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 <initializer_list>
17 #include <vector>
18
19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20 # pragma GCC system_header
21 #endif
22
23 _LIBCPP_PUSH_MACROS
24 #include <__undef_macros>
25
26 _LIBCPP_BEGIN_NAMESPACE_STD
27
28 class _LIBCPP_TEMPLATE_VIS seed_seq
29 {
30 public:
31 // types
32 typedef uint32_t result_type;
33
34 // constructors
35 _LIBCPP_INLINE_VISIBILITY
seed_seq()36 seed_seq() _NOEXCEPT {}
37 #ifndef _LIBCPP_CXX03_LANG
38 template<class _Tp, __enable_if_t<is_integral<_Tp>::value>* = nullptr>
39 _LIBCPP_INLINE_VISIBILITY
seed_seq(initializer_list<_Tp> __il)40 seed_seq(initializer_list<_Tp> __il) {
41 __init(__il.begin(), __il.end());
42 }
43 #endif // _LIBCPP_CXX03_LANG
44
45 template<class _InputIterator>
46 _LIBCPP_INLINE_VISIBILITY
seed_seq(_InputIterator __first,_InputIterator __last)47 seed_seq(_InputIterator __first, _InputIterator __last) {
48 static_assert(is_integral<typename iterator_traits<_InputIterator>::value_type>::value,
49 "Mandates: iterator_traits<InputIterator>::value_type is an integer type");
50 __init(__first, __last);
51 }
52
53 // generating functions
54 template<class _RandomAccessIterator>
55 void generate(_RandomAccessIterator __first, _RandomAccessIterator __last);
56
57 // property functions
58 _LIBCPP_INLINE_VISIBILITY
size()59 size_t size() const _NOEXCEPT {return __v_.size();}
60 template<class _OutputIterator>
61 _LIBCPP_INLINE_VISIBILITY
param(_OutputIterator __dest)62 void param(_OutputIterator __dest) const
63 {_VSTD::copy(__v_.begin(), __v_.end(), __dest);}
64
65 seed_seq(const seed_seq&) = delete;
66 void operator=(const seed_seq&) = delete;
67
68 _LIBCPP_INLINE_VISIBILITY
_Tp(result_type __x)69 static result_type _Tp(result_type __x) {return __x ^ (__x >> 27);}
70
71 private:
72 template<class _InputIterator>
73 void __init(_InputIterator __first, _InputIterator __last);
74
75 vector<result_type> __v_;
76 };
77
78 template<class _InputIterator>
79 void
__init(_InputIterator __first,_InputIterator __last)80 seed_seq::__init(_InputIterator __first, _InputIterator __last)
81 {
82 for (_InputIterator __s = __first; __s != __last; ++__s)
83 __v_.push_back(*__s & 0xFFFFFFFF);
84 }
85
86 template<class _RandomAccessIterator>
87 void
generate(_RandomAccessIterator __first,_RandomAccessIterator __last)88 seed_seq::generate(_RandomAccessIterator __first, _RandomAccessIterator __last)
89 {
90 if (__first != __last)
91 {
92 _VSTD::fill(__first, __last, 0x8b8b8b8b);
93 const size_t __n = static_cast<size_t>(__last - __first);
94 const size_t __s = __v_.size();
95 const size_t __t = (__n >= 623) ? 11
96 : (__n >= 68) ? 7
97 : (__n >= 39) ? 5
98 : (__n >= 7) ? 3
99 : (__n - 1) / 2;
100 const size_t __p = (__n - __t) / 2;
101 const size_t __q = __p + __t;
102 const size_t __m = _VSTD::max(__s + 1, __n);
103 // __k = 0;
104 {
105 result_type __r = 1664525 * _Tp(__first[0] ^ __first[__p]
106 ^ __first[__n - 1]);
107 __first[__p] += __r;
108 __r += __s;
109 __first[__q] += __r;
110 __first[0] = __r;
111 }
112 // Initialize indexing terms used with if statements as an optimization to
113 // avoid calculating modulo n on every loop iteration for each term.
114 size_t __kmodn = 0; // __k % __n
115 size_t __k1modn = __n - 1; // (__k - 1) % __n
116 size_t __kpmodn = __p % __n; // (__k + __p) % __n
117 size_t __kqmodn = __q % __n; // (__k + __q) % __n
118
119 for (size_t __k = 1; __k <= __s; ++__k)
120 {
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 + __v_[__k - 1];
133 __first[__kqmodn] += __r;
134 __first[__kmodn] = __r;
135 }
136 for (size_t __k = __s + 1; __k < __m; ++__k)
137 {
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 = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]);
148 __first[__kpmodn] += __r;
149 __r += __kmodn;
150 __first[__kqmodn] += __r;
151 __first[__kmodn] = __r;
152 }
153 for (size_t __k = __m; __k < __m + __n; ++__k)
154 {
155 if (++__kmodn == __n)
156 __kmodn = 0;
157 if (++__k1modn == __n)
158 __k1modn = 0;
159 if (++__kpmodn == __n)
160 __kpmodn = 0;
161 if (++__kqmodn == __n)
162 __kqmodn = 0;
163
164 result_type __r = 1566083941 * _Tp(__first[__kmodn] + __first[__kpmodn] + __first[__k1modn]);
165 __first[__kpmodn] ^= __r;
166 __r -= __kmodn;
167 __first[__kqmodn] ^= __r;
168 __first[__kmodn] = __r;
169 }
170 }
171 }
172
173 _LIBCPP_END_NAMESPACE_STD
174
175 _LIBCPP_POP_MACROS
176
177 #endif // _LIBCPP___RANDOM_SEED_SEQ_H
178