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___CXX03___RANDOM_SEED_SEQ_H
10 #define _LIBCPP___CXX03___RANDOM_SEED_SEQ_H
11
12 #include <__cxx03/__algorithm/copy.h>
13 #include <__cxx03/__algorithm/fill.h>
14 #include <__cxx03/__algorithm/max.h>
15 #include <__cxx03/__config>
16 #include <__cxx03/__iterator/iterator_traits.h>
17 #include <__cxx03/__type_traits/is_unsigned.h>
18 #include <__cxx03/cstdint>
19 #include <__cxx03/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 <__cxx03/__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
38 template <class _InputIterator>
seed_seq(_InputIterator __first,_InputIterator __last)39 _LIBCPP_HIDE_FROM_ABI seed_seq(_InputIterator __first, _InputIterator __last) {
40 static_assert(is_integral<typename iterator_traits<_InputIterator>::value_type>::value,
41 "Mandates: iterator_traits<InputIterator>::value_type is an integer type");
42 __init(__first, __last);
43 }
44
45 // generating functions
46 template <class _RandomAccessIterator>
47 _LIBCPP_HIDE_FROM_ABI void generate(_RandomAccessIterator __first, _RandomAccessIterator __last);
48
49 // property functions
size()50 _LIBCPP_HIDE_FROM_ABI size_t size() const _NOEXCEPT { return __v_.size(); }
51 template <class _OutputIterator>
param(_OutputIterator __dest)52 _LIBCPP_HIDE_FROM_ABI void param(_OutputIterator __dest) const {
53 std::copy(__v_.begin(), __v_.end(), __dest);
54 }
55
56 seed_seq(const seed_seq&) = delete;
57 void operator=(const seed_seq&) = delete;
58
_Tp(result_type __x)59 _LIBCPP_HIDE_FROM_ABI static result_type _Tp(result_type __x) { return __x ^ (__x >> 27); }
60
61 private:
62 template <class _InputIterator>
63 _LIBCPP_HIDE_FROM_ABI void __init(_InputIterator __first, _InputIterator __last);
64
65 vector<result_type> __v_;
66 };
67
68 template <class _InputIterator>
__init(_InputIterator __first,_InputIterator __last)69 void seed_seq::__init(_InputIterator __first, _InputIterator __last) {
70 for (_InputIterator __s = __first; __s != __last; ++__s)
71 __v_.push_back(*__s & 0xFFFFFFFF);
72 }
73
74 template <class _RandomAccessIterator>
generate(_RandomAccessIterator __first,_RandomAccessIterator __last)75 void seed_seq::generate(_RandomAccessIterator __first, _RandomAccessIterator __last) {
76 using _ValueType = typename iterator_traits<_RandomAccessIterator>::value_type;
77 static_assert(is_unsigned<_ValueType>::value && sizeof(_ValueType) >= sizeof(uint32_t),
78 "[rand.util.seedseq]/7 requires the value_type of the iterator to be an unsigned "
79 "integer capable of accommodating 32-bit quantities.");
80
81 if (__first != __last) {
82 std::fill(__first, __last, 0x8b8b8b8b);
83 const size_t __n = static_cast<size_t>(__last - __first);
84 const size_t __s = __v_.size();
85 const size_t __t = (__n >= 623) ? 11 : (__n >= 68) ? 7 : (__n >= 39) ? 5 : (__n >= 7) ? 3 : (__n - 1) / 2;
86 const size_t __p = (__n - __t) / 2;
87 const size_t __q = __p + __t;
88 const size_t __m = std::max(__s + 1, __n);
89 // __k = 0;
90 {
91 result_type __r = 1664525 * _Tp(__first[0] ^ __first[__p] ^ __first[__n - 1]);
92 __first[__p] += __r;
93 __r += __s;
94 __first[__q] += __r;
95 __first[0] = __r;
96 }
97 // Initialize indexing terms used with if statements as an optimization to
98 // avoid calculating modulo n on every loop iteration for each term.
99 size_t __kmodn = 0; // __k % __n
100 size_t __k1modn = __n - 1; // (__k - 1) % __n
101 size_t __kpmodn = __p % __n; // (__k + __p) % __n
102 size_t __kqmodn = __q % __n; // (__k + __q) % __n
103
104 for (size_t __k = 1; __k <= __s; ++__k) {
105 if (++__kmodn == __n)
106 __kmodn = 0;
107 if (++__k1modn == __n)
108 __k1modn = 0;
109 if (++__kpmodn == __n)
110 __kpmodn = 0;
111 if (++__kqmodn == __n)
112 __kqmodn = 0;
113
114 result_type __r = 1664525 * _Tp(__first[__kmodn] ^ __first[__kpmodn] ^ __first[__k1modn]);
115 __first[__kpmodn] += __r;
116 __r += __kmodn + __v_[__k - 1];
117 __first[__kqmodn] += __r;
118 __first[__kmodn] = __r;
119 }
120 for (size_t __k = __s + 1; __k < __m; ++__k) {
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;
133 __first[__kqmodn] += __r;
134 __first[__kmodn] = __r;
135 }
136 for (size_t __k = __m; __k < __m + __n; ++__k) {
137 if (++__kmodn == __n)
138 __kmodn = 0;
139 if (++__k1modn == __n)
140 __k1modn = 0;
141 if (++__kpmodn == __n)
142 __kpmodn = 0;
143 if (++__kqmodn == __n)
144 __kqmodn = 0;
145
146 result_type __r = 1566083941 * _Tp(__first[__kmodn] + __first[__kpmodn] + __first[__k1modn]);
147 __first[__kpmodn] ^= __r;
148 __r -= __kmodn;
149 __first[__kqmodn] ^= __r;
150 __first[__kmodn] = __r;
151 }
152 }
153 }
154
155 _LIBCPP_END_NAMESPACE_STD
156
157 _LIBCPP_POP_MACROS
158
159 #endif // _LIBCPP___CXX03___RANDOM_SEED_SEQ_H
160