/* Test how fast my laptop can XOR to memory.
 *
 * This program runs on my laptop in 4.4 to 4.5 seconds.
 *
 * During that time, on one of the four cores, it is looping ten
 * million times over a thousand-element array of 64-bit words, XORing
 * each element, for a total of 640 billion bit-XOR operations, or
 * about 142 billion per second.  This means the machine as a whole
 * (exclusive of the GPU) is capable of about 570 billion bit-XOR
 * operations per second.
 */

#include <stdio.h>
#include <stdlib.h>

#define ARRAY_SIZE(a) (sizeof(a)/sizeof(*a))

long x[1000];
int main()
{
  if (!fread(x, sizeof(x), 1, stdin)) abort();
  for (int i = 0; i < 10000000; i++) {
    for (int j = 1; j < ARRAY_SIZE(x); j++) {
      x[j] ^= x[j-1];
    }
    x[0] ^= x[ARRAY_SIZE(x)-1];
  }
  if (!fwrite(x, sizeof(x), 1, stdout)) abort();
  return 0;
}