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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_SUBTRACT_WITH_CARRY_ENGINE_H
10#define _LIBCPP___RANDOM_SUBTRACT_WITH_CARRY_ENGINE_H
11
12#include <__algorithm/equal.h>
13#include <__algorithm/min.h>
14#include <__config>
15#include <__cstddef/size_t.h>
16#include <__random/is_seed_sequence.h>
17#include <__random/linear_congruential_engine.h>
18#include <__type_traits/enable_if.h>
19#include <cstdint>
20#include <iosfwd>
21#include <limits>
22
23#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
24# pragma GCC system_header
25#endif
26
27_LIBCPP_PUSH_MACROS
28#include <__undef_macros>
29
30_LIBCPP_BEGIN_NAMESPACE_STD
31
32template <class _UIntType, size_t __w, size_t __s, size_t __r>
33class subtract_with_carry_engine;
34
35template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
36_LIBCPP_HIDE_FROM_ABI bool operator==(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
37 const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
38
39template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
40_LIBCPP_HIDE_FROM_ABI bool operator!=(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
41 const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
42
43template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
44_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
45operator<<(basic_ostream<_CharT, _Traits>& __os, const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
46
47template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
48_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
49operator>>(basic_istream<_CharT, _Traits>& __is, subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
50
51template <class _UIntType, size_t __w, size_t __s, size_t __r>
52class subtract_with_carry_engine {
53public:
54 // types
55 typedef _UIntType result_type;
56
57private:
58 result_type __x_[__r];
59 result_type __c_;
60 size_t __i_;
61
62 static _LIBCPP_CONSTEXPR const result_type _Dt = numeric_limits<result_type>::digits;
63 static_assert(0 < __w, "subtract_with_carry_engine invalid parameters");
64 static_assert(__w <= _Dt, "subtract_with_carry_engine invalid parameters");
65 static_assert(0 < __s, "subtract_with_carry_engine invalid parameters");
66 static_assert(__s < __r, "subtract_with_carry_engine invalid parameters");
67
68public:
69 static _LIBCPP_CONSTEXPR const result_type _Min = 0;
70 static _LIBCPP_CONSTEXPR const result_type _Max =
71 __w == _Dt ? result_type(~0) : (result_type(1) << __w) - result_type(1);
72 static_assert(_Min < _Max, "subtract_with_carry_engine invalid parameters");
73
74 // engine characteristics
75 static inline _LIBCPP_CONSTEXPR const size_t word_size = __w;
76 static inline _LIBCPP_CONSTEXPR const size_t short_lag = __s;
77 static inline _LIBCPP_CONSTEXPR const size_t long_lag = __r;
78 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type min() { return _Min; }
79 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type max() { return _Max; }
80 static inline _LIBCPP_CONSTEXPR const result_type default_seed = 19780503u;
81
82 // constructors and seeding functions
83#ifndef _LIBCPP_CXX03_LANG
84 _LIBCPP_HIDE_FROM_ABI subtract_with_carry_engine() : subtract_with_carry_engine(default_seed) {}
85 _LIBCPP_HIDE_FROM_ABI explicit subtract_with_carry_engine(result_type __sd) { seed(__sd); }
86#else
87 _LIBCPP_HIDE_FROM_ABI explicit subtract_with_carry_engine(result_type __sd = default_seed) { seed(__sd); }
88#endif
89 template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, subtract_with_carry_engine>::value, int> = 0>
90 _LIBCPP_HIDE_FROM_ABI explicit subtract_with_carry_engine(_Sseq& __q) {
91 seed(__q);
92 }
93 _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd = default_seed) {
94 seed(__sd, integral_constant<unsigned, 1 + (__w - 1) / 32>());
95 }
96 template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, subtract_with_carry_engine>::value, int> = 0>
97 _LIBCPP_HIDE_FROM_ABI void seed(_Sseq& __q) {
98 __seed(__q, integral_constant<unsigned, 1 + (__w - 1) / 32>());
99 }
100
101 // generating functions
102 _LIBCPP_HIDE_FROM_ABI result_type operator()();
103 _LIBCPP_HIDE_FROM_ABI void discard(unsigned long long __z) {
104 for (; __z; --__z)
105 operator()();
106 }
107
108 template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
109 friend bool operator==(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
110 const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
111
112 template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
113 friend bool operator!=(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
114 const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
115
116 template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
117 friend basic_ostream<_CharT, _Traits>&
118 operator<<(basic_ostream<_CharT, _Traits>& __os, const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
119
120 template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
121 friend basic_istream<_CharT, _Traits>&
122 operator>>(basic_istream<_CharT, _Traits>& __is, subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
123
124private:
125 _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd, integral_constant<unsigned, 1>);
126 _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd, integral_constant<unsigned, 2>);
127 template <class _Sseq>
128 _LIBCPP_HIDE_FROM_ABI void __seed(_Sseq& __q, integral_constant<unsigned, 1>);
129 template <class _Sseq>
130 _LIBCPP_HIDE_FROM_ABI void __seed(_Sseq& __q, integral_constant<unsigned, 2>);
131};
132
133template <class _UIntType, size_t __w, size_t __s, size_t __r>
134void subtract_with_carry_engine<_UIntType, __w, __s, __r>::seed(result_type __sd, integral_constant<unsigned, 1>) {
135 linear_congruential_engine<result_type, 40014u, 0u, 2147483563u> __e(__sd == 0u ? default_seed : __sd);
136 for (size_t __i = 0; __i < __r; ++__i)
137 __x_[__i] = static_cast<result_type>(__e() & _Max);
138 __c_ = __x_[__r - 1] == 0;
139 __i_ = 0;
140}
141
142template <class _UIntType, size_t __w, size_t __s, size_t __r>
143void subtract_with_carry_engine<_UIntType, __w, __s, __r>::seed(result_type __sd, integral_constant<unsigned, 2>) {
144 linear_congruential_engine<result_type, 40014u, 0u, 2147483563u> __e(__sd == 0u ? default_seed : __sd);
145 for (size_t __i = 0; __i < __r; ++__i) {
146 result_type __e0 = __e();
147 __x_[__i] = static_cast<result_type>((__e0 + ((uint64_t)__e() << 32)) & _Max);
148 }
149 __c_ = __x_[__r - 1] == 0;
150 __i_ = 0;
151}
152
153template <class _UIntType, size_t __w, size_t __s, size_t __r>
154template <class _Sseq>
155void subtract_with_carry_engine<_UIntType, __w, __s, __r>::__seed(_Sseq& __q, integral_constant<unsigned, 1>) {
156 const unsigned __k = 1;
157 uint32_t __ar[__r * __k];
158 __q.generate(__ar, __ar + __r * __k);
159 for (size_t __i = 0; __i < __r; ++__i)
160 __x_[__i] = static_cast<result_type>(__ar[__i] & _Max);
161 __c_ = __x_[__r - 1] == 0;
162 __i_ = 0;
163}
164
165template <class _UIntType, size_t __w, size_t __s, size_t __r>
166template <class _Sseq>
167void subtract_with_carry_engine<_UIntType, __w, __s, __r>::__seed(_Sseq& __q, integral_constant<unsigned, 2>) {
168 const unsigned __k = 2;
169 uint32_t __ar[__r * __k];
170 __q.generate(__ar, __ar + __r * __k);
171 for (size_t __i = 0; __i < __r; ++__i)
172 __x_[__i] = static_cast<result_type>((__ar[2 * __i] + ((uint64_t)__ar[2 * __i + 1] << 32)) & _Max);
173 __c_ = __x_[__r - 1] == 0;
174 __i_ = 0;
175}
176
177template <class _UIntType, size_t __w, size_t __s, size_t __r>
178_UIntType subtract_with_carry_engine<_UIntType, __w, __s, __r>::operator()() {
179 const result_type& __xs = __x_[(__i_ + (__r - __s)) % __r];
180 result_type& __xr = __x_[__i_];
181 result_type __new_c = __c_ == 0 ? __xs < __xr : __xs != 0 ? __xs <= __xr : 1;
182 __xr = (__xs - __xr - __c_) & _Max;
183 __c_ = __new_c;
184 __i_ = (__i_ + 1) % __r;
185 return __xr;
186}
187
188template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
189_LIBCPP_HIDE_FROM_ABI bool operator==(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
190 const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y) {
191 if (__x.__c_ != __y.__c_)
192 return false;
193 if (__x.__i_ == __y.__i_)
194 return std::equal(__x.__x_, __x.__x_ + _Rp, __y.__x_);
195 if (__x.__i_ == 0 || __y.__i_ == 0) {
196 size_t __j = std::min(_Rp - __x.__i_, _Rp - __y.__i_);
197 if (!std::equal(__x.__x_ + __x.__i_, __x.__x_ + __x.__i_ + __j, __y.__x_ + __y.__i_))
198 return false;
199 if (__x.__i_ == 0)
200 return std::equal(__x.__x_ + __j, __x.__x_ + _Rp, __y.__x_);
201 return std::equal(__x.__x_, __x.__x_ + (_Rp - __j), __y.__x_ + __j);
202 }
203 if (__x.__i_ < __y.__i_) {
204 size_t __j = _Rp - __y.__i_;
205 if (!std::equal(__x.__x_ + __x.__i_, __x.__x_ + (__x.__i_ + __j), __y.__x_ + __y.__i_))
206 return false;
207 if (!std::equal(__x.__x_ + (__x.__i_ + __j), __x.__x_ + _Rp, __y.__x_))
208 return false;
209 return std::equal(__x.__x_, __x.__x_ + __x.__i_, __y.__x_ + (_Rp - (__x.__i_ + __j)));
210 }
211 size_t __j = _Rp - __x.__i_;
212 if (!std::equal(__y.__x_ + __y.__i_, __y.__x_ + (__y.__i_ + __j), __x.__x_ + __x.__i_))
213 return false;
214 if (!std::equal(__y.__x_ + (__y.__i_ + __j), __y.__x_ + _Rp, __x.__x_))
215 return false;
216 return std::equal(__y.__x_, __y.__x_ + __y.__i_, __x.__x_ + (_Rp - (__y.__i_ + __j)));
217}
218
219template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
220inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
221 const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y) {
222 return !(__x == __y);
223}
224
225template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
226_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
227operator<<(basic_ostream<_CharT, _Traits>& __os, const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x) {
228 __save_flags<_CharT, _Traits> __lx(__os);
229 typedef basic_ostream<_CharT, _Traits> _Ostream;
230 __os.flags(_Ostream::dec | _Ostream::left);
231 _CharT __sp = __os.widen(' ');
232 __os.fill(__sp);
233 __os << __x.__x_[__x.__i_];
234 for (size_t __j = __x.__i_ + 1; __j < _Rp; ++__j)
235 __os << __sp << __x.__x_[__j];
236 for (size_t __j = 0; __j < __x.__i_; ++__j)
237 __os << __sp << __x.__x_[__j];
238 __os << __sp << __x.__c_;
239 return __os;
240}
241
242template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
243_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
244operator>>(basic_istream<_CharT, _Traits>& __is, subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x) {
245 __save_flags<_CharT, _Traits> __lx(__is);
246 typedef basic_istream<_CharT, _Traits> _Istream;
247 __is.flags(_Istream::dec | _Istream::skipws);
248 _UInt __t[_Rp + 1];
249 for (size_t __i = 0; __i < _Rp + 1; ++__i)
250 __is >> __t[__i];
251 if (!__is.fail()) {
252 for (size_t __i = 0; __i < _Rp; ++__i)
253 __x.__x_[__i] = __t[__i];
254 __x.__c_ = __t[_Rp];
255 __x.__i_ = 0;
256 }
257 return __is;
258}
259
260_LIBCPP_END_NAMESPACE_STD
261
262_LIBCPP_POP_MACROS
263
264#endif // _LIBCPP___RANDOM_SUBTRACT_WITH_CARRY_ENGINE_H