCH64_LRCPC, lrcpc, "lrcpc", AARCH64_HWCAP_LRCPC, 0)              \
+  FEATURE(AARCH64_DCPOP, dcpop, "dcpop", AARCH64_HWCAP_DCPOP, 0)              \
+  FEATURE(AARCH64_SHA3, sha3, "sha3", AARCH64_HWCAP_SHA3, 0)                  \
+  FEATURE(AARCH64_SM3, sm3, "sm3", AARCH64_HWCAP_SM3, 0)                      \
+  FEATURE(AARCH64_SM4, sm4, "sm4", AARCH64_HWCAP_SM4, 0)                      \
+  FEATURE(AARCH64_ASIMDDP, asimddp, "asimddp", AARCH64_HWCAP_ASIMDDP, 0)      \
+  FEATURE(AARCH64_SHA512, sha512, "sha512", AARCH64_HWCAP_SHA512, 0)          \
+  FEATURE(AARCH64_SVE, sve, "sve", AARCH64_HWCAP_SVE, 0)                      \
+  FEATURE(AARCH64_ASIMDFHM, asimdfhm, "asimdfhm", AARCH64_HWCAP_ASIMDFHM, 0)  \
+  FEATURE(AARCH64_DIT, dit, "dit", AARCH64_HWCAP_DIT, 0)                      \
+  FEATURE(AARCH64_USCAT, uscat, "uscat", AARCH64_HWCAP_USCAT, 0)              \
+  FEATURE(AARCH64_ILRCPC, ilrcpc, "ilrcpc", AARCH64_HWCAP_ILRCPC, 0)          \
+  FEATURE(AARCH64_FLAGM, flagm, "flagm", AARCH64_HWCAP_FLAGM, 0)              \
+  FEATURE(AARCH64_SSBS, ssbs, "ssbs", AARCH64_HWCAP_SSBS, 0)                  \
+  FEATURE(AARCH64_SB, sb, "sb", AARCH64_HWCAP_SB, 0)                          \
+  FEATURE(AARCH64_PACA, paca, "paca", AARCH64_HWCAP_PACA, 0)                  \
+  FEATURE(AARCH64_PACG, pacg, "pacg", AARCH64_HWCAP_PACG, 0)                  \
+  FEATURE(AARCH64_DCPODP, dcpodp, "dcpodp", 0, AARCH64_HWCAP2_DCPODP)         \
+  FEATURE(AARCH64_SVE2, sve2, "sve2", 0, AARCH64_HWCAP2_SVE2)                 \
+  FEATURE(AARCH64_SVEAES, sveaes, "sveaes", 0, AARCH64_HWCAP2_SVEAES)         \
+  FEATURE(AARCH64_SVEPMULL, svepmull, "svepmull", 0, AARCH64_HWCAP2_SVEPMULL) \
+  FEATURE(AARCH64_SVEBITPERM, svebitperm, "svebitperm", 0,                    \
+          AARCH64_HWCAP2_SVEBITPERM)                                          \
+  FEATURE(AARCH64_SVESHA3, svesha3, "svesha3", 0, AARCH64_HWCAP2_SVESHA3)     \
+  FEATURE(AARCH64_SVESM4, svesm4, "svesm4", 0, AARCH64_HWCAP2_SVESM4)         \
+  FEATURE(AARCH64_FLAGM2, flagm2, "flagm2", 0, AARCH64_HWCAP2_FLAGM2)         \
+  FEATURE(AARCH64_FRINT, frint, "frint", 0, AARCH64_HWCAP2_FRINT)             \
+  FEATURE(AARCH64_SVEI8MM, svei8mm, "svei8mm", 0, AARCH64_HWCAP2_SVEI8MM)     \
+  FEATURE(AARCH64_SVEF32MM, svef32mm, "svef32mm", 0, AARCH64_HWCAP2_SVEF32MM) \
+  FEATURE(AARCH64_SVEF64MM, svef64mm, "svef64mm", 0, AARCH64_HWCAP2_SVEF64MM) \
+  FEATURE(AARCH64_SVEBF16, svebf16, "svebf16", 0, AARCH64_HWCAP2_SVEBF16)     \
+  FEATURE(AARCH64_I8MM, i8mm, "i8mm", 0, AARCH64_HWCAP2_I8MM)                 \
+  FEATURE(AARCH64_BF16, bf16, "bf16", 0, AARCH64_HWCAP2_BF16)                 \
+  FEATURE(AARCH64_DGH, dgh, "dgh", 0, AARCH64_HWCAP2_DGH)                     \
+  FEATURE(AARCH64_RNG, rng, "rng", 0, AARCH64_HWCAP2_RNG)                     \
+  FEATURE(AARCH64_BTI, bti, "bti", 0, AARCH64_HWCAP2_BTI)
+#define DEFINE_TABLE_FEATURE_TYPE Aarch64Features
+#include "define_tables.h"
+
+static bool HandleAarch64Line(const LineResult result,
+                              Aarch64Info* const info) {
+  StringView line = result.line;
+  StringView key, value;
+  if (CpuFeatures_StringView_GetAttributeKeyValue(line, &key, &value)) {
+    if (CpuFeatures_StringView_IsEquals(key, str("Features"))) {
+      for (size_t i = 0; i < AARCH64_LAST_; ++i) {
+        kSetters[i](&info->features,
+                    CpuFeatures_StringView_HasWord(value, kCpuInfoFlags[i]));
+      }
+    } else if (CpuFeatures_StringView_IsEquals(key, str("CPU implementer"))) {
+      info->implementer = CpuFeatures_StringView_ParsePositiveNumber(value);
+    } else if (CpuFeatures_StringView_IsEquals(key, str("CPU variant"))) {
+      info->variant = CpuFeatures_StringView_ParsePositiveNumber(value);
+    } else if (CpuFeatures_StringView_IsEquals(key, str("CPU part"))) {
+      info->part = CpuFeatures_StringView_ParsePositiveNumber(value);
+    } else if (CpuFeatures_StringView_IsEquals(key, str("CPU revision"))) {
+      info->revision = CpuFeatures_StringView_ParsePositiveNumber(value);
+    }
+  }
+  return !result.eof;
+}
+
+static void FillProcCpuInfoData(Aarch64Info* const info) {
+  const int fd = CpuFeatures_OpenFile("/proc/cpuinfo");
+  if (fd >= 0) {
+    StackLineReader reader;
+    StackLineReader_Initialize(&reader, fd);
+    for (;;) {
+      if (!HandleAarch64Line(StackLineReader_NextLine(&reader), info)) {
+        break;
+      }
+    }
+    CpuFeatures_CloseFile(fd);
+  }
+}
+
+static const Aarch64Info kEmptyAarch64Info;
+
+Aarch64Info GetAarch64Info(void) {
+  // capabilities are fetched from both getauxval and /proc/cpuinfo so we can
+  // have some information if the executable is sandboxed (aka no access to
+  // /proc/cpuinfo).
+  Aarch64Info info = kEmptyAarch64Info;
+
+  FillProcCpuInfoData(&info);
+  const HardwareCapabilities hwcaps = CpuFeatures_GetHardwareCapabilities();
+  for (size_t i = 0; i < AARCH64_LAST_; ++i) {
+    if (CpuFeatures_IsHwCapsSet(kHardwareCapabilities[i], hwcaps)) {
+      kSetters[i](&info.features, true);
+    }
+  }
+
+  return info;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Introspection functions
+
+int GetAarch64FeaturesEnumValue(const Aarch64Features* features,
+                                Aarch64FeaturesEnum value) {
+  if (value >= AARCH64_LAST_) return false;
+  return kGetters[value](features);
+}
+
+const char* GetAarch64FeaturesEnumName(Aarch64FeaturesEnum value) {
+  if (value >= AARCH64_LAST_) return "unknown feature";
+  return kCpuInfoFlags[value];
+}

cpu_features/src/cpuinfo_arm.c

@@ -0,0 +1,212 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cpuinfo_arm.h"
+
+#include <assert.h>
+#include <ctype.h>
+
+#include "internal/bit_utils.h"
+#include "internal/filesystem.h"
+#include "internal/hwcaps.h"
+#include "internal/stack_line_reader.h"
+#include "internal/string_view.h"
+
+// Generation of feature's getters/setters functions and kGetters, kSetters,
+// kCpuInfoFlags and kHardwareCapabilities global tables.
+#define DEFINE_TABLE_FEATURES                                         \
+  FEATURE(ARM_SWP, swp, "swp", ARM_HWCAP_SWP, 0)                      \
+  FEATURE(ARM_HALF, half, "half", ARM_HWCAP_HALF, 0)                  \
+  FEATURE(ARM_THUMB, thumb, "thumb", ARM_HWCAP_THUMB, 0)              \
+  FEATURE(ARM_26BIT, _26bit, "26bit", ARM_HWCAP_26BIT, 0)             \
+  FEATURE(ARM_FASTMULT, fastmult, "fastmult", ARM_HWCAP_FAST_MULT, 0) \
+  FEATURE(ARM_FPA, fpa, "fpa", ARM_HWCAP_FPA, 0)                      \
+  FEATURE(ARM_VFP, vfp, "vfp", ARM_HWCAP_VFP, 0)                      \
+  FEATURE(ARM_EDSP, edsp, "edsp", ARM_HWCAP_EDSP, 0)                  \
+  FEATURE(ARM_JAVA, java, "java", ARM_HWCAP_JAVA, 0)                  \
+  FEATURE(ARM_IWMMXT, iwmmxt, "iwmmxt", ARM_HWCAP_IWMMXT, 0)          \
+  FEATURE(ARM_CRUNCH, crunch, "crunch", ARM_HWCAP_CRUNCH, 0)          \
+  FEATURE(ARM_THUMBEE, thumbee, "thumbee", ARM_HWCAP_THUMBEE, 0)      \
+  FEATURE(ARM_NEON, neon, "neon", ARM_HWCAP_NEON, 0)                  \
+  FEATURE(ARM_VFPV3, vfpv3, "vfpv3", ARM_HWCAP_VFPV3, 0)              \
+  FEATURE(ARM_VFPV3D16, vfpv3d16, "vfpv3d16", ARM_HWCAP_VFPV3D16, 0)  \
+  FEATURE(ARM_TLS, tls, "tls", ARM_HWCAP_TLS, 0)                      \
+  FEATURE(ARM_VFPV4, vfpv4, "vfpv4", ARM_HWCAP_VFPV4, 0)              \
+  FEATURE(ARM_IDIVA, idiva, "idiva", ARM_HWCAP_IDIVA, 0)              \
+  FEATURE(ARM_IDIVT, idivt, "idivt", ARM_HWCAP_IDIVT, 0)              \
+  FEATURE(ARM_VFPD32, vfpd32, "vfpd32", ARM_HWCAP_VFPD32, 0)          \
+  FEATURE(ARM_LPAE, lpae, "lpae", ARM_HWCAP_LPAE, 0)                  \
+  FEATURE(ARM_EVTSTRM, evtstrm, "evtstrm", ARM_HWCAP_EVTSTRM, 0)      \
+  FEATURE(ARM_AES, aes, "aes", 0, ARM_HWCAP2_AES)                     \
+  FEATURE(ARM_PMULL, pmull, "pmull", 0, ARM_HWCAP2_PMULL)             \
+  FEATURE(ARM_SHA1, sha1, "sha1", 0, ARM_HWCAP2_SHA1)                 \
+  FEATURE(ARM_SHA2, sha2, "sha2", 0, ARM_HWCAP2_SHA2)                 \
+  FEATURE(ARM_CRC32, crc32, "crc32", 0, ARM_HWCAP2_CRC32)
+#define DEFINE_TABLE_FEATURE_TYPE ArmFeatures
+#include "define_tables.h"
+
+typedef struct {
+  bool processor_reports_armv6;
+  bool hardware_reports_goldfish;
+} ProcCpuInfoData;
+
+static int IndexOfNonDigit(StringView str) {
+  size_t index = 0;
+  while (str.size && isdigit(CpuFeatures_StringView_Front(str))) {
+    str = CpuFeatures_StringView_PopFront(str, 1);
+    ++index;
+  }
+  return index;
+}
+
+static bool HandleArmLine(const LineResult result, ArmInfo* const info,
+                          ProcCpuInfoData* const proc_info) {
+  StringView line = result.line;
+  StringView key, value;
+  if (CpuFeatures_StringView_GetAttributeKeyValue(line, &key, &value)) {
+    if (CpuFeatures_StringView_IsEquals(key, str("Features"))) {
+      for (size_t i = 0; i < ARM_LAST_; ++i) {
+        kSetters[i](&info->features,
+                    CpuFeatures_StringView_HasWord(value, kCpuInfoFlags[i]));
+      }
+    } else if (CpuFeatures_StringView_IsEquals(key, str("CPU implementer"))) {
+      info->implementer = CpuFeatures_StringView_ParsePositiveNumber(value);
+    } else if (CpuFeatures_StringView_IsEquals(key, str("CPU variant"))) {
+      info->variant = CpuFeatures_StringView_ParsePositiveNumber(value);
+    } else if (CpuFeatures_StringView_IsEquals(key, str("CPU part"))) {
+      info->part = CpuFeatures_StringView_ParsePositiveNumber(value);
+    } else if (CpuFeatures_StringView_IsEquals(key, str("CPU revision"))) {
+      info->revision = CpuFeatures_StringView_ParsePositiveNumber(value);
+    } else if (CpuFeatures_StringView_IsEquals(key, str("CPU architecture"))) {
+      // CPU architecture is a number that may be followed by letters. e.g.
+      // "6TEJ", "7".
+      const StringView digits =
+          CpuFeatures_StringView_KeepFront(value, IndexOfNonDigit(value));
+      info->architecture = CpuFeatures_StringView_ParsePositiveNumber(digits);
+    } else if (CpuFeatures_StringView_IsEquals(key, str("Processor")) ||
+               CpuFeatures_StringView_IsEquals(key, str("model name"))) {
+      // Android reports this in a non-Linux standard "Processor" but sometimes
+      // also in "model name", Linux reports it only in "model name"
+      // see RaspberryPiZero (Linux) vs InvalidArmv7 (Android) test-cases
+      proc_info->processor_reports_armv6 =
+          CpuFeatures_StringView_IndexOf(value, str("(v6l)")) >= 0;
+    } else if (CpuFeatures_StringView_IsEquals(key, str("Hardware"))) {
+      proc_info->hardware_reports_goldfish =
+          CpuFeatures_StringView_IsEquals(value, str("Goldfish"));
+    }
+  }
+  return !result.eof;
+}
+
+uint32_t GetArmCpuId(const ArmInfo* const info) {
+  return (ExtractBitRange(info->implementer, 7, 0) << 24) |
+         (ExtractBitRange(info->variant, 3, 0) << 20) |
+         (ExtractBitRange(info->part, 11, 0) << 4) |
+         (ExtractBitRange(info->revision, 3, 0) << 0);
+}
+
+static void FixErrors(ArmInfo* const info,
+                      ProcCpuInfoData* const proc_cpu_info_data) {
+  // Fixing Samsung kernel reporting invalid cpu architecture.
+  // http://code.google.com/p/android/issues/detail?id=10812
+  if (proc_cpu_info_data->processor_reports_armv6 && info->architecture >= 7) {
+    info->architecture = 6;
+  }
+
+  // Handle kernel configuration bugs that prevent the correct reporting of CPU
+  // features.
+  switch (GetArmCpuId(info)) {
+    case 0x4100C080:
+      // Special case: The emulator-specific Android 4.2 kernel fails to report
+      // support for the 32-bit ARM IDIV instruction. Technically, this is a
+      // feature of the virtual CPU implemented by the emulator. Note that it
+      // could also support Thumb IDIV in the future, and this will have to be
+      // slightly updated.
+      if (info->architecture >= 7 &&
+          proc_cpu_info_data->hardware_reports_goldfish) {
+        info->features.idiva = true;
+      }
+      break;
+    case 0x511004D0:
+      // https://crbug.com/341598.
+      info->features.neon = false;
+      break;
+    case 0x510006F2:
+    case 0x510006F3:
+      // The Nexus 4 (Qualcomm Krait) kernel configuration forgets to report
+      // IDIV support.
+      info->features.idiva = true;
+      info->features.idivt = true;
+      break;
+  }
+
+  // Propagate cpu features.
+  if (info->features.vfpv4) info->features.vfpv3 = true;
+  if (info->features.neon) info->features.vfpv3 = true;
+  if (info->features.vfpv3) info->features.vfp = true;
+}
+
+static void FillProcCpuInfoData(ArmInfo* const info,
+                                ProcCpuInfoData* proc_cpu_info_data) {
+  const int fd = CpuFeatures_OpenFile("/proc/cpuinfo");
+  if (fd >= 0) {
+    StackLineReader reader;
+    StackLineReader_Initialize(&reader, fd);
+    for (;;) {
+      if (!HandleArmLine(StackLineReader_NextLine(&reader), info,
+                         proc_cpu_info_data)) {
+        break;
+      }
+    }
+    CpuFeatures_CloseFile(fd);
+  }
+}
+
+static const ArmInfo kEmptyArmInfo;
+
+static const ProcCpuInfoData kEmptyProcCpuInfoData;
+
+ArmInfo GetArmInfo(void) {
+  // capabilities are fetched from both getauxval and /proc/cpuinfo so we can
+  // have some information if the executable is sandboxed (aka no access to
+  // /proc/cpuinfo).
+  ArmInfo info = kEmptyArmInfo;
+  ProcCpuInfoData proc_cpu_info_data = kEmptyProcCpuInfoData;
+
+  FillProcCpuInfoData(&info, &proc_cpu_info_data);
+  const HardwareCapabilities hwcaps = CpuFeatures_GetHardwareCapabilities();
+  for (size_t i = 0; i < ARM_LAST_; ++i) {
+    if (CpuFeatures_IsHwCapsSet(kHardwareCapabilities[i], hwcaps)) {
+      kSetters[i](&info.features, true);
+    }
+  }
+
+  FixErrors(&info, &proc_cpu_info_data);
+
+  return info;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Introspection functions
+
+int GetArmFeaturesEnumValue(const ArmFeatures* features,
+                            ArmFeaturesEnum value) {
+  if (value >= ARM_LAST_) return false;
+  return kGetters[value](features);
+}
+
+const char* GetArmFeaturesEnumName(ArmFeaturesEnum value) {
+  if (value >= ARM_LAST_) return "unknown feature";
+  return kCpuInfoFlags[value];
+}

cpu_features/src/cpuinfo_mips.c

@@ -0,0 +1,92 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cpuinfo_mips.h"
+
+#include <assert.h>
+
+#include "internal/filesystem.h"
+#include "internal/hwcaps.h"
+#include "internal/stack_line_reader.h"
+#include "internal/string_view.h"
+
+// Generation of feature's getters/setters functions and kGetters, kSetters,
+// kCpuInfoFlags and kHardwareCapabilities global tables.
+#define DEFINE_TABLE_FEATURES                      \
+  FEATURE(MIPS_MSA, msa, "msa", MIPS_HWCAP_MSA, 0) \
+  FEATURE(MIPS_EVA, eva, "eva", 0, 0)              \
+  FEATURE(MIPS_R6, r6, "r6", MIPS_HWCAP_R6, 0)
+#define DEFINE_TABLE_FEATURE_TYPE MipsFeatures
+#include "define_tables.h"
+
+static bool HandleMipsLine(const LineResult result,
+                           MipsFeatures* const features) {
+  StringView key, value;
+  // See tests for an example.
+  if (CpuFeatures_StringView_GetAttributeKeyValue(result.line, &key, &value)) {
+    if (CpuFeatures_StringView_IsEquals(key, str("ASEs implemented"))) {
+      for (size_t i = 0; i < MIPS_LAST_; ++i) {
+        kSetters[i](features,
+                    CpuFeatures_StringView_HasWord(value, kCpuInfoFlags[i]));
+      }
+    }
+  }
+  return !result.eof;
+}
+
+static void FillProcCpuInfoData(MipsFeatures* const features) {
+  const int fd = CpuFeatures_OpenFile("/proc/cpuinfo");
+  if (fd >= 0) {
+    StackLineReader reader;
+    StackLineReader_Initialize(&reader, fd);
+    for (;;) {
+      if (!HandleMipsLine(StackLineReader_NextLine(&reader), features)) {
+        break;
+      }
+    }
+    CpuFeatures_CloseFile(fd);
+  }
+}
+
+static const MipsInfo kEmptyMipsInfo;
+
+MipsInfo GetMipsInfo(void) {
+  // capabilities are fetched from both getauxval and /proc/cpuinfo so we can
+  // have some information if the executable is sandboxed (aka no access to
+  // /proc/cpuinfo).
+  MipsInfo info = kEmptyMipsInfo;
+
+  FillProcCpuInfoData(&info.features);
+  const HardwareCapabilities hwcaps = CpuFeatures_GetHardwareCapabilities();
+  for (size_t i = 0; i < MIPS_LAST_; ++i) {
+    if (CpuFeatures_IsHwCapsSet(kHardwareCapabilities[i], hwcaps)) {
+      kSetters[i](&info.features, true);
+    }
+  }
+  return info;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Introspection functions
+
+int GetMipsFeaturesEnumValue(const MipsFeatures* features,
+                             MipsFeaturesEnum value) {
+  if (value >= MIPS_LAST_) return false;
+  return kGetters[value](features);
+}
+
+const char* GetMipsFeaturesEnumName(MipsFeaturesEnum value) {
+  if (value >= MIPS_LAST_) return "unknown feature";
+  return kCpuInfoFlags[value];
+}

cpu_features/src/cpuinfo_ppc.c

@@ -0,0 +1,154 @@
+// Copyright 2018 IBM.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cpuinfo_ppc.h"
+
+#include <assert.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include "internal/bit_utils.h"
+#include "internal/filesystem.h"
+#include "internal/stack_line_reader.h"
+#include "internal/string_view.h"
+
+// Generation of feature's getters/setters functions and kGetters, kSetters,
+// kCpuInfoFlags and kHardwareCapabilities global tables.
+#define DEFINE_TABLE_FEATURES                                                  \
+  FEATURE(PPC_32, ppc32, "ppc32", PPC_FEATURE_32, 0)                           \
+  FEATURE(PPC_64, ppc64, "ppc64", PPC_FEATURE_64, 0)                           \
+  FEATURE(PPC_601_INSTR, ppc601, "ppc601", PPC_FEATURE_601_INSTR, 0)           \
+  FEATURE(PPC_HAS_ALTIVEC, altivec, "altivec", PPC_FEATURE_HAS_ALTIVEC, 0)     \
+  FEATURE(PPC_HAS_FPU, fpu, "fpu", PPC_FEATURE_HAS_FPU, 0)                     \
+  FEATURE(PPC_HAS_MMU, mmu, "mmu", PPC_FEATURE_HAS_MMU, 0)                     \
+  FEATURE(PPC_HAS_4xxMAC, mac_4xx, "4xxmac", PPC_FEATURE_HAS_4xxMAC, 0)        \
+  FEATURE(PPC_UNIFIED_CACHE, unifiedcache, "ucache",                           \
+          PPC_FEATURE_UNIFIED_CACHE, 0)                                        \
+  FEATURE(PPC_HAS_SPE, spe, "spe", PPC_FEATURE_HAS_SPE, 0)                     \
+  FEATURE(PPC_HAS_EFP_SINGLE, efpsingle, "efpsingle",                          \
+          PPC_FEATURE_HAS_EFP_SINGLE, 0)                                       \
+  FEATURE(PPC_HAS_EFP_DOUBLE, efpdouble, "efpdouble",                          \
+          PPC_FEATURE_HAS_EFP_DOUBLE, 0)                                       \
+  FEATURE(PPC_NO_TB, no_tb, "notb", PPC_FEATURE_NO_TB, 0)                      \
+  FEATURE(PPC_POWER4, power4, "power4", PPC_FEATURE_POWER4, 0)                 \
+  FEATURE(PPC_POWER5, power5, "power5", PPC_FEATURE_POWER5, 0)                 \
+  FEATURE(PPC_POWER5_PLUS, power5plus, "power5+", PPC_FEATURE_POWER5_PLUS, 0)  \
+  FEATURE(PPC_CELL, cell, "cellbe", PPC_FEATURE_CELL, 0)                       \
+  FEATURE(PPC_BOOKE, booke, "booke", PPC_FEATURE_BOOKE, 0)                     \
+  FEATURE(PPC_SMT, smt, "smt", PPC_FEATURE_SMT, 0)                             \
+  FEATURE(PPC_ICACHE_SNOOP, icachesnoop, "ic_snoop", PPC_FEATURE_ICACHE_SNOOP, \
+          0)                                                                   \
+  FEATURE(PPC_ARCH_2_05, arch205, "arch_2_05", PPC_FEATURE_ARCH_2_05, 0)       \
+  FEATURE(PPC_PA6T, pa6t, "pa6t", PPC_FEATURE_PA6T, 0)                         \
+  FEATURE(PPC_HAS_DFP, dfp, "dfp", PPC_FEATURE_HAS_DFP, 0)                     \
+  FEATURE(PPC_POWER6_EXT, power6ext, "power6x", PPC_FEATURE_POWER6_EXT, 0)     \
+  FEATURE(PPC_ARCH_2_06, arch206, "arch_2_06", PPC_FEATURE_ARCH_2_06, 0)       \
+  FEATURE(PPC_HAS_VSX, vsx, "vsx", PPC_FEATURE_HAS_VSX, 0)                     \
+  FEATURE(PPC_PSERIES_PERFMON_COMPAT, pseries_perfmon_compat, "archpmu",       \
+          PPC_FEATURE_PSERIES_PERFMON_COMPAT, 0)                               \
+  FEATURE(PPC_TRUE_LE, truele, "true_le", PPC_FEATURE_TRUE_LE, 0)              \
+  FEATURE(PPC_PPC_LE, ppcle, "ppcle", PPC_FEATURE_PPC_LE, 0)                   \
+  FEATURE(PPC_ARCH_2_07, arch207, "arch_2_07", 0, PPC_FEATURE2_ARCH_2_07)      \
+  FEATURE(PPC_HTM, htm, "htm", 0, PPC_FEATURE2_HTM)                            \
+  FEATURE(PPC_DSCR, dscr, "dscr", 0, PPC_FEATURE2_DSCR)                        \
+  FEATURE(PPC_EBB, ebb, "ebb", 0, PPC_FEATURE2_EBB)                            \
+  FEATURE(PPC_ISEL, isel, "isel", 0, PPC_FEATURE2_ISEL)                        \
+  FEATURE(PPC_TAR, tar, "tar", 0, PPC_FEATURE2_TAR)                            \
+  FEATURE(PPC_VEC_CRYPTO, vcrypto, "vcrypto", 0, PPC_FEATURE2_VEC_CRYPTO)      \
+  FEATURE(PPC_HTM_NOSC, htm_nosc, "htm-nosc", 0, PPC_FEATURE2_HTM_NOSC)        \
+  FEATURE(PPC_ARCH_3_00, arch300, "arch_3_00", 0, PPC_FEATURE2_ARCH_3_00)      \
+  FEATURE(PPC_HAS_IEEE128, ieee128, "ieee128", 0, PPC_FEATURE2_HAS_IEEE128)    \
+  FEATURE(PPC_DARN, darn, "darn", 0, PPC_FEATURE2_DARN)                        \
+  FEATURE(PPC_SCV, scv, "scv", 0, PPC_FEATURE2_SCV)                            \
+  FEATURE(PPC_HTM_NO_SUSPEND, htm_no_suspend, "htm-no-suspend", 0,             \
+          PPC_FEATURE2_HTM_NO_SUSPEND)
+#define DEFINE_TABLE_FEATURE_TYPE PPCFeatures
+#include "define_tables.h"
+
+static bool HandlePPCLine(const LineResult result,
+                          PPCPlatformStrings* const strings) {
+  StringView line = result.line;
+  StringView key, value;
+  if (CpuFeatures_StringView_GetAttributeKeyValue(line, &key, &value)) {
+    if (CpuFeatures_StringView_HasWord(key, "platform")) {
+      CpuFeatures_StringView_CopyString(value, strings->platform,
+                                        sizeof(strings->platform));
+    } else if (CpuFeatures_StringView_IsEquals(key, str("model"))) {
+      CpuFeatures_StringView_CopyString(value, strings->model,
+                                        sizeof(strings->platform));
+    } else if (CpuFeatures_StringView_IsEquals(key, str("machine"))) {
+      CpuFeatures_StringView_CopyString(value, strings->machine,
+                                        sizeof(strings->platform));
+    } else if (CpuFeatures_StringView_IsEquals(key, str("cpu"))) {
+      CpuFeatures_StringView_CopyString(value, strings->cpu,
+                                        sizeof(strings->platform));
+    }
+  }
+  return !result.eof;
+}
+
+static void FillProcCpuInfoData(PPCPlatformStrings* const strings) {
+  const int fd = CpuFeatures_OpenFile("/proc/cpuinfo");
+  if (fd >= 0) {
+    StackLineReader reader;
+    StackLineReader_Initialize(&reader, fd);
+    for (;;) {
+      if (!HandlePPCLine(StackLineReader_NextLine(&reader), strings)) {
+        break;
+      }
+    }
+    CpuFeatures_CloseFile(fd);
+  }
+}
+
+static const PPCInfo kEmptyPPCInfo;
+
+PPCInfo GetPPCInfo(void) {
+  /*
+   * On Power feature flags aren't currently in cpuinfo so we only look at
+   * the auxilary vector.
+   */
+  PPCInfo info = kEmptyPPCInfo;
+  const HardwareCapabilities hwcaps = CpuFeatures_GetHardwareCapabilities();
+  for (size_t i = 0; i < PPC_LAST_; ++i) {
+    if (CpuFeatures_IsHwCapsSet(kHardwareCapabilities[i], hwcaps)) {
+      kSetters[i](&info.features, true);
+    }
+  }
+  return info;
+}
+
+static const PPCPlatformStrings kEmptyPPCPlatformStrings;
+
+PPCPlatformStrings GetPPCPlatformStrings(void) {
+  PPCPlatformStrings strings = kEmptyPPCPlatformStrings;
+
+  FillProcCpuInfoData(&strings);
+  strings.type = CpuFeatures_GetPlatformType();
+  return strings;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Introspection functions
+
+int GetPPCFeaturesEnumValue(const PPCFeatures* features,
+                            PPCFeaturesEnum value) {
+  if (value >= PPC_LAST_) return false;
+  return kGetters[value](features);
+}
+
+const char* GetPPCFeaturesEnumName(PPCFeaturesEnum value) {
+  if (value >= PPC_LAST_) return "unknown feature";
+  return kCpuInfoFlags[value];
+}

cpu_features/src/define_tables.h

@@ -0,0 +1,67 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// The following preprocessor constants must be defined before including this
+// file:
+//  - DEFINE_TABLE_FEATURE_TYPE, the underlying type (e.g. X86Features)
+//  - DEFINE_TABLE_FEATURES, the list of FEATURE macros to be inserted.
+
+// This file is to be included once per `cpuinfo_XXX.c` in order to construct
+// feature getters and setters functions as well as several enum indexed tables
+// from the db file.
+// - `kGetters` a table of getters function pointers from feature enum to
+// retrieve a feature,
+// - `kSetters` a table of setters function pointers from feature enum to set a
+// feature,
+// - `kCpuInfoFlags` a table of strings from feature enum to /proc/cpuinfo
+// flags,
+// - `kHardwareCapabilities` a table of HardwareCapabilities structs indexed by
+// their feature enum.
+
+#ifndef SRC_DEFINE_TABLES_H_
+#define SRC_DEFINE_TABLES_H_
+
+#define FEATURE(ENUM, NAME, CPUINFO_FLAG, HWCAP, HWCAP2) [ENUM] = CPUINFO_FLAG,
+static const char* kCpuInfoFlags[] = {DEFINE_TABLE_FEATURES};
+#undef FEATURE
+
+#ifndef DEFINE_TABLE_DONT_GENERATE_HWCAPS
+#define FEATURE(ENUM, NAME, CPUINFO_FLAG, HWCAP, HWCAP2) \
+  [ENUM] = (HardwareCapabilities){HWCAP, HWCAP2},
+static const HardwareCapabilities kHardwareCapabilities[] = {
+    DEFINE_TABLE_FEATURES};
+#undef FEATURE
+#endif  // DEFINE_TABLE_DONT_GENERATE_HWCAPS
+
+#define FEATURE(ENUM, NAME, CPUINFO_FLAG, HWCAP, HWCAP2)                    \
+  static void set_##ENUM(DEFINE_TABLE_FEATURE_TYPE* features, bool value) { \
+    features->NAME = value;                                                 \
+  }                                                                         \
+  static int get_##ENUM(const DEFINE_TABLE_FEATURE_TYPE* features) {        \
+    return features->NAME;                                                  \
+  }
+DEFINE_TABLE_FEATURES
+#undef FEATURE
+
+#define FEATURE(ENUM, NAME, CPUINFO_FLAG, HWCAP, HWCAP2) [ENUM] = set_##ENUM,
+static void (*const kSetters[])(DEFINE_TABLE_FEATURE_TYPE*,
+                                bool) = {DEFINE_TABLE_FEATURES};
+#undef FEATURE
+
+#define FEATURE(ENUM, NAME, CPUINFO_FLAG, HWCAP, HWCAP2) [ENUM] = get_##ENUM,
+static int (*const kGetters[])(const DEFINE_TABLE_FEATURE_TYPE*) = {
+    DEFINE_TABLE_FEATURES};
+#undef FEATURE
+
+#endif  // SRC_DEFINE_TABLES_H_

cpu_features/src/filesystem.c

@@ -0,0 +1,62 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/filesystem.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#if defined(CPU_FEATURES_MOCK_FILESYSTEM)
+// Implementation will be provided by test/filesystem_for_testing.cc.
+#elif defined(_MSC_VER)
+#include <io.h>
+int CpuFeatures_OpenFile(const char* filename) {
+  int fd = -1;
+  _sopen_s(&fd, filename, _O_RDONLY, _SH_DENYWR, _S_IREAD);
+  return fd;
+}
+
+void CpuFeatures_CloseFile(int file_descriptor) { _close(file_descriptor); }
+
+int CpuFeatures_ReadFile(int file_descriptor, void* buffer,
+                         size_t buffer_size) {
+  return _read(file_descriptor, buffer, (unsigned int)buffer_size);
+}
+
+#else
+#include <unistd.h>
+
+int CpuFeatures_OpenFile(const char* filename) {
+  int result;
+  do {
+    result = open(filename, O_RDONLY);
+  } while (result == -1L && errno == EINTR);
+  return result;
+}
+
+void CpuFeatures_CloseFile(int file_descriptor) { close(file_descriptor); }
+
+int CpuFeatures_ReadFile(int file_descriptor, void* buffer,
+                         size_t buffer_size) {
+  int result;
+  do {
+    result = read(file_descriptor, buffer, buffer_size);
+  } while (result == -1L && errno == EINTR);
+  return result;
+}
+
+#endif

cpu_features/src/hwcaps.c

@@ -0,0 +1,182 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/hwcaps.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "cpu_features_macros.h"
+#include "internal/filesystem.h"
+#include "internal/string_view.h"
+
+static bool IsSet(const uint32_t mask, const uint32_t value) {
+  if (mask == 0) return false;
+  return (value & mask) == mask;
+}
+
+bool CpuFeatures_IsHwCapsSet(const HardwareCapabilities hwcaps_mask,
+                             const HardwareCapabilities hwcaps) {
+  return IsSet(hwcaps_mask.hwcaps, hwcaps.hwcaps) ||
+         IsSet(hwcaps_mask.hwcaps2, hwcaps.hwcaps2);
+}
+
+#ifdef CPU_FEATURES_TEST
+// In test mode, hwcaps_for_testing will define the following functions.
+HardwareCapabilities CpuFeatures_GetHardwareCapabilities(void);
+PlatformType CpuFeatures_GetPlatformType(void);
+#else
+
+// Debug facilities
+#if defined(NDEBUG)
+#define D(...)
+#else
+#include <stdio.h>
+#define D(...)           \
+  do {                   \
+    printf(__VA_ARGS__); \
+    fflush(stdout);      \
+  } while (0)
+#endif
+
+////////////////////////////////////////////////////////////////////////////////
+// Implementation of GetElfHwcapFromGetauxval
+////////////////////////////////////////////////////////////////////////////////
+
+#define AT_HWCAP 16
+#define AT_HWCAP2 26
+#define AT_PLATFORM 15
+#define AT_BASE_PLATFORM 24
+
+#if defined(HAVE_STRONG_GETAUXVAL)
+#include <sys/auxv.h>
+static unsigned long GetElfHwcapFromGetauxval(uint32_t hwcap_type) {
+  return getauxval(hwcap_type);
+}
+#elif defined(HAVE_DLFCN_H)
+// On Android we probe the system's C library for a 'getauxval' function and
+// call it if it exits, or return 0 for failure. This function is available
+// since API level 20.
+//
+// This code does *NOT* check for '__ANDROID_API__ >= 20' to support the edge
+// case where some NDK developers use headers for a platform that is newer than
+// the one really targetted by their application. This is typically done to use
+// newer native APIs only when running on more recent Android versions, and
+// requires careful symbol management.
+//
+// Note that getauxval() can't really be re-implemented here, because its
+// implementation does not parse /proc/self/auxv. Instead it depends on values
+// that are passed by the kernel at process-init time to the C runtime
+// initialization layer.
+
+#include <dlfcn.h>
+
+typedef unsigned long getauxval_func_t(unsigned long);
+
+static uint32_t GetElfHwcapFromGetauxval(uint32_t hwcap_type) {
+  uint32_t ret = 0;
+  void *libc_handle = NULL;
+  getauxval_func_t *func = NULL;
+
+  dlerror();  // Cleaning error state before calling dlopen.
+  libc_handle = dlopen("libc.so", RTLD_NOW);
+  if (!libc_handle) {
+    D("Could not dlopen() C library: %s\n", dlerror());
+    return 0;
+  }
+  func = (getauxval_func_t *)dlsym(libc_handle, "getauxval");
+  if (!func) {
+    D("Could not find getauxval() in C library\n");
+  } else {
+    // Note: getauxval() returns 0 on failure. Doesn't touch errno.
+    ret = (uint32_t)(*func)(hwcap_type);
+  }
+  dlclose(libc_handle);
+  return ret;
+}
+#else
+#error "This platform does not provide hardware capabilities."
+#endif
+
+// Implementation of GetHardwareCapabilities for OS that provide
+// GetElfHwcapFromGetauxval().
+
+// Fallback when getauxval is not available, retrieves hwcaps from
+// "/proc/self/auxv".
+static uint32_t GetElfHwcapFromProcSelfAuxv(uint32_t hwcap_type) {
+  struct {
+    uint32_t tag;
+    uint32_t value;
+  } entry;
+  uint32_t result = 0;
+  const char filepath[] = "/proc/self/auxv";
+  const int fd = CpuFeatures_OpenFile(filepath);
+  if (fd < 0) {
+    D("Could not open %s\n", filepath);
+    return 0;
+  }
+  for (;;) {
+    const int ret = CpuFeatures_ReadFile(fd, (char *)&entry, sizeof entry);
+    if (ret < 0) {
+      D("Error while reading %s\n", filepath);
+      break;
+    }
+    // Detect end of list.
+    if (ret == 0 || (entry.tag == 0 && entry.value == 0)) {
+      break;
+    }
+    if (entry.tag == hwcap_type) {
+      result = entry.value;
+      break;
+    }
+  }
+  CpuFeatures_CloseFile(fd);
+  return result;
+}
+
+// Retrieves hardware capabilities by first trying to call getauxval, if not
+// available falls back to reading "/proc/self/auxv".
+static unsigned long GetHardwareCapabilitiesFor(uint32_t type) {
+  unsigned long hwcaps = GetElfHwcapFromGetauxval(type);
+  if (!hwcaps) {
+    D("Parsing /proc/self/auxv to extract ELF hwcaps!\n");
+    hwcaps = GetElfHwcapFromProcSelfAuxv(type);
+  }
+  return hwcaps;
+}
+
+HardwareCapabilities CpuFeatures_GetHardwareCapabilities(void) {
+  HardwareCapabilities capabilities;
+  capabilities.hwcaps = GetHardwareCapabilitiesFor(AT_HWCAP);
+  capabilities.hwcaps2 = GetHardwareCapabilitiesFor(AT_HWCAP2);
+  return capabilities;
+}
+
+PlatformType kEmptyPlatformType;
+
+PlatformType CpuFeatures_GetPlatformType(void) {
+  PlatformType type = kEmptyPlatformType;
+  char *platform = (char *)GetHardwareCapabilitiesFor(AT_PLATFORM);
+  char *base_platform = (char *)GetHardwareCapabilitiesFor(AT_BASE_PLATFORM);
+
+  if (platform != NULL)
+    CpuFeatures_StringView_CopyString(str(platform), type.platform,
+                                      sizeof(type.platform));
+  if (base_platform != NULL)
+    CpuFeatures_StringView_CopyString(str(base_platform), type.base_platform,
+                                      sizeof(type.base_platform));
+  return type;
+}
+
+#endif  // CPU_FEATURES_TEST

cpu_features/src/stack_line_reader.c

@@ -0,0 +1,132 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/stack_line_reader.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <stdio.h>
+
+#include "internal/filesystem.h"
+
+void StackLineReader_Initialize(StackLineReader* reader, int fd) {
+  reader->view.ptr = reader->buffer;
+  reader->view.size = 0;
+  reader->skip_mode = false;
+  reader->fd = fd;
+}
+
+// Replaces the content of buffer with bytes from the file.
+static int LoadFullBuffer(StackLineReader* reader) {
+  const int read = CpuFeatures_ReadFile(reader->fd, reader->buffer,
+                                        STACK_LINE_READER_BUFFER_SIZE);
+  assert(read >= 0);
+  reader->view.ptr = reader->buffer;
+  reader->view.size = read;
+  return read;
+}
+
+// Appends with bytes from the file to buffer, filling the remaining space.
+static int LoadMore(StackLineReader* reader) {
+  char* const ptr = reader->buffer + reader->view.size;
+  const size_t size_to_read = STACK_LINE_READER_BUFFER_SIZE - reader->view.size;
+  const int read = CpuFeatures_ReadFile(reader->fd, ptr, size_to_read);
+  assert(read >= 0);
+  assert(read <= (int)size_to_read);
+  reader->view.size += read;
+  return read;
+}
+
+static int IndexOfEol(StackLineReader* reader) {
+  return CpuFeatures_StringView_IndexOfChar(reader->view, '\n');
+}
+
+// Relocate buffer's pending bytes at the beginning of the array and fills the
+// remaining space with bytes from the file.
+static int BringToFrontAndLoadMore(StackLineReader* reader) {
+  if (reader->view.size && reader->view.ptr != reader->buffer) {
+    memmove(reader->buffer, reader->view.ptr, reader->view.size);
+  }
+  reader->view.ptr = reader->buffer;
+  return LoadMore(reader);
+}
+
+// Loads chunks of buffer size from disks until it contains a newline character
+// or end of file.
+static void SkipToNextLine(StackLineReader* reader) {
+  for (;;) {
+    const int read = LoadFullBuffer(reader);
+    if (read == 0) {
+      break;
+    } else {
+      const int eol_index = IndexOfEol(reader);
+      if (eol_index >= 0) {
+        reader->view =
+            CpuFeatures_StringView_PopFront(reader->view, eol_index + 1);
+        break;
+      }
+    }
+  }
+}
+
+static LineResult CreateLineResult(bool eof, bool full_line, StringView view) {
+  LineResult result;
+  result.eof = eof;
+  result.full_line = full_line;
+  result.line = view;
+  return result;
+}
+
+// Helper methods to provide clearer semantic in StackLineReader_NextLine.
+static LineResult CreateEOFLineResult(StringView view) {
+  return CreateLineResult(true, true, view);
+}
+
+static LineResult CreateTruncatedLineResult(StringView view) {
+  return CreateLineResult(false, false, view);
+}
+
+static LineResult CreateValidLineResult(StringView view) {
+  return CreateLineResult(false, true, view);
+}
+
+LineResult StackLineReader_NextLine(StackLineReader* reader) {
+  if (reader->skip_mode) {
+    SkipToNextLine(reader);
+    reader->skip_mode = false;
+  }
+  {
+    const bool can_load_more =
+        reader->view.size < STACK_LINE_READER_BUFFER_SIZE;
+    int eol_index = IndexOfEol(reader);
+    if (eol_index < 0 && can_load_more) {
+      const int read = BringToFrontAndLoadMore(reader);
+      if (read == 0) {
+        return CreateEOFLineResult(reader->view);
+      }
+      eol_index = IndexOfEol(reader);
+    }
+    if (eol_index < 0) {
+      reader->skip_mode = true;
+      return CreateTruncatedLineResult(reader->view);
+    }
+    {
+      StringView line =
+          CpuFeatures_StringView_KeepFront(reader->view, eol_index);
+      reader->view =
+          CpuFeatures_StringView_PopFront(reader->view, eol_index + 1);
+      return CreateValidLineResult(line);
+    }
+  }
+}

cpu_features/src/string_view.c

@@ -0,0 +1,182 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/string_view.h"
+
+#include <assert.h>
+#include <ctype.h>
+#include <string.h>
+
+int CpuFeatures_StringView_IndexOfChar(const StringView view, char c) {
+  if (view.ptr && view.size) {
+    const char* const found = (const char*)memchr(view.ptr, c, view.size);
+    if (found) {
+      return (int)(found - view.ptr);
+    }
+  }
+  return -1;
+}
+
+int CpuFeatures_StringView_IndexOf(const StringView view,
+                                   const StringView sub_view) {
+  if (sub_view.size) {
+    StringView remainder = view;
+    while (remainder.size >= sub_view.size) {
+      const int found_index =
+          CpuFeatures_StringView_IndexOfChar(remainder, sub_view.ptr[0]);
+      if (found_index < 0) break;
+      remainder = CpuFeatures_StringView_PopFront(remainder, found_index);
+      if (CpuFeatures_StringView_StartsWith(remainder, sub_view)) {
+        return (int)(remainder.ptr - view.ptr);
+      }
+      remainder = CpuFeatures_StringView_PopFront(remainder, 1);
+    }
+  }
+  return -1;
+}
+
+bool CpuFeatures_StringView_IsEquals(const StringView a, const StringView b) {
+  if (a.size == b.size) {
+    return a.ptr == b.ptr || memcmp(a.ptr, b.ptr, b.size) == 0;
+  }
+  return false;
+}
+
+bool CpuFeatures_StringView_StartsWith(const StringView a, const StringView b) {
+  return a.ptr && b.ptr && b.size && a.size >= b.size
+             ? memcmp(a.ptr, b.ptr, b.size) == 0
+             : false;
+}
+
+StringView CpuFeatures_StringView_PopFront(const StringView str_view,
+                                           size_t count) {
+  if (count > str_view.size) {
+    return kEmptyStringView;
+  }
+  return view(str_view.ptr + count, str_view.size - count);
+}
+
+StringView CpuFeatures_StringView_PopBack(const StringView str_view,
+                                          size_t count) {
+  if (count > str_view.size) {
+    return kEmptyStringView;
+  }
+  return view(str_view.ptr, str_view.size - count);
+}
+
+StringView CpuFeatures_StringView_KeepFront(const StringView str_view,
+                                            size_t count) {
+  return count <= str_view.size ? view(str_view.ptr, count) : str_view;
+}
+
+char CpuFeatures_StringView_Front(const StringView view) {
+  assert(view.size);
+  assert(view.ptr);
+  return view.ptr[0];
+}
+
+char CpuFeatures_StringView_Back(const StringView view) {
+  assert(view.size);
+  return view.ptr[view.size - 1];
+}
+
+StringView CpuFeatures_StringView_TrimWhitespace(StringView view) {
+  while (view.size && isspace(CpuFeatures_StringView_Front(view)))
+    view = CpuFeatures_StringView_PopFront(view, 1);
+  while (view.size && isspace(CpuFeatures_StringView_Back(view)))
+    view = CpuFeatures_StringView_PopBack(view, 1);
+  return view;
+}
+
+static int HexValue(const char c) {
+  if (c >= '0' && c <= '9') return c - '0';
+  if (c >= 'a' && c <= 'f') return c - 'a' + 10;
+  if (c >= 'A' && c <= 'F') return c - 'A' + 10;
+  return -1;
+}
+
+// Returns -1 if view contains non digits.
+static int ParsePositiveNumberWithBase(const StringView view, int base) {
+  int result = 0;
+  StringView remainder = view;
+  for (; remainder.size;
+       remainder = CpuFeatures_StringView_PopFront(remainder, 1)) {
+    const int value = HexValue(CpuFeatures_StringView_Front(remainder));
+    if (value < 0 || value >= base) return -1;
+    result = (result * base) + value;
+  }
+  return result;
+}
+
+int CpuFeatures_StringView_ParsePositiveNumber(const StringView view) {
+  if (view.size) {
+    const StringView hex_prefix = str("0x");
+    if (CpuFeatures_StringView_StartsWith(view, hex_prefix)) {
+      const StringView span_no_prefix =
+          CpuFeatures_StringView_PopFront(view, hex_prefix.size);
+      return ParsePositiveNumberWithBase(span_no_prefix, 16);
+    }
+    return ParsePositiveNumberWithBase(view, 10);
+  }
+  return -1;
+}
+
+void CpuFeatures_StringView_CopyString(const StringView src, char* dst,
+                                       size_t dst_size) {
+  if (dst_size > 0) {
+    const size_t max_copy_size = dst_size - 1;
+    const size_t copy_size =
+        src.size > max_copy_size ? max_copy_size : src.size;
+    memcpy(dst, src.ptr, copy_size);
+    dst[copy_size] = '\0';
+  }
+}
+
+bool CpuFeatures_StringView_HasWord(const StringView line,
+                                    const char* const word_str) {
+  const StringView word = str(word_str);
+  StringView remainder = line;
+  for (;;) {
+    const int index_of_word = CpuFeatures_StringView_IndexOf(remainder, word);
+    if (index_of_word < 0) {
+      return false;
+    } else {
+      const StringView before =
+          CpuFeatures_StringView_KeepFront(line, index_of_word);
+      const StringView after =
+          CpuFeatures_StringView_PopFront(line, index_of_word + word.size);
+      const bool valid_before =
+          before.size == 0 || CpuFeatures_StringView_Back(before) == ' ';
+      const bool valid_after =
+          after.size == 0 || CpuFeatures_StringView_Front(after) == ' ';
+      if (valid_before && valid_after) return true;
+      remainder =
+          CpuFeatures_StringView_PopFront(remainder, index_of_word + word.size);
+    }
+  }
+  return false;
+}
+
+bool CpuFeatures_StringView_GetAttributeKeyValue(const StringView line,
+                                                 StringView* key,
+                                                 StringView* value) {
+  const StringView sep = str(": ");
+  const int index_of_separator = CpuFeatures_StringView_IndexOf(line, sep);
+  if (index_of_separator < 0) return false;
+  *value = CpuFeatures_StringView_TrimWhitespace(
+      CpuFeatures_StringView_PopFront(line, index_of_separator + sep.size));
+  *key = CpuFeatures_StringView_TrimWhitespace(
+      CpuFeatures_StringView_KeepFront(line, index_of_separator));
+  return true;
+}

cpu_features/src/utils/list_cpu_features.c

@@ -0,0 +1,438 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// This program dumps current host data to the standard output.
+// Output can be text or json if the `--json` flag is passed.
+
+#include <assert.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "cpu_features_macros.h"
+
+#if defined(CPU_FEATURES_ARCH_X86)
+#include "cpuinfo_x86.h"
+#elif defined(CPU_FEATURES_ARCH_ARM)
+#include "cpuinfo_arm.h"
+#elif defined(CPU_FEATURES_ARCH_AARCH64)
+#include "cpuinfo_aarch64.h"
+#elif defined(CPU_FEATURES_ARCH_MIPS)
+#include "cpuinfo_mips.h"
+#elif defined(CPU_FEATURES_ARCH_PPC)
+#include "cpuinfo_ppc.h"
+#endif
+
+// Design principles
+// -----------------
+// We build a tree structure containing all the data to be displayed.
+// Then depending on the output type (text or json) we walk the tree and display
+// the data accordingly.
+
+// We use a bump allocator to allocate strings and nodes of the tree,
+// Memory is not intended to be reclaimed.
+typedef struct {
+  char* ptr;
+  size_t size;
+} BumpAllocator;
+
+char gGlobalBuffer[64 * 1024];
+BumpAllocator gBumpAllocator = {.ptr = gGlobalBuffer,
+                                .size = sizeof(gGlobalBuffer)};
+
+static void internal_error() {
+  fputs("internal error\n", stderr);
+  exit(EXIT_FAILURE);
+}
+
+#define ALIGN 8
+
+static void assertAligned() {
+  if ((uintptr_t)(gBumpAllocator.ptr) % ALIGN) internal_error();
+}
+
+static void BA_Align() {
+  while (gBumpAllocator.size && (uintptr_t)(gBumpAllocator.ptr) % ALIGN) {
+    --gBumpAllocator.size;
+    ++gBumpAllocator.ptr;
+  }
+  assertAligned();
+}
+
+// Update the available memory left in the BumpAllocator.
+static void* BA_Bump(size_t size) {
+  assertAligned();
+  // Align size to next 8B boundary.
+  size = (size + ALIGN - 1) / ALIGN * ALIGN;
+  if (gBumpAllocator.size < size) internal_error();
+  void* ptr = gBumpAllocator.ptr;
+  gBumpAllocator.size -= size;
+  gBumpAllocator.ptr += size;
+  return ptr;
+}
+
+// The type of the nodes in the tree.
+typedef enum {
+  NT_INVALID,
+  NT_INT,
+  NT_MAP,
+  NT_MAP_ENTRY,
+  NT_ARRAY,
+  NT_ARRAY_ELEMENT,
+  NT_STRING,
+} NodeType;
+
+// The node in the tree.
+typedef struct Node {
+  NodeType type;
+  unsigned integer;
+  const char* string;
+  struct Node* value;
+  struct Node* next;
+} Node;
+
+// Creates an initialized Node.
+static Node* BA_CreateNode(NodeType type) {
+  Node* tv = (Node*)BA_Bump(sizeof(Node));
+  assert(tv);
+  *tv = (Node){.type = type};
+  return tv;
+}
+
+// Adds an integer node.
+static Node* CreateInt(int value) {
+  Node* tv = BA_CreateNode(NT_INT);
+  tv->integer = value;
+  return tv;
+}
+
+// Adds a string node.
+// `value` must outlive the tree.
+static Node* CreateConstantString(const char* value) {
+  Node* tv = BA_CreateNode(NT_STRING);
+  tv->string = value;
+  return tv;
+}
+
+// Adds a map node.
+static Node* CreateMap() { return BA_CreateNode(NT_MAP); }
+
+// Adds an array node.
+static Node* CreateArray() { return BA_CreateNode(NT_ARRAY); }
+
+// Adds a formatted string node.
+static Node* CreatePrintfString(const char* format, ...) {
+  va_list arglist;
+  va_start(arglist, format);
+  char* const ptr = gBumpAllocator.ptr;
+  const int written = vsnprintf(ptr, gBumpAllocator.size, format, arglist);
+  va_end(arglist);
+  if (written < 0 || written >= (int)gBumpAllocator.size) internal_error();
+  return CreateConstantString((char*)BA_Bump(written));
+}
+
+// Adds a string node.
+static Node* CreateString(const char* value) {
+  return CreatePrintfString("%s", value);
+}
+
+// Adds a map entry node.
+static void AddMapEntry(Node* map, const char* key, Node* value) {
+  assert(map && map->type == NT_MAP);
+  Node* current = map;
+  while (current->next) current = current->next;
+  current->next = (Node*)BA_Bump(sizeof(Node));
+  *current->next = (Node){.type = NT_MAP_ENTRY, .string = key, .value = value};
+}
+
+// Adds an array element node.
+static void AddArrayElement(Node* array, Node* value) {
+  assert(array && array->type == NT_ARRAY);
+  Node* current = array;
+  while (current->next) current = current->next;
+  current->next = (Node*)BA_Bump(sizeof(Node));
+  *current->next = (Node){.type = NT_ARRAY_ELEMENT, .value = value};
+}
+
+static int cmp(const void* p1, const void* p2) {
+  return strcmp(*(const char* const*)p1, *(const char* const*)p2);
+}
+
+#define DEFINE_ADD_FLAGS(HasFeature, FeatureName, FeatureType, LastEnum) \
+  static void AddFlags(Node* map, const FeatureType* features) {         \
+    size_t i;                                                            \
+    const char* ptrs[LastEnum] = {0};                                    \
+    size_t count = 0;                                                    \
+    for (i = 0; i < LastEnum; ++i) {                                     \
+      if (HasFeature(features, i)) {                                     \
+        ptrs[count] = FeatureName(i);                                    \
+        ++count;                                                         \
+      }                                                                  \
+    }                                                                    \
+    qsort((void*)ptrs, count, sizeof(char*), cmp);                       \
+    Node* const array = CreateArray();                                   \
+    for (i = 0; i < count; ++i)                                          \
+      AddArrayElement(array, CreateConstantString(ptrs[i]));             \
+    AddMapEntry(map, "flags", array);                                    \
+  }
+
+#if defined(CPU_FEATURES_ARCH_X86)
+DEFINE_ADD_FLAGS(GetX86FeaturesEnumValue, GetX86FeaturesEnumName, X86Features,
+                 X86_LAST_)
+#elif defined(CPU_FEATURES_ARCH_ARM)
+DEFINE_ADD_FLAGS(GetArmFeaturesEnumValue, GetArmFeaturesEnumName, ArmFeatures,
+                 ARM_LAST_)
+#elif defined(CPU_FEATURES_ARCH_AARCH64)
+DEFINE_ADD_FLAGS(GetAarch64FeaturesEnumValue, GetAarch64FeaturesEnumName,
+                 Aarch64Features, AARCH64_LAST_)
+#elif defined(CPU_FEATURES_ARCH_MIPS)
+DEFINE_ADD_FLAGS(GetMipsFeaturesEnumValue, GetMipsFeaturesEnumName,
+                 MipsFeatures, MIPS_LAST_)
+#elif defined(CPU_FEATURES_ARCH_PPC)
+DEFINE_ADD_FLAGS(GetPPCFeaturesEnumValue, GetPPCFeaturesEnumName, PPCFeatures,
+                 PPC_LAST_)
+#endif
+
+// Prints a json string with characters escaping.
+static void printJsonString(const char* str) {
+  putchar('"');
+  for (; str && *str; ++str) {
+    switch (*str) {
+      case '\"':
+      case '\\':
+      case '/':
+      case '\b':
+      case '\f':
+      case '\n':
+      case '\r':
+      case '\t':
+        putchar('\\');
+    }
+    putchar(*str);
+  }
+  putchar('"');
+}
+
+// Walks a Node and print it as json.
+static void printJson(const Node* current) {
+  assert(current);
+  switch (current->type) {
+    case NT_INVALID:
+      break;
+    case NT_INT:
+      printf("%d", current->integer);
+      break;
+    case NT_STRING:
+      printJsonString(current->string);
+      break;
+    case NT_ARRAY:
+      putchar('[');
+      if (current->next) printJson(current->next);
+      putchar(']');
+      break;
+    case NT_MAP:
+      putchar('{');
+      if (current->next) printJson(current->next);
+      putchar('}');
+      break;
+    case NT_MAP_ENTRY:
+      printf("\"%s\":", current->string);
+      printJson(current->value);
+      if (current->next) {
+        putchar(',');
+        printJson(current->next);
+      }
+      break;
+    case NT_ARRAY_ELEMENT:
+      printJson(current->value);
+      if (current->next) {
+        putchar(',');
+        printJson(current->next);
+      }
+      break;
+  }
+}
+
+// Walks a Node and print it as text.
+static void printTextField(const Node* current) {
+  switch (current->type) {
+    case NT_INVALID:
+      break;
+    case NT_INT:
+      printf("%3d (0x%02X)", current->integer, current->integer);
+      break;
+    case NT_STRING:
+      fputs(current->string, stdout);
+      break;
+    case NT_ARRAY:
+      if (current->next) printTextField(current->next);
+      break;
+    case NT_MAP:
+      if (current->next) {
+        printf("{");
+        printJson(current->next);
+        printf("}");
+      }
+      break;
+    case NT_MAP_ENTRY:
+      printf("%-15s : ", current->string);
+      printTextField(current->value);
+      if (current->next) {
+        putchar('\n');
+        printTextField(current->next);
+      }
+      break;
+    case NT_ARRAY_ELEMENT:
+      printTextField(current->value);
+      if (current->next) {
+        putchar(',');
+        printTextField(current->next);
+      }
+      break;
+  }
+}
+
+static void printTextRoot(const Node* current) {
+  if (current->type == NT_MAP && current->next) printTextField(current->next);
+}
+
+static void showUsage(const char* name) {
+  printf(
+      "\n"
+      "Usage: %s [options]\n"
+      "      Options:\n"
+      "      -h | --help     Show help message.\n"
+      "      -j | --json     Format output as json instead of plain text.\n"
+      "\n",
+      name);
+}
+
+static Node* GetCacheTypeString(CacheType cache_type) {
+  switch (cache_type) {
+    case CPU_FEATURE_CACHE_NULL:
+      return CreateConstantString("null");
+    case CPU_FEATURE_CACHE_DATA:
+      return CreateConstantString("data");
+    case CPU_FEATURE_CACHE_INSTRUCTION:
+      return CreateConstantString("instruction");
+    case CPU_FEATURE_CACHE_UNIFIED:
+      return CreateConstantString("unified");
+    case CPU_FEATURE_CACHE_TLB:
+      return CreateConstantString("tlb");
+    case CPU_FEATURE_CACHE_DTLB:
+      return CreateConstantString("dtlb");
+    case CPU_FEATURE_CACHE_STLB:
+      return CreateConstantString("stlb");
+    case CPU_FEATURE_CACHE_PREFETCH:
+      return CreateConstantString("prefetch");
+  }
+}
+
+static void AddCacheInfo(Node* root, const CacheInfo* cache_info) {
+  Node* array = CreateArray();
+  for (int i = 0; i < cache_info->size; ++i) {
+    CacheLevelInfo info = cache_info->levels[i];
+    Node* map = CreateMap();
+    AddMapEntry(map, "level", CreateInt(info.level));
+    AddMapEntry(map, "cache_type", GetCacheTypeString(info.cache_type));
+    AddMapEntry(map, "cache_size", CreateInt(info.cache_size));
+    AddMapEntry(map, "ways", CreateInt(info.ways));
+    AddMapEntry(map, "line_size", CreateInt(info.line_size));
+    AddMapEntry(map, "tlb_entries", CreateInt(info.tlb_entries));
+    AddMapEntry(map, "partitioning", CreateInt(info.partitioning));
+    AddArrayElement(array, map);
+  }
+  AddMapEntry(root, "cache_info", array);
+}
+
+static Node* CreateTree() {
+  Node* root = CreateMap();
+#if defined(CPU_FEATURES_ARCH_X86)
+  char brand_string[49];
+  const X86Info info = GetX86Info();
+  const CacheInfo cache_info = GetX86CacheInfo();
+  FillX86BrandString(brand_string);
+  AddMapEntry(root, "arch", CreateString("x86"));
+  AddMapEntry(root, "brand", CreateString(brand_string));
+  AddMapEntry(root, "family", CreateInt(info.family));
+  AddMapEntry(root, "model", CreateInt(info.model));
+  AddMapEntry(root, "stepping", CreateInt(info.stepping));
+  AddMapEntry(root, "uarch",
+              CreateString(
+                  GetX86MicroarchitectureName(GetX86Microarchitecture(&info))));
+  AddFlags(root, &info.features);
+  AddCacheInfo(root, &cache_info);
+#elif defined(CPU_FEATURES_ARCH_ARM)
+  const ArmInfo info = GetArmInfo();
+  AddMapEntry(root, "arch", CreateString("ARM"));
+  AddMapEntry(root, "implementer", CreateInt(info.implementer));
+  AddMapEntry(root, "architecture", CreateInt(info.architecture));
+  AddMapEntry(root, "variant", CreateInt(info.variant));
+  AddMapEntry(root, "part", CreateInt(info.part));
+  AddMapEntry(root, "revision", CreateInt(info.revision));
+  AddFlags(root, &info.features);
+#elif defined(CPU_FEATURES_ARCH_AARCH64)
+  const Aarch64Info info = GetAarch64Info();
+  AddMapEntry(root, "arch", CreateString("aarch64"));
+  AddMapEntry(root, "implementer", CreateInt(info.implementer));
+  AddMapEntry(root, "variant", CreateInt(info.variant));
+  AddMapEntry(root, "part", CreateInt(info.part));
+  AddMapEntry(root, "revision", CreateInt(info.revision));
+  AddFlags(root, &info.features);
+#elif defined(CPU_FEATURES_ARCH_MIPS)
+  const MipsInfo info = GetMipsInfo();
+  AddMapEntry(root, "arch", CreateString("mips"));
+  AddFlags(root, &info.features);
+#elif defined(CPU_FEATURES_ARCH_PPC)
+  const PPCInfo info = GetPPCInfo();
+  const PPCPlatformStrings strings = GetPPCPlatformStrings();
+  AddMapEntry(root, "arch", CreateString("ppc"));
+  AddMapEntry(root, "platform", CreateString(strings.platform));
+  AddMapEntry(root, "model", CreateString(strings.model));
+  AddMapEntry(root, "machine", CreateString(strings.machine));
+  AddMapEntry(root, "cpu", CreateString(strings.cpu));
+  AddMapEntry(root, "instruction", CreateString(strings.type.platform));
+  AddMapEntry(root, "microarchitecture",
+              CreateString(strings.type.base_platform));
+  AddFlags(root, &info.features);
+#endif
+  return root;
+}
+
+int main(int argc, char** argv) {
+  BA_Align();
+  const Node* const root = CreateTree();
+  bool outputJson = false;
+  int i = 1;
+  for (; i < argc; ++i) {
+    const char* arg = argv[i];
+    if (strcmp(arg, "-j") == 0 || strcmp(arg, "--json") == 0) {
+      outputJson = true;
+    } else {
+      showUsage(argv[0]);
+      if (strcmp(arg, "-h") == 0 || strcmp(arg, "--help") == 0)
+        return EXIT_SUCCESS;
+      return EXIT_FAILURE;
+    }
+  }
+  if (outputJson)
+    printJson(root);
+  else
+    printTextRoot(root);
+  putchar('\n');
+  return EXIT_SUCCESS;
+}

cpu_features/test/CMakeLists.txt

@@ -0,0 +1,85 @@
+#
+# libraries for tests
+#
+
+include_directories(../include)
+add_definitions(-DCPU_FEATURES_TEST)
+
+##------------------------------------------------------------------------------
+add_library(string_view ../src/string_view.c)
+##------------------------------------------------------------------------------
+add_library(filesystem_for_testing filesystem_for_testing.cc)
+target_compile_definitions(filesystem_for_testing PUBLIC CPU_FEATURES_MOCK_FILESYSTEM)
+##------------------------------------------------------------------------------
+add_library(hwcaps_for_testing hwcaps_for_testing.cc)
+target_link_libraries(hwcaps_for_testing filesystem_for_testing)
+##------------------------------------------------------------------------------
+add_library(stack_line_reader ../src/stack_line_reader.c)
+target_compile_definitions(stack_line_reader PUBLIC STACK_LINE_READER_BUFFER_SIZE=1024)
+target_link_libraries(stack_line_reader string_view)
+##------------------------------------------------------------------------------
+add_library(stack_line_reader_for_test ../src/stack_line_reader.c)
+target_compile_definitions(stack_line_reader_for_test PUBLIC STACK_LINE_READER_BUFFER_SIZE=16)
+target_link_libraries(stack_line_reader_for_test string_view filesystem_for_testing)
+##------------------------------------------------------------------------------
+add_library(all_libraries ../src/hwcaps.c  ../src/stack_line_reader.c)
+target_link_libraries(all_libraries hwcaps_for_testing stack_line_reader string_view)
+
+#
+# tests
+#
+link_libraries(gtest gmock_main)
+
+## bit_utils_test
+add_executable(bit_utils_test bit_utils_test.cc)
+target_link_libraries(bit_utils_test)
+add_test(NAME bit_utils_test COMMAND bit_utils_test)
+##------------------------------------------------------------------------------
+## string_view_test
+add_executable(string_view_test string_view_test.cc ../src/string_view.c)
+target_link_libraries(string_view_test string_view)
+add_test(NAME string_view_test COMMAND string_view_test)
+##------------------------------------------------------------------------------
+## stack_line_reader_test
+add_executable(stack_line_reader_test stack_line_reader_test.cc)
+target_link_libraries(stack_line_reader_test stack_line_reader_for_test)
+add_test(NAME stack_line_reader_test COMMAND stack_line_reader_test)
+##------------------------------------------------------------------------------
+## cpuinfo_x86_test
+if(PROCESSOR_IS_X86)
+  add_executable(cpuinfo_x86_test cpuinfo_x86_test.cc ../src/cpuinfo_x86.c)
+  target_compile_definitions(cpuinfo_x86_test PUBLIC CPU_FEATURES_MOCK_CPUID_X86)
+  if(APPLE)
+    target_compile_definitions(cpuinfo_x86_test PRIVATE HAVE_SYSCTLBYNAME)
+  endif()
+  target_link_libraries(cpuinfo_x86_test all_libraries)
+  add_test(NAME cpuinfo_x86_test COMMAND cpuinfo_x86_test)
+endif()
+##------------------------------------------------------------------------------
+## cpuinfo_arm_test
+if(PROCESSOR_IS_ARM)
+  add_executable(cpuinfo_arm_test cpuinfo_arm_test.cc ../src/cpuinfo_arm.c)
+  target_link_libraries(cpuinfo_arm_test all_libraries)
+  add_test(NAME cpuinfo_arm_test COMMAND cpuinfo_arm_test)
+endif()
+##------------------------------------------------------------------------------
+## cpuinfo_aarch64_test
+if(PROCESSOR_IS_AARCH64)
+  add_executable(cpuinfo_aarch64_test cpuinfo_aarch64_test.cc ../src/cpuinfo_aarch64.c)
+  target_link_libraries(cpuinfo_aarch64_test all_libraries)
+  add_test(NAME cpuinfo_aarch64_test COMMAND cpuinfo_aarch64_test)
+endif()
+##------------------------------------------------------------------------------
+## cpuinfo_mips_test
+if(PROCESSOR_IS_MIPS)
+  add_executable(cpuinfo_mips_test cpuinfo_mips_test.cc  ../src/cpuinfo_mips.c)
+  target_link_libraries(cpuinfo_mips_test all_libraries)
+  add_test(NAME cpuinfo_mips_test COMMAND cpuinfo_mips_test)
+endif()
+##------------------------------------------------------------------------------
+## cpuinfo_ppc_test
+if(PROCESSOR_IS_POWER)
+  add_executable(cpuinfo_ppc_test cpuinfo_ppc_test.cc  ../src/cpuinfo_ppc.c)
+  target_link_libraries(cpuinfo_ppc_test all_libraries)
+  add_test(NAME cpuinfo_ppc_test COMMAND cpuinfo_ppc_test)
+endif()

cpu_features/test/bit_utils_test.cc

@@ -0,0 +1,53 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/bit_utils.h"
+
+#include "gtest/gtest.h"
+
+namespace cpu_features {
+namespace {
+
+TEST(UtilsTest, IsBitSet) {
+  for (size_t bit_set = 0; bit_set < 32; ++bit_set) {
+    const uint32_t value = 1UL << bit_set;
+    for (uint32_t i = 0; i < 32; ++i) {
+      EXPECT_EQ(IsBitSet(value, i), i == bit_set);
+    }
+  }
+
+  // testing 0, all bits should be 0.
+  for (uint32_t i = 0; i < 32; ++i) {
+    EXPECT_FALSE(IsBitSet(0, i));
+  }
+
+  // testing ~0, all bits should be 1.
+  for (uint32_t i = 0; i < 32; ++i) {
+    EXPECT_TRUE(IsBitSet(-1, i));
+  }
+}
+
+TEST(UtilsTest, ExtractBitRange) {
+  // Extracting all bits gives the same number.
+  EXPECT_EQ(ExtractBitRange(123, 31, 0), 123);
+  // Extracting 1 bit gives parity.
+  EXPECT_EQ(ExtractBitRange(123, 0, 0), 1);
+  EXPECT_EQ(ExtractBitRange(122, 0, 0), 0);
+
+  EXPECT_EQ(ExtractBitRange(0xF0, 7, 4), 0xF);
+  EXPECT_EQ(ExtractBitRange(0x42 << 2, 10, 2), 0x42);
+}
+
+}  // namespace
+}  // namespace cpu_features

cpu_features/test/cpuinfo_aarch64_test.cc

@@ -0,0 +1,171 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cpuinfo_aarch64.h"
+
+#include "filesystem_for_testing.h"
+#include "gtest/gtest.h"
+#include "hwcaps_for_testing.h"
+
+namespace cpu_features {
+namespace {
+
+void DisableHardwareCapabilities() { SetHardwareCapabilities(0, 0); }
+
+TEST(CpuinfoAarch64Test, FromHardwareCap) {
+  SetHardwareCapabilities(AARCH64_HWCAP_FP | AARCH64_HWCAP_AES, 0);
+  GetEmptyFilesystem();  // disabling /proc/cpuinfo
+  const auto info = GetAarch64Info();
+  EXPECT_TRUE(info.features.fp);
+  EXPECT_FALSE(info.features.asimd);
+  EXPECT_FALSE(info.features.evtstrm);
+  EXPECT_TRUE(info.features.aes);
+  EXPECT_FALSE(info.features.pmull);
+  EXPECT_FALSE(info.features.sha1);
+  EXPECT_FALSE(info.features.sha2);
+  EXPECT_FALSE(info.features.crc32);
+  EXPECT_FALSE(info.features.atomics);
+  EXPECT_FALSE(info.features.fphp);
+  EXPECT_FALSE(info.features.asimdhp);
+  EXPECT_FALSE(info.features.cpuid);
+  EXPECT_FALSE(info.features.asimdrdm);
+  EXPECT_FALSE(info.features.jscvt);
+  EXPECT_FALSE(info.features.fcma);
+  EXPECT_FALSE(info.features.lrcpc);
+  EXPECT_FALSE(info.features.dcpop);
+  EXPECT_FALSE(info.features.sha3);
+  EXPECT_FALSE(info.features.sm3);
+  EXPECT_FALSE(info.features.sm4);
+  EXPECT_FALSE(info.features.asimddp);
+  EXPECT_FALSE(info.features.sha512);
+  EXPECT_FALSE(info.features.sve);
+  EXPECT_FALSE(info.features.asimdfhm);
+  EXPECT_FALSE(info.features.dit);
+  EXPECT_FALSE(info.features.uscat);
+  EXPECT_FALSE(info.features.ilrcpc);
+  EXPECT_FALSE(info.features.flagm);
+  EXPECT_FALSE(info.features.ssbs);
+  EXPECT_FALSE(info.features.sb);
+  EXPECT_FALSE(info.features.paca);
+  EXPECT_FALSE(info.features.pacg);
+}
+
+TEST(CpuinfoAarch64Test, FromHardwareCap2) {
+  SetHardwareCapabilities(AARCH64_HWCAP_FP,
+                          AARCH64_HWCAP2_SVE2 | AARCH64_HWCAP2_BTI);
+  GetEmptyFilesystem();  // disabling /proc/cpuinfo
+  const auto info = GetAarch64Info();
+  EXPECT_TRUE(info.features.fp);
+
+  EXPECT_TRUE(info.features.sve2);
+  EXPECT_TRUE(info.features.bti);
+
+  EXPECT_FALSE(info.features.dcpodp);
+  EXPECT_FALSE(info.features.sveaes);
+  EXPECT_FALSE(info.features.svepmull);
+  EXPECT_FALSE(info.features.svebitperm);
+  EXPECT_FALSE(info.features.svesha3);
+  EXPECT_FALSE(info.features.svesm4);
+  EXPECT_FALSE(info.features.flagm2);
+  EXPECT_FALSE(info.features.frint);
+  EXPECT_FALSE(info.features.svei8mm);
+  EXPECT_FALSE(info.features.svef32mm);
+  EXPECT_FALSE(info.features.svef64mm);
+  EXPECT_FALSE(info.features.svebf16);
+  EXPECT_FALSE(info.features.i8mm);
+  EXPECT_FALSE(info.features.bf16);
+  EXPECT_FALSE(info.features.dgh);
+  EXPECT_FALSE(info.features.rng);
+}
+
+TEST(CpuinfoAarch64Test, ARMCortexA53) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(Processor   : AArch64 Processor rev 3 (aarch64)
+processor   : 0
+processor   : 1
+processor   : 2
+processor   : 3
+processor   : 4
+processor   : 5
+processor   : 6
+processor   : 7
+Features    : fp asimd evtstrm aes pmull sha1 sha2 crc32
+CPU implementer : 0x41
+CPU architecture: AArch64
+CPU variant : 0x0
+CPU part    : 0xd03
+CPU revision    : 3)");
+  const auto info = GetAarch64Info();
+  EXPECT_EQ(info.implementer, 0x41);
+  EXPECT_EQ(info.variant, 0x0);
+  EXPECT_EQ(info.part, 0xd03);
+  EXPECT_EQ(info.revision, 3);
+
+  EXPECT_TRUE(info.features.fp);
+  EXPECT_TRUE(info.features.asimd);
+  EXPECT_TRUE(info.features.evtstrm);
+  EXPECT_TRUE(info.features.aes);
+  EXPECT_TRUE(info.features.pmull);
+  EXPECT_TRUE(info.features.sha1);
+  EXPECT_TRUE(info.features.sha2);
+  EXPECT_TRUE(info.features.crc32);
+
+  EXPECT_FALSE(info.features.atomics);
+  EXPECT_FALSE(info.features.fphp);
+  EXPECT_FALSE(info.features.asimdhp);
+  EXPECT_FALSE(info.features.cpuid);
+  EXPECT_FALSE(info.features.asimdrdm);
+  EXPECT_FALSE(info.features.jscvt);
+  EXPECT_FALSE(info.features.fcma);
+  EXPECT_FALSE(info.features.lrcpc);
+  EXPECT_FALSE(info.features.dcpop);
+  EXPECT_FALSE(info.features.sha3);
+  EXPECT_FALSE(info.features.sm3);
+  EXPECT_FALSE(info.features.sm4);
+  EXPECT_FALSE(info.features.asimddp);
+  EXPECT_FALSE(info.features.sha512);
+  EXPECT_FALSE(info.features.sve);
+  EXPECT_FALSE(info.features.asimdfhm);
+  EXPECT_FALSE(info.features.dit);
+  EXPECT_FALSE(info.features.uscat);
+  EXPECT_FALSE(info.features.ilrcpc);
+  EXPECT_FALSE(info.features.flagm);
+  EXPECT_FALSE(info.features.ssbs);
+  EXPECT_FALSE(info.features.sb);
+  EXPECT_FALSE(info.features.paca);
+  EXPECT_FALSE(info.features.pacg);
+  EXPECT_FALSE(info.features.dcpodp);
+  EXPECT_FALSE(info.features.sve2);
+  EXPECT_FALSE(info.features.sveaes);
+  EXPECT_FALSE(info.features.svepmull);
+  EXPECT_FALSE(info.features.svebitperm);
+  EXPECT_FALSE(info.features.svesha3);
+  EXPECT_FALSE(info.features.svesm4);
+  EXPECT_FALSE(info.features.flagm2);
+  EXPECT_FALSE(info.features.frint);
+  EXPECT_FALSE(info.features.svei8mm);
+  EXPECT_FALSE(info.features.svef32mm);
+  EXPECT_FALSE(info.features.svef64mm);
+  EXPECT_FALSE(info.features.svebf16);
+  EXPECT_FALSE(info.features.i8mm);
+  EXPECT_FALSE(info.features.bf16);
+  EXPECT_FALSE(info.features.dgh);
+  EXPECT_FALSE(info.features.rng);
+  EXPECT_FALSE(info.features.bti);
+}
+
+}  // namespace
+}  // namespace cpu_features

cpu_features/test/cpuinfo_arm_test.cc

@@ -0,0 +1,354 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cpuinfo_arm.h"
+
+#include "filesystem_for_testing.h"
+#include "gtest/gtest.h"
+#include "hwcaps_for_testing.h"
+
+namespace cpu_features {
+namespace {
+
+void DisableHardwareCapabilities() { SetHardwareCapabilities(0, 0); }
+
+TEST(CpuinfoArmTest, FromHardwareCap) {
+  SetHardwareCapabilities(ARM_HWCAP_NEON, ARM_HWCAP2_AES | ARM_HWCAP2_CRC32);
+  GetEmptyFilesystem();  // disabling /proc/cpuinfo
+  const auto info = GetArmInfo();
+  EXPECT_TRUE(info.features.vfp);    // triggered by vfpv3
+  EXPECT_TRUE(info.features.vfpv3);  // triggered by neon
+  EXPECT_TRUE(info.features.neon);
+  EXPECT_TRUE(info.features.aes);
+  EXPECT_TRUE(info.features.crc32);
+
+  EXPECT_FALSE(info.features.vfpv4);
+  EXPECT_FALSE(info.features.iwmmxt);
+  EXPECT_FALSE(info.features.crunch);
+  EXPECT_FALSE(info.features.thumbee);
+  EXPECT_FALSE(info.features.vfpv3d16);
+  EXPECT_FALSE(info.features.idiva);
+  EXPECT_FALSE(info.features.idivt);
+  EXPECT_FALSE(info.features.pmull);
+  EXPECT_FALSE(info.features.sha1);
+  EXPECT_FALSE(info.features.sha2);
+
+  // check some random features with EnumValue():
+  EXPECT_TRUE(GetArmFeaturesEnumValue(&info.features, ARM_VFP));
+  EXPECT_FALSE(GetArmFeaturesEnumValue(&info.features, ARM_VFPV4));
+  // out of bound EnumValue() check
+  EXPECT_FALSE(GetArmFeaturesEnumValue(&info.features, (ArmFeaturesEnum)~0x0));
+}
+
+TEST(CpuinfoArmTest, ODroidFromCpuInfo) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo", R"(processor       : 0
+model name      : ARMv7 Processor rev 3 (v71)
+BogoMIPS        : 120.00
+Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae
+CPU implementer : 0x41
+CPU architecture: 7
+CPU variant     : 0x2
+CPU part        : 0xc0f
+CPU revision    : 3)");
+  const auto info = GetArmInfo();
+  EXPECT_EQ(info.implementer, 0x41);
+  EXPECT_EQ(info.variant, 0x2);
+  EXPECT_EQ(info.part, 0xc0f);
+  EXPECT_EQ(info.revision, 3);
+  EXPECT_EQ(info.architecture, 7);
+
+  EXPECT_FALSE(info.features.swp);
+  EXPECT_TRUE(info.features.half);
+  EXPECT_TRUE(info.features.thumb);
+  EXPECT_FALSE(info.features._26bit);
+  EXPECT_TRUE(info.features.fastmult);
+  EXPECT_FALSE(info.features.fpa);
+  EXPECT_TRUE(info.features.vfp);
+  EXPECT_TRUE(info.features.edsp);
+  EXPECT_FALSE(info.features.java);
+  EXPECT_FALSE(info.features.iwmmxt);
+  EXPECT_FALSE(info.features.crunch);
+  EXPECT_FALSE(info.features.thumbee);
+  EXPECT_TRUE(info.features.neon);
+  EXPECT_TRUE(info.features.vfpv3);
+  EXPECT_FALSE(info.features.vfpv3d16);
+  EXPECT_TRUE(info.features.tls);
+  EXPECT_TRUE(info.features.vfpv4);
+  EXPECT_TRUE(info.features.idiva);
+  EXPECT_TRUE(info.features.idivt);
+  EXPECT_TRUE(info.features.vfpd32);
+  EXPECT_TRUE(info.features.lpae);
+  EXPECT_FALSE(info.features.evtstrm);
+  EXPECT_FALSE(info.features.aes);
+  EXPECT_FALSE(info.features.pmull);
+  EXPECT_FALSE(info.features.sha1);
+  EXPECT_FALSE(info.features.sha2);
+  EXPECT_FALSE(info.features.crc32);
+}
+
+// Linux test-case
+TEST(CpuinfoArmTest, RaspberryPiZeroFromCpuInfo) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo", R"(processor       : 0
+model name      : ARMv6-compatible processor rev 7 (v6l)
+BogoMIPS        : 697.95
+Features        : half thumb fastmult vfp edsp java tls
+CPU implementer : 0x41
+CPU architecture: 7
+CPU variant     : 0x0
+CPU part        : 0xb76
+CPU revision    : 7
+
+Hardware        : BCM2835
+Revision        : 9000c1
+Serial          : 000000006cd946f3)");
+  const auto info = GetArmInfo();
+  EXPECT_EQ(info.implementer, 0x41);
+  EXPECT_EQ(info.variant, 0x0);
+  EXPECT_EQ(info.part, 0xb76);
+  EXPECT_EQ(info.revision, 7);
+  EXPECT_EQ(info.architecture, 6);
+
+  EXPECT_FALSE(info.features.swp);
+  EXPECT_TRUE(info.features.half);
+  EXPECT_TRUE(info.features.thumb);
+  EXPECT_FALSE(info.features._26bit);
+  EXPECT_TRUE(info.features.fastmult);
+  EXPECT_FALSE(info.features.fpa);
+  EXPECT_TRUE(info.features.vfp);
+  EXPECT_TRUE(info.features.edsp);
+  EXPECT_TRUE(info.features.java);
+  EXPECT_FALSE(info.features.iwmmxt);
+  EXPECT_FALSE(info.features.crunch);
+  EXPECT_FALSE(info.features.thumbee);
+  EXPECT_FALSE(info.features.neon);
+  EXPECT_FALSE(info.features.vfpv3);
+  EXPECT_FALSE(info.features.vfpv3d16);
+  EXPECT_TRUE(info.features.tls);
+  EXPECT_FALSE(info.features.vfpv4);
+  EXPECT_FALSE(info.features.idiva);
+  EXPECT_FALSE(info.features.idivt);
+  EXPECT_FALSE(info.features.vfpd32);
+  EXPECT_FALSE(info.features.lpae);
+  EXPECT_FALSE(info.features.evtstrm);
+  EXPECT_FALSE(info.features.aes);
+  EXPECT_FALSE(info.features.pmull);
+  EXPECT_FALSE(info.features.sha1);
+  EXPECT_FALSE(info.features.sha2);
+  EXPECT_FALSE(info.features.crc32);
+}
+
+TEST(CpuinfoArmTest, MarvellArmadaFromCpuInfo) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo", R"(processor       : 0
+model name      : ARMv7 Processor rev 1 (v7l)
+BogoMIPS        : 50.00
+Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpd32
+CPU implementer : 0x41
+CPU architecture: 7
+CPU variant     : 0x4
+CPU part        : 0xc09
+CPU revision    : 1
+
+processor       : 1
+model name      : ARMv7 Processor rev 1 (v7l)
+BogoMIPS        : 50.00
+Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpd32
+CPU implementer : 0x41
+CPU architecture: 7
+CPU variant     : 0x4
+CPU part        : 0xc09
+CPU revision    : 1
+
+Hardware        : Marvell Armada 380/385 (Device Tree)
+Revision        : 0000
+Serial          : 0000000000000000)");
+  const auto info = GetArmInfo();
+  EXPECT_EQ(info.implementer, 0x41);
+  EXPECT_EQ(info.variant, 0x4);
+  EXPECT_EQ(info.part, 0xc09);
+  EXPECT_EQ(info.revision, 1);
+  EXPECT_EQ(info.architecture, 7);
+
+  EXPECT_FALSE(info.features.swp);
+  EXPECT_TRUE(info.features.half);
+  EXPECT_TRUE(info.features.thumb);
+  EXPECT_FALSE(info.features._26bit);
+  EXPECT_TRUE(info.features.fastmult);
+  EXPECT_FALSE(info.features.fpa);
+  EXPECT_TRUE(info.features.vfp);
+  EXPECT_TRUE(info.features.edsp);
+  EXPECT_FALSE(info.features.java);
+  EXPECT_FALSE(info.features.iwmmxt);
+  EXPECT_FALSE(info.features.crunch);
+  EXPECT_FALSE(info.features.thumbee);
+  EXPECT_TRUE(info.features.neon);
+  EXPECT_TRUE(info.features.vfpv3);
+  EXPECT_FALSE(info.features.vfpv3d16);
+  EXPECT_TRUE(info.features.tls);
+  EXPECT_FALSE(info.features.vfpv4);
+  EXPECT_FALSE(info.features.idiva);
+  EXPECT_FALSE(info.features.idivt);
+  EXPECT_TRUE(info.features.vfpd32);
+  EXPECT_FALSE(info.features.lpae);
+  EXPECT_FALSE(info.features.evtstrm);
+  EXPECT_FALSE(info.features.aes);
+  EXPECT_FALSE(info.features.pmull);
+  EXPECT_FALSE(info.features.sha1);
+  EXPECT_FALSE(info.features.sha2);
+  EXPECT_FALSE(info.features.crc32);
+}
+
+// Android test-case
+// http://code.google.com/p/android/issues/detail?id=10812
+TEST(CpuinfoArmTest, InvalidArmv7) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(Processor       : ARMv6-compatible processor rev 6 (v6l)
+BogoMIPS        : 199.47
+Features        : swp half thumb fastmult vfp edsp java
+CPU implementer : 0x41
+CPU architecture: 7
+CPU variant     : 0x0
+CPU part        : 0xb76
+CPU revision    : 6
+
+Hardware        : SPICA
+Revision        : 0020
+Serial          : 33323613546d00ec )");
+  const auto info = GetArmInfo();
+  EXPECT_EQ(info.architecture, 6);
+
+  EXPECT_TRUE(info.features.swp);
+  EXPECT_TRUE(info.features.half);
+  EXPECT_TRUE(info.features.thumb);
+  EXPECT_FALSE(info.features._26bit);
+  EXPECT_TRUE(info.features.fastmult);
+  EXPECT_FALSE(info.features.fpa);
+  EXPECT_TRUE(info.features.vfp);
+  EXPECT_TRUE(info.features.edsp);
+  EXPECT_TRUE(info.features.java);
+  EXPECT_FALSE(info.features.iwmmxt);
+  EXPECT_FALSE(info.features.crunch);
+  EXPECT_FALSE(info.features.thumbee);
+  EXPECT_FALSE(info.features.neon);
+  EXPECT_FALSE(info.features.vfpv3);
+  EXPECT_FALSE(info.features.vfpv3d16);
+  EXPECT_FALSE(info.features.tls);
+  EXPECT_FALSE(info.features.vfpv4);
+  EXPECT_FALSE(info.features.idiva);
+  EXPECT_FALSE(info.features.idivt);
+  EXPECT_FALSE(info.features.vfpd32);
+  EXPECT_FALSE(info.features.lpae);
+  EXPECT_FALSE(info.features.evtstrm);
+  EXPECT_FALSE(info.features.aes);
+  EXPECT_FALSE(info.features.pmull);
+  EXPECT_FALSE(info.features.sha1);
+  EXPECT_FALSE(info.features.sha2);
+  EXPECT_FALSE(info.features.crc32);
+}
+
+// Android test-case
+// https://crbug.com/341598.
+TEST(CpuinfoArmTest, InvalidNeon) {
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(Processor: ARMv7 Processory rev 0 (v71)
+processor: 0
+BogoMIPS: 13.50
+
+Processor: 1
+BogoMIPS: 13.50
+
+Features: swp half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt
+CPU implementer : 0x51
+CPU architecture: 7
+CPU variant: 0x1
+CPU part: 0x04d
+CPU revision: 0
+
+Hardware: SAMSUNG M2
+Revision: 0010
+Serial: 00001e030000354e)");
+  const auto info = GetArmInfo();
+  EXPECT_TRUE(info.features.swp);
+  EXPECT_FALSE(info.features.neon);
+}
+
+// The Nexus 4 (Qualcomm Krait) kernel configuration forgets to report IDIV
+// support.
+TEST(CpuinfoArmTest, Nexus4_0x510006f2) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(CPU implementer	: 0x51
+CPU architecture: 7
+CPU variant	: 0x0
+CPU part	: 0x6f
+CPU revision	: 2)");
+  const auto info = GetArmInfo();
+  EXPECT_TRUE(info.features.idiva);
+  EXPECT_TRUE(info.features.idivt);
+
+  EXPECT_EQ(GetArmCpuId(&info), 0x510006f2);
+}
+
+// The Nexus 4 (Qualcomm Krait) kernel configuration forgets to report IDIV
+// support.
+TEST(CpuinfoArmTest, Nexus4_0x510006f3) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(CPU implementer	: 0x51
+CPU architecture: 7
+CPU variant	: 0x0
+CPU part	: 0x6f
+CPU revision	: 3)");
+  const auto info = GetArmInfo();
+  EXPECT_TRUE(info.features.idiva);
+  EXPECT_TRUE(info.features.idivt);
+
+  EXPECT_EQ(GetArmCpuId(&info), 0x510006f3);
+}
+
+// The emulator-specific Android 4.2 kernel fails to report support for the
+// 32-bit ARM IDIV instruction. Technically, this is a feature of the virtual
+// CPU implemented by the emulator.
+TEST(CpuinfoArmTest, EmulatorSpecificIdiv) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(Processor	: ARMv7 Processor rev 0 (v7l)
+BogoMIPS	: 629.14
+Features	: swp half thumb fastmult vfp edsp neon vfpv3
+CPU implementer	: 0x41
+CPU architecture: 7
+CPU variant	: 0x0
+CPU part	: 0xc08
+CPU revision	: 0
+
+Hardware	: Goldfish
+Revision	: 0000
+Serial		: 0000000000000000)");
+  const auto info = GetArmInfo();
+  EXPECT_TRUE(info.features.idiva);
+}
+
+}  // namespace
+}  // namespace cpu_features

cpu_features/test/cpuinfo_mips_test.cc

@@ -0,0 +1,126 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cpuinfo_mips.h"
+
+#include "filesystem_for_testing.h"
+#include "gtest/gtest.h"
+#include "hwcaps_for_testing.h"
+#include "internal/stack_line_reader.h"
+#include "internal/string_view.h"
+
+namespace cpu_features {
+
+namespace {
+
+void DisableHardwareCapabilities() { SetHardwareCapabilities(0, 0); }
+
+TEST(CpuinfoMipsTest, FromHardwareCapBoth) {
+  SetHardwareCapabilities(MIPS_HWCAP_MSA | MIPS_HWCAP_R6, 0);
+  GetEmptyFilesystem();  // disabling /proc/cpuinfo
+  const auto info = GetMipsInfo();
+  EXPECT_TRUE(info.features.msa);
+  EXPECT_FALSE(info.features.eva);
+  EXPECT_TRUE(info.features.r6);
+}
+
+TEST(CpuinfoMipsTest, FromHardwareCapOnlyOne) {
+  SetHardwareCapabilities(MIPS_HWCAP_MSA, 0);
+  GetEmptyFilesystem();  // disabling /proc/cpuinfo
+  const auto info = GetMipsInfo();
+  EXPECT_TRUE(info.features.msa);
+  EXPECT_FALSE(info.features.eva);
+}
+
+TEST(CpuinfoMipsTest, Ci40) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo", R"(system type : IMG Pistachio SoC (B0)
+machine : IMG Marduk – Ci40 with cc2520
+processor : 0
+cpu model : MIPS interAptiv (multi) V2.0 FPU V0.0
+BogoMIPS : 363.72
+wait instruction : yes
+microsecond timers : yes
+tlb_entries : 64
+extra interrupt vector : yes
+hardware watchpoint : yes, count: 4, address/irw mask: [0x0ffc, 0x0ffc, 0x0ffb, 0x0ffb]
+isa : mips1 mips2 mips32r1 mips32r2
+ASEs implemented : mips16 dsp mt eva
+shadow register sets : 1
+kscratch registers : 0
+package : 0
+core : 0
+VCED exceptions : not available
+VCEI exceptions : not available
+VPE : 0
+)");
+  const auto info = GetMipsInfo();
+  EXPECT_FALSE(info.features.msa);
+  EXPECT_TRUE(info.features.eva);
+}
+
+TEST(CpuinfoMipsTest, AR7161) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(system type             : Atheros AR7161 rev 2
+machine                 : NETGEAR WNDR3700/WNDR3800/WNDRMAC
+processor               : 0
+cpu model               : MIPS 24Kc V7.4
+BogoMIPS                : 452.19
+wait instruction        : yes
+microsecond timers      : yes
+tlb_entries             : 16
+extra interrupt vector  : yes
+hardware watchpoint     : yes, count: 4, address/irw mask: [0x0000, 0x0f98, 0x0f78, 0x0df8]
+ASEs implemented        : mips16
+shadow register sets    : 1
+kscratch registers      : 0
+core                    : 0
+VCED exceptions         : not available
+VCEI exceptions         : not available
+)");
+  const auto info = GetMipsInfo();
+  EXPECT_FALSE(info.features.msa);
+  EXPECT_FALSE(info.features.eva);
+}
+
+TEST(CpuinfoMipsTest, Goldfish) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo", R"(system type		: MIPS-Goldfish
+Hardware		: goldfish
+Revison		: 1
+processor		: 0
+cpu model		: MIPS 24Kc V0.0  FPU V0.0
+BogoMIPS		: 1042.02
+wait instruction	: yes
+microsecond timers	: yes
+tlb_entries		: 16
+extra interrupt vector	: yes
+hardware watchpoint	: yes, count: 1, address/irw mask: [0x0ff8]
+ASEs implemented	:
+shadow register sets	: 1
+core			: 0
+VCED exceptions		: not available
+VCEI exceptions		: not available
+)");
+  const auto info = GetMipsInfo();
+  EXPECT_FALSE(info.features.msa);
+  EXPECT_FALSE(info.features.eva);
+}
+
+}  // namespace
+}  // namespace cpu_features

cpu_features/test/cpuinfo_ppc_test.cc

@@ -0,0 +1,119 @@
+// Copyright 2018 IBM.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cpuinfo_ppc.h"
+
+#include "filesystem_for_testing.h"
+#include "gtest/gtest.h"
+#include "hwcaps_for_testing.h"
+#include "internal/string_view.h"
+
+namespace cpu_features {
+namespace {
+
+void DisableHardwareCapabilities() { SetHardwareCapabilities(0, 0); }
+
+TEST(CpustringsPPCTest, FromHardwareCap) {
+  SetHardwareCapabilities(PPC_FEATURE_HAS_FPU | PPC_FEATURE_HAS_VSX,
+                          PPC_FEATURE2_ARCH_3_00);
+  GetEmptyFilesystem();  // disabling /proc/cpuinfo
+  const auto info = GetPPCInfo();
+  EXPECT_TRUE(info.features.fpu);
+  EXPECT_FALSE(info.features.mmu);
+  EXPECT_TRUE(info.features.vsx);
+  EXPECT_TRUE(info.features.arch300);
+  EXPECT_FALSE(info.features.power4);
+  EXPECT_FALSE(info.features.altivec);
+  EXPECT_FALSE(info.features.vcrypto);
+  EXPECT_FALSE(info.features.htm);
+}
+
+TEST(CpustringsPPCTest, Blade) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(processor       : 14
+cpu             : POWER7 (architected), altivec supported
+clock           : 3000.000000MHz
+revision        : 2.1 (pvr 003f 0201)
+
+processor       : 15
+cpu             : POWER7 (architected), altivec supported
+clock           : 3000.000000MHz
+revision        : 2.1 (pvr 003f 0201)
+
+timebase        : 512000000
+platform        : pSeries
+model           : IBM,8406-70Y
+machine         : CHRP IBM,8406-70Y)");
+  SetPlatformTypes("power7", "power8");
+  const auto strings = GetPPCPlatformStrings();
+  ASSERT_STREQ(strings.platform, "pSeries");
+  ASSERT_STREQ(strings.model, "IBM,8406-70Y");
+  ASSERT_STREQ(strings.machine, "CHRP IBM,8406-70Y");
+  ASSERT_STREQ(strings.cpu, "POWER7 (architected), altivec supported");
+  ASSERT_STREQ(strings.type.platform, "power7");
+  ASSERT_STREQ(strings.type.base_platform, "power8");
+}
+
+TEST(CpustringsPPCTest, Firestone) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(processor       : 126
+cpu             : POWER8 (raw), altivec supported
+clock           : 2061.000000MHz
+revision        : 2.0 (pvr 004d 0200)
+
+processor       : 127
+cpu             : POWER8 (raw), altivec supported
+clock           : 2061.000000MHz
+revision        : 2.0 (pvr 004d 0200)
+
+timebase        : 512000000
+platform        : PowerNV
+model           : 8335-GTA
+machine         : PowerNV 8335-GTA
+firmware        : OPAL v3)");
+  const auto strings = GetPPCPlatformStrings();
+  ASSERT_STREQ(strings.platform, "PowerNV");
+  ASSERT_STREQ(strings.model, "8335-GTA");
+  ASSERT_STREQ(strings.machine, "PowerNV 8335-GTA");
+  ASSERT_STREQ(strings.cpu, "POWER8 (raw), altivec supported");
+}
+
+TEST(CpustringsPPCTest, w8) {
+  DisableHardwareCapabilities();
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo",
+                R"(processor       : 143
+cpu             : POWER9, altivec supported
+clock           : 2300.000000MHz
+revision        : 2.2 (pvr 004e 1202)
+
+timebase        : 512000000
+platform        : PowerNV
+model           : 0000000000000000
+machine         : PowerNV 0000000000000000
+firmware        : OPAL
+MMU             : Radix)");
+  const auto strings = GetPPCPlatformStrings();
+  ASSERT_STREQ(strings.platform, "PowerNV");
+  ASSERT_STREQ(strings.model, "0000000000000000");
+  ASSERT_STREQ(strings.machine, "PowerNV 0000000000000000");
+  ASSERT_STREQ(strings.cpu, "POWER9, altivec supported");
+}
+
+}  // namespace
+}  // namespace cpu_features

cpu_features/test/cpuinfo_x86_test.cc

@@ -0,0 +1,533 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cpuinfo_x86.h"
+
+#include <cassert>
+#include <cstdio>
+#include <map>
+#include <set>
+#if defined(CPU_FEATURES_OS_WINDOWS)
+#include <windows.h>  // IsProcessorFeaturePresent
+#endif                // CPU_FEATURES_OS_WINDOWS
+
+#include "filesystem_for_testing.h"
+#include "gtest/gtest.h"
+#include "internal/cpuid_x86.h"
+
+namespace cpu_features {
+
+class FakeCpu {
+ public:
+  Leaf GetCpuidLeaf(uint32_t leaf_id, int ecx) const {
+    const auto itr = cpuid_leaves_.find(std::make_pair(leaf_id, ecx));
+    if (itr != cpuid_leaves_.end()) {
+      return itr->second;
+    }
+    return {0, 0, 0, 0};
+  }
+
+  uint32_t GetXCR0Eax() const { return xcr0_eax_; }
+
+  void SetLeaves(std::map<std::pair<uint32_t, int>, Leaf> configuration) {
+    cpuid_leaves_ = std::move(configuration);
+  }
+
+  void SetOsBackupsExtendedRegisters(bool os_backups_extended_registers) {
+    xcr0_eax_ = os_backups_extended_registers ? -1 : 0;
+  }
+
+#if defined(CPU_FEATURES_OS_DARWIN)
+  bool GetDarwinSysCtlByName(std::string name) const {
+    return darwin_sysctlbyname_.count(name);
+  }
+
+  void SetDarwinSysCtlByName(std::string name) {
+    darwin_sysctlbyname_.insert(name);
+  }
+#endif  // CPU_FEATURES_OS_DARWIN
+
+#if defined(CPU_FEATURES_OS_WINDOWS)
+  bool GetWindowsIsProcessorFeaturePresent(DWORD ProcessorFeature) {
+    return windows_isprocessorfeaturepresent_.count(ProcessorFeature);
+  }
+
+  void SetWindowsIsProcessorFeaturePresent(DWORD ProcessorFeature) {
+    windows_isprocessorfeaturepresent_.insert(ProcessorFeature);
+  }
+#endif  // CPU_FEATURES_OS_WINDOWS
+
+ private:
+  std::map<std::pair<uint32_t, int>, Leaf> cpuid_leaves_;
+#if defined(CPU_FEATURES_OS_DARWIN)
+  std::set<std::string> darwin_sysctlbyname_;
+#endif  // CPU_FEATURES_OS_DARWIN
+#if defined(CPU_FEATURES_OS_WINDOWS)
+  std::set<DWORD> windows_isprocessorfeaturepresent_;
+#endif  // CPU_FEATURES_OS_WINDOWS
+  uint32_t xcr0_eax_;
+};
+
+FakeCpu* g_fake_cpu = nullptr;
+
+extern "C" Leaf GetCpuidLeaf(uint32_t leaf_id, int ecx) {
+  return g_fake_cpu->GetCpuidLeaf(leaf_id, ecx);
+}
+
+extern "C" uint32_t GetXCR0Eax(void) { return g_fake_cpu->GetXCR0Eax(); }
+
+#if defined(CPU_FEATURES_OS_DARWIN)
+extern "C" bool GetDarwinSysCtlByName(const char* name) {
+  return g_fake_cpu->GetDarwinSysCtlByName(name);
+}
+#endif  // CPU_FEATURES_OS_DARWIN
+
+#if defined(CPU_FEATURES_OS_WINDOWS)
+extern "C" bool GetWindowsIsProcessorFeaturePresent(DWORD ProcessorFeature) {
+  return g_fake_cpu->GetWindowsIsProcessorFeaturePresent(ProcessorFeature);
+}
+#endif  // CPU_FEATURES_OS_WINDOWS
+
+namespace {
+
+class CpuidX86Test : public ::testing::Test {
+ protected:
+  void SetUp() override { g_fake_cpu = new FakeCpu(); }
+  void TearDown() override { delete g_fake_cpu; }
+};
+
+TEST_F(CpuidX86Test, SandyBridge) {
+  g_fake_cpu->SetOsBackupsExtendedRegisters(true);
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x0000000D, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x000206A6, 0x00100800, 0x1F9AE3BF, 0xBFEBFBFF}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+  });
+  const auto info = GetX86Info();
+  EXPECT_STREQ(info.vendor, "GenuineIntel");
+  EXPECT_EQ(info.family, 0x06);
+  EXPECT_EQ(info.model, 0x02A);
+  EXPECT_EQ(info.stepping, 0x06);
+  // Leaf 7 is zeroed out so none of the Leaf 7 flags are set.
+  const auto features = info.features;
+  EXPECT_FALSE(features.erms);
+  EXPECT_FALSE(features.avx2);
+  EXPECT_FALSE(features.avx512f);
+  EXPECT_FALSE(features.avx512cd);
+  EXPECT_FALSE(features.avx512er);
+  EXPECT_FALSE(features.avx512pf);
+  EXPECT_FALSE(features.avx512bw);
+  EXPECT_FALSE(features.avx512dq);
+  EXPECT_FALSE(features.avx512vl);
+  EXPECT_FALSE(features.avx512ifma);
+  EXPECT_FALSE(features.avx512vbmi);
+  EXPECT_FALSE(features.avx512vbmi2);
+  EXPECT_FALSE(features.avx512vnni);
+  EXPECT_FALSE(features.avx512bitalg);
+  EXPECT_FALSE(features.avx512vpopcntdq);
+  EXPECT_FALSE(features.avx512_4vnniw);
+  EXPECT_FALSE(features.avx512_4fmaps);
+  // All old cpu features should be set.
+  EXPECT_TRUE(features.aes);
+  EXPECT_TRUE(features.ssse3);
+  EXPECT_TRUE(features.sse4_1);
+  EXPECT_TRUE(features.sse4_2);
+  EXPECT_TRUE(features.avx);
+  EXPECT_FALSE(features.sha);
+  EXPECT_TRUE(features.popcnt);
+  EXPECT_FALSE(features.movbe);
+  EXPECT_FALSE(features.rdrnd);
+}
+
+const int KiB = 1024;
+const int MiB = 1024 * KiB;
+
+TEST_F(CpuidX86Test, SandyBridgeTestOsSupport) {
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x0000000D, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x000206A6, 0x00100800, 0x1F9AE3BF, 0xBFEBFBFF}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+  });
+  // avx is disabled if os does not support backing up ymm registers.
+  g_fake_cpu->SetOsBackupsExtendedRegisters(false);
+  EXPECT_FALSE(GetX86Info().features.avx);
+  // avx is disabled if os does not support backing up ymm registers.
+  g_fake_cpu->SetOsBackupsExtendedRegisters(true);
+  EXPECT_TRUE(GetX86Info().features.avx);
+}
+
+TEST_F(CpuidX86Test, SkyLake) {
+  g_fake_cpu->SetOsBackupsExtendedRegisters(true);
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x00000016, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x000406E3, 0x00100800, 0x7FFAFBBF, 0xBFEBFBFF}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x029C67AF, 0x00000000, 0x00000000}},
+  });
+  const auto info = GetX86Info();
+  EXPECT_STREQ(info.vendor, "GenuineIntel");
+  EXPECT_EQ(info.family, 0x06);
+  EXPECT_EQ(info.model, 0x04E);
+  EXPECT_EQ(info.stepping, 0x03);
+  EXPECT_EQ(GetX86Microarchitecture(&info), X86Microarchitecture::INTEL_SKL);
+}
+
+TEST_F(CpuidX86Test, Branding) {
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x00000016, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x000406E3, 0x00100800, 0x7FFAFBBF, 0xBFEBFBFF}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x029C67AF, 0x00000000, 0x00000000}},
+      {{0x80000000, 0}, Leaf{0x80000008, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000001, 0}, Leaf{0x00000000, 0x00000000, 0x00000121, 0x2C100000}},
+      {{0x80000002, 0}, Leaf{0x65746E49, 0x2952286C, 0x726F4320, 0x4D542865}},
+      {{0x80000003, 0}, Leaf{0x37692029, 0x3035362D, 0x43205530, 0x40205550}},
+      {{0x80000004, 0}, Leaf{0x352E3220, 0x7A484730, 0x00000000, 0x00000000}},
+  });
+  char brand_string[49];
+  FillX86BrandString(brand_string);
+  EXPECT_STREQ(brand_string, "Intel(R) Core(TM) i7-6500U CPU @ 2.50GHz");
+}
+
+TEST_F(CpuidX86Test, KabyLakeCache) {
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x00000016, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x000406E3, 0x00100800, 0x7FFAFBBF, 0xBFEBFBFF}},
+      {{0x00000004, 0}, Leaf{0x1C004121, 0x01C0003F, 0x0000003F, 0x00000000}},
+      {{0x00000004, 1}, Leaf{0x1C004122, 0x01C0003F, 0x0000003F, 0x00000000}},
+      {{0x00000004, 2}, Leaf{0x1C004143, 0x00C0003F, 0x000003FF, 0x00000000}},
+      {{0x00000004, 3}, Leaf{0x1C03C163, 0x02C0003F, 0x00001FFF, 0x00000002}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x029C67AF, 0x00000000, 0x00000000}},
+      {{0x80000000, 0}, Leaf{0x80000008, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000001, 0}, Leaf{0x00000000, 0x00000000, 0x00000121, 0x2C100000}},
+      {{0x80000002, 0}, Leaf{0x65746E49, 0x2952286C, 0x726F4320, 0x4D542865}},
+      {{0x80000003, 0}, Leaf{0x37692029, 0x3035362D, 0x43205530, 0x40205550}},
+  });
+  const auto info = GetX86CacheInfo();
+  EXPECT_EQ(info.size, 4);
+  EXPECT_EQ(info.levels[0].level, 1);
+  EXPECT_EQ(info.levels[0].cache_type, 1);
+  EXPECT_EQ(info.levels[0].cache_size, 32 * KiB);
+  EXPECT_EQ(info.levels[0].ways, 8);
+  EXPECT_EQ(info.levels[0].line_size, 64);
+  EXPECT_EQ(info.levels[0].tlb_entries, 64);
+  EXPECT_EQ(info.levels[0].partitioning, 1);
+
+  EXPECT_EQ(info.levels[1].level, 1);
+  EXPECT_EQ(info.levels[1].cache_type, 2);
+  EXPECT_EQ(info.levels[1].cache_size, 32 * KiB);
+  EXPECT_EQ(info.levels[1].ways, 8);
+  EXPECT_EQ(info.levels[1].line_size, 64);
+  EXPECT_EQ(info.levels[1].tlb_entries, 64);
+  EXPECT_EQ(info.levels[1].partitioning, 1);
+
+  EXPECT_EQ(info.levels[2].level, 2);
+  EXPECT_EQ(info.levels[2].cache_type, 3);
+  EXPECT_EQ(info.levels[2].cache_size, 256 * KiB);
+  EXPECT_EQ(info.levels[2].ways, 4);
+  EXPECT_EQ(info.levels[2].line_size, 64);
+  EXPECT_EQ(info.levels[2].tlb_entries, 1024);
+  EXPECT_EQ(info.levels[2].partitioning, 1);
+
+  EXPECT_EQ(info.levels[3].level, 3);
+  EXPECT_EQ(info.levels[3].cache_type, 3);
+  EXPECT_EQ(info.levels[3].cache_size, 6 * MiB);
+  EXPECT_EQ(info.levels[3].ways, 12);
+  EXPECT_EQ(info.levels[3].line_size, 64);
+  EXPECT_EQ(info.levels[3].tlb_entries, 8192);
+  EXPECT_EQ(info.levels[3].partitioning, 1);
+}
+
+TEST_F(CpuidX86Test, HSWCache) {
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x00000016, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x000406E3, 0x00100800, 0x7FFAFBBF, 0xBFEBFBFF}},
+      {{0x00000004, 0}, Leaf{0x1C004121, 0x01C0003F, 0x0000003F, 0x00000000}},
+      {{0x00000004, 1}, Leaf{0x1C004122, 0x01C0003F, 0x0000003F, 0x00000000}},
+      {{0x00000004, 2}, Leaf{0x1C004143, 0x01C0003F, 0x000001FF, 0x00000000}},
+      {{0x00000004, 3}, Leaf{0x1C03C163, 0x02C0003F, 0x00001FFF, 0x00000006}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x029C67AF, 0x00000000, 0x00000000}},
+      {{0x80000000, 0}, Leaf{0x80000008, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000001, 0}, Leaf{0x00000000, 0x00000000, 0x00000121, 0x2C100000}},
+      {{0x80000002, 0}, Leaf{0x65746E49, 0x2952286C, 0x726F4320, 0x4D542865}},
+      {{0x80000003, 0}, Leaf{0x37692029, 0x3035362D, 0x43205530, 0x40205550}},
+  });
+  const auto info = GetX86CacheInfo();
+  EXPECT_EQ(info.size, 4);
+  EXPECT_EQ(info.levels[0].level, 1);
+  EXPECT_EQ(info.levels[0].cache_type, 1);
+  EXPECT_EQ(info.levels[0].cache_size, 32 * KiB);
+  EXPECT_EQ(info.levels[0].ways, 8);
+  EXPECT_EQ(info.levels[0].line_size, 64);
+  EXPECT_EQ(info.levels[0].tlb_entries, 64);
+  EXPECT_EQ(info.levels[0].partitioning, 1);
+
+  EXPECT_EQ(info.levels[1].level, 1);
+  EXPECT_EQ(info.levels[1].cache_type, 2);
+  EXPECT_EQ(info.levels[1].cache_size, 32 * KiB);
+  EXPECT_EQ(info.levels[1].ways, 8);
+  EXPECT_EQ(info.levels[1].line_size, 64);
+  EXPECT_EQ(info.levels[1].tlb_entries, 64);
+  EXPECT_EQ(info.levels[1].partitioning, 1);
+
+  EXPECT_EQ(info.levels[2].level, 2);
+  EXPECT_EQ(info.levels[2].cache_type, 3);
+  EXPECT_EQ(info.levels[2].cache_size, 256 * KiB);
+  EXPECT_EQ(info.levels[2].ways, 8);
+  EXPECT_EQ(info.levels[2].line_size, 64);
+  EXPECT_EQ(info.levels[2].tlb_entries, 512);
+  EXPECT_EQ(info.levels[2].partitioning, 1);
+
+  EXPECT_EQ(info.levels[3].level, 3);
+  EXPECT_EQ(info.levels[3].cache_type, 3);
+  EXPECT_EQ(info.levels[3].cache_size, 6 * MiB);
+  EXPECT_EQ(info.levels[3].ways, 12);
+  EXPECT_EQ(info.levels[3].line_size, 64);
+  EXPECT_EQ(info.levels[3].tlb_entries, 8192);
+  EXPECT_EQ(info.levels[3].partitioning, 1);
+}
+
+// http://users.atw.hu/instlatx64/AuthenticAMD0630F81_K15_Godavari_CPUID.txt
+TEST_F(CpuidX86Test, AMD_K15) {
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x0000000D, 0x68747541, 0x444D4163, 0x69746E65}},
+      {{0x00000001, 0}, Leaf{0x00630F81, 0x00040800, 0x3E98320B, 0x178BFBFF}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000000, 0}, Leaf{0x8000001E, 0x68747541, 0x444D4163, 0x69746E65}},
+      {{0x80000001, 0}, Leaf{0x00630F81, 0x10000000, 0x0FEBBFFF, 0x2FD3FBFF}},
+      {{0x80000002, 0}, Leaf{0x20444D41, 0x372D3841, 0x4B303736, 0x64615220}},
+      {{0x80000003, 0}, Leaf{0x206E6F65, 0x202C3752, 0x43203031, 0x75706D6F}},
+      {{0x80000004, 0}, Leaf{0x43206574, 0x7365726F, 0x2B433420, 0x00204736}},
+      {{0x80000005, 0}, Leaf{0xFF40FF18, 0xFF40FF30, 0x10040140, 0x60030140}},
+  });
+  const auto info = GetX86Info();
+
+  EXPECT_STREQ(info.vendor, "AuthenticAMD");
+  EXPECT_EQ(info.family, 0x15);
+  EXPECT_EQ(info.model, 0x38);
+  EXPECT_EQ(info.stepping, 0x01);
+  EXPECT_EQ(GetX86Microarchitecture(&info),
+            X86Microarchitecture::AMD_BULLDOZER);
+
+  char brand_string[49];
+  FillX86BrandString(brand_string);
+  EXPECT_STREQ(brand_string, "AMD A8-7670K Radeon R7, 10 Compute Cores 4C+6G ");
+}
+
+// https://github.com/InstLatx64/InstLatx64/blob/master/GenuineIntel/GenuineIntel00106A1_Nehalem_CPUID.txt
+TEST_F(CpuidX86Test, Nehalem) {
+  // Pre AVX cpus don't have xsave
+  g_fake_cpu->SetOsBackupsExtendedRegisters(false);
+#if defined(CPU_FEATURES_OS_WINDOWS)
+  g_fake_cpu->SetWindowsIsProcessorFeaturePresent(
+      PF_XMMI_INSTRUCTIONS_AVAILABLE);
+  g_fake_cpu->SetWindowsIsProcessorFeaturePresent(
+      PF_XMMI64_INSTRUCTIONS_AVAILABLE);
+  g_fake_cpu->SetWindowsIsProcessorFeaturePresent(
+      PF_SSE3_INSTRUCTIONS_AVAILABLE);
+#endif  // CPU_FEATURES_OS_WINDOWS
+#if defined(CPU_FEATURES_OS_DARWIN)
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse2");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse3");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.supplementalsse3");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse4_1");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse4_2");
+#endif  // CPU_FEATURES_OS_DARWIN
+#if defined(CPU_FEATURES_OS_LINUX_OR_ANDROID)
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo", R"(processor       :
+flags           : fpu mmx sse sse2 sse3 ssse3 sse4_1 sse4_2
+)");
+#endif  // CPU_FEATURES_OS_LINUX_OR_ANDROID
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x0000000B, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x000106A2, 0x00100800, 0x00BCE3BD, 0xBFEBFBFF}},
+      {{0x00000002, 0}, Leaf{0x55035A01, 0x00F0B0E3, 0x00000000, 0x09CA212C}},
+      {{0x00000003, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x00000004, 0}, Leaf{0x1C004121, 0x01C0003F, 0x0000003F, 0x00000000}},
+      {{0x00000004, 0}, Leaf{0x1C004122, 0x00C0003F, 0x0000007F, 0x00000000}},
+      {{0x00000004, 0}, Leaf{0x1C004143, 0x01C0003F, 0x000001FF, 0x00000000}},
+      {{0x00000004, 0}, Leaf{0x1C03C163, 0x03C0003F, 0x00000FFF, 0x00000002}},
+      {{0x00000005, 0}, Leaf{0x00000040, 0x00000040, 0x00000003, 0x00021120}},
+      {{0x00000006, 0}, Leaf{0x00000001, 0x00000002, 0x00000001, 0x00000000}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x00000008, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x00000009, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x0000000A, 0}, Leaf{0x07300403, 0x00000000, 0x00000000, 0x00000603}},
+      {{0x0000000B, 0}, Leaf{0x00000001, 0x00000001, 0x00000100, 0x00000000}},
+      {{0x0000000B, 0}, Leaf{0x00000004, 0x00000002, 0x00000201, 0x00000000}},
+      {{0x80000000, 0}, Leaf{0x80000008, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000001, 0}, Leaf{0x00000000, 0x00000000, 0x00000001, 0x28100000}},
+      {{0x80000002, 0}, Leaf{0x756E6547, 0x20656E69, 0x65746E49, 0x2952286C}},
+      {{0x80000003, 0}, Leaf{0x55504320, 0x20202020, 0x20202020, 0x40202020}},
+      {{0x80000004, 0}, Leaf{0x30303020, 0x20402030, 0x37382E31, 0x007A4847}},
+      {{0x80000005, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000006, 0}, Leaf{0x00000000, 0x00000000, 0x01006040, 0x00000000}},
+      {{0x80000007, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000100}},
+      {{0x80000008, 0}, Leaf{0x00003028, 0x00000000, 0x00000000, 0x00000000}},
+  });
+  const auto info = GetX86Info();
+
+  EXPECT_STREQ(info.vendor, "GenuineIntel");
+  EXPECT_EQ(info.family, 0x06);
+  EXPECT_EQ(info.model, 0x1A);
+  EXPECT_EQ(info.stepping, 0x02);
+  EXPECT_EQ(GetX86Microarchitecture(&info), X86Microarchitecture::INTEL_NHM);
+
+  char brand_string[49];
+  FillX86BrandString(brand_string);
+  EXPECT_STREQ(brand_string, "Genuine Intel(R) CPU           @ 0000 @ 1.87GHz");
+
+  EXPECT_TRUE(info.features.sse);
+  EXPECT_TRUE(info.features.sse2);
+  EXPECT_TRUE(info.features.sse3);
+#ifndef CPU_FEATURES_OS_WINDOWS
+  // Currently disabled on Windows as IsProcessorFeaturePresent do not support
+  // feature detection > sse3.
+  EXPECT_TRUE(info.features.ssse3);
+  EXPECT_TRUE(info.features.sse4_1);
+  EXPECT_TRUE(info.features.sse4_2);
+#endif  // CPU_FEATURES_OS_WINDOWS
+}
+
+// https://github.com/InstLatx64/InstLatx64/blob/master/GenuineIntel/GenuineIntel0030673_Silvermont3_CPUID.txt
+TEST_F(CpuidX86Test, Atom) {
+  // Pre AVX cpus don't have xsave
+  g_fake_cpu->SetOsBackupsExtendedRegisters(false);
+#if defined(CPU_FEATURES_OS_WINDOWS)
+  g_fake_cpu->SetWindowsIsProcessorFeaturePresent(
+      PF_XMMI_INSTRUCTIONS_AVAILABLE);
+  g_fake_cpu->SetWindowsIsProcessorFeaturePresent(
+      PF_XMMI64_INSTRUCTIONS_AVAILABLE);
+  g_fake_cpu->SetWindowsIsProcessorFeaturePresent(
+      PF_SSE3_INSTRUCTIONS_AVAILABLE);
+#endif  // CPU_FEATURES_OS_WINDOWS
+#if defined(CPU_FEATURES_OS_DARWIN)
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse2");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse3");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.supplementalsse3");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse4_1");
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse4_2");
+#endif  // CPU_FEATURES_OS_DARWIN
+#if defined(CPU_FEATURES_OS_LINUX_OR_ANDROID)
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo", R"(
+flags           : fpu mmx sse sse2 sse3 ssse3 sse4_1 sse4_2
+)");
+#endif  // CPU_FEATURES_OS_LINUX_OR_ANDROID
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x0000000B, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x00030673, 0x00100800, 0x41D8E3BF, 0xBFEBFBFF}},
+      {{0x00000002, 0}, Leaf{0x61B3A001, 0x0000FFC2, 0x00000000, 0x00000000}},
+      {{0x00000003, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x00000004, 0}, Leaf{0x1C000121, 0x0140003F, 0x0000003F, 0x00000001}},
+      {{0x00000004, 1}, Leaf{0x1C000122, 0x01C0003F, 0x0000003F, 0x00000001}},
+      {{0x00000004, 2}, Leaf{0x1C00C143, 0x03C0003F, 0x000003FF, 0x00000001}},
+      {{0x00000005, 0}, Leaf{0x00000040, 0x00000040, 0x00000003, 0x33000020}},
+      {{0x00000006, 0}, Leaf{0x00000005, 0x00000002, 0x00000009, 0x00000000}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x00002282, 0x00000000, 0x00000000}},
+      {{0x00000008, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x00000009, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x0000000A, 0}, Leaf{0x07280203, 0x00000000, 0x00000000, 0x00004503}},
+      {{0x0000000B, 0}, Leaf{0x00000001, 0x00000001, 0x00000100, 0x00000000}},
+      {{0x0000000B, 1}, Leaf{0x00000004, 0x00000004, 0x00000201, 0x00000000}},
+      {{0x80000000, 0}, Leaf{0x80000008, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000001, 0}, Leaf{0x00000000, 0x00000000, 0x00000101, 0x28100000}},
+      {{0x80000002, 0}, Leaf{0x20202020, 0x6E492020, 0x286C6574, 0x43202952}},
+      {{0x80000003, 0}, Leaf{0x72656C65, 0x52286E6F, 0x50432029, 0x4A202055}},
+      {{0x80000004, 0}, Leaf{0x30303931, 0x20402020, 0x39392E31, 0x007A4847}},
+      {{0x80000005, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000006, 0}, Leaf{0x00000000, 0x00000000, 0x04008040, 0x00000000}},
+      {{0x80000007, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000100}},
+      {{0x80000008, 0}, Leaf{0x00003024, 0x00000000, 0x00000000, 0x00000000}},
+  });
+  const auto info = GetX86Info();
+
+  EXPECT_STREQ(info.vendor, "GenuineIntel");
+  EXPECT_EQ(info.family, 0x06);
+  EXPECT_EQ(info.model, 0x37);
+  EXPECT_EQ(info.stepping, 0x03);
+  EXPECT_EQ(GetX86Microarchitecture(&info),
+            X86Microarchitecture::INTEL_ATOM_SMT);
+
+  char brand_string[49];
+  FillX86BrandString(brand_string);
+  EXPECT_STREQ(brand_string, "      Intel(R) Celeron(R) CPU  J1900  @ 1.99GHz");
+
+  EXPECT_TRUE(info.features.sse);
+  EXPECT_TRUE(info.features.sse2);
+  EXPECT_TRUE(info.features.sse3);
+#ifndef CPU_FEATURES_OS_WINDOWS
+  // Currently disabled on Windows as IsProcessorFeaturePresent do not support
+  // feature detection > sse3.
+  EXPECT_TRUE(info.features.ssse3);
+  EXPECT_TRUE(info.features.sse4_1);
+  EXPECT_TRUE(info.features.sse4_2);
+#endif  // CPU_FEATURES_OS_WINDOWS
+}
+
+// https://github.com/InstLatx64/InstLatx64/blob/master/GenuineIntel/GenuineIntel0000673_P3_KatmaiDP_CPUID.txt
+TEST_F(CpuidX86Test, P3) {
+  // Pre AVX cpus don't have xsave
+  g_fake_cpu->SetOsBackupsExtendedRegisters(false);
+#if defined(CPU_FEATURES_OS_WINDOWS)
+  g_fake_cpu->SetWindowsIsProcessorFeaturePresent(
+      PF_XMMI_INSTRUCTIONS_AVAILABLE);
+#endif  // CPU_FEATURES_OS_WINDOWS
+#if defined(CPU_FEATURES_OS_DARWIN)
+  g_fake_cpu->SetDarwinSysCtlByName("hw.optional.sse");
+#endif  // CPU_FEATURES_OS_DARWIN
+#if defined(CPU_FEATURES_OS_LINUX_OR_ANDROID)
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/proc/cpuinfo", R"(
+flags           : fpu mmx sse
+)");
+#endif  // CPU_FEATURES_OS_LINUX_OR_ANDROID
+  g_fake_cpu->SetLeaves({
+      {{0x00000000, 0}, Leaf{0x00000003, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x00000673, 0x00000000, 0x00000000, 0x0387FBFF}},
+      {{0x00000002, 0}, Leaf{0x03020101, 0x00000000, 0x00000000, 0x0C040843}},
+      {{0x00000003, 0}, Leaf{0x00000000, 0x00000000, 0x4CECC782, 0x00006778}},
+  });
+  const auto info = GetX86Info();
+
+  EXPECT_STREQ(info.vendor, "GenuineIntel");
+  EXPECT_EQ(info.family, 0x06);
+  EXPECT_EQ(info.model, 0x07);
+  EXPECT_EQ(info.stepping, 0x03);
+  EXPECT_EQ(GetX86Microarchitecture(&info), X86Microarchitecture::X86_UNKNOWN);
+
+  char brand_string[49];
+  FillX86BrandString(brand_string);
+  EXPECT_STREQ(brand_string, "");
+
+  EXPECT_TRUE(info.features.mmx);
+  EXPECT_TRUE(info.features.sse);
+  EXPECT_FALSE(info.features.sse2);
+  EXPECT_FALSE(info.features.sse3);
+#ifndef CPU_FEATURES_OS_WINDOWS
+  // Currently disabled on Windows as IsProcessorFeaturePresent do not support
+  // feature detection > sse3.
+  EXPECT_FALSE(info.features.ssse3);
+  EXPECT_FALSE(info.features.sse4_1);
+  EXPECT_FALSE(info.features.sse4_2);
+#endif  // CPU_FEATURES_OS_WINDOWS
+}
+
+// TODO(user): test what happens when xsave/osxsave are not present.
+// TODO(user): test what happens when xmm/ymm/zmm os support are not
+// present.
+
+}  // namespace
+}  // namespace cpu_features

cpu_features/test/filesystem_for_testing.cc

@@ -0,0 +1,103 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "filesystem_for_testing.h"
+
+#include <cassert>
+#include <climits>
+#include <cstdio>
+#include <cstring>
+#include <utility>
+
+namespace cpu_features {
+
+FakeFile::FakeFile(int file_descriptor, const char* content)
+    : file_descriptor_(file_descriptor), content_(content) {}
+
+FakeFile::~FakeFile() { assert(!opened_); }
+
+void FakeFile::Open() {
+  assert(!opened_);
+  opened_ = true;
+}
+
+void FakeFile::Close() {
+  assert(opened_);
+  opened_ = false;
+}
+
+int FakeFile::Read(int fd, void* buf, size_t count) {
+  assert(count < INT_MAX);
+  assert(fd == file_descriptor_);
+  const size_t remainder = content_.size() - head_index_;
+  const size_t read = count > remainder ? remainder : count;
+  memcpy(buf, content_.data() + head_index_, read);
+  head_index_ += read;
+  assert(read < INT_MAX);
+  return (int)read;
+}
+
+void FakeFilesystem::Reset() { files_.clear(); }
+
+FakeFile* FakeFilesystem::CreateFile(const std::string& filename,
+                                     const char* content) {
+  auto& file = files_[filename];
+  file =
+      std::unique_ptr<FakeFile>(new FakeFile(next_file_descriptor_++, content));
+  return file.get();
+}
+
+FakeFile* FakeFilesystem::FindFileOrNull(const std::string& filename) const {
+  const auto itr = files_.find(filename);
+  return itr == files_.end() ? nullptr : itr->second.get();
+}
+
+FakeFile* FakeFilesystem::FindFileOrDie(const int file_descriptor) const {
+  for (const auto& filename_file_pair : files_) {
+    FakeFile* const file_ptr = filename_file_pair.second.get();
+    if (file_ptr->GetFileDescriptor() == file_descriptor) {
+      return file_ptr;
+    }
+  }
+  assert(false);
+  return nullptr;
+}
+
+static FakeFilesystem* kFilesystem = new FakeFilesystem();
+
+FakeFilesystem& GetEmptyFilesystem() {
+  kFilesystem->Reset();
+  return *kFilesystem;
+}
+
+extern "C" int CpuFeatures_OpenFile(const char* filename) {
+  auto* const file = kFilesystem->FindFileOrNull(filename);
+  if (file) {
+    file->Open();
+    return file->GetFileDescriptor();
+  }
+  return -1;
+}
+
+extern "C" void CpuFeatures_CloseFile(int file_descriptor) {
+  kFilesystem->FindFileOrDie(file_descriptor)->Close();
+}
+
+extern "C" int CpuFeatures_ReadFile(int file_descriptor, void* buffer,
+                                    size_t buffer_size) {
+  return kFilesystem->FindFileOrDie(file_descriptor)
+      ->Read(file_descriptor, buffer, buffer_size);
+}
+
+}  // namespace cpu_features

cpu_features/test/filesystem_for_testing.h

@@ -0,0 +1,61 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Implements a fake filesystem, useful for tests.
+#ifndef CPU_FEATURES_TEST_FILESYSTEM_FOR_TESTING_H_
+#define CPU_FEATURES_TEST_FILESYSTEM_FOR_TESTING_H_
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+#include "internal/filesystem.h"
+
+namespace cpu_features {
+
+class FakeFile {
+ public:
+  explicit FakeFile(int file_descriptor, const char* content);
+  ~FakeFile();
+
+  void Open();
+  void Close();
+  int Read(int fd, void* buf, size_t count);
+
+  int GetFileDescriptor() const { return file_descriptor_; }
+
+ private:
+  const int file_descriptor_;
+  const std::string content_;
+  bool opened_ = false;
+  size_t head_index_ = 0;
+};
+
+class FakeFilesystem {
+ public:
+  void Reset();
+  FakeFile* CreateFile(const std::string& filename, const char* content);
+  FakeFile* FindFileOrDie(const int file_descriptor) const;
+  FakeFile* FindFileOrNull(const std::string& filename) const;
+
+ private:
+  int next_file_descriptor_ = 0;
+  std::unordered_map<std::string, std::unique_ptr<FakeFile>> files_;
+};
+
+FakeFilesystem& GetEmptyFilesystem();
+
+}  // namespace cpu_features
+
+#endif  // CPU_FEATURES_TEST_FILESYSTEM_FOR_TESTING_H_

cpu_features/test/hwcaps_for_testing.cc

@@ -0,0 +1,46 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "hwcaps_for_testing.h"
+
+#include <string.h>
+
+#include "internal/string_view.h"
+
+namespace cpu_features {
+
+namespace {
+static auto* const g_hardware_capabilities = new HardwareCapabilities();
+static auto* const g_platform_types = new PlatformType();
+}  // namespace
+
+void SetHardwareCapabilities(uint32_t hwcaps, uint32_t hwcaps2) {
+  g_hardware_capabilities->hwcaps = hwcaps;
+  g_hardware_capabilities->hwcaps2 = hwcaps2;
+}
+
+HardwareCapabilities CpuFeatures_GetHardwareCapabilities(void) {
+  return *g_hardware_capabilities;
+}
+
+void SetPlatformTypes(const char* platform, const char* base_platform) {
+  CpuFeatures_StringView_CopyString(str(platform), g_platform_types->platform,
+                                    sizeof(g_platform_types->platform));
+  CpuFeatures_StringView_CopyString(str(base_platform),
+                                    g_platform_types->base_platform,
+                                    sizeof(g_platform_types->base_platform));
+}
+
+PlatformType CpuFeatures_GetPlatformType(void) { return *g_platform_types; }
+}  // namespace cpu_features

cpu_features/test/hwcaps_for_testing.h

@@ -0,0 +1,27 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CPU_FEATURES_TEST_HWCAPS_FOR_TESTING_H_
+#define CPU_FEATURES_TEST_HWCAPS_FOR_TESTING_H_
+
+#include "internal/hwcaps.h"
+
+namespace cpu_features {
+
+void SetHardwareCapabilities(uint32_t hwcaps, uint32_t hwcaps2);
+void SetPlatformTypes(const char *platform, const char *base_platform);
+
+}  // namespace cpu_features
+
+#endif  // CPU_FEATURES_TEST_HWCAPS_FOR_TESTING_H_

cpu_features/test/stack_line_reader_test.cc

@@ -0,0 +1,132 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/stack_line_reader.h"
+
+#include "filesystem_for_testing.h"
+#include "gtest/gtest.h"
+
+namespace cpu_features {
+
+bool operator==(const StringView& a, const StringView& b) {
+  return CpuFeatures_StringView_IsEquals(a, b);
+}
+
+namespace {
+
+std::string ToString(StringView view) { return {view.ptr, view.size}; }
+
+TEST(StackLineReaderTest, Empty) {
+  auto& fs = GetEmptyFilesystem();
+  auto* file = fs.CreateFile("/proc/cpuinfo", "");
+  StackLineReader reader;
+  StackLineReader_Initialize(&reader, file->GetFileDescriptor());
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_TRUE(result.eof);
+    EXPECT_TRUE(result.full_line);
+    EXPECT_EQ(result.line, str(""));
+  }
+}
+
+TEST(StackLineReaderTest, ManySmallLines) {
+  auto& fs = GetEmptyFilesystem();
+  auto* file = fs.CreateFile("/proc/cpuinfo", "a\nb\nc");
+
+  StackLineReader reader;
+  StackLineReader_Initialize(&reader, file->GetFileDescriptor());
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_FALSE(result.eof);
+    EXPECT_TRUE(result.full_line);
+    EXPECT_EQ(result.line, str("a"));
+  }
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_FALSE(result.eof);
+    EXPECT_TRUE(result.full_line);
+    EXPECT_EQ(result.line, str("b"));
+  }
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_TRUE(result.eof);
+    EXPECT_TRUE(result.full_line);
+    EXPECT_EQ(result.line, str("c"));
+  }
+}
+
+TEST(StackLineReaderTest, TruncatedLine) {
+  auto& fs = GetEmptyFilesystem();
+  auto* file = fs.CreateFile("/proc/cpuinfo", R"(First
+Second
+More than 16 characters, this will be truncated.
+last)");
+
+  StackLineReader reader;
+  StackLineReader_Initialize(&reader, file->GetFileDescriptor());
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_FALSE(result.eof);
+    EXPECT_TRUE(result.full_line);
+    EXPECT_EQ(result.line, str("First"));
+  }
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_FALSE(result.eof);
+    EXPECT_TRUE(result.full_line);
+    EXPECT_EQ(result.line, str("Second"));
+  }
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_FALSE(result.eof);
+    EXPECT_FALSE(result.full_line);
+    EXPECT_EQ(result.line, str("More than 16 cha"));
+  }
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_TRUE(result.eof);
+    EXPECT_TRUE(result.full_line);
+    EXPECT_EQ(result.line, str("last"));
+  }
+}
+
+TEST(StackLineReaderTest, TruncatedLines) {
+  auto& fs = GetEmptyFilesystem();
+  auto* file = fs.CreateFile("/proc/cpuinfo", R"(More than 16 characters
+Another line that is too long)");
+
+  StackLineReader reader;
+  StackLineReader_Initialize(&reader, file->GetFileDescriptor());
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_FALSE(result.eof);
+    EXPECT_FALSE(result.full_line);
+    EXPECT_EQ(result.line, str("More than 16 cha"));
+  }
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_FALSE(result.eof);
+    EXPECT_FALSE(result.full_line);
+    EXPECT_EQ(result.line, str("Another line tha"));
+  }
+  {
+    const auto result = StackLineReader_NextLine(&reader);
+    EXPECT_TRUE(result.eof);
+    EXPECT_TRUE(result.full_line);
+    EXPECT_EQ(result.line, str(""));
+  }
+}
+
+}  // namespace
+}  // namespace cpu_features

cpu_features/test/string_view_test.cc

@@ -0,0 +1,192 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/string_view.h"
+
+#include "gtest/gtest.h"
+
+namespace cpu_features {
+
+bool operator==(const StringView& a, const StringView& b) {
+  return CpuFeatures_StringView_IsEquals(a, b);
+}
+
+namespace {
+
+TEST(StringViewTest, Empty) {
+  EXPECT_EQ(kEmptyStringView.ptr, nullptr);
+  EXPECT_EQ(kEmptyStringView.size, 0);
+}
+
+TEST(StringViewTest, Build) {
+  const auto view = str("test");
+  EXPECT_EQ(view.ptr[0], 't');
+  EXPECT_EQ(view.size, 4);
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_IndexOfChar) {
+  // Found.
+  EXPECT_EQ(CpuFeatures_StringView_IndexOfChar(str("test"), 'e'), 1);
+  EXPECT_EQ(CpuFeatures_StringView_IndexOfChar(str("test"), 't'), 0);
+  EXPECT_EQ(CpuFeatures_StringView_IndexOfChar(str("beef"), 'e'), 1);
+  // Not found.
+  EXPECT_EQ(CpuFeatures_StringView_IndexOfChar(str("test"), 'z'), -1);
+  // Empty.
+  EXPECT_EQ(CpuFeatures_StringView_IndexOfChar(kEmptyStringView, 'z'), -1);
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_IndexOf) {
+  // Found.
+  EXPECT_EQ(CpuFeatures_StringView_IndexOf(str("test"), str("es")), 1);
+  EXPECT_EQ(CpuFeatures_StringView_IndexOf(str("test"), str("test")), 0);
+  EXPECT_EQ(CpuFeatures_StringView_IndexOf(str("tesstest"), str("test")), 4);
+  // Not found.
+  EXPECT_EQ(CpuFeatures_StringView_IndexOf(str("test"), str("aa")), -1);
+  // Empty.
+  EXPECT_EQ(CpuFeatures_StringView_IndexOf(kEmptyStringView, str("aa")), -1);
+  EXPECT_EQ(CpuFeatures_StringView_IndexOf(str("aa"), kEmptyStringView), -1);
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_StartsWith) {
+  EXPECT_TRUE(CpuFeatures_StringView_StartsWith(str("test"), str("te")));
+  EXPECT_TRUE(CpuFeatures_StringView_StartsWith(str("test"), str("test")));
+  EXPECT_FALSE(CpuFeatures_StringView_StartsWith(str("test"), str("st")));
+  EXPECT_FALSE(CpuFeatures_StringView_StartsWith(str("test"), str("est")));
+  EXPECT_FALSE(CpuFeatures_StringView_StartsWith(str("test"), str("")));
+  EXPECT_FALSE(
+      CpuFeatures_StringView_StartsWith(str("test"), kEmptyStringView));
+  EXPECT_FALSE(
+      CpuFeatures_StringView_StartsWith(kEmptyStringView, str("test")));
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_IsEquals) {
+  EXPECT_TRUE(
+      CpuFeatures_StringView_IsEquals(kEmptyStringView, kEmptyStringView));
+  EXPECT_TRUE(CpuFeatures_StringView_IsEquals(kEmptyStringView, str("")));
+  EXPECT_TRUE(CpuFeatures_StringView_IsEquals(str(""), kEmptyStringView));
+  EXPECT_TRUE(CpuFeatures_StringView_IsEquals(str("test"), str("test")));
+  EXPECT_TRUE(CpuFeatures_StringView_IsEquals(str("a"), str("a")));
+  EXPECT_FALSE(CpuFeatures_StringView_IsEquals(str("a"), str("b")));
+  EXPECT_FALSE(CpuFeatures_StringView_IsEquals(str("aa"), str("a")));
+  EXPECT_FALSE(CpuFeatures_StringView_IsEquals(str("a"), str("aa")));
+  EXPECT_FALSE(CpuFeatures_StringView_IsEquals(str("a"), kEmptyStringView));
+  EXPECT_FALSE(CpuFeatures_StringView_IsEquals(kEmptyStringView, str("a")));
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_PopFront) {
+  EXPECT_EQ(CpuFeatures_StringView_PopFront(str("test"), 2), str("st"));
+  EXPECT_EQ(CpuFeatures_StringView_PopFront(str("test"), 0), str("test"));
+  EXPECT_EQ(CpuFeatures_StringView_PopFront(str("test"), 4), str(""));
+  EXPECT_EQ(CpuFeatures_StringView_PopFront(str("test"), 100), str(""));
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_PopBack) {
+  EXPECT_EQ(CpuFeatures_StringView_PopBack(str("test"), 2), str("te"));
+  EXPECT_EQ(CpuFeatures_StringView_PopBack(str("test"), 0), str("test"));
+  EXPECT_EQ(CpuFeatures_StringView_PopBack(str("test"), 4), str(""));
+  EXPECT_EQ(CpuFeatures_StringView_PopBack(str("test"), 100), str(""));
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_KeepFront) {
+  EXPECT_EQ(CpuFeatures_StringView_KeepFront(str("test"), 2), str("te"));
+  EXPECT_EQ(CpuFeatures_StringView_KeepFront(str("test"), 0), str(""));
+  EXPECT_EQ(CpuFeatures_StringView_KeepFront(str("test"), 4), str("test"));
+  EXPECT_EQ(CpuFeatures_StringView_KeepFront(str("test"), 6), str("test"));
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_Front) {
+  EXPECT_EQ(CpuFeatures_StringView_Front(str("apple")), 'a');
+  EXPECT_EQ(CpuFeatures_StringView_Front(str("a")), 'a');
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_Back) {
+  EXPECT_EQ(CpuFeatures_StringView_Back(str("apple")), 'e');
+  EXPECT_EQ(CpuFeatures_StringView_Back(str("a")), 'a');
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_TrimWhitespace) {
+  EXPECT_EQ(CpuFeatures_StringView_TrimWhitespace(str("  first middle last  ")),
+            str("first middle last"));
+  EXPECT_EQ(CpuFeatures_StringView_TrimWhitespace(str("first middle last  ")),
+            str("first middle last"));
+  EXPECT_EQ(CpuFeatures_StringView_TrimWhitespace(str("  first middle last")),
+            str("first middle last"));
+  EXPECT_EQ(CpuFeatures_StringView_TrimWhitespace(str("first middle last")),
+            str("first middle last"));
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_ParsePositiveNumber) {
+  EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("42")), 42);
+  EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x2a")), 42);
+  EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x2A")), 42);
+  EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x2A2a")), 10794);
+  EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x2a2A")), 10794);
+
+  EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("-10")), -1);
+  EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("-0x2A")), -1);
+  EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("abc")), -1);
+  EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("")), -1);
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_CopyString) {
+  char buf[4];
+  buf[0] = 'X';
+
+  // Empty
+  CpuFeatures_StringView_CopyString(str(""), buf, sizeof(buf));
+  EXPECT_STREQ(buf, "");
+
+  // Less
+  CpuFeatures_StringView_CopyString(str("a"), buf, sizeof(buf));
+  EXPECT_STREQ(buf, "a");
+
+  // exact
+  CpuFeatures_StringView_CopyString(str("abc"), buf, sizeof(buf));
+  EXPECT_STREQ(buf, "abc");
+
+  // More
+  CpuFeatures_StringView_CopyString(str("abcd"), buf, sizeof(buf));
+  EXPECT_STREQ(buf, "abc");
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_HasWord) {
+  // Find flags at beginning, middle and end.
+  EXPECT_TRUE(
+      CpuFeatures_StringView_HasWord(str("first middle last"), "first"));
+  EXPECT_TRUE(
+      CpuFeatures_StringView_HasWord(str("first middle last"), "middle"));
+  EXPECT_TRUE(CpuFeatures_StringView_HasWord(str("first middle last"), "last"));
+  // Do not match partial flags
+  EXPECT_FALSE(
+      CpuFeatures_StringView_HasWord(str("first middle last"), "irst"));
+  EXPECT_FALSE(CpuFeatures_StringView_HasWord(str("first middle last"), "mid"));
+  EXPECT_FALSE(CpuFeatures_StringView_HasWord(str("first middle last"), "las"));
+}
+
+TEST(StringViewTest, CpuFeatures_StringView_GetAttributeKeyValue) {
+  const StringView line = str(" key :   first middle last   ");
+  StringView key, value;
+  EXPECT_TRUE(CpuFeatures_StringView_GetAttributeKeyValue(line, &key, &value));
+  EXPECT_EQ(key, str("key"));
+  EXPECT_EQ(value, str("first middle last"));
+}
+
+TEST(StringViewTest, FailingGetAttributeKeyValue) {
+  const StringView line = str("key  first middle last");
+  StringView key, value;
+  EXPECT_FALSE(CpuFeatures_StringView_GetAttributeKeyValue(line, &key, &value));
+}
+
+}  // namespace
+}  // namespace cpu_features

crc.c

@@ -0,0 +1,554 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// crc.h: Mode S CRC calculation and error correction.
+//
+// Copyright (c) 2014,2015 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "dump1090.h"
+
+#include <assert.h>
+
+// Errorinfo for "no errors"
+static struct errorinfo NO_ERRORS;
+
+// Generator polynomial for the Mode S CRC:
+#define MODES_GENERATOR_POLY 0xfff409U
+
+// CRC values for all single-byte messages;
+// used to speed up CRC calculation.
+static uint32_t crc_table[256];
+
+// Syndrome values for all single-bit errors;
+// used to speed up construction of error-
+// correction tables.
+static uint32_t single_bit_syndrome[112];
+
+static void initLookupTables()
+{
+    int i;
+    uint8_t msg[112/8];
+
+    for (i = 0; i < 256; ++i) {
+        uint32_t c = i << 16;
+        int j;
+        for (j = 0; j < 8; ++j) {
+            if (c & 0x800000)
+                c = (c<<1) ^ MODES_GENERATOR_POLY;
+            else
+                c = (c<<1);
+        }
+
+        crc_table[i] = c & 0x00ffffff;
+    }
+
+    memset(msg, 0, sizeof(msg));
+    for (i = 0; i < 112; ++i) {
+        msg[i/8] ^= 1 << (7 - (i & 7));
+        single_bit_syndrome[i] = modesChecksum(msg, 112);
+        msg[i/8] ^= 1 << (7 - (i & 7));
+    }
+}
+
+uint32_t modesChecksum(const uint8_t *message, int bits)
+{
+    uint32_t rem = 0;
+    int i;
+    int n = bits/8;
+
+    assert(bits % 8 == 0);
+    assert(n >= 3);
+
+    for (i = 0; i < n-3; ++i) {
+        rem = (rem << 8) ^ crc_table[message[i] ^ ((rem & 0xff0000) >> 16)];
+        rem = rem & 0xffffff;
+    }
+
+    rem = rem ^ (message[n-3] << 16) ^ (message[n-2] << 8) ^ (message[n-1]);
+    return rem;
+}
+
+static struct errorinfo *bitErrorTable_short;
+static int bitErrorTableSize_short;
+
+static struct errorinfo *bitErrorTable_long;
+static int bitErrorTableSize_long;
+
+// compare two errorinfo structures
+static int syndrome_compare(const void *x, const void *y) {
+    struct errorinfo *ex = (struct errorinfo*)x;
+    struct errorinfo *ey = (struct errorinfo*)y;
+    return (int)ex->syndrome - (int)ey->syndrome;
+}
+
+// (n k), the number of ways of selecting k distinct items from a set of n items
+static int combinations(int n, int k)
+{
+    int result = 1, i;
+
+    if (k == 0 || k == n)
+        return 1;
+
+    if (k > n)
+        return 0;
+
+    for (i = 1; i <= k; ++i) {
+        result = result * n / i;
+        n = n - 1;
+    }
+
+    return result;
+}
+
+// Recursively populates an errorinfo table with error syndromes
+//
+// in:
+//   table:      the table to fill
+//   n:          first entry to fill
+//   maxSize:    max size of table
+//   offset:     start bit offset for checksum calculation
+//   startbit:   first bit to introduce errors into
+//   endbit:     (one past) last bit to introduce errors info
+//   base_entry: template entry to start from
+//   error_bit:  how many error bits have already been set
+//   max_errors: maximum total error bits to set
+// out:
+//   returns:    the next free entry in the table
+//   table:      has been populated between [n, return value)
+static int prepareSubtable(struct errorinfo *table, int n, int maxsize, int offset, int startbit, int endbit, struct errorinfo *base_entry, int error_bit, int max_errors)
+{
+    int i = 0;
+
+    if (error_bit >= max_errors)
+        return n;
+
+    for (i = startbit; i < endbit; ++i) {
+        assert(n < maxsize);
+
+        table[n] = *base_entry;
+        table[n].syndrome ^= single_bit_syndrome[i + offset];
+        table[n].errors = error_bit+1;
+        table[n].bit[error_bit] = i;
+
+        ++n;
+        n = prepareSubtable(table, n, maxsize, offset, i + 1, endbit, &table[n-1], error_bit + 1, max_errors);
+    }
+
+    return n;
+}
+
+static int flagCollisions(struct errorinfo *table, int tablesize, int offset, int startbit, int endbit, uint32_t base_syndrome, int error_bit, int first_error, int last_error)
+{
+    int i = 0;
+    int count = 0;
+
+    if (error_bit > last_error)
+        return 0;
+
+    for (i = startbit; i < endbit; ++i) {
+        struct errorinfo ei;
+
+        ei.syndrome = base_syndrome ^ single_bit_syndrome[i + offset];
+
+        if (error_bit >= first_error) {
+            struct errorinfo *collision = bsearch(&ei, table, tablesize, sizeof(struct errorinfo), syndrome_compare);
+            if (collision != NULL && collision->errors != -1) {
+                ++count;
+                collision->errors = -1;
+            }
+        }
+
+        count += flagCollisions(table, tablesize, offset, i+1, endbit, ei.syndrome, error_bit + 1, first_error, last_error);
+    }
+
+    return count;
+}
+
+
+// Allocate and build an error table for messages of length "bits" (max 112)
+// returns a pointer to the new table and sets *size_out to the table length
+static struct errorinfo *prepareErrorTable(int bits, int max_correct, int max_detect, int *size_out)
+{
+    int maxsize, usedsize;
+    struct errorinfo *table;
+    struct errorinfo base_entry;
+    int i, j;
+
+    assert (bits >= 0 && bits <= 112);
+    assert (max_correct >=0 && max_correct <= MODES_MAX_BITERRORS);
+    assert (max_detect >= max_correct);
+
+    if (!max_correct) {
+        *size_out = 0;
+        return NULL;
+    }
+
+    maxsize = 0;
+    for (i = 1; i <= max_correct; ++i) {
+        maxsize += combinations(bits, i); // space needed for all i-bit errors
+    }
+
+#ifdef CRCDEBUG
+    fprintf(stderr, "Preparing syndrome table to correct up to %d-bit errors (detecting %d-bit errors) in a %d-bit message (max %d entries)\n", max_correct, max_detect, bits, maxsize);
+#endif
+
+    table = malloc(maxsize * sizeof(struct errorinfo));
+    base_entry.syndrome = 0;
+    base_entry.errors = 0;
+    for (i = 0; i < MODES_MAX_BITERRORS; ++i)
+        base_entry.bit[i] = -1;
+
+    usedsize = prepareSubtable(table, 0, maxsize, 112 - bits, 0, bits, &base_entry, 0, max_correct);
+
+#ifdef CRCDEBUG
+    fprintf(stderr, "%d syndromes (expected %d).\n", usedsize, maxsize);
+    fprintf(stderr, "Sorting syndromes..\n");
+#endif
+
+    qsort(table, usedsize, sizeof(struct errorinfo), syndrome_compare);
+
+#ifdef CRCDEBUG
+    {
+        // Show the table stats
+        fprintf(stderr, "Undetectable errors:\n");
+        for (i = 1; i <= max_correct; ++i) {
+            int j, count;
+
+            count = 0;
+            for (j = 0; j < usedsize; ++j)
+                if (table[j].errors == i && table[j].syndrome == 0)
+                    ++count;
+
+            fprintf(stderr, "  %d undetectable %d-bit errors\n", count, i);
+        }
+    }
+#endif
+
+    // Handle ambiguous cases, where there is more than one possible error pattern
+    // that produces a given syndrome (this happens with >2 bit errors).
+
+#ifdef CRCDEBUG
+    fprintf(stderr, "Finding collisions..\n");
+#endif
+    for (i = 0, j = 0; i < usedsize; ++i) {
+        if (i < usedsize-1 && table[i+1].syndrome == table[i].syndrome) {
+            // skip over this entry and all collisions
+            while (i < usedsize && table[i+1].syndrome == table[i].syndrome)
+                ++i;
+
+            // now table[i] is the last duplicate
+            continue;
+        }
+
+        if (i != j)
+            table[j] = table[i];
+        ++j;
+    }
+
+    if (j < usedsize) {
+#ifdef CRCDEBUG
+        fprintf(stderr, "Discarded %d collisions.\n", usedsize - j);
+#endif
+        usedsize = j;
+    }
+
+    // Flag collisions we want to detect but not correct
+    if (max_detect > max_correct) {
+        int flagged;
+
+#ifdef CRCDEBUG
+        fprintf(stderr, "Flagging collisions between %d - %d bits..\n", max_correct+1, max_detect);
+#endif
+
+        flagged = flagCollisions(table, usedsize, 112 - bits, 0, bits, 0, 1, max_correct+1, max_detect);
+
+#ifdef CRCDEBUG
+        fprintf(stderr, "Flagged %d collisions for removal.\n", flagged);
+#else
+#endif
+
+        if (flagged > 0) {
+            for (i = 0, j = 0; i < usedsize; ++i) {
+                if (table[i].errors != -1) {
+                    if (i != j)
+                        table[j] = table[i];
+                    ++j;
+                }
+            }
+
+#ifdef CRCDEBUG
+            fprintf(stderr, "Discarded %d flagged collisions.\n", usedsize - j);
+#endif
+            usedsize = j;
+        }
+    }
+
+    if (usedsize < maxsize) {
+#ifdef CRCDEBUG
+        fprintf(stderr, "Shrinking table from %d to %d..\n", maxsize, usedsize);
+        table = realloc(table, usedsize * sizeof(struct errorinfo));
+#endif
+    }
+
+    *size_out = usedsize;
+
+#ifdef CRCDEBUG
+    {
+        // Check the table.
+        unsigned char *msg = malloc(bits/8);
+
+        for (i = 0; i < usedsize; ++i) {
+            int j;
+            struct errorinfo *ei;
+            uint32_t result;
+
+            memset(msg, 0, bits/8);
+            ei = &table[i];
+            for (j = 0; j < ei->errors; ++j) {
+                msg[ei->bit[j] >> 3] ^= 1 << (7 - (ei->bit[j]&7));
+            }
+
+            result = modesChecksum(msg, bits);
+            if (result != ei->syndrome) {
+                fprintf(stderr, "PROBLEM: entry %6d/%6d  syndrome %06x  errors %d  bits ", i, usedsize, ei->syndrome, ei->errors);
+                for (j = 0; j < ei->errors; ++j)
+                    fprintf(stderr, "%3d ", ei->bit[j]);
+                fprintf(stderr, " checksum %06x\n", result);
+            }
+        }
+        free(msg);
+
+        // Show the table stats
+        fprintf(stderr, "Syndrome table summary:\n");
+        for (i = 1; i <= max_correct; ++i) {
+            int j, count, possible;
+
+            count = 0;
+            for (j = 0; j < usedsize; ++j)
+                if (table[j].errors == i)
+                    ++count;
+
+            possible = combinations(bits, i);
+            fprintf(stderr, "  %d entries for %d-bit errors (%d possible, %d%% coverage)\n", count, i, possible, 100 * count / possible);
+        }
+
+        fprintf(stderr, "  %d entries total\n", usedsize);
+    }
+#endif
+
+    return table;
+}
+
+// Precompute syndrome tables for 56- and 112-bit messages.
+void modesChecksumInit(int fixBits)
+{
+    initLookupTables();
+
+    switch (fixBits) {
+    case 0:
+        bitErrorTable_short = bitErrorTable_long = NULL;
+        bitErrorTableSize_short = bitErrorTableSize_long = 0;
+        break;
+
+    case 1:
+        // For 1 bit correction, we have 100% coverage up to 4 bit detection, so don't bother
+        // with flagging collisions there.
+        bitErrorTable_short = prepareErrorTable(MODES_SHORT_MSG_BITS, 1, 1, &bitErrorTableSize_short);
+        bitErrorTable_long = prepareErrorTable(MODES_LONG_MSG_BITS, 1, 1, &bitErrorTableSize_long);
+        break;
+
+    default:
+        // Detect out to 4 bit errors; this reduces our 2-bit coverage to about 65%.
+        // This can take a little while - tell the user.
+        fprintf(stderr, "Preparing error correction tables.. ");
+        bitErrorTable_short = prepareErrorTable(MODES_SHORT_MSG_BITS, 2, 4, &bitErrorTableSize_short);
+        bitErrorTable_long = prepareErrorTable(MODES_LONG_MSG_BITS, 2, 4, &bitErrorTableSize_long);
+        fprintf(stderr, "done.\n");
+        break;
+    }
+}
+
+// Given an error syndrome and message length, return
+// an error-correction descriptor, or NULL if the
+// syndrome is uncorrectable
+struct errorinfo *modesChecksumDiagnose(uint32_t syndrome, int bitlen)
+{
+    struct errorinfo *table;
+    int tablesize;
+
+    struct errorinfo ei;
+
+    if (syndrome == 0)
+        return &NO_ERRORS;
+
+    assert (bitlen == 56 || bitlen == 112);
+    if (bitlen == 56) { table = bitErrorTable_short; tablesize = bitErrorTableSize_short; }
+    else { table = bitErrorTable_long; tablesize = bitErrorTableSize_long; }
+
+    if (!table)
+        return NULL;
+
+    ei.syndrome = syndrome;
+    return bsearch(&ei, table, tablesize, sizeof(struct errorinfo), syndrome_compare);
+}
+
+// Given a message and an error-correction descriptor,
+// apply the error correction to the given message.
+void modesChecksumFix(uint8_t *msg, struct errorinfo *info)
+{
+    int i;
+
+    if (!info)
+        return;
+
+    for (i = 0; i < info->errors; ++i)
+        msg[info->bit[i] >> 3] ^= 1 << (7 - (info->bit[i] & 7));
+}
+
+#ifdef CRCDEBUG
+int main(int argc, char **argv)
+{
+    int shortlen, longlen;
+    int i;
+    struct errorinfo *shorttable, *longtable;
+
+    if (argc < 3) {
+        fprintf(stderr, "syntax: crctests <ncorrect> <ndetect>\n");
+        return 1;
+    }
+
+    initLookupTables();
+    shorttable = prepareErrorTable(MODES_SHORT_MSG_BITS, atoi(argv[1]), atoi(argv[2]), &shortlen);
+    longtable = prepareErrorTable(MODES_LONG_MSG_BITS, atoi(argv[1]), atoi(argv[2]), &longlen);
+
+    // check for DF11 correction syndromes where there is a syndrome with lower 7 bits all zero
+    // (which would be used for DF11 error correction), but there's also a syndrome which has
+    // the same upper 17 bits but nonzero lower 7 bits.
+
+    // empirically, with ncorrect=1 ndetect=2 we get no ambiguous syndromes;
+    // for ncorrect=2 ndetect=4 we get 11 ambiguous syndromes:
+
+    /*
+  syndrome 1 = 000C00  bits=[ 44 45 ]
+  syndrome 2 = 000C1B  bits=[ 30 43 ]
+
+  syndrome 1 = 001400  bits=[ 43 45 ]
+  syndrome 2 = 00141B  bits=[ 30 44 ]
+
+  syndrome 1 = 001800  bits=[ 43 44 ]
+  syndrome 2 = 00181B  bits=[ 30 45 ]
+
+  syndrome 1 = 001800  bits=[ 43 44 ]
+  syndrome 2 = 001836  bits=[ 29 42 ]
+
+  syndrome 1 = 002400  bits=[ 42 45 ]
+  syndrome 2 = 00242D  bits=[ 29 30 ]
+
+  syndrome 1 = 002800  bits=[ 42 44 ]
+  syndrome 2 = 002836  bits=[ 29 43 ]
+
+  syndrome 1 = 003000  bits=[ 42 43 ]
+  syndrome 2 = 003036  bits=[ 29 44 ]
+
+  syndrome 1 = 003000  bits=[ 42 43 ]
+  syndrome 2 = 00306C  bits=[ 28 41 ]
+
+  syndrome 1 = 004800  bits=[ 41 44 ]
+  syndrome 2 = 00485A  bits=[ 28 29 ]
+
+  syndrome 1 = 005000  bits=[ 41 43 ]
+  syndrome 2 = 00506C  bits=[ 28 42 ]
+
+  syndrome 1 = 006000  bits=[ 41 42 ]
+  syndrome 2 = 00606C  bits=[ 28 43 ]
+    */
+
+    // So in the DF11 correction logic, we just discard messages that require more than a 1 bit fix.
+
+    fprintf(stderr, "checking %d syndromes for DF11 collisions..\n", shortlen);
+    for (i = 0; i < shortlen; ++i) {
+        if ((shorttable[i].syndrome & 0xFF) == 0) {
+            int j;
+            // all syndromes with the same first 17 bits should sort immediately after entry i,
+            // so this is fairly easy
+            for (j = i+1; j < shortlen; ++j) {
+                if ((shorttable[i].syndrome & 0xFFFF80) == (shorttable[j].syndrome & 0xFFFF80)) {
+                    int k;
+                    int mismatch = 0;
+
+                    // we don't care if the only differences are in bits that lie in the checksum
+                    for (k = 0; k < shorttable[i].errors; ++k) {
+                        int l, matched = 0;
+
+                        if (shorttable[i].bit[k] >= 49)
+                            continue; // bit is in the final 7 bits, we don't care
+
+                        for (l = 0; l < shorttable[j].errors; ++l) {
+                            if (shorttable[i].bit[k] == shorttable[j].bit[l]) {
+                                matched = 1;
+                                break;
+                            }
+                        }
+
+                        if (!matched)
+                            mismatch = 1;
+                    }
+
+                    for (k = 0; k < shorttable[j].errors; ++k) {
+                        int l, matched = 0;
+
+                        if (shorttable[j].bit[k] >= 49)
+                            continue; // bit is in the final 7 bits, we don't care
+
+                        for (l = 0; l < shorttable[i].errors; ++l) {
+                            if (shorttable[j].bit[k] == shorttable[i].bit[l]) {
+                                matched = 1;
+                                break;
+                            }
+                        }
+
+                        if (!matched)
+                            mismatch = 1;
+                    }
+
+                    if (mismatch) {
+                        fprintf(stderr,
+                                "DF11 correction collision: \n"
+                                "  syndrome 1 = %06X  bits=[",
+                                shorttable[i].syndrome);
+                        for (k = 0; k < shorttable[i].errors; ++k)
+                            fprintf(stderr, " %d", shorttable[i].bit[k]);
+                        fprintf(stderr, " ]\n");
+
+                        fprintf(stderr,
+                                "  syndrome 2 = %06X  bits=[",
+                                shorttable[j].syndrome);
+                        for (k = 0; k < shorttable[j].errors; ++k)
+                            fprintf(stderr, " %d", shorttable[j].bit[k]);
+                        fprintf(stderr, " ]\n");
+                    }
+                } else {
+                    break;
+                }
+            }
+        }
+    }
+
+    free(shorttable);
+    free(longtable);
+
+    return 0;
+}
+#endif

crc.h

@@ -0,0 +1,39 @@
+// Part of dump1090, a Mode S message decoder for RTLSDR devices.
+//
+// crc.h: Mode S checksum prototypes.
+//
+// Copyright (c) 2014,2015 Oliver Jowett <oliver@mutability.co.uk>
+//
+// This file is free software: you may copy, redistribute and/or modify it
+// under the terms of the GNU General Public License as published by the
+// Free Software Foundation, either version 2 of the License, or (at your
+// option) any later version.
+//
+// This file is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef DUMP1090_CRC_H
+#define DUMP1090_CRC_H
+
+#include <stdint.h>
+
+// Global max for fixable bit erros
+#define MODES_MAX_BITERRORS 2
+
+struct errorinfo {
+    uint32_t syndrome;                 // CRC syndrome
+    int      errors;                   // number of errors
+    int8_t   bit[MODES_MAX_BITERRORS]; // bit positions to fix (-1 = no bit)
+};
+
+void modesChecksumInit(int fixBits);
+uint32_t modesChecksum(const uint8_t *msg, int bitlen);
+struct errorinfo *modesChecksumDiagnose(uint32_t syndrome, int bitlen);
+void modesChecksumFix(uint8_t *msg, struct errorinfo *info);
+
+#endif

debian-stretch/control

@@ -0,0 +1,30 @@
+Source: dump1090-fa
+Section: embedded
+Priority: extra
+Maintainer: Oliver Jowett <oliver.jowett@flightaware.com>
+Build-Depends: debhelper(>=10), librtlsdr-dev, libusb-1.0-0-dev, pkg-config, libncurses5-dev, libbladerf-dev
+Standards-Version: 3.9.3
+Homepage: http://www.flightaware.com/
+Vcs-Git: https://github.com/flightaware/dump1090.git
+
+Package: dump1090
+Architecture: all
+Depends: dump1090-fa, ${misc:Depends}
+Priority: extra
+Section: oldlibs
+Description: transitional dummy package for dump1090
+  This is a transitional dummy package to handle upgrades from
+  the old package name of "dump1090" to the new package name of
+  "dump1090-fa". It can safely be removed.
+
+Package: dump1090-fa
+Architecture: any
+Depends: ${shlibs:Depends}, ${misc:Depends}, libbladerf1 (>= 0.2016.06), adduser, lighttpd
+Replaces: dump1090 (<< 3.0)
+Breaks: dump1090 (<< 3.0)
+Description: ADS-B Ground Station System for RTL-SDR
+ Networked Aviation Mode S / ADS-B decoder/translator with RTL-SDR software
+ defined radio USB device support.
+ .
+ This is FlightAware's fork of dump1090-mutability, customized for use
+ in the PiAware sdcard images.

debian-stretch/rules

@@ -0,0 +1,35 @@
+#!/usr/bin/make -f
+# -*- makefile -*-
+# Sample debian/rules that uses debhelper.
+# This file was originally written by Joey Hess and Craig Small.
+# As a special exception, when this file is copied by dh-make into a
+# dh-make output file, you may use that output file without restriction.
+# This special exception was added by Craig Small in version 0.37 of dh-make.
+
+# Uncomment this to turn on verbose mode.
+export DH_VERBOSE=1
+
+export DEB_BUILD_MAINT_OPTIONS = hardening=+all
+
+DPKG_EXPORT_BUILDFLAGS = 1
+include /usr/share/dpkg/default.mk
+
+override_dh_auto_build:
+	# starch's gcc doesn't support the compiler flags needed for ARM-specific starch flavors;
+	# turn off runtime CPU detection
+	dh_auto_build -- RTLSDR=yes BLADERF=yes HACKRF=no LIMESDR=no DUMP1090_VERSION=$(DEB_VERSION) CPUFEATURES=no
+
+override_dh_install:
+	dh_install
+	install -d debian/dump1090-fa/usr/bin
+	cp -a dump1090 debian/dump1090-fa/usr/bin/dump1090-fa
+	cp -a view1090 debian/dump1090-fa/usr/bin/view1090-fa
+
+override_dh_installinit:
+	dh_installinit --no-stop-on-upgrade --no-restart-after-upgrade
+
+override_dh_systemd_start:
+	dh_systemd_start --no-stop-on-upgrade --no-restart-after-upgrade --name=dump1090-fa.service
+
+%:
+	dh $@ --with=systemd

debian/README.librtlsdr

@@ -0,0 +1,18 @@
+This package includes binaries that are statically linked against librtlsdr,
+which is licensed under the GPL:
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+The upstream source is available at https://github.com/steve-m/librtlsdr