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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___RANDOM_SEED_SEQ_H10#define _LIBCPP___RANDOM_SEED_SEQ_H11 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_header26#endif27 28_LIBCPP_PUSH_MACROS29#include <__undef_macros>30 31_LIBCPP_BEGIN_NAMESPACE_STD32 33class seed_seq {34public:35 // types36 typedef uint32_t result_type;37 38 // constructors39 _LIBCPP_HIDE_FROM_ABI seed_seq() _NOEXCEPT {}40#ifndef _LIBCPP_CXX03_LANG41 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_LANG46 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 functions55 template <class _RandomAccessIterator>56 _LIBCPP_HIDE_FROM_ABI void generate(_RandomAccessIterator __first, _RandomAccessIterator __last);57 58 // property functions59 _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 70private:71 template <class _InputIterator>72 _LIBCPP_HIDE_FROM_ABI void __init(_InputIterator __first, _InputIterator __last);73 74 vector<result_type> __v_;75};76 77template <class _InputIterator>78void seed_seq::__init(_InputIterator __first, _InputIterator __last) {79 for (_InputIterator __s = __first; __s != __last; ++__s)80 __v_.push_back(*__s & 0xFFFFFFFF);81}82 83template <class _RandomAccessIterator>84void 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 to107 // avoid calculating modulo n on every loop iteration for each term.108 size_t __kmodn = 0; // __k % __n109 size_t __k1modn = __n - 1; // (__k - 1) % __n110 size_t __kpmodn = __p % __n; // (__k + __p) % __n111 size_t __kqmodn = __q % __n; // (__k + __q) % __n112 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_STD165 166_LIBCPP_POP_MACROS167 168#endif // _LIBCPP___RANDOM_SEED_SEQ_H169