mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
synced 2024-11-14 10:39:05 +00:00
382 lines
15 KiB
C++
382 lines
15 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2015 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_CONGRUENTIAL_HPP
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#define SPROUT_RANDOM_LINEAR_CONGRUENTIAL_HPP
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#include <cstdint>
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#include <istream>
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#include <ostream>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/limits.hpp>
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#include <sprout/random/detail/const_mod.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/random/results.hpp>
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#include <sprout/type_traits/enabler_if.hpp>
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#include <sprout/math/greater_equal.hpp>
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#include <sprout/utility/while_loop.hpp>
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#include <sprout/assert.hpp>
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namespace sprout {
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namespace random {
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//
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// linear_congruential_engine
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//
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template<typename UIntType, UIntType a, UIntType c, UIntType m>
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class linear_congruential_engine {
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static_assert(sprout::numeric_limits<UIntType>::is_integer, "sprout::numeric_limits<UIntType>::is_integer");
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static_assert(m == 0 || a < m, "m == 0 || a < m");
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static_assert(m == 0 || c < m, "m == 0 || c < m");
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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 result_type multiplier = a;
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SPROUT_STATIC_CONSTEXPR result_type increment = c;
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SPROUT_STATIC_CONSTEXPR result_type modulus = m;
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SPROUT_STATIC_CONSTEXPR result_type default_seed = 1;
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public:
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static SPROUT_CONSTEXPR result_type static_min() SPROUT_NOEXCEPT {
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return increment == 0 ? 1 : 0;
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}
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static SPROUT_CONSTEXPR result_type static_max() SPROUT_NOEXCEPT {
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return modulus - 1;
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}
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private:
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static SPROUT_CONSTEXPR result_type init_seed_3(result_type x0) {
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return SPROUT_ASSERT(sprout::math::greater_equal(x0, static_min())), SPROUT_ASSERT(x0 <= static_max()), x0;
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}
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static SPROUT_CONSTEXPR result_type init_seed_2(result_type x0) {
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return init_seed_3(increment == 0 && x0 == 0 ? 1 : x0);
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}
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static SPROUT_CONSTEXPR result_type init_seed_1(result_type x0) {
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return init_seed_2(x0 <= 0 && x0 != 0 ? x0 + modulus : 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(modulus == 0 ? x0 : x0 % modulus);
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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, modulus>(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, modulus>(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, modulus>(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_congruential_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_congruential_engine> generate(result_type result) const {
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return sprout::random::random_result<linear_congruential_engine>(
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result,
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linear_congruential_engine(result, private_construct_t())
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);
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}
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struct discard_init {
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public:
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unsigned long long exponent;
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result_type b_gcd;
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result_type a_zm1_over_gcd;
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result_type a_km1_over_gcd;
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};
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struct discard_pred {
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public:
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SPROUT_CONSTEXPR bool operator()(discard_init const& init) const {
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return static_cast<bool>(init.exponent);
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}
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};
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struct discard_op {
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public:
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SPROUT_CONSTEXPR discard_init operator()(discard_init const& init) const {
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typedef sprout::random::detail::const_mod<result_type, modulus> mod_type;
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return discard_init{
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init.exponent / 2,
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init.b_gcd,
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!(init.exponent % 2 == 1) ? init.a_zm1_over_gcd
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: mod_type::mult_add(
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init.b_gcd,
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mod_type::mult(init.a_zm1_over_gcd, init.a_km1_over_gcd),
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mod_type::add(init.a_zm1_over_gcd, init.a_km1_over_gcd)
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)
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,
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mod_type::mult_add(
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init.b_gcd,
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mod_type::mult(init.a_km1_over_gcd, init.a_km1_over_gcd),
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mod_type::add(init.a_km1_over_gcd, init.a_km1_over_gcd)
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)
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};
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}
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};
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SPROUT_CONSTEXPR linear_congruential_engine const discard_impl_1_2(result_type b_gcd, result_type a_zm1_over_gcd) const {
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typedef sprout::random::detail::const_mod<result_type, modulus> mod_type;
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return linear_congruential_engine(
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mod_type::mult_add(
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mod_type::mult_add(b_gcd, a_zm1_over_gcd, 1),
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x_,
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mod_type::mult(mod_type::invert((multiplier - 1) / b_gcd), mod_type::mult(increment, a_zm1_over_gcd))
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),
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private_construct_t()
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);
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}
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SPROUT_CONSTEXPR linear_congruential_engine const discard_impl_1_1(result_type b_inv, result_type a_z) const {
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typedef sprout::random::detail::const_mod<result_type, modulus> mod_type;
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return linear_congruential_engine(
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mod_type::mult_add(a_z, x_, mod_type::mult(mod_type::mult(increment, b_inv), a_z - 1)),
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private_construct_t()
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);
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}
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SPROUT_CONSTEXPR linear_congruential_engine const discard_impl_1(unsigned long long z, result_type b_inv, result_type b_gcd) const {
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typedef sprout::random::detail::const_mod<result_type, modulus> mod_type;
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return b_gcd == 1 ? discard_impl_1_1(b_inv, mod_type::pow(multiplier, z))
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: discard_impl_1_2(
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b_gcd,
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sprout::while_loop(
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discard_init{z, b_gcd, 0, (multiplier - 1) / b_gcd},
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discard_pred(),
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discard_op()
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).a_zm1_over_gcd
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)
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;
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}
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SPROUT_CONSTEXPR linear_congruential_engine const discard_impl(unsigned long long z, result_type b_inv) const {
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typedef sprout::random::detail::const_mod<result_type, modulus> mod_type;
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return discard_impl_1(
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z, b_inv,
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mod_type::mult(multiplier - 1, b_inv)
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);
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}
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public:
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SPROUT_CONSTEXPR linear_congruential_engine()
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: x_(init_seed())
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{}
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linear_congruential_engine(linear_congruential_engine const&) = default;
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explicit SPROUT_CONSTEXPR linear_congruential_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_congruential_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_congruential_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_congruential_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_ = sprout::random::detail::const_mod<result_type, modulus>::mult_add(a, x_, c);
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return x_;
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}
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SPROUT_CONSTEXPR sprout::random::random_result<linear_congruential_engine> const operator()() const {
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return generate(sprout::random::detail::const_mod<result_type, modulus>::mult_add(a, x_, c));
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}
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SPROUT_CONSTEXPR linear_congruential_engine const discard(unsigned long long z) const {
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typedef sprout::random::detail::const_mod<result_type, modulus> mod_type;
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return discard_impl(z, mod_type::invert(multiplier - 1));
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}
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SPROUT_CXX14_CONSTEXPR void discard(unsigned long long z) {
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typedef sprout::random::detail::const_mod<result_type, modulus> mod_type;
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result_type b_inv = mod_type::invert(multiplier - 1);
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result_type b_gcd = mod_type::mult(multiplier - 1, b_inv);
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if (b_gcd == 1) {
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result_type a_z = mod_type::pow(multiplier, z);
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x_ = mod_type::mult_add(a_z, x_, mod_type::mult(mod_type::mult(increment, b_inv), a_z - 1));
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} else {
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result_type a_zm1_over_gcd = 0;
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result_type a_km1_over_gcd = (multiplier - 1) / b_gcd;
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unsigned long long exponent = z;
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while (exponent) {
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if (exponent % 2 == 1) {
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a_zm1_over_gcd = mod_type::mult_add(
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b_gcd,
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mod_type::mult(a_zm1_over_gcd, a_km1_over_gcd),
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mod_type::add(a_zm1_over_gcd, a_km1_over_gcd)
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);
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}
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a_km1_over_gcd = mod_type::mult_add(
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b_gcd,
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mod_type::mult(a_km1_over_gcd, a_km1_over_gcd),
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mod_type::add(a_km1_over_gcd, a_km1_over_gcd)
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);
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exponent /= 2;
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}
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x_ = mod_type::mult_add(
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mod_type::mult_add(b_gcd, a_zm1_over_gcd, 1),
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x_,
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mod_type::mult(mod_type::invert((multiplier - 1) / b_gcd), mod_type::mult(increment, a_zm1_over_gcd))
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);
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}
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}
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friend SPROUT_CONSTEXPR bool operator==(linear_congruential_engine const& lhs, linear_congruential_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_congruential_engine const& lhs, linear_congruential_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_congruential_engine& rhs
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)
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{
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result_type x;
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if (lhs >> x) {
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if (sprout::math::greater_equal(x, static_min()) && x <= static_max()) {
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rhs.x_ = x;
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} else {
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lhs.setstate(std::ios_base::failbit);
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}
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}
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return lhs;
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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_congruential_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, UIntType a, UIntType c, UIntType m>
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SPROUT_CONSTEXPR_OR_CONST UIntType sprout::random::linear_congruential_engine<UIntType, a, c, m>::multiplier;
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template<typename UIntType, UIntType a, UIntType c, UIntType m>
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SPROUT_CONSTEXPR_OR_CONST UIntType sprout::random::linear_congruential_engine<UIntType, a, c, m>::increment;
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template<typename UIntType, UIntType a, UIntType c, UIntType m>
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SPROUT_CONSTEXPR_OR_CONST UIntType sprout::random::linear_congruential_engine<UIntType, a, c, m>::modulus;
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template<typename UIntType, UIntType a, UIntType c, UIntType m>
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SPROUT_CONSTEXPR_OR_CONST UIntType sprout::random::linear_congruential_engine<UIntType, a, c, m>::default_seed;
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//
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// minstd_rand0
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// minstd_rand
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//
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typedef sprout::random::linear_congruential_engine<std::uint_fast32_t, 16807, 0, 2147483647> minstd_rand0;
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typedef sprout::random::linear_congruential_engine<std::uint_fast32_t, 48271, 0, 2147483647> minstd_rand;
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//
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// rand48
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//
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class rand48 {
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public:
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typedef std::uint32_t result_type;
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private:
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struct private_construct_t {};
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typedef sprout::random::linear_congruential_engine<
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std::uint64_t,
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std::uint64_t(0xDEECE66DUL) | (std::uint64_t(0x5) << 32),
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0xB,
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std::uint64_t(1) << 48
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> lcf_type;
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private:
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static SPROUT_CONSTEXPR result_type static_min() {
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return 0;
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}
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static SPROUT_CONSTEXPR result_type static_max() {
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return 0x7FFFFFFF;
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}
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static SPROUT_CONSTEXPR std::uint64_t cnv(std::uint32_t x) {
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return (static_cast<std::uint64_t>(x) << 16) | 0x330e;
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}
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private:
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lcf_type lcf_;
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private:
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SPROUT_CONSTEXPR rand48(lcf_type const& lcf, private_construct_t)
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: lcf_(lcf)
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{}
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template<typename EngineResult>
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SPROUT_CONSTEXPR sprout::random::random_result<rand48> generate(EngineResult const& rnd) const {
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return sprout::random::random_result<rand48>(
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static_cast<result_type>(sprout::random::result(rnd)) >> 17,
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rand48(sprout::random::next(rnd), private_construct_t())
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);
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}
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public:
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SPROUT_CONSTEXPR rand48()
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: lcf_(cnv(static_cast<std::uint32_t>(1)))
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{}
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explicit SPROUT_CONSTEXPR rand48(result_type x0)
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: lcf_(cnv(x0))
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{}
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SPROUT_CONSTEXPR result_type min() const {
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return static_min();
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}
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SPROUT_CONSTEXPR result_type max() const {
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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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return static_cast<result_type>(static_cast<result_type>(lcf_()) >> 17);
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}
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SPROUT_CONSTEXPR sprout::random::random_result<rand48> const operator()() const {
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return generate(lcf_());
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}
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friend SPROUT_CONSTEXPR bool operator==(rand48 const& lhs, rand48 const& rhs) {
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return lhs.lcf_ == rhs.lcf_;
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}
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friend SPROUT_CONSTEXPR bool operator!=(rand48 const& lhs, rand48 const& rhs) {
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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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rand48& rhs
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)
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{
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return lhs >> rhs.lcf_;
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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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rand48 const& rhs
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)
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{
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return lhs << rhs.lcf_;
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}
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};
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} // namespace random
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using sprout::random::linear_congruential_engine;
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using sprout::random::minstd_rand0;
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using sprout::random::minstd_rand;
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using sprout::random::rand48;
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} // namespace sprout
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#endif // #ifndef SPROUT_RANDOM_LINEAR_CONGRUENTIAL_HPP
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