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_INDEPENDENT_BITS_ENGINE_H
10 #define _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H
11
12 #include <__config>
13 #include <__random/is_seed_sequence.h>
14 #include <__random/log2.h>
15 #include <__type_traits/conditional.h>
16 #include <__type_traits/enable_if.h>
17 #include <__type_traits/is_convertible.h>
18 #include <__utility/move.h>
19 #include <cstddef>
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
32 template<class _Engine, size_t __w, class _UIntType>
33 class _LIBCPP_TEMPLATE_VIS independent_bits_engine
34 {
35 template <class _UInt, _UInt _R0, size_t _Wp, size_t _Mp>
36 class __get_n
37 {
38 static _LIBCPP_CONSTEXPR const size_t _Dt = numeric_limits<_UInt>::digits;
39 static _LIBCPP_CONSTEXPR const size_t _Np = _Wp / _Mp + (_Wp % _Mp != 0);
40 static _LIBCPP_CONSTEXPR const size_t _W0 = _Wp / _Np;
41 static _LIBCPP_CONSTEXPR const _UInt _Y0 = _W0 >= _Dt ? 0 : (_R0 >> _W0) << _W0;
42 public:
43 static _LIBCPP_CONSTEXPR const size_t value = _R0 - _Y0 > _Y0 / _Np ? _Np + 1 : _Np;
44 };
45 public:
46 // types
47 typedef _UIntType result_type;
48
49 private:
50 _Engine __e_;
51
52 static _LIBCPP_CONSTEXPR const result_type _Dt = numeric_limits<result_type>::digits;
53 static_assert( 0 < __w, "independent_bits_engine invalid parameters");
54 static_assert(__w <= _Dt, "independent_bits_engine invalid parameters");
55
56 typedef typename _Engine::result_type _Engine_result_type;
57 typedef __conditional_t<sizeof(_Engine_result_type) <= sizeof(result_type), result_type, _Engine_result_type>
58 _Working_result_type;
59 #ifdef _LIBCPP_CXX03_LANG
60 static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min
61 + _Working_result_type(1);
62 #else
63 static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min()
64 + _Working_result_type(1);
65 #endif
66 static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
67 static _LIBCPP_CONSTEXPR const size_t __n = __get_n<_Working_result_type, _Rp, __w, __m>::value;
68 static _LIBCPP_CONSTEXPR const size_t __w0 = __w / __n;
69 static _LIBCPP_CONSTEXPR const size_t __n0 = __n - __w % __n;
70 static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
71 static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
72 static _LIBCPP_CONSTEXPR const _Working_result_type __y0 = __w0 >= _WDt ? 0 :
73 (_Rp >> __w0) << __w0;
74 static _LIBCPP_CONSTEXPR const _Working_result_type __y1 = __w0 >= _WDt - 1 ? 0 :
75 (_Rp >> (__w0+1)) << (__w0+1);
76 static _LIBCPP_CONSTEXPR const _Engine_result_type __mask0 = __w0 > 0 ?
77 _Engine_result_type(~0) >> (_EDt - __w0) :
78 _Engine_result_type(0);
79 static _LIBCPP_CONSTEXPR const _Engine_result_type __mask1 = __w0 < _EDt - 1 ?
80 _Engine_result_type(~0) >> (_EDt - (__w0 + 1)) :
81 _Engine_result_type(~0);
82 public:
83 static _LIBCPP_CONSTEXPR const result_type _Min = 0;
84 static _LIBCPP_CONSTEXPR const result_type _Max = __w == _Dt ? result_type(~0) :
85 (result_type(1) << __w) - result_type(1);
86 static_assert(_Min < _Max, "independent_bits_engine invalid parameters");
87
88 // engine characteristics
89 _LIBCPP_INLINE_VISIBILITY
min()90 static _LIBCPP_CONSTEXPR result_type min() { return _Min; }
91 _LIBCPP_INLINE_VISIBILITY
max()92 static _LIBCPP_CONSTEXPR result_type max() { return _Max; }
93
94 // constructors and seeding functions
95 _LIBCPP_INLINE_VISIBILITY
independent_bits_engine()96 independent_bits_engine() {}
97 _LIBCPP_INLINE_VISIBILITY
independent_bits_engine(const _Engine & __e)98 explicit independent_bits_engine(const _Engine& __e)
99 : __e_(__e) {}
100 #ifndef _LIBCPP_CXX03_LANG
101 _LIBCPP_INLINE_VISIBILITY
independent_bits_engine(_Engine && __e)102 explicit independent_bits_engine(_Engine&& __e)
103 : __e_(_VSTD::move(__e)) {}
104 #endif // _LIBCPP_CXX03_LANG
105 _LIBCPP_INLINE_VISIBILITY
independent_bits_engine(result_type __sd)106 explicit independent_bits_engine(result_type __sd) : __e_(__sd) {}
107 template<class _Sseq>
108 _LIBCPP_INLINE_VISIBILITY
109 explicit independent_bits_engine(_Sseq& __q,
110 typename enable_if<__is_seed_sequence<_Sseq, independent_bits_engine>::value &&
111 !is_convertible<_Sseq, _Engine>::value>::type* = 0)
__e_(__q)112 : __e_(__q) {}
113 _LIBCPP_INLINE_VISIBILITY
seed()114 void seed() {__e_.seed();}
115 _LIBCPP_INLINE_VISIBILITY
seed(result_type __sd)116 void seed(result_type __sd) {__e_.seed(__sd);}
117 template<class _Sseq>
118 _LIBCPP_INLINE_VISIBILITY
119 typename enable_if
120 <
121 __is_seed_sequence<_Sseq, independent_bits_engine>::value,
122 void
123 >::type
seed(_Sseq & __q)124 seed(_Sseq& __q) {__e_.seed(__q);}
125
126 // generating functions
127 _LIBCPP_INLINE_VISIBILITY
operator()128 result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
129 _LIBCPP_INLINE_VISIBILITY
discard(unsigned long long __z)130 void discard(unsigned long long __z) {for (; __z; --__z) operator()();}
131
132 // property functions
133 _LIBCPP_INLINE_VISIBILITY
base()134 const _Engine& base() const _NOEXCEPT {return __e_;}
135
136 template<class _Eng, size_t _Wp, class _UInt>
137 friend
138 bool
139 operator==(
140 const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
141 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);
142
143 template<class _Eng, size_t _Wp, class _UInt>
144 friend
145 bool
146 operator!=(
147 const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
148 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);
149
150 template <class _CharT, class _Traits,
151 class _Eng, size_t _Wp, class _UInt>
152 friend
153 basic_ostream<_CharT, _Traits>&
154 operator<<(basic_ostream<_CharT, _Traits>& __os,
155 const independent_bits_engine<_Eng, _Wp, _UInt>& __x);
156
157 template <class _CharT, class _Traits,
158 class _Eng, size_t _Wp, class _UInt>
159 friend
160 basic_istream<_CharT, _Traits>&
161 operator>>(basic_istream<_CharT, _Traits>& __is,
162 independent_bits_engine<_Eng, _Wp, _UInt>& __x);
163
164 private:
165 _LIBCPP_INLINE_VISIBILITY
166 result_type __eval(false_type);
167 _LIBCPP_HIDE_FROM_ABI result_type __eval(true_type);
168
169 template <size_t __count>
170 _LIBCPP_INLINE_VISIBILITY
171 static
172 typename enable_if
173 <
174 __count < _Dt,
175 result_type
176 >::type
177 __lshift(result_type __x) {return __x << __count;}
178
179 template <size_t __count>
180 _LIBCPP_INLINE_VISIBILITY
181 static
182 typename enable_if
183 <
184 (__count >= _Dt),
185 result_type
186 >::type
__lshift(result_type)187 __lshift(result_type) {return result_type(0);}
188 };
189
190 template<class _Engine, size_t __w, class _UIntType>
191 inline
192 _UIntType
__eval(false_type)193 independent_bits_engine<_Engine, __w, _UIntType>::__eval(false_type)
194 {
195 return static_cast<result_type>(__e_() & __mask0);
196 }
197
198 template<class _Engine, size_t __w, class _UIntType>
199 _UIntType
__eval(true_type)200 independent_bits_engine<_Engine, __w, _UIntType>::__eval(true_type)
201 {
202 result_type __sp = 0;
203 for (size_t __k = 0; __k < __n0; ++__k)
204 {
205 _Engine_result_type __u;
206 do
207 {
208 __u = __e_() - _Engine::min();
209 } while (__u >= __y0);
210 __sp = static_cast<result_type>(__lshift<__w0>(__sp) + (__u & __mask0));
211 }
212 for (size_t __k = __n0; __k < __n; ++__k)
213 {
214 _Engine_result_type __u;
215 do
216 {
217 __u = __e_() - _Engine::min();
218 } while (__u >= __y1);
219 __sp = static_cast<result_type>(__lshift<__w0+1>(__sp) + (__u & __mask1));
220 }
221 return __sp;
222 }
223
224 template<class _Eng, size_t _Wp, class _UInt>
225 inline _LIBCPP_INLINE_VISIBILITY
226 bool
227 operator==(
228 const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
229 const independent_bits_engine<_Eng, _Wp, _UInt>& __y)
230 {
231 return __x.base() == __y.base();
232 }
233
234 template<class _Eng, size_t _Wp, class _UInt>
235 inline _LIBCPP_INLINE_VISIBILITY
236 bool
237 operator!=(
238 const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
239 const independent_bits_engine<_Eng, _Wp, _UInt>& __y)
240 {
241 return !(__x == __y);
242 }
243
244 template <class _CharT, class _Traits,
245 class _Eng, size_t _Wp, class _UInt>
246 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
247 operator<<(basic_ostream<_CharT, _Traits>& __os,
248 const independent_bits_engine<_Eng, _Wp, _UInt>& __x)
249 {
250 return __os << __x.base();
251 }
252
253 template <class _CharT, class _Traits,
254 class _Eng, size_t _Wp, class _UInt>
255 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
256 operator>>(basic_istream<_CharT, _Traits>& __is,
257 independent_bits_engine<_Eng, _Wp, _UInt>& __x)
258 {
259 _Eng __e;
260 __is >> __e;
261 if (!__is.fail())
262 __x.__e_ = __e;
263 return __is;
264 }
265
266 _LIBCPP_END_NAMESPACE_STD
267
268 _LIBCPP_POP_MACROS
269
270 #endif // _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H
271