/* boost random/inversive_congruential.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: inversive_congruential.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_INVERSIVE_CONGRUENTIAL_HPP

 #define BOOST_RANDOM_INVERSIVE_CONGRUENTIAL_HPP

 #include <iostream>

 #include <cassert>

 #include <boost/config.hpp>

 #include <boost/static_assert.hpp>

 #include <boost/random/detail/const_mod.hpp>

 namespace boost {

 namespace random {

 // Eichenauer and Lehn 1986

 template<class IntType, IntType a, IntType b, IntType p, IntType val>

 class inversive_congruential

 {

 public:

   typedef IntType result_type;

 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION

   static const bool has_fixed_range = true;

   static const result_type min_value = (b == 0 ? 1 : 0);

   static const result_type max_value = p-1;

 #else

   BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);

 #endif

   BOOST_STATIC_CONSTANT(result_type, multiplier = a);

   BOOST_STATIC_CONSTANT(result_type, increment = b);

   BOOST_STATIC_CONSTANT(result_type, modulus = p);

   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return b == 0 ? 1 : 0; }

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

   explicit inversive_congruential(IntType y0 = 1) : value(y0)

   {

     BOOST_STATIC_ASSERT(b >= 0);

     BOOST_STATIC_ASSERT(p > 1);

     BOOST_STATIC_ASSERT(a >= 1);

     if(b == 0) 

       assert(y0 > 0); 

   }

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

   { seed(first, last); }

   void seed(IntType y0 = 1) { value = y0; if(b == 0) assert(y0 > 0); }

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

   {

     if(first == last)

       throw std::invalid_argument("inversive_congruential::seed");

     value = *first++;

   }

   IntType operator()()

   {

     typedef const_mod<IntType, p> do_mod;

     value = do_mod::mult_add(a, do_mod::invert(value), b);

     return value;

   }

   bool validation(result_type x) const { 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, inversive_congruential x)

   { os << x.value; return os; }

   template<class CharT, class Traits>

   friend std::basic_istream<CharT,Traits>&

   operator>>(std::basic_istream<CharT,Traits>& is, inversive_congruential& x)

   { is >> x.value; return is; }

 #endif

   friend bool operator==(inversive_congruential x, inversive_congruential y)

   { return x.value == y.value; }

   friend bool operator!=(inversive_congruential x, inversive_congruential y)

   { return !(x == y); }

 #else

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

   bool operator==(inversive_congruential rhs) const

   { return value == rhs.value; }

   bool operator!=(inversive_congruential rhs) const

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

 #endif

 private:

   IntType value;

 };

 #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION

 //  A definition is required even for integral static constants

 template<class IntType, IntType a, IntType b, IntType p, IntType val>

 const bool inversive_congruential<IntType, a, b, p, val>::has_fixed_range;

 template<class IntType, IntType a, IntType b, IntType p, IntType val>

 const typename inversive_congruential<IntType, a, b, p, val>::result_type inversive_congruential<IntType, a, b, p, val>::min_value;

 template<class IntType, IntType a, IntType b, IntType p, IntType val>

 const typename inversive_congruential<IntType, a, b, p, val>::result_type inversive_congruential<IntType, a, b, p, val>::max_value;

 template<class IntType, IntType a, IntType b, IntType p, IntType val>

 const typename inversive_congruential<IntType, a, b, p, val>::result_type inversive_congruential<IntType, a, b, p, val>::multiplier;

 template<class IntType, IntType a, IntType b, IntType p, IntType val>

 const typename inversive_congruential<IntType, a, b, p, val>::result_type inversive_congruential<IntType, a, b, p, val>::increment;

 template<class IntType, IntType a, IntType b, IntType p, IntType val>

 const typename inversive_congruential<IntType, a, b, p, val>::result_type inversive_congruential<IntType, a, b, p, val>::modulus;

 #endif

 } // namespace random

 typedef random::inversive_congruential<int32_t, 9102, 2147483647-36884165,

   2147483647, 0> hellekalek1995;

 } // namespace boost

 #endif // BOOST_RANDOM_INVERSIVE_CONGRUENTIAL_HPP