X-Git-Url: https://git.ao2.it/experiments/fps-limit.git/blobdiff_plain/79510a9d3bee77059bd543413ccc9aa739881c52..HEAD:/fps-limit.c

diff --git a/fps-limit.c b/fps-limit.c
index 3ed784f..2c24807 100644
--- a/fps-limit.c
+++ b/fps-limit.c
@@ -17,77 +17,10 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stdio.h>
-#include <string.h>
-#include <time.h>
-
-#ifdef DEBUG
-#define dbg(...)                     \
-	do {                         \
-		printf(__VA_ARGS__); \
-		printf("\n");        \
-		fflush(stdout);      \
-	} while(0)
-#else
-#define dbg(...) do {} while(0)
-#endif
+#include "fps-limit.h"
 
 #define FPS 60
 
-#define NSEC_PER_SEC 1000000000
-
-#define timespecsub(a, b, result)                                \
-	do {                                                     \
-		(result)->tv_sec = (a)->tv_sec - (b)->tv_sec;    \
-		(result)->tv_nsec = (a)->tv_nsec - (b)->tv_nsec; \
-		if ((result)->tv_nsec < 0) {                     \
-			--(result)->tv_sec;                      \
-			(result)->tv_nsec += 1000000000;         \
-		}                                                \
-	} while(0)
-
-struct fps_limit_stats {
-	struct timespec time_start;
-	struct timespec time_end;
-	unsigned int fps;
-};
-
-static void fps_limit_init(struct fps_limit_stats *stats, unsigned int fps)
-{
-	memset(stats, 0, sizeof(*stats));
-
-	clock_gettime(CLOCK_MONOTONIC, &stats->time_start);
-	dbg("Init time: s: %ld, ns: %ld", stats->time_start.tv_sec, stats->time_start.tv_nsec);
-
-	stats->fps = fps;
-}
-
-static void fps_limit_sleep(struct fps_limit_stats *stats)
-{
-	struct timespec elapsed;
-
-	dbg("Start time: s: %ld, ns: %ld", stats->time_start.tv_sec, stats->time_start.tv_nsec);
-
-	clock_gettime(CLOCK_MONOTONIC, &stats->time_end);
-	dbg("End time: s: %ld, ns: %ld", stats->time_end.tv_sec, stats->time_end.tv_nsec);
-
-	timespecsub(&stats->time_end, &stats->time_start, &elapsed);
-	dbg("Elapsed s: %ld ns: %ld", elapsed.tv_sec, elapsed.tv_nsec);
-
-	if (elapsed.tv_sec == 0 && elapsed.tv_nsec < NSEC_PER_SEC / stats->fps) {
-		struct timespec remaining = {0, 0};
-
-		/* remaining delay, _relative_ to time_end */
-		remaining.tv_nsec = (NSEC_PER_SEC / stats->fps) - elapsed.tv_nsec;
-		dbg("Sleeping for: ns: %ld", remaining.tv_nsec);
-
-		clock_nanosleep(CLOCK_MONOTONIC, 0, &remaining, NULL);
-	}
-
-	/* update the stats for the next iteration */
-	clock_gettime(CLOCK_MONOTONIC, &stats->time_start);
-}
-
 int main(void)
 {
 	struct fps_limit_stats stats;
@@ -95,11 +28,14 @@ int main(void)
 
 	fps_limit_init(&stats, FPS);
 	while (1) {
-		dbg("Doing some work, max: %d", NSEC_PER_SEC / FPS);
+		fps_limit_dbg("Doing some work, minimum: %dns", NSEC_PER_SEC / FPS);
+
+		/* simulate a shorter workload */
 		tmp.tv_sec = 0;
 		tmp.tv_nsec = (NSEC_PER_SEC / FPS) * 2 / 3;
 		nanosleep(&tmp, NULL);
 
+		/* and wait for the delay imposed by the limit */
 		fps_limit_sleep(&stats);
 	}