Move all converters to starch-based implementations (#97)
* Switch all conversion routines to use starch.
main user-visible changes:
* ensure you check out submodules ('git clone --recurse-submodules")
* --version shows the CPU features and DSP implementations in use
* --wisdom allows overriding of the built-in architecture wisdom
* --dcfilter no longer supported
* "starch-benchmark" binary will benchmark all options on the
current machine and can produce a wisdom file to feed to
the --wisdom option
If you have a usecase for --dcfilter, please get in touch and
let me know - it's an edge case and for now there's no starch/DSP
support for it, but support can be written if needed.
In almost all cases the new conversion routines are slightly or
substantially faster than the old conversion routines. The only case
that is slower is SC16/SC16Q11 on a Pi 0, which is around 10% slower
due to changing from heavily approximated lookup tables to higher
quality results (but SC16 is probably already out of reach of a Pi 0)
* No need to build with SC16Q11_TABLE_BITS any more
* Add oneoff/uc8_capture_stats
(reads a UC8 capture; measures min/max/mean I and Q)
* Switch UC8 conversion to 127.4 center, 128 range.
Looking at actual UC8 captures from a RTL2832, the mean I and Q
are actually at 127.4, so use that as the zero point.
This means that the resulting I/Q maximum values could be as large as
127.6. Switch to 128 for simplicity.
* Switch to the new UC8 zero offset in benchmarks, fix some bugs
* Fix some bugs in SC16/SC16Q11 validation, tighten the max error requirements
* Ditch UC8 approximation path, add a NEON VRQSQRTE path.
* Tweak the SC16 exact path, add a new impl that uses a mix of
u32 & floats.
* SC16Q11 impl tweaks:
* add a u32->float exact path
* ditch the approximation path
* add a NEON VRSQRTE path
* add a 12-bit table path (using the full signed I/Q value, not absolute value)
* Ditch SC16 approximation path, add NEON vrsqrte path
* Add oneoff/dsp_error_measurement
This runs sample input through the DSP functions that are
allowed to be inexact and dumps the results as a TSV suitable for
feeding to gnuplot to look at the actual errors.
* Update make clean, make wisdom targets
* Update wisdom based on benchmarking
* Preserve the raw wisdom benchmark data
* Update to latest starch
* Update .gitignore for new wisdom files
* Update starch generated code
* Build starch-benchmark as part of the 'all' target
* Use wisdom from /etc/dump1090-fa/wisdom.local if present
* Package starch-benchmark and a helper script to generate local wisdom data
* Remove submodules in preparation for importing them directly
* Import cpu_features v0.6.0 from https://github.com/google/cpu_features/releases/tag/v0.6.0
* Import starch at commit a725c8491dc33a321565d451b385131e589d8490
from https://github.com/flightaware/starch
2021-01-21 11:45:00 +00:00
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# derived from wisdom.i7-6500u / wisdom.i7-6500u.generic
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magnitude_power_uc8 twopass_x86_avx2 # 65331 ns/call
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magnitude_power_uc8 twopass_generic # 72679 ns/call
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magnitude_power_uc8_aligned twopass_x86_avx2_aligned # 66294 ns/call
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magnitude_power_uc8_aligned twopass_generic # 68415 ns/call
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magnitude_sc16 exact_float_x86_avx2 # 238602 ns/call
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magnitude_sc16 exact_float_generic # 1359997 ns/call
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magnitude_sc16_aligned exact_float_x86_avx2_aligned # 202484 ns/call
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magnitude_sc16_aligned exact_float_generic # 1351564 ns/call
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magnitude_sc16q11 exact_float_x86_avx2 # 65311 ns/call
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magnitude_sc16q11 exact_float_generic # 513012 ns/call
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magnitude_sc16q11_aligned exact_float_x86_avx2_aligned # 56217 ns/call
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magnitude_sc16q11_aligned exact_float_generic # 510226 ns/call
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magnitude_uc8 lookup_unroll_4_x86_avx2 # 53581 ns/call
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magnitude_uc8 lookup_unroll_4_generic # 52709 ns/call
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magnitude_uc8_aligned lookup_unroll_4_x86_avx2 # 53870 ns/call
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magnitude_uc8_aligned lookup_unroll_4_generic # 54033 ns/call
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mean_power_u16 u32_x86_avx2 # 11627 ns/call
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mean_power_u16 u32_generic # 18252 ns/call
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mean_power_u16_aligned u32_x86_avx2_aligned # 11572 ns/call
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mean_power_u16_aligned u32_generic # 18207 ns/call
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2021-07-08 10:53:02 +00:00
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count_above_u16 generic_x86_avx2 # 20 ns/call
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count_above_u16 generic_generic # 30 ns/call
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count_above_u16_aligned generic_x86_avx2_aligned # 15 ns/call
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count_above_u16_aligned generic_generic # 31 ns/call
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