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
seed_seq()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>
seed_seq(initializer_list<_Tp> __il)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>
seed_seq(_InputIterator __first,_InputIterator __last)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
size()56 _LIBCPP_HIDE_FROM_ABI size_t size() const _NOEXCEPT { return __v_.size(); }
57 template <class _OutputIterator>
param(_OutputIterator __dest)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
_Tp(result_type __x)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>
__init(_InputIterator __first,_InputIterator __last)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>
generate(_RandomAccessIterator __first,_RandomAccessIterator __last)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