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/*
* Copyright 2008-2012 NVIDIA Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*! \file linear_congruential_engine.h
* \brief A linear congruential pseudorandom number engine.
*/
#pragma once
#include <thrust/detail/config.h>
#include <iostream>
#include <thrust/detail/cstdint.h>
#include <thrust/random/detail/random_core_access.h>
#include <thrust/random/detail/linear_congruential_engine_discard.h>
namespace thrust
{
namespace random
{
/*! \addtogroup random_number_engine_templates Random Number Engine Class Templates
* \ingroup random
* \{
*/
/*! \class linear_congruential_engine
* \brief A \p linear_congruential_engine random number engine produces unsigned integer
* random numbers using a linear congruential random number generation algorithm.
*
* The generation algorithm has the form <tt>x_i = (a * x_{i-1} + c) mod m</tt>.
*
* \tparam UIntType The type of unsigned integer to produce.
* \tparam a The multiplier used in the generation algorithm.
* \tparam c The increment used in the generation algorithm.
* \tparam m The modulus used in the generation algorithm.
*
* \note Inexperienced users should not use this class template directly. Instead, use
* \p minstd_rand or \p minstd_rand0.
*
* The following code snippet shows examples of use of a \p linear_congruential_engine instance:
*
* \code
* #include <thrust/random/linear_congruential_engine.h>
* #include <iostream>
*
* int main(void)
* {
* // create a minstd_rand object, which is an instance of linear_congruential_engine
* thrust::minstd_rand rng1;
*
* // output some random values to cout
* std::cout << rng1() << std::endl;
*
* // a random value is printed
*
* // create a new minstd_rand from a seed
* thrust::minstd_rand rng2(13);
*
* // discard some random values
* rng2.discard(13);
*
* // stream the object to an iostream
* std::cout << rng2 << std::endl;
*
* // rng2's current state is printed
*
* // print the minimum and maximum values that minstd_rand can produce
* std::cout << thrust::minstd_rand::min << std::endl;
* std::cout << thrust::minstd_rand::max << std::endl;
*
* // the range of minstd_rand is printed
*
* // save the state of rng2 to a different object
* thrust::minstd_rand rng3 = rng2;
*
* // compare rng2 and rng3
* std::cout << (rng2 == rng3) << std::endl;
*
* // 1 is printed
*
* // re-seed rng2 with a different seed
* rng2.seed(7);
*
* // compare rng2 and rng3
* std::cout << (rng2 == rng3) << std::endl;
*
* // 0 is printed
*
* return 0;
* }
*
* \endcode
*
* \see thrust::random::minstd_rand
* \see thrust::random::minstd_rand0
*/
template<typename UIntType, UIntType a, UIntType c, UIntType m>
class linear_congruential_engine
{
public:
// types
/*! \typedef result_type
* \brief The type of the unsigned integer produced by this \p linear_congruential_engine.
*/
typedef UIntType result_type;
// engine characteristics
/*! The multiplier used in the generation algorithm.
*/
static const result_type multiplier = a;
/*! The increment used in the generation algorithm.
*/
static const result_type increment = c;
/*! The modulus used in the generation algorithm.
*/
static const result_type modulus = m;
/*! The smallest value this \p linear_congruential_engine may potentially produce.
*/
static const result_type min = c == 0u ? 1u : 0u;
/*! The largest value this \p linear_congruential_engine may potentially produce.
*/
static const result_type max = m - 1u;
/*! The default seed of this \p linear_congruential_engine.
*/
static const result_type default_seed = 1u;
// constructors and seeding functions
/*! This constructor, which optionally accepts a seed, initializes a new
* \p linear_congruential_engine.
*
* \param s The seed used to intialize this \p linear_congruential_engine's state.
*/
__host__ __device__
explicit linear_congruential_engine(result_type s = default_seed);
/*! This method initializes this \p linear_congruential_engine's state, and optionally accepts
* a seed value.
*
* \param s The seed used to initializes this \p linear_congruential_engine's state.
*/
__host__ __device__
void seed(result_type s = default_seed);
// generating functions
/*! This member function produces a new random value and updates this \p linear_congruential_engine's state.
* \return A new random number.
*/
__host__ __device__
result_type operator()(void);
/*! This member function advances this \p linear_congruential_engine's state a given number of times
* and discards the results.
*
* \param z The number of random values to discard.
* \note This function is provided because an implementation may be able to accelerate it.
*/
__host__ __device__
void discard(unsigned long long z);
/*! \cond
*/
private:
result_type m_x;
static void transition(result_type &state);
friend struct thrust::random::detail::random_core_access;
friend struct thrust::random::detail::linear_congruential_engine_discard;
__host__ __device__
bool equal(const linear_congruential_engine &rhs) const;
template<typename CharT, typename Traits>
std::basic_ostream<CharT,Traits>& stream_out(std::basic_ostream<CharT,Traits> &os) const;
template<typename CharT, typename Traits>
std::basic_istream<CharT,Traits>& stream_in(std::basic_istream<CharT,Traits> &is);
/*! \endcond
*/
}; // end linear_congruential_engine
/*! This function checks two \p linear_congruential_engines for equality.
* \param lhs The first \p linear_congruential_engine to test.
* \param rhs The second \p linear_congruential_engine to test.
* \return \c true if \p lhs is equal to \p rhs; \c false, otherwise.
*/
template<typename UIntType_, UIntType_ a_, UIntType_ c_, UIntType_ m_>
__host__ __device__
bool operator==(const linear_congruential_engine<UIntType_,a_,c_,m_> &lhs,
const linear_congruential_engine<UIntType_,a_,c_,m_> &rhs);
/*! This function checks two \p linear_congruential_engines for inequality.
* \param lhs The first \p linear_congruential_engine to test.
* \param rhs The second \p linear_congruential_engine to test.
* \return \c true if \p lhs is not equal to \p rhs; \c false, otherwise.
*/
template<typename UIntType_, UIntType_ a_, UIntType_ c_, UIntType_ m_>
__host__ __device__
bool operator!=(const linear_congruential_engine<UIntType_,a_,c_,m_> &lhs,
const linear_congruential_engine<UIntType_,a_,c_,m_> &rhs);
/*! This function streams a linear_congruential_engine to a \p std::basic_ostream.
* \param os The \p basic_ostream to stream out to.
* \param e The \p linear_congruential_engine to stream out.
* \return \p os
*/
template<typename UIntType_, UIntType_ a_, UIntType_ c_, UIntType_ m_,
typename CharT, typename Traits>
std::basic_ostream<CharT,Traits>&
operator<<(std::basic_ostream<CharT,Traits> &os,
const linear_congruential_engine<UIntType_,a_,c_,m_> &e);
/*! This function streams a linear_congruential_engine in from a std::basic_istream.
* \param is The \p basic_istream to stream from.
* \param e The \p linear_congruential_engine to stream in.
* \return \p is
*/
template<typename UIntType_, UIntType_ a_, UIntType_ c_, UIntType_ m_,
typename CharT, typename Traits>
std::basic_istream<CharT,Traits>&
operator>>(std::basic_istream<CharT,Traits> &is,
linear_congruential_engine<UIntType_,a_,c_,m_> &e);
/*! \} // random_number_engine_templates
*/
/*! \addtogroup predefined_random
* \{
*/
// XXX the type N2111 used here was uint_fast32_t
/*! \typedef minstd_rand0
* \brief A random number engine with predefined parameters which implements a version of
* the Minimal Standard random number generation algorithm.
* \note The 10000th consecutive invocation of a default-constructed object of type \p minstd_rand0
* shall produce the value \c 1043618065 .
*/
typedef linear_congruential_engine<thrust::detail::uint32_t, 16807, 0, 2147483647> minstd_rand0;
/*! \typedef minstd_rand
* \brief A random number engine with predefined parameters which implements a version of
* the Minimal Standard random number generation algorithm.
* \note The 10000th consecutive invocation of a default-constructed object of type \p minstd_rand
* shall produce the value \c 399268537 .
*/
typedef linear_congruential_engine<thrust::detail::uint32_t, 48271, 0, 2147483647> minstd_rand;
/*! \} // predefined_random
*/
} // end random
// import names into thrust::
using random::linear_congruential_engine;
using random::minstd_rand;
using random::minstd_rand0;
} // end thrust
#include <thrust/random/detail/linear_congruential_engine.inl>
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