From c32ed2866ef4e316f769bf0f217cabb736aaab4d Mon Sep 17 00:00:00 2001
From: Gluttton <gluttton@ukr.net>
Date: Thu, 30 Jul 2020 23:22:15 +0300
Subject: [PATCH] limesdr: add ability to set normalized gain

Add ability to set the combined normalized gain via command line
options. By default the gain is equal to 0.75.

Test: connect LimeSDR device, try to set different gain and check logs:
    $ ./dump1090 --device-type limesdr --limesdr-gain 0.01
    $ ./dump1090 --device-type limesdr --limesdr-gain 0.5
    $ ./dump1090 --device-type limesdr --limesdr-gain 0.99

Signed-off-by: Gluttton <gluttton@ukr.net>
---
 sdr_limesdr.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sdr_limesdr.c b/sdr_limesdr.c
index 770edba..757fbae 100644
--- a/sdr_limesdr.c
+++ b/sdr_limesdr.c
@@ -59,6 +59,7 @@ static struct {
     bool is_stop;
     char verbosity;
     size_t oversample;
+    float gain;
     lms_info_str_t serial;
     int bytes_in_sample;
     iq_convert_fn converter;
@@ -100,6 +101,7 @@ void limesdrInitConfig()
     LimeSDR.is_stop = false;
     LimeSDR.verbosity = LMS_LOG_INFO;
     LimeSDR.oversample = 0; // default oversample
+    LimeSDR.gain = 0.75;
     LimeSDR.serial[0] = '\0';
     LimeSDR.bytes_in_sample = 2 * sizeof(int16_t); // hardcoded for LMS_FMT_I16
 
@@ -114,6 +116,7 @@ void limesdrShowHelp()
     printf("--limesdr-serial         serial number of desired device\n");
     printf("--limesdr-channel        set number of an RX channel\n");
     printf("--limesdr-oversample     set RF oversampling ratio\n");
+    printf("--limesdr-gain           set normalized gain\n");
     printf("\n");
 }
 
@@ -130,6 +133,8 @@ bool limesdrHandleOption(int argc, char **argv, int *jptr)
         LimeSDR.stream.channel = atoi(argv[++j]);
     } else if (!strcmp(argv[j], "--limesdr-oversample") && more) {
         LimeSDR.oversample = atoi(argv[++j]);
+    } else if (!strcmp(argv[j], "--limesdr-gain") && more) {
+        LimeSDR.gain = atof(argv[++j]);
     } else {
         return false;
     }
@@ -208,7 +213,7 @@ bool limesdrOpen(void)
         goto error;
     }
 
-    if (LMS_SetNormalizedGain(LimeSDR.dev, LMS_CH_RX, LimeSDR.stream.channel, 0.85)) {
+    if (LMS_SetNormalizedGain(LimeSDR.dev, LMS_CH_RX, LimeSDR.stream.channel, LimeSDR.gain)) {
         limesdrLogHandler(LMS_LOG_ERROR, "unable to set gain");
         goto error;
     }