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/enable_if.h> 18 #include <__type_traits/is_integral.h> 19 #include <__type_traits/is_unsigned.h> 20 #include <__vector/vector.h> 21 #include <cstdint> 22 #include <initializer_list> 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 class _LIBCPP_TEMPLATE_VIS seed_seq { 34 public: 35 // types 36 typedef uint32_t result_type; 37 38 // constructors 39 _LIBCPP_HIDE_FROM_ABI seed_seq() _NOEXCEPT {} 40 #ifndef _LIBCPP_CXX03_LANG 41 template <class _Tp, __enable_if_t<is_integral<_Tp>::value, int> = 0> 42 _LIBCPP_HIDE_FROM_ABI seed_seq(initializer_list<_Tp> __il) { 43 __init(__il.begin(), __il.end()); 44 } 45 #endif // _LIBCPP_CXX03_LANG 46 47 template <class _InputIterator> 48 _LIBCPP_HIDE_FROM_ABI seed_seq(_InputIterator __first, _InputIterator __last) { 49 static_assert(is_integral<typename iterator_traits<_InputIterator>::value_type>::value, 50 "Mandates: iterator_traits<InputIterator>::value_type is an integer type"); 51 __init(__first, __last); 52 } 53 54 // generating functions 55 template <class _RandomAccessIterator> 56 _LIBCPP_HIDE_FROM_ABI void generate(_RandomAccessIterator __first, _RandomAccessIterator __last); 57 58 // property functions 59 _LIBCPP_HIDE_FROM_ABI size_t size() const _NOEXCEPT { return __v_.size(); } 60 template <class _OutputIterator> 61 _LIBCPP_HIDE_FROM_ABI void param(_OutputIterator __dest) const { 62 std::copy(__v_.begin(), __v_.end(), __dest); 63 } 64 65 seed_seq(const seed_seq&) = delete; 66 void operator=(const seed_seq&) = delete; 67 68 _LIBCPP_HIDE_FROM_ABI static result_type _Tp(result_type __x) { return __x ^ (__x >> 27); } 69 70 private: 71 template <class _InputIterator> 72 _LIBCPP_HIDE_FROM_ABI void __init(_InputIterator __first, _InputIterator __last); 73 74 vector<result_type> __v_; 75 }; 76 77 template <class _InputIterator> 78 void seed_seq::__init(_InputIterator __first, _InputIterator __last) { 79 for (_InputIterator __s = __first; __s != __last; ++__s) 80 __v_.push_back(*__s & 0xFFFFFFFF); 81 } 82 83 template <class _RandomAccessIterator> 84 void seed_seq::generate(_RandomAccessIterator __first, _RandomAccessIterator __last) { 85 using _ValueType = typename iterator_traits<_RandomAccessIterator>::value_type; 86 static_assert(is_unsigned<_ValueType>::value && sizeof(_ValueType) >= sizeof(uint32_t), 87 "[rand.util.seedseq]/7 requires the value_type of the iterator to be an unsigned " 88 "integer capable of accommodating 32-bit quantities."); 89 90 if (__first != __last) { 91 std::fill(__first, __last, 0x8b8b8b8b); 92 const size_t __n = static_cast<size_t>(__last - __first); 93 const size_t __s = __v_.size(); 94 const size_t __t = (__n >= 623) ? 11 : (__n >= 68) ? 7 : (__n >= 39) ? 5 : (__n >= 7) ? 3 : (__n - 1) / 2; 95 const size_t __p = (__n - __t) / 2; 96 const size_t __q = __p + __t; 97 const size_t __m = std::max(__s + 1, __n); 98 // __k = 0; 99 { 100 result_type __r = 1664525 * _Tp(__first[0] ^ __first[__p] ^ __first[__n - 1]); 101 __first[__p] += __r; 102 __r += __s; 103 __first[__q] += __r; 104 __first[0] = __r; 105 } 106 // Initialize indexing terms used with if statements as an optimization to 107 // avoid calculating modulo n on every loop iteration for each term. 108 size_t __kmodn = 0; // __k % __n 109 size_t __k1modn = __n - 1; // (__k - 1) % __n 110 size_t __kpmodn = __p % __n; // (__k + __p) % __n 111 size_t __kqmodn = __q % __n; // (__k + __q) % __n 112 113 for (size_t __k = 1; __k <= __s; ++__k) { 114 if (++__kmodn == __n) 115 __kmodn = 0; 116 if (++__k1modn == __n) 117 __k1modn = 0; 118 if (++__kpmodn == __n) 119 __kpmodn = 0; 120 if (++__kqmodn == __n) 121 __kqmodn = 0; 122 123 result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]); 124 __first[__kpmodn] += __r; 125 __r += __kmodn + __v_[__k - 1]; 126 __first[__kqmodn] += __r; 127 __first[__kmodn] = __r; 128 } 129 for (size_t __k = __s + 1; __k < __m; ++__k) { 130 if (++__kmodn == __n) 131 __kmodn = 0; 132 if (++__k1modn == __n) 133 __k1modn = 0; 134 if (++__kpmodn == __n) 135 __kpmodn = 0; 136 if (++__kqmodn == __n) 137 __kqmodn = 0; 138 139 result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]); 140 __first[__kpmodn] += __r; 141 __r += __kmodn; 142 __first[__kqmodn] += __r; 143 __first[__kmodn] = __r; 144 } 145 for (size_t __k = __m; __k < __m + __n; ++__k) { 146 if (++__kmodn == __n) 147 __kmodn = 0; 148 if (++__k1modn == __n) 149 __k1modn = 0; 150 if (++__kpmodn == __n) 151 __kpmodn = 0; 152 if (++__kqmodn == __n) 153 __kqmodn = 0; 154 155 result_type __r = 1566083941 * _Tp(__first[__kmodn] + __first[__kpmodn] + __first[__k1modn]); 156 __first[__kpmodn] ^= __r; 157 __r -= __kmodn; 158 __first[__kqmodn] ^= __r; 159 __first[__kmodn] = __r; 160 } 161 } 162 } 163 164 _LIBCPP_END_NAMESPACE_STD 165 166 _LIBCPP_POP_MACROS 167 168 #endif // _LIBCPP___RANDOM_SEED_SEQ_H 169