mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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168 lines
7.3 KiB
C++
168 lines
7.3 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2014 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef SPROUT_RANDOM_LINEAR_FEEDBACK_SHIFT_HPP
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#define SPROUT_RANDOM_LINEAR_FEEDBACK_SHIFT_HPP
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#include <ios>
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#include <sprout/config.hpp>
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#include <sprout/detail/integer/integer_mask.hpp>
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#include <sprout/random/detail/seed_impl.hpp>
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#include <sprout/random/random_result.hpp>
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#include <sprout/random/type_traits.hpp>
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#include <sprout/type_traits/enabler_if.hpp>
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namespace sprout {
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namespace random {
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//
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// linear_feedback_shift_engine
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//
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template<typename UIntType, int w, int k, int q, int s>
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class linear_feedback_shift_engine {
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public:
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typedef UIntType result_type;
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private:
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struct private_construct_t {};
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public:
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SPROUT_STATIC_CONSTEXPR int word_size = w;
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SPROUT_STATIC_CONSTEXPR int exponent1 = k;
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SPROUT_STATIC_CONSTEXPR int exponent2 = q;
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SPROUT_STATIC_CONSTEXPR int step_size = s;
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SPROUT_STATIC_CONSTEXPR result_type default_seed = 341;
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public:
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static_assert(w > 0, "w > 0");
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static_assert(q > 0, "q > 0");
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static_assert(k < w, "k < w");
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static_assert(0 < 2 * q && 2 * q < k, "0 < 2 * q && 2 * q < k");
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static_assert(0 < s && s <= k - q, "0 < s && s <= k - q");
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public:
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static SPROUT_CONSTEXPR result_type static_min() SPROUT_NOEXCEPT {
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return 0;
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}
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static SPROUT_CONSTEXPR result_type static_max() SPROUT_NOEXCEPT {
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return wordmask();
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}
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private:
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static SPROUT_CONSTEXPR result_type wordmask() {
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return sprout::detail::low_bits_mask_t<w>::sig_bits;
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}
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static SPROUT_CONSTEXPR result_type init_seed_1(result_type x0) {
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return x0 < (1 << (w - k)) ? x0 + (1 << (w - k)) : x0;
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}
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static SPROUT_CONSTEXPR result_type init_seed(result_type x0 = default_seed) {
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return init_seed_1(x0 & wordmask());
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}
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template<typename Sseq, typename sprout::enabler_if<sprout::random::is_seed_seq<Sseq>::value>::type = sprout::enabler>
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static SPROUT_CXX14_CONSTEXPR result_type init_seed(Sseq& seq) {
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return init_seed(sprout::random::detail::seed_one_int<result_type, (result_type(2) << (w - 1))>(seq));
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}
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template<typename Sseq, typename sprout::enabler_if<sprout::random::is_seed_seq<Sseq>::value>::type = sprout::enabler>
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static SPROUT_CONSTEXPR result_type init_seed(Sseq const& seq) {
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return init_seed(sprout::random::detail::seed_one_int<result_type, (result_type(2) << (w - 1))>(seq));
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}
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template<typename InputIterator>
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static SPROUT_CONSTEXPR result_type init_seed(InputIterator first, InputIterator last) {
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return init_seed(sprout::random::detail::get_one_int<result_type, (result_type(2) << (w - 1))>(first, last));
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}
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private:
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result_type x_;
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private:
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SPROUT_CONSTEXPR linear_feedback_shift_engine(result_type x, private_construct_t)
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: x_(x)
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{}
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SPROUT_CONSTEXPR sprout::random::random_result<linear_feedback_shift_engine> generate(result_type result) const {
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return sprout::random::random_result<linear_feedback_shift_engine>(
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result,
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linear_feedback_shift_engine(result, private_construct_t())
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);
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}
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public:
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SPROUT_CONSTEXPR linear_feedback_shift_engine()
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: x_(init_seed(default_seed))
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{}
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explicit SPROUT_CONSTEXPR linear_feedback_shift_engine(result_type x0)
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: x_(init_seed(x0))
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{}
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template<typename Sseq, typename sprout::enabler_if<sprout::random::is_seed_seq<Sseq>::value>::type = sprout::enabler>
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explicit SPROUT_CXX14_CONSTEXPR linear_feedback_shift_engine(Sseq& seq)
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: x_(init_seed(seq))
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{}
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template<typename Sseq, typename sprout::enabler_if<sprout::random::is_seed_seq<Sseq>::value>::type = sprout::enabler>
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explicit SPROUT_CONSTEXPR linear_feedback_shift_engine(Sseq const& seq)
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: x_(init_seed(seq))
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{}
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template<typename InputIterator>
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SPROUT_CONSTEXPR linear_feedback_shift_engine(InputIterator first, InputIterator last)
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: x_(init_seed(first, last))
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{}
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SPROUT_CXX14_CONSTEXPR void seed(result_type x0 = default_seed) {
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x_ = init_seed(x0);
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}
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template<typename Sseq, typename sprout::enabler_if<sprout::random::is_seed_seq<Sseq>::value>::type = sprout::enabler>
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SPROUT_CXX14_CONSTEXPR void seed(Sseq& seq) {
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x_ = init_seed(seq);
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}
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template<typename Sseq, typename sprout::enabler_if<sprout::random::is_seed_seq<Sseq>::value>::type = sprout::enabler>
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SPROUT_CXX14_CONSTEXPR void seed(Sseq const& seq) {
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x_ = init_seed(seq);
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}
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template<typename InputIterator>
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SPROUT_CXX14_CONSTEXPR void seed(InputIterator first, InputIterator last) {
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x_ = init_seed(first, last);
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}
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SPROUT_CONSTEXPR result_type min() const SPROUT_NOEXCEPT {
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return static_min();
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}
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SPROUT_CONSTEXPR result_type max() const SPROUT_NOEXCEPT {
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return static_max();
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}
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SPROUT_CXX14_CONSTEXPR result_type operator()() {
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x_ = ((x_ & ((wordmask() << (w - k)) & wordmask())) << s) ^ ((((x_ << q) ^ x_) & wordmask()) >> (k - s));
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return x_;
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}
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SPROUT_CONSTEXPR sprout::random::random_result<linear_feedback_shift_engine> const operator()() const {
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return generate(((x_ & ((wordmask() << (w - k)) & wordmask())) << s) ^ ((((x_ << q) ^ x_) & wordmask()) >> (k - s)));
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}
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friend SPROUT_CONSTEXPR bool operator==(linear_feedback_shift_engine const& lhs, linear_feedback_shift_engine const& rhs) SPROUT_NOEXCEPT {
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return lhs.x_ == rhs.x_;
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}
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friend SPROUT_CONSTEXPR bool operator!=(linear_feedback_shift_engine const& lhs, linear_feedback_shift_engine const& rhs) SPROUT_NOEXCEPT {
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return !(lhs == rhs);
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}
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template<typename Elem, typename Traits>
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friend SPROUT_NON_CONSTEXPR std::basic_istream<Elem, Traits>& operator>>(
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std::basic_istream<Elem, Traits>& lhs,
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linear_feedback_shift_engine& rhs
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)
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{
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return lhs >> rhs.x_;
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}
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template<typename Elem, typename Traits>
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friend SPROUT_NON_CONSTEXPR std::basic_ostream<Elem, Traits>& operator<<(
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std::basic_ostream<Elem, Traits>& lhs,
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linear_feedback_shift_engine const& rhs
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)
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{
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return lhs << rhs.x_;
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}
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};
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template<typename UIntType, int w, int k, int q, int s>
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SPROUT_CONSTEXPR_OR_CONST int sprout::random::linear_feedback_shift_engine<UIntType, w, k, q, s>::word_size;
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template<typename UIntType, int w, int k, int q, int s>
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SPROUT_CONSTEXPR_OR_CONST int sprout::random::linear_feedback_shift_engine<UIntType, w, k, q, s>::exponent1;
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template<typename UIntType, int w, int k, int q, int s>
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SPROUT_CONSTEXPR_OR_CONST int sprout::random::linear_feedback_shift_engine<UIntType, w, k, q, s>::exponent2;
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template<typename UIntType, int w, int k, int q, int s>
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SPROUT_CONSTEXPR_OR_CONST int sprout::random::linear_feedback_shift_engine<UIntType, w, k, q, s>::step_size;
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template<typename UIntType, int w, int k, int q, int s>
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SPROUT_CONSTEXPR_OR_CONST UIntType sprout::random::linear_feedback_shift_engine<UIntType, w, k, q, s>::default_seed;
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} // namespace random
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using sprout::random::linear_feedback_shift_engine;
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} // namespace sprout
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#endif // #ifndef SPROUT_RANDOM_LINEAR_FEEDBACK_SHIFT_HPP
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