bsnes/nall/random.hpp

#ifndef NALL_RANDOM_HPP
#define NALL_RANDOM_HPP

//pseudo-random number generator
//very low-quality, but very fast (based on CRC32 polynomial)

namespace nall {

inline unsigned prng() {
  static unsigned n = 0;
  return n = (n >> 1) ^ (((n & 1) - 1) & 0xedb88320);
}

struct random_lfsr {
  inline void seed(unsigned seed__) {
    seed_ = seed__;
  }

  inline unsigned operator()() {
    return seed_ = (seed_ >> 1) ^ (((seed_ & 1) - 1) & 0xedb88320);
  }

  random_lfsr() : seed_(0) {
  }

private:
  unsigned seed_;
};

}

#endif