/* boost random/additive_combine.hpp header file

 *

 * Copyright Jens Maurer 2000-2001

 * Distributed under the Boost Software License, Version 1.0. (See

 * accompanying file LICENSE_1_0.txt or copy at

 * http://www.boost.org/LICENSE_1_0.txt)

 *

 * See http://www.boost.org for most recent version including documentation.

 *

 * $Id: additive_combine.hpp,v 1.11 2005/05/21 15:57:00 dgregor Exp $

 *

 * Revision history

 *  2001-02-18  moved to individual header files

 */

#ifndef BOOST_RANDOM_ADDITIVE_COMBINE_HPP

#define BOOST_RANDOM_ADDITIVE_COMBINE_HPP

#include <iostream>

#include <algorithm> // for std::min and std::max

#include <boost/config.hpp>

#include <boost/cstdint.hpp>

#include <boost/random/linear_congruential.hpp>

namespace boost {

namespace random {

// L'Ecuyer 1988

template<class MLCG1, class MLCG2,

#ifndef BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS

  typename MLCG1::result_type 

#else

  int32_t

#endif

  val>

class additive_combine

{

public:

  typedef MLCG1 first_base;

  typedef MLCG2 second_base;

  typedef typename MLCG1::result_type result_type;

#ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION

  static const bool has_fixed_range = true;

  static const result_type min_value = 1;

  static const result_type max_value = MLCG1::max_value-1;

#else

  enum { has_fixed_range = false };

#endif

  result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return 1; }

  result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return (_mlcg1.max)()-1; }

  additive_combine() : _mlcg1(), _mlcg2() { }

  additive_combine(typename MLCG1::result_type seed1, 

                   typename MLCG2::result_type seed2)

    : _mlcg1(seed1), _mlcg2(seed2) { }

  template<class It> additive_combine(It& first, It last)

    : _mlcg1(first, last), _mlcg2(first, last) { }

  void seed()

  {

    _mlcg1.seed();

    _mlcg2.seed();

  }

  void seed(typename MLCG1::result_type seed1,

            typename MLCG2::result_type seed2)

  {

    _mlcg1(seed1);

    _mlcg2(seed2);

  }

  template<class It> void seed(It& first, It last)

  {

    _mlcg1.seed(first, last);

    _mlcg2.seed(first, last);

  }

  result_type operator()() {

    result_type z = _mlcg1() - _mlcg2();

    if(z < 1)

      z += MLCG1::modulus-1;

    return z;

  }

  static bool validation(result_type x) { return val == x; }

#ifndef BOOST_NO_OPERATORS_IN_NAMESPACE

#ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS

  template<class CharT, class Traits>

  friend std::basic_ostream<CharT,Traits>&

  operator<<(std::basic_ostream<CharT,Traits>& os, const additive_combine& r)

  { os << r._mlcg1 << " " << r._mlcg2; return os; }

  template<class CharT, class Traits>

  friend std::basic_istream<CharT,Traits>&

  operator>>(std::basic_istream<CharT,Traits>& is, additive_combine& r)

  { is >> r._mlcg1 >> std::ws >> r._mlcg2; return is; }

#endif

  friend bool operator==(const additive_combine& x, const additive_combine& y)

  { return x._mlcg1 == y._mlcg1 && x._mlcg2 == y._mlcg2; }

  friend bool operator!=(const additive_combine& x, const additive_combine& y)

  { return !(x == y); }

#else

  // Use a member function; Streamable concept not supported.

  bool operator==(const additive_combine& rhs) const

  { return _mlcg1 == rhs._mlcg1 && _mlcg2 == rhs._mlcg2; }

  bool operator!=(const additive_combine& rhs) const

  { return !(*this == rhs); }

#endif

private:

  MLCG1 _mlcg1;

  MLCG2 _mlcg2;

};

} // namespace random

typedef random::additive_combine<

    random::linear_congruential<int32_t, 40014, 0, 2147483563, 0>,

    random::linear_congruential<int32_t, 40692, 0, 2147483399, 0>,

  2060321752> ecuyer1988;

} // namespace boost

#endif // BOOST_RANDOM_ADDITIVE_COMBINE_HPP