src/util/rand_xor.c

   1 #include "rand_xor.h"
   2
   3 /* Super fast random number generator.
   4  *
   5  * This rand_xorshift128plus function by Sebastiano Vigna belongs
   6  * to the public domain.
   7  */
   8 uint64_t
   9 rand_xorshift128plus(uint64_t *seed)
  10 {
  11    uint64_t *s = seed;
  12
  13    uint64_t s1 = s[0];
  14    const uint64_t s0 = s[1];
  15    s[0] = s0;
  16    s1 ^= s1 << 23;
  17    s[1] = s1 ^ s0 ^ (s1 >> 18) ^ (s0 >> 5);
  18
  19    return s[1] + s0;
  20 }