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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___CXX03___RANDOM_SEED_SEQ_H10#define _LIBCPP___CXX03___RANDOM_SEED_SEQ_H11 12#include <__cxx03/__algorithm/copy.h>13#include <__cxx03/__algorithm/fill.h>14#include <__cxx03/__algorithm/max.h>15#include <__cxx03/__config>16#include <__cxx03/__iterator/iterator_traits.h>17#include <__cxx03/__type_traits/is_unsigned.h>18#include <__cxx03/cstdint>19#include <__cxx03/vector>20 21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)22# pragma GCC system_header23#endif24 25_LIBCPP_PUSH_MACROS26#include <__cxx03/__undef_macros>27 28_LIBCPP_BEGIN_NAMESPACE_STD29 30class _LIBCPP_TEMPLATE_VIS seed_seq {31public:32 // types33 typedef uint32_t result_type;34 35 // constructors36 _LIBCPP_HIDE_FROM_ABI seed_seq() _NOEXCEPT {}37 38 template <class _InputIterator>39 _LIBCPP_HIDE_FROM_ABI seed_seq(_InputIterator __first, _InputIterator __last) {40 static_assert(is_integral<typename iterator_traits<_InputIterator>::value_type>::value,41 "Mandates: iterator_traits<InputIterator>::value_type is an integer type");42 __init(__first, __last);43 }44 45 // generating functions46 template <class _RandomAccessIterator>47 _LIBCPP_HIDE_FROM_ABI void generate(_RandomAccessIterator __first, _RandomAccessIterator __last);48 49 // property functions50 _LIBCPP_HIDE_FROM_ABI size_t size() const _NOEXCEPT { return __v_.size(); }51 template <class _OutputIterator>52 _LIBCPP_HIDE_FROM_ABI void param(_OutputIterator __dest) const {53 std::copy(__v_.begin(), __v_.end(), __dest);54 }55 56 seed_seq(const seed_seq&) = delete;57 void operator=(const seed_seq&) = delete;58 59 _LIBCPP_HIDE_FROM_ABI static result_type _Tp(result_type __x) { return __x ^ (__x >> 27); }60 61private:62 template <class _InputIterator>63 _LIBCPP_HIDE_FROM_ABI void __init(_InputIterator __first, _InputIterator __last);64 65 vector<result_type> __v_;66};67 68template <class _InputIterator>69void seed_seq::__init(_InputIterator __first, _InputIterator __last) {70 for (_InputIterator __s = __first; __s != __last; ++__s)71 __v_.push_back(*__s & 0xFFFFFFFF);72}73 74template <class _RandomAccessIterator>75void seed_seq::generate(_RandomAccessIterator __first, _RandomAccessIterator __last) {76 using _ValueType = typename iterator_traits<_RandomAccessIterator>::value_type;77 static_assert(is_unsigned<_ValueType>::value && sizeof(_ValueType) >= sizeof(uint32_t),78 "[rand.util.seedseq]/7 requires the value_type of the iterator to be an unsigned "79 "integer capable of accommodating 32-bit quantities.");80 81 if (__first != __last) {82 std::fill(__first, __last, 0x8b8b8b8b);83 const size_t __n = static_cast<size_t>(__last - __first);84 const size_t __s = __v_.size();85 const size_t __t = (__n >= 623) ? 11 : (__n >= 68) ? 7 : (__n >= 39) ? 5 : (__n >= 7) ? 3 : (__n - 1) / 2;86 const size_t __p = (__n - __t) / 2;87 const size_t __q = __p + __t;88 const size_t __m = std::max(__s + 1, __n);89 // __k = 0;90 {91 result_type __r = 1664525 * _Tp(__first[0] ^ __first[__p] ^ __first[__n - 1]);92 __first[__p] += __r;93 __r += __s;94 __first[__q] += __r;95 __first[0] = __r;96 }97 // Initialize indexing terms used with if statements as an optimization to98 // avoid calculating modulo n on every loop iteration for each term.99 size_t __kmodn = 0; // __k % __n100 size_t __k1modn = __n - 1; // (__k - 1) % __n101 size_t __kpmodn = __p % __n; // (__k + __p) % __n102 size_t __kqmodn = __q % __n; // (__k + __q) % __n103 104 for (size_t __k = 1; __k <= __s; ++__k) {105 if (++__kmodn == __n)106 __kmodn = 0;107 if (++__k1modn == __n)108 __k1modn = 0;109 if (++__kpmodn == __n)110 __kpmodn = 0;111 if (++__kqmodn == __n)112 __kqmodn = 0;113 114 result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]);115 __first[__kpmodn] += __r;116 __r += __kmodn + __v_[__k - 1];117 __first[__kqmodn] += __r;118 __first[__kmodn] = __r;119 }120 for (size_t __k = __s + 1; __k < __m; ++__k) {121 if (++__kmodn == __n)122 __kmodn = 0;123 if (++__k1modn == __n)124 __k1modn = 0;125 if (++__kpmodn == __n)126 __kpmodn = 0;127 if (++__kqmodn == __n)128 __kqmodn = 0;129 130 result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]);131 __first[__kpmodn] += __r;132 __r += __kmodn;133 __first[__kqmodn] += __r;134 __first[__kmodn] = __r;135 }136 for (size_t __k = __m; __k < __m + __n; ++__k) {137 if (++__kmodn == __n)138 __kmodn = 0;139 if (++__k1modn == __n)140 __k1modn = 0;141 if (++__kpmodn == __n)142 __kpmodn = 0;143 if (++__kqmodn == __n)144 __kqmodn = 0;145 146 result_type __r = 1566083941 * _Tp(__first[__kmodn] + __first[__kpmodn] + __first[__k1modn]);147 __first[__kpmodn] ^= __r;148 __r -= __kmodn;149 __first[__kqmodn] ^= __r;150 __first[__kmodn] = __r;151 }152 }153}154 155_LIBCPP_END_NAMESPACE_STD156 157_LIBCPP_POP_MACROS158 159#endif // _LIBCPP___CXX03___RANDOM_SEED_SEQ_H160