// This is a C++ version of the mt19937-64 code found here:
// http://www.math.sci.hiroshima-u.ac.jp/~%20m-mat/MT/VERSIONS/C-LANG/mt19937-64.c

// This is the original copyright and license:

/*
   Copyright (C) 2004, Makoto Matsumoto and Takuji Nishimura,
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

     1. Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.

     2. Redistributions in binary form must reproduce the above copyright
        notice, this list of conditions and the following disclaimer in the
        documentation and/or other materials provided with the distribution.

     3. The names of its contributors may not be used to endorse or promote
        products derived from this software without specific prior written
        permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#ifndef MT19937_64_HPP
#define MT19937_64_HPP

#include <uv.h>

#define NN 312
#define MM 156
#define MATRIX_A 0xB5026F5AA96619E9ULL
#define UM 0xFFFFFFFF80000000ULL /* Most significant 33 bits */
#define LM 0x7FFFFFFFULL /* Least significant 31 bits */

class MT19937_64 {
  public:
    static const uint64_t DEFAULT_SEED = 5489ULL;

    MT19937_64(uint64_t seed = DEFAULT_SEED)
      : mti_(NN) {
      int i;
      uint64_t* mt = mt_;

      mt[0] = seed;
      for (i=1; i<NN; i++)
        mt[i] =  (6364136223846793005ULL * (mt[i-1] ^ (mt[i-1] >> 62)) + i);
    }

    uint64_t operator()() {
      int i;
      uint64_t x;
      uint64_t* mt = mt_;

      static const uint64_t mag01[2]={0ULL, MATRIX_A};

      if (mti_ >= NN) { /* generate NN words at one time */
        for (i=0; i < NN - MM; i++) {
          x = (mt[i]&UM)|(mt[i+1]&LM);
          mt[i] = mt[i+MM] ^ (x>>1) ^ mag01[(int)(x&1ULL)];
        }
        for (;i<NN-1;i++) {
          x = (mt[i]&UM)|(mt[i+1]&LM);
          mt[i] = mt[i+(MM-NN)] ^ (x>>1) ^ mag01[(int)(x&1ULL)];
        }
        x = (mt[NN-1]&UM)|(mt[0]&LM);
        mt[NN-1] = mt[MM-1] ^ (x>>1) ^ mag01[(int)(x&1ULL)];

        mti_ = 0;
      }

      x = mt[mti_++];

      x ^= (x >> 29) & 0x5555555555555555ULL;
      x ^= (x << 17) & 0x71D67FFFEDA60000ULL;
      x ^= (x << 37) & 0xFFF7EEE000000000ULL;
      x ^= (x >> 43);

      return x;
    }

  private:
    uint64_t mt_[NN]; /* The array for the state vector */
    int mti_;
};

#undef NN
#undef MM
#undef MATRIX_A
#undef UM
#undef LM

#endif