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 <__random/is_seed_sequence.h>
16 #include <__random/linear_congruential_engine.h>
17 #include <cstddef>
18 #include <cstdint>
19 #include <iosfwd>
20 #include <limits>
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 template <class _UIntType, size_t __w, size_t __s, size_t __r>
32 class _LIBCPP_TEMPLATE_VIS subtract_with_carry_engine;
33 
34 template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
35 _LIBCPP_HIDE_FROM_ABI bool operator==(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
36                                       const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
37 
38 template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
39 _LIBCPP_HIDE_FROM_ABI bool operator!=(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
40                                       const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
41 
42 template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
43 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
44 operator<<(basic_ostream<_CharT, _Traits>& __os, const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
45 
46 template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
47 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
48 operator>>(basic_istream<_CharT, _Traits>& __is, subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
49 
50 template <class _UIntType, size_t __w, size_t __s, size_t __r>
51 class _LIBCPP_TEMPLATE_VIS subtract_with_carry_engine {
52 public:
53   // types
54   typedef _UIntType result_type;
55 
56 private:
57   result_type __x_[__r];
58   result_type __c_;
59   size_t __i_;
60 
61   static _LIBCPP_CONSTEXPR const result_type _Dt = numeric_limits<result_type>::digits;
62   static_assert(0 < __w, "subtract_with_carry_engine invalid parameters");
63   static_assert(__w <= _Dt, "subtract_with_carry_engine invalid parameters");
64   static_assert(0 < __s, "subtract_with_carry_engine invalid parameters");
65   static_assert(__s < __r, "subtract_with_carry_engine invalid parameters");
66 
67 public:
68   static _LIBCPP_CONSTEXPR const result_type _Min = 0;
69   static _LIBCPP_CONSTEXPR const result_type _Max =
70       __w == _Dt ? result_type(~0) : (result_type(1) << __w) - result_type(1);
71   static_assert(_Min < _Max, "subtract_with_carry_engine invalid parameters");
72 
73   // engine characteristics
74   static _LIBCPP_CONSTEXPR const size_t word_size = __w;
75   static _LIBCPP_CONSTEXPR const size_t short_lag = __s;
76   static _LIBCPP_CONSTEXPR const size_t long_lag  = __r;
min()77   _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type min() { return _Min; }
max()78   _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type max() { return _Max; }
79   static _LIBCPP_CONSTEXPR const result_type default_seed = 19780503u;
80 
81   // constructors and seeding functions
82 #ifndef _LIBCPP_CXX03_LANG
subtract_with_carry_engine()83   _LIBCPP_HIDE_FROM_ABI subtract_with_carry_engine() : subtract_with_carry_engine(default_seed) {}
subtract_with_carry_engine(result_type __sd)84   _LIBCPP_HIDE_FROM_ABI explicit subtract_with_carry_engine(result_type __sd) { seed(__sd); }
85 #else
86   _LIBCPP_HIDE_FROM_ABI explicit subtract_with_carry_engine(result_type __sd = default_seed) { seed(__sd); }
87 #endif
88   template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, subtract_with_carry_engine>::value, int> = 0>
subtract_with_carry_engine(_Sseq & __q)89   _LIBCPP_HIDE_FROM_ABI explicit subtract_with_carry_engine(_Sseq& __q) {
90     seed(__q);
91   }
92   _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd = default_seed) {
93     seed(__sd, integral_constant<unsigned, 1 + (__w - 1) / 32>());
94   }
95   template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, subtract_with_carry_engine>::value, int> = 0>
seed(_Sseq & __q)96   _LIBCPP_HIDE_FROM_ABI void seed(_Sseq& __q) {
97     __seed(__q, integral_constant<unsigned, 1 + (__w - 1) / 32>());
98   }
99 
100   // generating functions
101   _LIBCPP_HIDE_FROM_ABI result_type operator()();
discard(unsigned long long __z)102   _LIBCPP_HIDE_FROM_ABI void discard(unsigned long long __z) {
103     for (; __z; --__z)
104       operator()();
105   }
106 
107   template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
108   friend bool operator==(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
109                          const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
110 
111   template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
112   friend bool operator!=(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
113                          const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y);
114 
115   template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
116   friend basic_ostream<_CharT, _Traits>&
117   operator<<(basic_ostream<_CharT, _Traits>& __os, const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
118 
119   template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
120   friend basic_istream<_CharT, _Traits>&
121   operator>>(basic_istream<_CharT, _Traits>& __is, subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x);
122 
123 private:
124   _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd, integral_constant<unsigned, 1>);
125   _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd, integral_constant<unsigned, 2>);
126   template <class _Sseq>
127   _LIBCPP_HIDE_FROM_ABI void __seed(_Sseq& __q, integral_constant<unsigned, 1>);
128   template <class _Sseq>
129   _LIBCPP_HIDE_FROM_ABI void __seed(_Sseq& __q, integral_constant<unsigned, 2>);
130 };
131 
132 template <class _UIntType, size_t __w, size_t __s, size_t __r>
133 _LIBCPP_CONSTEXPR const size_t subtract_with_carry_engine<_UIntType, __w, __s, __r>::word_size;
134 
135 template <class _UIntType, size_t __w, size_t __s, size_t __r>
136 _LIBCPP_CONSTEXPR const size_t subtract_with_carry_engine<_UIntType, __w, __s, __r>::short_lag;
137 
138 template <class _UIntType, size_t __w, size_t __s, size_t __r>
139 _LIBCPP_CONSTEXPR const size_t subtract_with_carry_engine<_UIntType, __w, __s, __r>::long_lag;
140 
141 template <class _UIntType, size_t __w, size_t __s, size_t __r>
142 _LIBCPP_CONSTEXPR const typename subtract_with_carry_engine<_UIntType, __w, __s, __r>::result_type
143     subtract_with_carry_engine<_UIntType, __w, __s, __r>::default_seed;
144 
145 template <class _UIntType, size_t __w, size_t __s, size_t __r>
seed(result_type __sd,integral_constant<unsigned,1>)146 void subtract_with_carry_engine<_UIntType, __w, __s, __r>::seed(result_type __sd, integral_constant<unsigned, 1>) {
147   linear_congruential_engine<result_type, 40014u, 0u, 2147483563u> __e(__sd == 0u ? default_seed : __sd);
148   for (size_t __i = 0; __i < __r; ++__i)
149     __x_[__i] = static_cast<result_type>(__e() & _Max);
150   __c_ = __x_[__r - 1] == 0;
151   __i_ = 0;
152 }
153 
154 template <class _UIntType, size_t __w, size_t __s, size_t __r>
seed(result_type __sd,integral_constant<unsigned,2>)155 void subtract_with_carry_engine<_UIntType, __w, __s, __r>::seed(result_type __sd, integral_constant<unsigned, 2>) {
156   linear_congruential_engine<result_type, 40014u, 0u, 2147483563u> __e(__sd == 0u ? default_seed : __sd);
157   for (size_t __i = 0; __i < __r; ++__i) {
158     result_type __e0 = __e();
159     __x_[__i]        = static_cast<result_type>((__e0 + ((uint64_t)__e() << 32)) & _Max);
160   }
161   __c_ = __x_[__r - 1] == 0;
162   __i_ = 0;
163 }
164 
165 template <class _UIntType, size_t __w, size_t __s, size_t __r>
166 template <class _Sseq>
__seed(_Sseq & __q,integral_constant<unsigned,1>)167 void subtract_with_carry_engine<_UIntType, __w, __s, __r>::__seed(_Sseq& __q, integral_constant<unsigned, 1>) {
168   const unsigned __k = 1;
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[__i] & _Max);
173   __c_ = __x_[__r - 1] == 0;
174   __i_ = 0;
175 }
176 
177 template <class _UIntType, size_t __w, size_t __s, size_t __r>
178 template <class _Sseq>
__seed(_Sseq & __q,integral_constant<unsigned,2>)179 void subtract_with_carry_engine<_UIntType, __w, __s, __r>::__seed(_Sseq& __q, integral_constant<unsigned, 2>) {
180   const unsigned __k = 2;
181   uint32_t __ar[__r * __k];
182   __q.generate(__ar, __ar + __r * __k);
183   for (size_t __i = 0; __i < __r; ++__i)
184     __x_[__i] = static_cast<result_type>((__ar[2 * __i] + ((uint64_t)__ar[2 * __i + 1] << 32)) & _Max);
185   __c_ = __x_[__r - 1] == 0;
186   __i_ = 0;
187 }
188 
189 template <class _UIntType, size_t __w, size_t __s, size_t __r>
operator()190 _UIntType subtract_with_carry_engine<_UIntType, __w, __s, __r>::operator()() {
191   const result_type& __xs = __x_[(__i_ + (__r - __s)) % __r];
192   result_type& __xr       = __x_[__i_];
193   result_type __new_c     = __c_ == 0 ? __xs < __xr : __xs != 0 ? __xs <= __xr : 1;
194   __xr                    = (__xs - __xr - __c_) & _Max;
195   __c_                    = __new_c;
196   __i_                    = (__i_ + 1) % __r;
197   return __xr;
198 }
199 
200 template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
201 _LIBCPP_HIDE_FROM_ABI bool operator==(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
202                                       const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y) {
203   if (__x.__c_ != __y.__c_)
204     return false;
205   if (__x.__i_ == __y.__i_)
206     return std::equal(__x.__x_, __x.__x_ + _Rp, __y.__x_);
207   if (__x.__i_ == 0 || __y.__i_ == 0) {
208     size_t __j = std::min(_Rp - __x.__i_, _Rp - __y.__i_);
209     if (!std::equal(__x.__x_ + __x.__i_, __x.__x_ + __x.__i_ + __j, __y.__x_ + __y.__i_))
210       return false;
211     if (__x.__i_ == 0)
212       return std::equal(__x.__x_ + __j, __x.__x_ + _Rp, __y.__x_);
213     return std::equal(__x.__x_, __x.__x_ + (_Rp - __j), __y.__x_ + __j);
214   }
215   if (__x.__i_ < __y.__i_) {
216     size_t __j = _Rp - __y.__i_;
217     if (!std::equal(__x.__x_ + __x.__i_, __x.__x_ + (__x.__i_ + __j), __y.__x_ + __y.__i_))
218       return false;
219     if (!std::equal(__x.__x_ + (__x.__i_ + __j), __x.__x_ + _Rp, __y.__x_))
220       return false;
221     return std::equal(__x.__x_, __x.__x_ + __x.__i_, __y.__x_ + (_Rp - (__x.__i_ + __j)));
222   }
223   size_t __j = _Rp - __x.__i_;
224   if (!std::equal(__y.__x_ + __y.__i_, __y.__x_ + (__y.__i_ + __j), __x.__x_ + __x.__i_))
225     return false;
226   if (!std::equal(__y.__x_ + (__y.__i_ + __j), __y.__x_ + _Rp, __x.__x_))
227     return false;
228   return std::equal(__y.__x_, __y.__x_ + __y.__i_, __x.__x_ + (_Rp - (__y.__i_ + __j)));
229 }
230 
231 template <class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
232 inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x,
233                                              const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __y) {
234   return !(__x == __y);
235 }
236 
237 template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
238 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
239 operator<<(basic_ostream<_CharT, _Traits>& __os, const subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x) {
240   __save_flags<_CharT, _Traits> __lx(__os);
241   typedef basic_ostream<_CharT, _Traits> _Ostream;
242   __os.flags(_Ostream::dec | _Ostream::left);
243   _CharT __sp = __os.widen(' ');
244   __os.fill(__sp);
245   __os << __x.__x_[__x.__i_];
246   for (size_t __j = __x.__i_ + 1; __j < _Rp; ++__j)
247     __os << __sp << __x.__x_[__j];
248   for (size_t __j = 0; __j < __x.__i_; ++__j)
249     __os << __sp << __x.__x_[__j];
250   __os << __sp << __x.__c_;
251   return __os;
252 }
253 
254 template <class _CharT, class _Traits, class _UInt, size_t _Wp, size_t _Sp, size_t _Rp>
255 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
256 operator>>(basic_istream<_CharT, _Traits>& __is, subtract_with_carry_engine<_UInt, _Wp, _Sp, _Rp>& __x) {
257   __save_flags<_CharT, _Traits> __lx(__is);
258   typedef basic_istream<_CharT, _Traits> _Istream;
259   __is.flags(_Istream::dec | _Istream::skipws);
260   _UInt __t[_Rp + 1];
261   for (size_t __i = 0; __i < _Rp + 1; ++__i)
262     __is >> __t[__i];
263   if (!__is.fail()) {
264     for (size_t __i = 0; __i < _Rp; ++__i)
265       __x.__x_[__i] = __t[__i];
266     __x.__c_ = __t[_Rp];
267     __x.__i_ = 0;
268   }
269   return __is;
270 }
271 
272 _LIBCPP_END_NAMESPACE_STD
273 
274 _LIBCPP_POP_MACROS
275 
276 #endif // _LIBCPP___RANDOM_SUBTRACT_WITH_CARRY_ENGINE_H
277