/* Generate 16 bit random numbers using PCG.

   Copied from various bits here:
   https://github.com/imneme/pcg-c/blob/master/include/pcg_variants.h
*/

#include<stdio.h>

#define OUTPUT_WIDTH  256
#define OUTPUT_HEIGHT 256

#define PCG_DEFAULT_MULTIPLIER_32  747796405U
#define PCG_DEFAULT_INCREMENT_32   2891336453U

static unsigned int state = 0x46b56677;

static int pcg_random()
{
   int output;

   /* pcg_oneseq_32_step_r */
   state = state * PCG_DEFAULT_MULTIPLIER_32 + PCG_DEFAULT_INCREMENT_32;

   /* pcg_output_xsh_rs_32_16 */
   output = ((state >> 11) ^ state) >> ((state >> 30) + 11);

   return output & 0xffff;
}

int main(int argc, char **argv)
{
   int x, y;

   printf("P2\n%d %d\n255\n", OUTPUT_WIDTH, OUTPUT_HEIGHT);
   for(y = 0; y < OUTPUT_HEIGHT; y++)
   {
      for(x = 0; x < OUTPUT_WIDTH; x++)
         printf(" %d", pcg_random() >> 8);
      putchar('\n');
   }
   return 0;
}