From 8520c7c3d7286e32e2d867adb2419a0410866bec Mon Sep 17 00:00:00 2001 From: Kyle Keen Date: Thu, 23 Jan 2014 00:17:06 -0500 Subject: rtl_adsb: fix threading Signed-off-by: Steve Markgraf --- src/rtl_adsb.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/src/rtl_adsb.c b/src/rtl_adsb.c index 10447cd..bb0c8d2 100644 --- a/src/rtl_adsb.c +++ b/src/rtl_adsb.c @@ -59,7 +59,8 @@ #define BADSAMPLE 255 static pthread_t demod_thread; -static pthread_mutex_t data_ready; /* locked when no data available */ +static pthread_cond_t ready; +static pthread_mutex_t ready_m; static volatile int do_exit = 0; static rtlsdr_dev_t *dev = NULL; @@ -77,6 +78,10 @@ int adsb_frame[14]; #define long_frame 112 #define short_frame 56 +/* signals are not threadsafe by default */ +#define safe_cond_signal(n, m) pthread_mutex_lock(m); pthread_cond_signal(n); pthread_mutex_unlock(m) +#define safe_cond_wait(n, m) pthread_mutex_lock(m); pthread_cond_wait(n, m); pthread_mutex_unlock(m) + void usage(void) { fprintf(stderr, @@ -145,11 +150,11 @@ void display(int *frame, int len) } int abs8(int x) -/* do not subtract 128 from the raw iq, this handles it */ +/* do not subtract 127 from the raw iq, this handles it */ { - if (x >= 128) { - return x - 128;} - return 128 - x; + if (x >= 127) { + return x - 127;} + return 127 - x; } void squares_precompute(void) @@ -338,15 +343,14 @@ static void rtlsdr_callback(unsigned char *buf, uint32_t len, void *ctx) if (do_exit) { return;} memcpy(buffer, buf, len); - pthread_mutex_trylock(&data_ready); - pthread_mutex_unlock(&data_ready); + safe_cond_signal(&ready, &ready_m); } static void *demod_thread_fn(void *arg) { int len; while (!do_exit) { - pthread_mutex_lock(&data_ready); + safe_cond_wait(&ready, &ready_m); len = magnitute(buffer, DEFAULT_BUF_LENGTH); manchester((uint16_t*)buffer, len); messages((uint16_t*)buffer, len); @@ -366,7 +370,8 @@ int main(int argc, char **argv) int dev_index = 0; int dev_given = 0; int ppm_error = 0; - pthread_mutex_init(&data_ready, NULL); + pthread_cond_init(&ready, NULL); + pthread_mutex_init(&ready_m, NULL); squares_precompute(); while ((opt = getopt(argc, argv, "d:g:p:e:Q:VS")) != -1) @@ -477,7 +482,8 @@ int main(int argc, char **argv) else { fprintf(stderr, "\nLibrary error %d, exiting...\n", r);} rtlsdr_cancel_async(dev); - pthread_mutex_destroy(&data_ready); + pthread_cond_destroy(&ready); + pthread_mutex_destroy(&ready_m); if (file != stdout) { fclose(file);} -- cgit v1.2.3