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
33class seed_seq {
34public:
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
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(a: __s + 1, b: __n);
98 // __k = 0;
99 {
100 result_type __r = 1664525 * _Tp(x: __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(x: __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(x: __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(x: __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