// *******************************************************************
//   (C) Copyright 2013 Leiden Institute of Advanced Computer Science
//   Universiteit Leiden
//   All Rights Reserved
// *******************************************************************
// Dou Shou Qi (interface)
// *******************************************************************
// FILE INFORMATION:
//   File:     jlkiss64.h
//   Author:   Jonathan K. Vis
//   Revision: 1.01a
//   Date:     2013/04/18
// *******************************************************************
// DESCRIPTION:
//   64-bits random number generator based on: ``The KISS generator'',
//   G. Marsaglia and A. Zaman, 1993.
// *******************************************************************

#if !defined(__jlkiss64_h__)
#define __jlkiss64_h__

#include "../core/types.h"


class RNG
{
  public:
    static RNG next;


    static void seed(uint64_t const n);


    uint64_t operator()(void);


  private:
    inline RNG(void);


    static uint64_t _x;
    uint64_t _y;
    uint32_t _z1;
    uint32_t _c1;
    uint32_t _z2;
    uint32_t _c2;

}; // RNG

uint64_t RNG::_x = 123456789123ull;


inline void RNG::seed(uint64_t const n)
{
  _x = RNG::next() ^ n;
  return;
} // RNG::seed


inline uint64_t RNG::operator()(void)
{
  uint64_t t;

  _x = 1490024343005336237ull * _x + 123456789;
  _y ^= _y << 21;
  _y ^= _y >> 17;
  _y ^= _y << 30;
  t = 4294584393ull * _z1 + _c1;
  _c1 = t >> 32;
  _z1 = t;
  t = 4246477509ull * _z2 + _c2;
  _c2 = t >> 32;
  _z2 = t;
  return _x + _y + static_cast<uint64_t>(_z1) +
         (static_cast<uint64_t>(_z2) << 32);
} // RNG::operator()

inline RNG::RNG(void)
{
  _y = 987654321987ull;
  _z1 = 43219876;
  _c1 = 6543217;
  _z2 = 21987643;
  _c2 = 1732654;
} // RNG::RNG


RNG RNG::next;

#endif