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_SEED_SEQ_H 10 #define _LIBCPP___RANDOM_SEED_SEQ_H 11 12 #include <__algorithm/copy.h> 13 #include <__algorithm/fill.h> 14 #include <__algorithm/max.h> 15 #include <__config> 16 #include <__iterator/iterator_traits.h> 17 #include <__type_traits/is_unsigned.h> 18 #include <cstdint> 19 #include <initializer_list> 20 #include <vector> 21 22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 23 # pragma GCC system_header 24 #endif 25 26 _LIBCPP_PUSH_MACROS 27 #include <__undef_macros> 28 29 _LIBCPP_BEGIN_NAMESPACE_STD 30 31 class _LIBCPP_TEMPLATE_VIS seed_seq { 32 public: 33 // types 34 typedef uint32_t result_type; 35 36 // constructors 37 _LIBCPP_HIDE_FROM_ABI seed_seq() _NOEXCEPT {} 38 #ifndef _LIBCPP_CXX03_LANG 39 template <class _Tp, __enable_if_t<is_integral<_Tp>::value, int> = 0> 40 _LIBCPP_HIDE_FROM_ABI seed_seq(initializer_list<_Tp> __il) { 41 __init(__il.begin(), __il.end()); 42 } 43 #endif // _LIBCPP_CXX03_LANG 44 45 template <class _InputIterator> 46 _LIBCPP_HIDE_FROM_ABI seed_seq(_InputIterator __first, _InputIterator __last) { 47 static_assert(is_integral<typename iterator_traits<_InputIterator>::value_type>::value, 48 "Mandates: iterator_traits<InputIterator>::value_type is an integer type"); 49 __init(__first, __last); 50 } 51 52 // generating functions 53 template <class _RandomAccessIterator> 54 _LIBCPP_HIDE_FROM_ABI void generate(_RandomAccessIterator __first, _RandomAccessIterator __last); 55 56 // property functions 57 _LIBCPP_HIDE_FROM_ABI size_t size() const _NOEXCEPT { return __v_.size(); } 58 template <class _OutputIterator> 59 _LIBCPP_HIDE_FROM_ABI void param(_OutputIterator __dest) const { 60 std::copy(__v_.begin(), __v_.end(), __dest); 61 } 62 63 seed_seq(const seed_seq&) = delete; 64 void operator=(const seed_seq&) = delete; 65 66 _LIBCPP_HIDE_FROM_ABI static result_type _Tp(result_type __x) { return __x ^ (__x >> 27); } 67 68 private: 69 template <class _InputIterator> 70 _LIBCPP_HIDE_FROM_ABI void __init(_InputIterator __first, _InputIterator __last); 71 72 vector<result_type> __v_; 73 }; 74 75 template <class _InputIterator> 76 void seed_seq::__init(_InputIterator __first, _InputIterator __last) { 77 for (_InputIterator __s = __first; __s != __last; ++__s) 78 __v_.push_back(*__s & 0xFFFFFFFF); 79 } 80 81 template <class _RandomAccessIterator> 82 void seed_seq::generate(_RandomAccessIterator __first, _RandomAccessIterator __last) { 83 using _ValueType = typename iterator_traits<_RandomAccessIterator>::value_type; 84 static_assert(is_unsigned<_ValueType>::value && sizeof(_ValueType) >= sizeof(uint32_t), 85 "[rand.util.seedseq]/7 requires the value_type of the iterator to be an unsigned " 86 "integer capable of accommodating 32-bit quantities."); 87 88 if (__first != __last) { 89 std::fill(__first, __last, 0x8b8b8b8b); 90 const size_t __n = static_cast<size_t>(__last - __first); 91 const size_t __s = __v_.size(); 92 const size_t __t = (__n >= 623) ? 11 : (__n >= 68) ? 7 : (__n >= 39) ? 5 : (__n >= 7) ? 3 : (__n - 1) / 2; 93 const size_t __p = (__n - __t) / 2; 94 const size_t __q = __p + __t; 95 const size_t __m = std::max(__s + 1, __n); 96 // __k = 0; 97 { 98 result_type __r = 1664525 * _Tp(__first[0] ^ __first[__p] ^ __first[__n - 1]); 99 __first[__p] += __r; 100 __r += __s; 101 __first[__q] += __r; 102 __first[0] = __r; 103 } 104 // Initialize indexing terms used with if statements as an optimization to 105 // avoid calculating modulo n on every loop iteration for each term. 106 size_t __kmodn = 0; // __k % __n 107 size_t __k1modn = __n - 1; // (__k - 1) % __n 108 size_t __kpmodn = __p % __n; // (__k + __p) % __n 109 size_t __kqmodn = __q % __n; // (__k + __q) % __n 110 111 for (size_t __k = 1; __k <= __s; ++__k) { 112 if (++__kmodn == __n) 113 __kmodn = 0; 114 if (++__k1modn == __n) 115 __k1modn = 0; 116 if (++__kpmodn == __n) 117 __kpmodn = 0; 118 if (++__kqmodn == __n) 119 __kqmodn = 0; 120 121 result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]); 122 __first[__kpmodn] += __r; 123 __r += __kmodn + __v_[__k - 1]; 124 __first[__kqmodn] += __r; 125 __first[__kmodn] = __r; 126 } 127 for (size_t __k = __s + 1; __k < __m; ++__k) { 128 if (++__kmodn == __n) 129 __kmodn = 0; 130 if (++__k1modn == __n) 131 __k1modn = 0; 132 if (++__kpmodn == __n) 133 __kpmodn = 0; 134 if (++__kqmodn == __n) 135 __kqmodn = 0; 136 137 result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]); 138 __first[__kpmodn] += __r; 139 __r += __kmodn; 140 __first[__kqmodn] += __r; 141 __first[__kmodn] = __r; 142 } 143 for (size_t __k = __m; __k < __m + __n; ++__k) { 144 if (++__kmodn == __n) 145 __kmodn = 0; 146 if (++__k1modn == __n) 147 __k1modn = 0; 148 if (++__kpmodn == __n) 149 __kpmodn = 0; 150 if (++__kqmodn == __n) 151 __kqmodn = 0; 152 153 result_type __r = 1566083941 * _Tp(__first[__kmodn] + __first[__kpmodn] + __first[__k1modn]); 154 __first[__kpmodn] ^= __r; 155 __r -= __kmodn; 156 __first[__kqmodn] ^= __r; 157 __first[__kmodn] = __r; 158 } 159 } 160 } 161 162 _LIBCPP_END_NAMESPACE_STD 163 164 _LIBCPP_POP_MACROS 165 166 #endif // _LIBCPP___RANDOM_SEED_SEQ_H 167