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