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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <sys/time.h>
  4.  
  5. typedef struct pixel {
  6.     unsigned char r, g, b, x;
  7. } pixel;
  8.  
  9. int main(void)
  10. {
  11.     int width = 1920, height = 1080;
  12.     int length = width * height;
  13.     pixel *pixels = (pixel*)malloc(length * sizeof(pixel));
  14.     for (int i = 0; i < length; i++) {
  15.         int rnd = rand();
  16.         pixels[i].r = rnd & 0xFF;
  17.         pixels[i].g = rnd >> 8 & 0xFF;
  18.         pixels[i].b = rnd >> 16 & 0xFF;
  19.         pixels[i].x = 0;
  20.     }
  21.  
  22.     struct timeval tv0, tv1, tv2, tv3, tv4;
  23.  
  24.     gettimeofday(&tv0, NULL);
  25.  
  26.     for (int y = 0; y < height; ++y)
  27.         for (int x = 0; x < width; ++x) {
  28.             pixel *p = &pixels[x + y * width];
  29.             p->r ^= 0xff;
  30.             p->g ^= 0xff;
  31.             p->b ^= 0xff;
  32.         }
  33.  
  34.     gettimeofday(&tv1, NULL);
  35.  
  36.     for (int x = 0; x < width; x++)
  37.         for (int y = 0; y < height; ++y) {
  38.             pixel *p = &pixels[x + y * width];
  39.             p->r ^= 0xff;
  40.             p->g ^= 0xff;
  41.             p->b ^= 0xff;
  42.         }
  43.  
  44.     gettimeofday(&tv2, NULL);
  45.  
  46.     printf("Y-X pass: %d usec\n", 1000000 * (tv1.tv_sec - tv0.tv_sec) + tv1.tv_usec - tv0.tv_usec);
  47.     printf("X-Y pass: %d usec\n", 1000000 * (tv2.tv_sec - tv1.tv_sec) + tv2.tv_usec - tv1.tv_usec);
  48.  
  49.     return 0;
  50. }
  51.  
Success #stdin #stdout 0.05s 9592KB
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Standard input is empty
stdout
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Y-X pass: 3375 usec
X-Y pass: 18002 usec
https://ideone.com/0A4SZZ
language:
C (gcc 8.3)
created:
5 years ago
visibility:
public

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