mirror of
https://github.com/brain-hackers/lab
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64 lines
1.5 KiB
C
64 lines
1.5 KiB
C
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <time.h>
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const int width = 800;
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const int height = 480;
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// 1 loop = 2 draws
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// 30 loop = 60 draws = 1 sec (60 fps)
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const int nloop = 30 * 3;
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struct timespec diff(struct timespec start, struct timespec end);
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int main(void) {
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FILE *f;
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uint16_t buf1[width * height]; //RGB565
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uint16_t buf2[width * height];
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struct timespec ts1, ts2, d;
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int i, j;
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float elapsed;
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for (i = 0; i < height; i++) {
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for (j = 0; j < width; j++) {
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buf1[i * width + j] = (i << 8) + j;
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buf2[i * width + j] = ~((i << 8) + j);
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}
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}
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f = fopen("/dev/fb0", "w");
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if (f == NULL) {
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printf("Could not open /dev/fb0\n");
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return 1;
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}
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clock_gettime(CLOCK_MONOTONIC, &ts1);
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for (j = 0; j < nloop; j++) {
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fwrite(buf1, sizeof(buf1), 1, f);
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fseek(f, 0, SEEK_SET);
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fwrite(buf2, sizeof(buf2), 1, f);
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fseek(f, 0, SEEK_SET);
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}
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clock_gettime(CLOCK_MONOTONIC, &ts2);
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d = diff(ts1, ts2);
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elapsed = (float)d.tv_sec + ((float)d.tv_nsec * 1e-9);
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printf("Frames: %d\n", nloop * 2);
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printf("Elapsed: %f\n", elapsed);
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printf("Frames per second: %f\n", (float)(nloop * 2) / elapsed);
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}
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// https://www.guyrutenberg.com/2007/09/22/profiling-code-using-clock_gettime/
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struct timespec diff(struct timespec start, struct timespec end) {
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struct timespec temp;
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if ((end.tv_nsec-start.tv_nsec)<0) {
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temp.tv_sec = end.tv_sec-start.tv_sec-1;
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temp.tv_nsec = 1000000000+end.tv_nsec-start.tv_nsec;
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} else {
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temp.tv_sec = end.tv_sec-start.tv_sec;
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temp.tv_nsec = end.tv_nsec-start.tv_nsec;
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}
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return temp;
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}
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