From: Antonio Ospite <ospite@studenti.unina.it>
Date: Sun, 14 Jul 2013 10:53:36 +0000 (+0200)
Subject: Factor out some more useful functions
X-Git-Url: https://git.ao2.it/experiments/fps-meter.git/commitdiff_plain/d73b9869570111a3249139508e43f3f722adad2e

Factor out some more useful functions
---

diff --git a/fps-meter.c b/fps-meter.c
index c66cb69..0de937e 100644
--- a/fps-meter.c
+++ b/fps-meter.c
@@ -18,6 +18,7 @@
  */
 
 #include <stdio.h>
+#include <string.h>
 #include <time.h>
 
 #ifdef DEBUG
@@ -43,47 +44,66 @@
 		}                                                \
 	} while(0)
 
-int main(void)
-{
+struct fps_meter_stats {
 	struct timespec time_start;
 	struct timespec time_end;
 	struct timespec elapsed;
 
-	struct timespec tmp;
+	unsigned int frames;
+	double nsecs;
+};
 
-	unsigned int frames = 0;
-	double nsecs = 0;
-	float fps;
+static void fps_meter_init(struct fps_meter_stats *stats)
+{
+	memset(stats, 0, sizeof(*stats));
 
-	while (1) {
-		clock_gettime(CLOCK_MONOTONIC, &time_start);
-		dbg("Start time: s: %ld, ns: %ld", time_start.tv_sec, time_start.tv_nsec);
+	clock_gettime(CLOCK_MONOTONIC, &stats->time_start);
+	dbg("Init time: s: %ld, ns: %ld", stats->time_start.tv_sec, stats->time_start.tv_nsec);
+}
+
+static void fps_meter_update(struct fps_meter_stats *stats)
+{
+	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, &stats->elapsed);
+	dbg("Elapsed s: %ld ns: %ld", stats->elapsed.tv_sec, stats->elapsed.tv_nsec);
 
+	stats->frames++;
+	stats->nsecs += (stats->elapsed.tv_sec * NSEC_PER_SEC + stats->elapsed.tv_nsec);
+	if (stats->nsecs >= NSEC_PER_SEC) {
+		/* 
+		 * if we were garanteed that each frame took less than
+		 * a second, then just printing 'frames' would be enough here,
+		 * but if we want to cover the case when a frame may take more
+		 * than a second, some calculations have to be done.
+		 */
+		float fps = stats->frames / (stats->nsecs / NSEC_PER_SEC);
+		printf("(frames: %d, nsecs: %f) FPS: %.2f\n", stats->frames, stats->nsecs, fps);
+		stats->nsecs = 0;
+		stats->frames = 0;
+	}
+
+	/* update the stats for the next iteration */
+	clock_gettime(CLOCK_MONOTONIC, &stats->time_start);
+}
+
+int main(void)
+{
+	struct fps_meter_stats stats;
+	struct timespec tmp;
+
+	fps_meter_init(&stats);
+	while (1) {
 		/* simulate some workload of about 60fps */
 		dbg("Doing some work, which takes about %d ns", NSEC_PER_SEC / 60);
 		tmp.tv_sec = 0;
 		tmp.tv_nsec = NSEC_PER_SEC / 60;
 		clock_nanosleep(CLOCK_MONOTONIC, 0, &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);
-
-		frames++;
-		nsecs += (elapsed.tv_sec * NSEC_PER_SEC + elapsed.tv_nsec);
-		if (nsecs >= NSEC_PER_SEC) {
-			/* 
-			 * if each frame takes less than a second, then just
-			 * printing 'frames' is enough, but if we want to
-			 * cover the case when a frame may take more than
-			 * a second, some calculations have to be done.
-			 */
-			fps = frames / (nsecs / NSEC_PER_SEC);
-			printf("(frames: %d, nsecs: %f) FPS: %.2f\n", frames, nsecs, fps);
-			nsecs = 0;
-			frames = 0;
-		}
+		fps_meter_update(&stats);
 	}
 
 	return 0;