Random.cpp

#include "Random.h"
// fast and simple random number generator I put together
// randomness tested very well at http://www.cacert.at/random/
void Random::CalculateNext() {
  int y = (value ^ twist) - (mix ^ value);
  y ^= twist ^ value ^ mix;
  mix ^= twist ^ value;
  value ^= twist - mix;
  twist ^= value ^ y;
  value ^= (twist << 7) ^ (mix >> 16) ^ (y << 8);
}
Random::Random() { SetSeed(101); }
Random::Random(int seed) { SetSeed(seed); }
void Random::SetSeed(int seed) {
  this->seed = seed;
  mix = 51651237;
  twist = 895213268;
  value = seed;

  for (int i = 0; i < 50; ++i) {
    CalculateNext();
  }

  seed ^= (seed >> 15);
  value = 0x9417B3AF ^ seed;

  for (int i = 0; i < 950; ++i) {
    CalculateNext();
  }
}
int Random::Next1() {
  CalculateNext();
  return value & 0x7fffffff;
}
int Random::Next2() {
  if (seed == 0) {
    seed = 0x12345987;
  }
  int k = seed / 127773;
  seed = 16807 * (seed - k * 127773) - 2836 * k;
  if ((int)seed < 0) {
    seed += 2147483647;
  }
  return seed & 0x7fffffff;
}