Factor out some more useful functions

diff --git a/fps-limit.c b/fps-limit.c
index 7759349..3ed784f 100644 (file)
--- a/fps-limit.c
+++ b/fps-limit.c
@@ -18,6 +18,7 @@
  */
 
 #include <stdio.h>
+#include <string.h>
 #include <time.h>
 
 #ifdef DEBUG
@@ -45,34 +46,61 @@
                }                                                \
        } while(0)
 
-int main(void)
-{
+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;
-       struct timespec remaining = {0, 0};
 
+       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;
        struct timespec tmp;
 
+       fps_limit_init(&stats, FPS);
        while (1) {
-               clock_gettime(CLOCK_MONOTONIC, &time_start);
-               dbg("Start time: s: %ld, ns: %ld", time_start.tv_sec, time_start.tv_nsec);
-
                dbg("Doing some work, max: %d", NSEC_PER_SEC / FPS);
                tmp.tv_sec = 0;
                tmp.tv_nsec = (NSEC_PER_SEC / FPS) * 2 / 3;
                nanosleep(&tmp, NULL);
 
-               clock_gettime(CLOCK_MONOTONIC, &time_end);
-               dbg("End time: s: %ld, ns: %ld", time_end.tv_sec, time_end.tv_nsec);
-               timespecsub(&time_end, &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 / FPS) {
-                       /* remaining delay, _relative_ to time_end */
-                       remaining.tv_nsec = (NSEC_PER_SEC / FPS) - elapsed.tv_nsec;
-                       dbg("Sleeping for: ns: %ld", remaining.tv_nsec);
-                       clock_nanosleep(CLOCK_MONOTONIC, 0, &remaining, NULL);
-               }
+               fps_limit_sleep(&stats);
        }
 
        return 0;