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1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___CXX03___RANDOM_INDEPENDENT_BITS_ENGINE_H10#define _LIBCPP___CXX03___RANDOM_INDEPENDENT_BITS_ENGINE_H11 12#include <__cxx03/__config>13#include <__cxx03/__fwd/istream.h>14#include <__cxx03/__fwd/ostream.h>15#include <__cxx03/__random/is_seed_sequence.h>16#include <__cxx03/__random/log2.h>17#include <__cxx03/__type_traits/conditional.h>18#include <__cxx03/__type_traits/enable_if.h>19#include <__cxx03/__type_traits/is_convertible.h>20#include <__cxx03/__utility/move.h>21#include <__cxx03/cstddef>22#include <__cxx03/limits>23 24#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)25# pragma GCC system_header26#endif27 28_LIBCPP_PUSH_MACROS29#include <__cxx03/__undef_macros>30 31_LIBCPP_BEGIN_NAMESPACE_STD32 33template <class _Engine, size_t __w, class _UIntType>34class _LIBCPP_TEMPLATE_VIS independent_bits_engine {35 template <class _UInt, _UInt _R0, size_t _Wp, size_t _Mp>36 class __get_n {37 static const size_t _Dt = numeric_limits<_UInt>::digits;38 static const size_t _Np = _Wp / _Mp + (_Wp % _Mp != 0);39 static const size_t _W0 = _Wp / _Np;40 static const _UInt _Y0 = _W0 >= _Dt ? 0 : (_R0 >> _W0) << _W0;41 42 public:43 static const size_t value = _R0 - _Y0 > _Y0 / _Np ? _Np + 1 : _Np;44 };45 46public:47 // types48 typedef _UIntType result_type;49 50private:51 _Engine __e_;52 53 static const result_type _Dt = numeric_limits<result_type>::digits;54 static_assert(0 < __w, "independent_bits_engine invalid parameters");55 static_assert(__w <= _Dt, "independent_bits_engine invalid parameters");56 57 typedef typename _Engine::result_type _Engine_result_type;58 typedef __conditional_t<sizeof(_Engine_result_type) <= sizeof(result_type), result_type, _Engine_result_type>59 _Working_result_type;60 static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min + _Working_result_type(1);61 static const size_t __m = __log2<_Working_result_type, _Rp>::value;62 static const size_t __n = __get_n<_Working_result_type, _Rp, __w, __m>::value;63 static const size_t __w0 = __w / __n;64 static const size_t __n0 = __n - __w % __n;65 static const size_t _WDt = numeric_limits<_Working_result_type>::digits;66 static const size_t _EDt = numeric_limits<_Engine_result_type>::digits;67 static const _Working_result_type __y0 = __w0 >= _WDt ? 0 : (_Rp >> __w0) << __w0;68 static const _Working_result_type __y1 = __w0 >= _WDt - 1 ? 0 : (_Rp >> (__w0 + 1)) << (__w0 + 1);69 static const _Engine_result_type70 __mask0 = __w0 > 0 ? _Engine_result_type(~0) >> (_EDt - __w0) : _Engine_result_type(0);71 static const _Engine_result_type72 __mask1 = __w0 < _EDt - 1 ? _Engine_result_type(~0) >> (_EDt - (__w0 + 1)) : _Engine_result_type(~0);73 74public:75 static const result_type _Min = 0;76 static const result_type _Max = __w == _Dt ? result_type(~0) : (result_type(1) << __w) - result_type(1);77 static_assert(_Min < _Max, "independent_bits_engine invalid parameters");78 79 // engine characteristics80 _LIBCPP_HIDE_FROM_ABI static result_type min() { return _Min; }81 _LIBCPP_HIDE_FROM_ABI static result_type max() { return _Max; }82 83 // constructors and seeding functions84 _LIBCPP_HIDE_FROM_ABI independent_bits_engine() {}85 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(const _Engine& __e) : __e_(__e) {}86 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(result_type __sd) : __e_(__sd) {}87 template <88 class _Sseq,89 __enable_if_t<__is_seed_sequence<_Sseq, independent_bits_engine>::value && !is_convertible<_Sseq, _Engine>::value,90 int> = 0>91 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(_Sseq& __q) : __e_(__q) {}92 _LIBCPP_HIDE_FROM_ABI void seed() { __e_.seed(); }93 _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd) { __e_.seed(__sd); }94 template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, independent_bits_engine>::value, int> = 0>95 _LIBCPP_HIDE_FROM_ABI void seed(_Sseq& __q) {96 __e_.seed(__q);97 }98 99 // generating functions100 _LIBCPP_HIDE_FROM_ABI result_type operator()() { return __eval(integral_constant<bool, _Rp != 0>()); }101 _LIBCPP_HIDE_FROM_ABI void discard(unsigned long long __z) {102 for (; __z; --__z)103 operator()();104 }105 106 // property functions107 _LIBCPP_HIDE_FROM_ABI const _Engine& base() const _NOEXCEPT { return __e_; }108 109 template <class _Eng, size_t _Wp, class _UInt>110 friend bool operator==(const independent_bits_engine<_Eng, _Wp, _UInt>& __x,111 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);112 113 template <class _Eng, size_t _Wp, class _UInt>114 friend bool operator!=(const independent_bits_engine<_Eng, _Wp, _UInt>& __x,115 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);116 117 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>118 friend basic_ostream<_CharT, _Traits>&119 operator<<(basic_ostream<_CharT, _Traits>& __os, const independent_bits_engine<_Eng, _Wp, _UInt>& __x);120 121 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>122 friend basic_istream<_CharT, _Traits>&123 operator>>(basic_istream<_CharT, _Traits>& __is, independent_bits_engine<_Eng, _Wp, _UInt>& __x);124 125private:126 _LIBCPP_HIDE_FROM_ABI result_type __eval(false_type);127 _LIBCPP_HIDE_FROM_ABI result_type __eval(true_type);128 129 template <size_t __count,130 __enable_if_t<__count< _Dt, int> = 0> _LIBCPP_HIDE_FROM_ABI static result_type __lshift(result_type __x) {131 return __x << __count;132 }133 134 template <size_t __count, __enable_if_t<(__count >= _Dt), int> = 0>135 _LIBCPP_HIDE_FROM_ABI static result_type __lshift(result_type) {136 return result_type(0);137 }138};139 140template <class _Engine, size_t __w, class _UIntType>141inline _UIntType independent_bits_engine<_Engine, __w, _UIntType>::__eval(false_type) {142 return static_cast<result_type>(__e_() & __mask0);143}144 145template <class _Engine, size_t __w, class _UIntType>146_UIntType independent_bits_engine<_Engine, __w, _UIntType>::__eval(true_type) {147 result_type __sp = 0;148 for (size_t __k = 0; __k < __n0; ++__k) {149 _Engine_result_type __u;150 do {151 __u = __e_() - _Engine::min();152 } while (__u >= __y0);153 __sp = static_cast<result_type>(__lshift<__w0>(__sp) + (__u & __mask0));154 }155 for (size_t __k = __n0; __k < __n; ++__k) {156 _Engine_result_type __u;157 do {158 __u = __e_() - _Engine::min();159 } while (__u >= __y1);160 __sp = static_cast<result_type>(__lshift<__w0 + 1>(__sp) + (__u & __mask1));161 }162 return __sp;163}164 165template <class _Eng, size_t _Wp, class _UInt>166inline _LIBCPP_HIDE_FROM_ABI bool167operator==(const independent_bits_engine<_Eng, _Wp, _UInt>& __x, const independent_bits_engine<_Eng, _Wp, _UInt>& __y) {168 return __x.base() == __y.base();169}170 171template <class _Eng, size_t _Wp, class _UInt>172inline _LIBCPP_HIDE_FROM_ABI bool173operator!=(const independent_bits_engine<_Eng, _Wp, _UInt>& __x, const independent_bits_engine<_Eng, _Wp, _UInt>& __y) {174 return !(__x == __y);175}176 177template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>178_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&179operator<<(basic_ostream<_CharT, _Traits>& __os, const independent_bits_engine<_Eng, _Wp, _UInt>& __x) {180 return __os << __x.base();181}182 183template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>184_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&185operator>>(basic_istream<_CharT, _Traits>& __is, independent_bits_engine<_Eng, _Wp, _UInt>& __x) {186 _Eng __e;187 __is >> __e;188 if (!__is.fail())189 __x.__e_ = __e;190 return __is;191}192 193_LIBCPP_END_NAMESPACE_STD194 195_LIBCPP_POP_MACROS196 197#endif // _LIBCPP___CXX03___RANDOM_INDEPENDENT_BITS_ENGINE_H198