sl@0: /* boost random/linear_congruential.hpp header file
sl@0:  *
sl@0:  * Copyright Jens Maurer 2000-2001
sl@0:  * Distributed under the Boost Software License, Version 1.0. (See
sl@0:  * accompanying file LICENSE_1_0.txt or copy at
sl@0:  * http://www.boost.org/LICENSE_1_0.txt)
sl@0:  *
sl@0:  * See http://www.boost.org for most recent version including documentation.
sl@0:  *
sl@0:  * $Id: linear_congruential.hpp,v 1.22 2005/05/21 15:57:00 dgregor Exp $
sl@0:  *
sl@0:  * Revision history
sl@0:  *  2001-02-18  moved to individual header files
sl@0:  */
sl@0: 
sl@0: #ifndef BOOST_RANDOM_LINEAR_CONGRUENTIAL_HPP
sl@0: #define BOOST_RANDOM_LINEAR_CONGRUENTIAL_HPP
sl@0: 
sl@0: #include <iostream>
sl@0: #include <cassert>
sl@0: #include <stdexcept>
sl@0: #include <boost/config.hpp>
sl@0: #include <boost/limits.hpp>
sl@0: #include <boost/static_assert.hpp>
sl@0: #include <boost/random/detail/const_mod.hpp>
sl@0: #include <boost/detail/workaround.hpp>
sl@0: 
sl@0: namespace boost {
sl@0: namespace random {
sl@0: 
sl@0: // compile-time configurable linear congruential generator
sl@0: template<class IntType, IntType a, IntType c, IntType m, IntType val>
sl@0: class linear_congruential
sl@0: {
sl@0: public:
sl@0:   typedef IntType result_type;
sl@0: #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
sl@0:   static const bool has_fixed_range = true;
sl@0:   static const result_type min_value = ( c == 0 ? 1 : 0 );
sl@0:   static const result_type max_value = m-1;
sl@0: #else
sl@0:   BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
sl@0: #endif
sl@0:   BOOST_STATIC_CONSTANT(IntType, multiplier = a);
sl@0:   BOOST_STATIC_CONSTANT(IntType, increment = c);
sl@0:   BOOST_STATIC_CONSTANT(IntType, modulus = m);
sl@0: 
sl@0:   // MSVC 6 and possibly others crash when encountering complicated integral
sl@0:   // constant expressions.  Avoid the check for now.
sl@0:   // BOOST_STATIC_ASSERT(m == 0 || a < m);
sl@0:   // BOOST_STATIC_ASSERT(m == 0 || c < m);
sl@0: 
sl@0:   explicit linear_congruential(IntType x0 = 1)
sl@0:     : _modulus(modulus), _x(_modulus ? (x0 % _modulus) : x0)
sl@0:   { 
sl@0:     assert(c || x0); /* if c == 0 and x(0) == 0 then x(n) = 0 for all n */
sl@0:     // overflow check
sl@0:     // disabled because it gives spurious "divide by zero" gcc warnings
sl@0:     // assert(m == 0 || (a*(m-1)+c) % m == (c < a ? c-a+m : c-a)); 
sl@0: 
sl@0:     // MSVC fails BOOST_STATIC_ASSERT with std::numeric_limits at class scope
sl@0: #ifndef BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS
sl@0:     BOOST_STATIC_ASSERT(std::numeric_limits<IntType>::is_integer);
sl@0: #endif
sl@0:   }
sl@0: 
sl@0:   template<class It>
sl@0:   linear_congruential(It& first, It last) { seed(first, last); }
sl@0: 
sl@0:   // compiler-generated copy constructor and assignment operator are fine
sl@0:   void seed(IntType x0 = 1)
sl@0:   {
sl@0:     assert(c || x0);
sl@0:     _x = (_modulus ? (x0 % _modulus) : x0);
sl@0:   }
sl@0: 
sl@0:   template<class It>
sl@0:   void seed(It& first, It last)
sl@0:   {
sl@0:     if(first == last)
sl@0:       throw std::invalid_argument("linear_congruential::seed");
sl@0:     IntType value = *first++;
sl@0:     _x = (_modulus ? (value % _modulus) : value);
sl@0:   }
sl@0: 
sl@0:   result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return c == 0 ? 1 : 0; }
sl@0:   result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return modulus-1; }
sl@0: 
sl@0:   IntType operator()()
sl@0:   {
sl@0:     _x = const_mod<IntType, m>::mult_add(a, _x, c);
sl@0:     return _x;
sl@0:   }
sl@0: 
sl@0:   static bool validation(IntType x) { return val == x; }
sl@0: 
sl@0: #ifdef BOOST_NO_OPERATORS_IN_NAMESPACE
sl@0:     
sl@0:   // Use a member function; Streamable concept not supported.
sl@0:   bool operator==(const linear_congruential& rhs) const
sl@0:   { return _x == rhs._x; }
sl@0:   bool operator!=(const linear_congruential& rhs) const
sl@0:   { return !(*this == rhs); }
sl@0: 
sl@0: #else 
sl@0:   friend bool operator==(const linear_congruential& x,
sl@0:                          const linear_congruential& y)
sl@0:   { return x._x == y._x; }
sl@0:   friend bool operator!=(const linear_congruential& x,
sl@0:                          const linear_congruential& y)
sl@0:   { return !(x == y); }
sl@0:     
sl@0: #if !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS) && !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551))
sl@0:   template<class CharT, class Traits>
sl@0:   friend std::basic_ostream<CharT,Traits>&
sl@0:   operator<<(std::basic_ostream<CharT,Traits>& os,
sl@0:              const linear_congruential& lcg)
sl@0:   {
sl@0:     return os << lcg._x;
sl@0:   }
sl@0: 
sl@0:   template<class CharT, class Traits>
sl@0:   friend std::basic_istream<CharT,Traits>&
sl@0:   operator>>(std::basic_istream<CharT,Traits>& is,
sl@0:              linear_congruential& lcg)
sl@0:   {
sl@0:     return is >> lcg._x;
sl@0:   }
sl@0:  
sl@0: private:
sl@0: #endif
sl@0: #endif
sl@0:     
sl@0:   IntType _modulus;   // work-around for gcc "divide by zero" warning in ctor
sl@0:   IntType _x;
sl@0: };
sl@0: 
sl@0: // probably needs the "no native streams" caveat for STLPort
sl@0: #if !defined(__SGI_STL_PORT) && BOOST_WORKAROUND(__GNUC__, == 2)
sl@0: template<class IntType, IntType a, IntType c, IntType m, IntType val>
sl@0: std::ostream&
sl@0: operator<<(std::ostream& os,
sl@0:            const linear_congruential<IntType,a,c,m,val>& lcg)
sl@0: {
sl@0:     return os << lcg._x;
sl@0: }
sl@0: 
sl@0: template<class IntType, IntType a, IntType c, IntType m, IntType val>
sl@0: std::istream&
sl@0: operator>>(std::istream& is,
sl@0:            linear_congruential<IntType,a,c,m,val>& lcg)
sl@0: {
sl@0:     return is >> lcg._x;
sl@0: }
sl@0: #elif defined(BOOST_NO_OPERATORS_IN_NAMESPACE) || defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS) || BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551))
sl@0: template<class CharT, class Traits, class IntType, IntType a, IntType c, IntType m, IntType val>
sl@0: std::basic_ostream<CharT,Traits>&
sl@0: operator<<(std::basic_ostream<CharT,Traits>& os,
sl@0:            const linear_congruential<IntType,a,c,m,val>& lcg)
sl@0: {
sl@0:     return os << lcg._x;
sl@0: }
sl@0: 
sl@0: template<class CharT, class Traits, class IntType, IntType a, IntType c, IntType m, IntType val>
sl@0: std::basic_istream<CharT,Traits>&
sl@0: operator>>(std::basic_istream<CharT,Traits>& is,
sl@0:            linear_congruential<IntType,a,c,m,val>& lcg)
sl@0: {
sl@0:     return is >> lcg._x;
sl@0: }
sl@0: #endif
sl@0: 
sl@0: #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
sl@0: //  A definition is required even for integral static constants
sl@0: template<class IntType, IntType a, IntType c, IntType m, IntType val>
sl@0: const bool linear_congruential<IntType, a, c, m, val>::has_fixed_range;
sl@0: template<class IntType, IntType a, IntType c, IntType m, IntType val>
sl@0: const typename linear_congruential<IntType, a, c, m, val>::result_type linear_congruential<IntType, a, c, m, val>::min_value;
sl@0: template<class IntType, IntType a, IntType c, IntType m, IntType val>
sl@0: const typename linear_congruential<IntType, a, c, m, val>::result_type linear_congruential<IntType, a, c, m, val>::max_value;
sl@0: template<class IntType, IntType a, IntType c, IntType m, IntType val>
sl@0: const IntType linear_congruential<IntType,a,c,m,val>::modulus;
sl@0: #endif
sl@0: 
sl@0: } // namespace random
sl@0: 
sl@0: // validation values from the publications
sl@0: typedef random::linear_congruential<int32_t, 16807, 0, 2147483647, 
sl@0:   1043618065> minstd_rand0;
sl@0: typedef random::linear_congruential<int32_t, 48271, 0, 2147483647,
sl@0:   399268537> minstd_rand;
sl@0: 
sl@0: 
sl@0: #if !defined(BOOST_NO_INT64_T) && !defined(BOOST_NO_INTEGRAL_INT64_T)
sl@0: // emulate the lrand48() C library function; requires support for uint64_t
sl@0: class rand48 
sl@0: {
sl@0: public:
sl@0:   typedef int32_t result_type;
sl@0: #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
sl@0:   static const bool has_fixed_range = true;
sl@0:   static const int32_t min_value = 0;
sl@0:   static const int32_t max_value = integer_traits<int32_t>::const_max;
sl@0: #else
sl@0:   enum { has_fixed_range = false };
sl@0: #endif
sl@0:   int32_t min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return 0; }
sl@0:   int32_t max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return std::numeric_limits<int32_t>::max BOOST_PREVENT_MACRO_SUBSTITUTION (); }
sl@0:   
sl@0:   explicit rand48(int32_t x0 = 1) : lcf(cnv(x0)) { }
sl@0:   explicit rand48(uint64_t x0) : lcf(x0) { }
sl@0:   template<class It> rand48(It& first, It last) : lcf(first, last) { }
sl@0:   // compiler-generated copy ctor and assignment operator are fine
sl@0:   void seed(int32_t x0 = 1) { lcf.seed(cnv(x0)); }
sl@0:   void seed(uint64_t x0) { lcf.seed(x0); }
sl@0:   template<class It> void seed(It& first, It last) { lcf.seed(first,last); }
sl@0: 
sl@0:   int32_t operator()() { return static_cast<int32_t>(lcf() >> 17); }
sl@0:   // by experiment from lrand48()
sl@0:   static bool validation(int32_t x) { return x == 1993516219; }
sl@0: 
sl@0: #ifndef BOOST_NO_OPERATORS_IN_NAMESPACE
sl@0: 
sl@0: #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
sl@0:   template<class CharT,class Traits>
sl@0:   friend std::basic_ostream<CharT,Traits>&
sl@0:   operator<<(std::basic_ostream<CharT,Traits>& os, const rand48& r)
sl@0:   { os << r.lcf; return os; }
sl@0: 
sl@0:   template<class CharT,class Traits>
sl@0:   friend std::basic_istream<CharT,Traits>&
sl@0:   operator>>(std::basic_istream<CharT,Traits>& is, rand48& r)
sl@0:   { is >> r.lcf; return is; }
sl@0: #endif
sl@0: 
sl@0:   friend bool operator==(const rand48& x, const rand48& y)
sl@0:   { return x.lcf == y.lcf; }
sl@0:   friend bool operator!=(const rand48& x, const rand48& y)
sl@0:   { return !(x == y); }
sl@0: #else
sl@0:   // Use a member function; Streamable concept not supported.
sl@0:   bool operator==(const rand48& rhs) const
sl@0:   { return lcf == rhs.lcf; }
sl@0:   bool operator!=(const rand48& rhs) const
sl@0:   { return !(*this == rhs); }
sl@0: #endif
sl@0: private:
sl@0:   random::linear_congruential<uint64_t,
sl@0:     uint64_t(0xDEECE66DUL) | (uint64_t(0x5) << 32), // xxxxULL is not portable
sl@0:     0xB, uint64_t(1)<<48, /* unknown */ 0> lcf;
sl@0:   static uint64_t cnv(int32_t x) 
sl@0:   { return (static_cast<uint64_t>(x) << 16) | 0x330e;  }
sl@0: };
sl@0: #endif /* !BOOST_NO_INT64_T && !BOOST_NO_INTEGRAL_INT64_T */
sl@0: 
sl@0: } // namespace boost
sl@0: 
sl@0: #endif // BOOST_RANDOM_LINEAR_CONGRUENTIAL_HPP