outputfrompcg32.c

/***
result:

152ca78d
027c6003
cb07bbf3
f98befee
1cd777e3
a4e29590
661e4b6d
093b9e0e
b7e9851d
e71f2e4d
bdb2a071
469753f2
d4195b44
8d5b2e0a
e749bf46
7370bb1c
b9ad21f8
cfad21e0
843fa922
f16b535e
*/


/* Modified by D. Lemire based on original code by M. O'Neill, August 2017 */
#include <stdint.h>
#include <stdio.h>
struct pcg_state_setseq_64 {
  uint64_t
      state;    // RNG state.  All values are possible.  Will change over time.
  uint64_t inc; // Controls which RNG sequence (stream) is
  // selected. Must *always* be odd. Might be changed by the user, never by our
  // code.
};

typedef struct pcg_state_setseq_64 pcg32_random_t;

static pcg32_random_t pcg32_global; // global state

static inline uint32_t pcg32_random_r(pcg32_random_t *rng) {
  uint64_t oldstate = rng->state;
  rng->state = oldstate * UINT64_C(0x5851f42d4c957f2d) + rng->inc;
  uint32_t xorshifted = ((oldstate >> 18) ^ oldstate) >> 27;
  uint32_t rot = oldstate >> 59;
  return (xorshifted >> rot) | (xorshifted << (32 - rot));
}

static inline uint32_t pcg32(void) { return pcg32_random_r(&pcg32_global); }

int main() {
  pcg32_global.state = UINT64_C(0x853c49e6748fea9b);
  pcg32_global.inc = UINT64_C(0xda3e39cb94b95bdb);
  for (uint32_t t = 0; t < 20; t++) {
    printf("%08x\n", pcg32());
  }
}