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-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H 10 #define _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H 11 12 #include <__config> 13 #include <__fwd/istream.h> 14 #include <__fwd/ostream.h> 15 #include <__random/is_seed_sequence.h> 16 #include <__random/log2.h> 17 #include <__type_traits/conditional.h> 18 #include <__type_traits/enable_if.h> 19 #include <__type_traits/is_convertible.h> 20 #include <__utility/move.h> 21 #include <cstddef> 22 #include <limits> 23 24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 25 # pragma GCC system_header 26 #endif 27 28 _LIBCPP_PUSH_MACROS 29 #include <__undef_macros> 30 31 _LIBCPP_BEGIN_NAMESPACE_STD 32 33 template <class _Engine, size_t __w, class _UIntType> 34 class _LIBCPP_TEMPLATE_VIS 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 46 public: 47 // types 48 typedef _UIntType result_type; 49 50 private: 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_LANG 61 static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min + _Working_result_type(1); 62 #else 63 static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min() + _Working_result_type(1); 64 #endif 65 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 const 74 _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 78 public: 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 characteristics 85 _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 functions 89 _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_LANG 92 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(_Engine&& __e) : __e_(std::move(__e)) {} 93 #endif // _LIBCPP_CXX03_LANG 94 _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 functions 108 _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 functions 115 _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); 132 133 private: 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 }; 147 148 template <class _Engine, size_t __w, class _UIntType> 149 inline _UIntType independent_bits_engine<_Engine, __w, _UIntType>::__eval(false_type) { 150 return static_cast<result_type>(__e_() & __mask0); 151 } 152 153 template <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 } 172 173 template <class _Eng, size_t _Wp, class _UInt> 174 inline _LIBCPP_HIDE_FROM_ABI bool 175 operator==(const independent_bits_engine<_Eng, _Wp, _UInt>& __x, const independent_bits_engine<_Eng, _Wp, _UInt>& __y) { 176 return __x.base() == __y.base(); 177 } 178 179 template <class _Eng, size_t _Wp, class _UInt> 180 inline _LIBCPP_HIDE_FROM_ABI bool 181 operator!=(const independent_bits_engine<_Eng, _Wp, _UInt>& __x, const independent_bits_engine<_Eng, _Wp, _UInt>& __y) { 182 return !(__x == __y); 183 } 184 185 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt> 186 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& 187 operator<<(basic_ostream<_CharT, _Traits>& __os, const independent_bits_engine<_Eng, _Wp, _UInt>& __x) { 188 return __os << __x.base(); 189 } 190 191 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt> 192 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& 193 operator>>(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_STD 202 203 _LIBCPP_POP_MACROS 204 205 #endif // _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H 206