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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___RANDOM_INDEPENDENT_BITS_ENGINE_H10#define _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H11 12#include <__config>13#include <__cstddef/size_t.h>14#include <__fwd/istream.h>15#include <__fwd/ostream.h>16#include <__random/is_seed_sequence.h>17#include <__random/log2.h>18#include <__type_traits/conditional.h>19#include <__type_traits/enable_if.h>20#include <__type_traits/is_convertible.h>21#include <__utility/move.h>22#include <limits>23 24#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)25# pragma GCC system_header26#endif27 28_LIBCPP_PUSH_MACROS29#include <__undef_macros>30 31_LIBCPP_BEGIN_NAMESPACE_STD32 33template <class _Engine, size_t __w, class _UIntType>34class independent_bits_engine {35 template <class _UInt, _UInt _R0, size_t _Wp, size_t _Mp>36 class __get_n {37 static _LIBCPP_CONSTEXPR const size_t _Dt = numeric_limits<_UInt>::digits;38 static _LIBCPP_CONSTEXPR const size_t _Np = _Wp / _Mp + (_Wp % _Mp != 0);39 static _LIBCPP_CONSTEXPR const size_t _W0 = _Wp / _Np;40 static _LIBCPP_CONSTEXPR const _UInt _Y0 = _W0 >= _Dt ? 0 : (_R0 >> _W0) << _W0;41 42 public:43 static _LIBCPP_CONSTEXPR 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 _LIBCPP_CONSTEXPR 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#ifdef _LIBCPP_CXX03_LANG61 static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min + _Working_result_type(1);62#else63 static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min() + _Working_result_type(1);64#endif65 static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;66 static _LIBCPP_CONSTEXPR const size_t __n = __get_n<_Working_result_type, _Rp, __w, __m>::value;67 static _LIBCPP_CONSTEXPR const size_t __w0 = __w / __n;68 static _LIBCPP_CONSTEXPR const size_t __n0 = __n - __w % __n;69 static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;70 static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;71 static _LIBCPP_CONSTEXPR const _Working_result_type __y0 = __w0 >= _WDt ? 0 : (_Rp >> __w0) << __w0;72 static _LIBCPP_CONSTEXPR const _Working_result_type __y1 = __w0 >= _WDt - 1 ? 0 : (_Rp >> (__w0 + 1)) << (__w0 + 1);73 static _LIBCPP_CONSTEXPR const74 _Engine_result_type __mask0 = __w0 > 0 ? _Engine_result_type(~0) >> (_EDt - __w0) : _Engine_result_type(0);75 static _LIBCPP_CONSTEXPR const _Engine_result_type __mask1 =76 __w0 < _EDt - 1 ? _Engine_result_type(~0) >> (_EDt - (__w0 + 1)) : _Engine_result_type(~0);77 78public:79 static _LIBCPP_CONSTEXPR const result_type _Min = 0;80 static _LIBCPP_CONSTEXPR const result_type _Max =81 __w == _Dt ? result_type(~0) : (result_type(1) << __w) - result_type(1);82 static_assert(_Min < _Max, "independent_bits_engine invalid parameters");83 84 // engine characteristics85 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type min() { return _Min; }86 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type max() { return _Max; }87 88 // constructors and seeding functions89 _LIBCPP_HIDE_FROM_ABI independent_bits_engine() {}90 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(const _Engine& __e) : __e_(__e) {}91#ifndef _LIBCPP_CXX03_LANG92 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(_Engine&& __e) : __e_(std::move(__e)) {}93#endif // _LIBCPP_CXX03_LANG94 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(result_type __sd) : __e_(__sd) {}95 template <96 class _Sseq,97 __enable_if_t<__is_seed_sequence<_Sseq, independent_bits_engine>::value && !is_convertible<_Sseq, _Engine>::value,98 int> = 0>99 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(_Sseq& __q) : __e_(__q) {}100 _LIBCPP_HIDE_FROM_ABI void seed() { __e_.seed(); }101 _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd) { __e_.seed(__sd); }102 template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, independent_bits_engine>::value, int> = 0>103 _LIBCPP_HIDE_FROM_ABI void seed(_Sseq& __q) {104 __e_.seed(__q);105 }106 107 // generating functions108 _LIBCPP_HIDE_FROM_ABI result_type operator()() { return __eval(integral_constant<bool, _Rp != 0>()); }109 _LIBCPP_HIDE_FROM_ABI void discard(unsigned long long __z) {110 for (; __z; --__z)111 operator()();112 }113 114 // property functions115 _LIBCPP_HIDE_FROM_ABI const _Engine& base() const _NOEXCEPT { return __e_; }116 117 template <class _Eng, size_t _Wp, class _UInt>118 friend bool operator==(const independent_bits_engine<_Eng, _Wp, _UInt>& __x,119 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);120 121 template <class _Eng, size_t _Wp, class _UInt>122 friend bool operator!=(const independent_bits_engine<_Eng, _Wp, _UInt>& __x,123 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);124 125 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>126 friend basic_ostream<_CharT, _Traits>&127 operator<<(basic_ostream<_CharT, _Traits>& __os, const independent_bits_engine<_Eng, _Wp, _UInt>& __x);128 129 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>130 friend basic_istream<_CharT, _Traits>&131 operator>>(basic_istream<_CharT, _Traits>& __is, independent_bits_engine<_Eng, _Wp, _UInt>& __x);132 133private:134 _LIBCPP_HIDE_FROM_ABI result_type __eval(false_type);135 _LIBCPP_HIDE_FROM_ABI result_type __eval(true_type);136 137 template <size_t __count,138 __enable_if_t<__count< _Dt, int> = 0> _LIBCPP_HIDE_FROM_ABI static result_type __lshift(result_type __x) {139 return __x << __count;140 }141 142 template <size_t __count, __enable_if_t<(__count >= _Dt), int> = 0>143 _LIBCPP_HIDE_FROM_ABI static result_type __lshift(result_type) {144 return result_type(0);145 }146};147 148template <class _Engine, size_t __w, class _UIntType>149inline _UIntType independent_bits_engine<_Engine, __w, _UIntType>::__eval(false_type) {150 return static_cast<result_type>(__e_() & __mask0);151}152 153template <class _Engine, size_t __w, class _UIntType>154_UIntType independent_bits_engine<_Engine, __w, _UIntType>::__eval(true_type) {155 result_type __sp = 0;156 for (size_t __k = 0; __k < __n0; ++__k) {157 _Engine_result_type __u;158 do {159 __u = __e_() - _Engine::min();160 } while (__u >= __y0);161 __sp = static_cast<result_type>(__lshift<__w0>(__sp) + (__u & __mask0));162 }163 for (size_t __k = __n0; __k < __n; ++__k) {164 _Engine_result_type __u;165 do {166 __u = __e_() - _Engine::min();167 } while (__u >= __y1);168 __sp = static_cast<result_type>(__lshift<__w0 + 1>(__sp) + (__u & __mask1));169 }170 return __sp;171}172 173template <class _Eng, size_t _Wp, class _UInt>174inline _LIBCPP_HIDE_FROM_ABI bool175operator==(const independent_bits_engine<_Eng, _Wp, _UInt>& __x, const independent_bits_engine<_Eng, _Wp, _UInt>& __y) {176 return __x.base() == __y.base();177}178 179template <class _Eng, size_t _Wp, class _UInt>180inline _LIBCPP_HIDE_FROM_ABI bool181operator!=(const independent_bits_engine<_Eng, _Wp, _UInt>& __x, const independent_bits_engine<_Eng, _Wp, _UInt>& __y) {182 return !(__x == __y);183}184 185template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>186_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&187operator<<(basic_ostream<_CharT, _Traits>& __os, const independent_bits_engine<_Eng, _Wp, _UInt>& __x) {188 return __os << __x.base();189}190 191template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>192_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&193operator>>(basic_istream<_CharT, _Traits>& __is, independent_bits_engine<_Eng, _Wp, _UInt>& __x) {194 _Eng __e;195 __is >> __e;196 if (!__is.fail())197 __x.__e_ = __e;198 return __is;199}200 201_LIBCPP_END_NAMESPACE_STD202 203_LIBCPP_POP_MACROS204 205#endif // _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H206