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/is_unsigned.h>
18 #include <cstdint>
19 #include <initializer_list>
20 #include <vector>
21
22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
23 # pragma GCC system_header
24 #endif
25
26 _LIBCPP_PUSH_MACROS
27 #include <__undef_macros>
28
29 _LIBCPP_BEGIN_NAMESPACE_STD
30
31 class _LIBCPP_TEMPLATE_VIS seed_seq {
32 public:
33 // types
34 typedef uint32_t result_type;
35
36 // constructors
seed_seq()37 _LIBCPP_HIDE_FROM_ABI seed_seq() _NOEXCEPT {}
38 #ifndef _LIBCPP_CXX03_LANG
39 template <class _Tp, __enable_if_t<is_integral<_Tp>::value, int> = 0>
seed_seq(initializer_list<_Tp> __il)40 _LIBCPP_HIDE_FROM_ABI seed_seq(initializer_list<_Tp> __il) {
41 __init(__il.begin(), __il.end());
42 }
43 #endif // _LIBCPP_CXX03_LANG
44
45 template <class _InputIterator>
seed_seq(_InputIterator __first,_InputIterator __last)46 _LIBCPP_HIDE_FROM_ABI seed_seq(_InputIterator __first, _InputIterator __last) {
47 static_assert(is_integral<typename iterator_traits<_InputIterator>::value_type>::value,
48 "Mandates: iterator_traits<InputIterator>::value_type is an integer type");
49 __init(__first, __last);
50 }
51
52 // generating functions
53 template <class _RandomAccessIterator>
54 _LIBCPP_HIDE_FROM_ABI void generate(_RandomAccessIterator __first, _RandomAccessIterator __last);
55
56 // property functions
size()57 _LIBCPP_HIDE_FROM_ABI size_t size() const _NOEXCEPT { return __v_.size(); }
58 template <class _OutputIterator>
param(_OutputIterator __dest)59 _LIBCPP_HIDE_FROM_ABI void param(_OutputIterator __dest) const {
60 std::copy(__v_.begin(), __v_.end(), __dest);
61 }
62
63 seed_seq(const seed_seq&) = delete;
64 void operator=(const seed_seq&) = delete;
65
_Tp(result_type __x)66 _LIBCPP_HIDE_FROM_ABI static result_type _Tp(result_type __x) { return __x ^ (__x >> 27); }
67
68 private:
69 template <class _InputIterator>
70 _LIBCPP_HIDE_FROM_ABI void __init(_InputIterator __first, _InputIterator __last);
71
72 vector<result_type> __v_;
73 };
74
75 template <class _InputIterator>
__init(_InputIterator __first,_InputIterator __last)76 void seed_seq::__init(_InputIterator __first, _InputIterator __last) {
77 for (_InputIterator __s = __first; __s != __last; ++__s)
78 __v_.push_back(*__s & 0xFFFFFFFF);
79 }
80
81 template <class _RandomAccessIterator>
generate(_RandomAccessIterator __first,_RandomAccessIterator __last)82 void seed_seq::generate(_RandomAccessIterator __first, _RandomAccessIterator __last) {
83 using _ValueType = typename iterator_traits<_RandomAccessIterator>::value_type;
84 static_assert(is_unsigned<_ValueType>::value && sizeof(_ValueType) >= sizeof(uint32_t),
85 "[rand.util.seedseq]/7 requires the value_type of the iterator to be an unsigned "
86 "integer capable of accommodating 32-bit quantities.");
87
88 if (__first != __last) {
89 std::fill(__first, __last, 0x8b8b8b8b);
90 const size_t __n = static_cast<size_t>(__last - __first);
91 const size_t __s = __v_.size();
92 const size_t __t = (__n >= 623) ? 11 : (__n >= 68) ? 7 : (__n >= 39) ? 5 : (__n >= 7) ? 3 : (__n - 1) / 2;
93 const size_t __p = (__n - __t) / 2;
94 const size_t __q = __p + __t;
95 const size_t __m = std::max(__s + 1, __n);
96 // __k = 0;
97 {
98 result_type __r = 1664525 * _Tp(__first[0] ^ __first[__p] ^ __first[__n - 1]);
99 __first[__p] += __r;
100 __r += __s;
101 __first[__q] += __r;
102 __first[0] = __r;
103 }
104 // Initialize indexing terms used with if statements as an optimization to
105 // avoid calculating modulo n on every loop iteration for each term.
106 size_t __kmodn = 0; // __k % __n
107 size_t __k1modn = __n - 1; // (__k - 1) % __n
108 size_t __kpmodn = __p % __n; // (__k + __p) % __n
109 size_t __kqmodn = __q % __n; // (__k + __q) % __n
110
111 for (size_t __k = 1; __k <= __s; ++__k) {
112 if (++__kmodn == __n)
113 __kmodn = 0;
114 if (++__k1modn == __n)
115 __k1modn = 0;
116 if (++__kpmodn == __n)
117 __kpmodn = 0;
118 if (++__kqmodn == __n)
119 __kqmodn = 0;
120
121 result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]);
122 __first[__kpmodn] += __r;
123 __r += __kmodn + __v_[__k - 1];
124 __first[__kqmodn] += __r;
125 __first[__kmodn] = __r;
126 }
127 for (size_t __k = __s + 1; __k < __m; ++__k) {
128 if (++__kmodn == __n)
129 __kmodn = 0;
130 if (++__k1modn == __n)
131 __k1modn = 0;
132 if (++__kpmodn == __n)
133 __kpmodn = 0;
134 if (++__kqmodn == __n)
135 __kqmodn = 0;
136
137 result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]);
138 __first[__kpmodn] += __r;
139 __r += __kmodn;
140 __first[__kqmodn] += __r;
141 __first[__kmodn] = __r;
142 }
143 for (size_t __k = __m; __k < __m + __n; ++__k) {
144 if (++__kmodn == __n)
145 __kmodn = 0;
146 if (++__k1modn == __n)
147 __k1modn = 0;
148 if (++__kpmodn == __n)
149 __kpmodn = 0;
150 if (++__kqmodn == __n)
151 __kqmodn = 0;
152
153 result_type __r = 1566083941 * _Tp(__first[__kmodn] + __first[__kpmodn] + __first[__k1modn]);
154 __first[__kpmodn] ^= __r;
155 __r -= __kmodn;
156 __first[__kqmodn] ^= __r;
157 __first[__kmodn] = __r;
158 }
159 }
160 }
161
162 _LIBCPP_END_NAMESPACE_STD
163
164 _LIBCPP_POP_MACROS
165
166 #endif // _LIBCPP___RANDOM_SEED_SEQ_H
167