/* * fps-meter - Example program about how to measure frames per seconds * * Copyright (C) 2013 Antonio Ospite * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ #ifndef FPS_METER_H #define FPS_METER_H #include #include #include #ifdef DEBUG #define dbg(...) \ do { \ printf(__VA_ARGS__); \ printf("\n"); \ fflush(stdout); \ } while(0) #else #define dbg(...) do {} while(0) #endif #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_meter_stats { struct timespec time_start; struct timespec time_end; struct timespec elapsed; unsigned int frames; double nsecs; }; static void fps_meter_init(struct fps_meter_stats *stats) { 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); } 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); } #endif /* FPS_METER_H */