/*
  Reference Code of a Random Number Generator
  Combined Tausworthe : (31,13,12), (29,2,4), (28,3,17)
  JIS Z 9031:2012, pp.54-55
 */


static unsigned long s1, s2, s3, b;


void init_taus88(unsigned long s){
  int i;
  unsigned long x[3];
  s &= 0xffffffffUL;
  i = 0;
  while (i < 3) {
    if (s & 0xfffffff0UL) {
      x[i] = s;
      i++;
    }
    s = 1664525UL * s + 1UL;
    s &= 0xffffffffUL;
  }
  s1 = x[0]; s2 = x[1]; s3 = x[2];
}


/* 31 bit integer */
long taus88_31(void){
  b = (((s1 << 13) ^ s1) >> 19);
  s1 = (((s1 & 4294967294UL) << 12) ^ b);
  b = (((s2 << 2) ^ s2) >> 25);
  s2 = (((s2 & 4294967288UL) << 4) ^ b);
  b = (((s3 << 3) ^ s3) >> 11);
  s3 = (((s3 & 4294967280UL) << 17) ^ b);
  return ((s1 ^ s2 ^ s3) >> 1);
}


void random_generator_reference_init(unsigned int s){
  init_taus88(s);
}


unsigned int random_generator_reference(void){
  return taus88_31();
}