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 <__utility/move.h>
16 #include <iosfwd>
17 #include <limits>
18 #include <type_traits>
19
20 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21 # pragma GCC system_header
22 #endif
23
24 _LIBCPP_PUSH_MACROS
25 #include <__undef_macros>
26
27 _LIBCPP_BEGIN_NAMESPACE_STD
28
29 template<class _Engine, size_t __w, class _UIntType>
30 class _LIBCPP_TEMPLATE_VIS independent_bits_engine
31 {
32 template <class _UInt, _UInt _R0, size_t _Wp, size_t _Mp>
33 class __get_n
34 {
35 static _LIBCPP_CONSTEXPR const size_t _Dt = numeric_limits<_UInt>::digits;
36 static _LIBCPP_CONSTEXPR const size_t _Np = _Wp / _Mp + (_Wp % _Mp != 0);
37 static _LIBCPP_CONSTEXPR const size_t _W0 = _Wp / _Np;
38 static _LIBCPP_CONSTEXPR const _UInt _Y0 = _W0 >= _Dt ? 0 : (_R0 >> _W0) << _W0;
39 public:
40 static _LIBCPP_CONSTEXPR const size_t value = _R0 - _Y0 > _Y0 / _Np ? _Np + 1 : _Np;
41 };
42 public:
43 // types
44 typedef _UIntType result_type;
45
46 private:
47 _Engine __e_;
48
49 static _LIBCPP_CONSTEXPR const result_type _Dt = numeric_limits<result_type>::digits;
50 static_assert( 0 < __w, "independent_bits_engine invalid parameters");
51 static_assert(__w <= _Dt, "independent_bits_engine invalid parameters");
52
53 typedef typename _Engine::result_type _Engine_result_type;
54 typedef __conditional_t<sizeof(_Engine_result_type) <= sizeof(result_type), result_type, _Engine_result_type>
55 _Working_result_type;
56 #ifdef _LIBCPP_CXX03_LANG
57 static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min
58 + _Working_result_type(1);
59 #else
60 static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min()
61 + _Working_result_type(1);
62 #endif
63 static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
64 static _LIBCPP_CONSTEXPR const size_t __n = __get_n<_Working_result_type, _Rp, __w, __m>::value;
65 static _LIBCPP_CONSTEXPR const size_t __w0 = __w / __n;
66 static _LIBCPP_CONSTEXPR const size_t __n0 = __n - __w % __n;
67 static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
68 static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
69 static _LIBCPP_CONSTEXPR const _Working_result_type __y0 = __w0 >= _WDt ? 0 :
70 (_Rp >> __w0) << __w0;
71 static _LIBCPP_CONSTEXPR const _Working_result_type __y1 = __w0 >= _WDt - 1 ? 0 :
72 (_Rp >> (__w0+1)) << (__w0+1);
73 static _LIBCPP_CONSTEXPR const _Engine_result_type __mask0 = __w0 > 0 ?
74 _Engine_result_type(~0) >> (_EDt - __w0) :
75 _Engine_result_type(0);
76 static _LIBCPP_CONSTEXPR const _Engine_result_type __mask1 = __w0 < _EDt - 1 ?
77 _Engine_result_type(~0) >> (_EDt - (__w0 + 1)) :
78 _Engine_result_type(~0);
79 public:
80 static _LIBCPP_CONSTEXPR const result_type _Min = 0;
81 static _LIBCPP_CONSTEXPR const result_type _Max = __w == _Dt ? result_type(~0) :
82 (result_type(1) << __w) - result_type(1);
83 static_assert(_Min < _Max, "independent_bits_engine invalid parameters");
84
85 // engine characteristics
86 _LIBCPP_INLINE_VISIBILITY
min()87 static _LIBCPP_CONSTEXPR result_type min() { return _Min; }
88 _LIBCPP_INLINE_VISIBILITY
max()89 static _LIBCPP_CONSTEXPR result_type max() { return _Max; }
90
91 // constructors and seeding functions
92 _LIBCPP_INLINE_VISIBILITY
independent_bits_engine()93 independent_bits_engine() {}
94 _LIBCPP_INLINE_VISIBILITY
independent_bits_engine(const _Engine & __e)95 explicit independent_bits_engine(const _Engine& __e)
96 : __e_(__e) {}
97 #ifndef _LIBCPP_CXX03_LANG
98 _LIBCPP_INLINE_VISIBILITY
independent_bits_engine(_Engine && __e)99 explicit independent_bits_engine(_Engine&& __e)
100 : __e_(_VSTD::move(__e)) {}
101 #endif // _LIBCPP_CXX03_LANG
102 _LIBCPP_INLINE_VISIBILITY
independent_bits_engine(result_type __sd)103 explicit independent_bits_engine(result_type __sd) : __e_(__sd) {}
104 template<class _Sseq>
105 _LIBCPP_INLINE_VISIBILITY
106 explicit independent_bits_engine(_Sseq& __q,
107 typename enable_if<__is_seed_sequence<_Sseq, independent_bits_engine>::value &&
108 !is_convertible<_Sseq, _Engine>::value>::type* = 0)
__e_(__q)109 : __e_(__q) {}
110 _LIBCPP_INLINE_VISIBILITY
seed()111 void seed() {__e_.seed();}
112 _LIBCPP_INLINE_VISIBILITY
seed(result_type __sd)113 void seed(result_type __sd) {__e_.seed(__sd);}
114 template<class _Sseq>
115 _LIBCPP_INLINE_VISIBILITY
116 typename enable_if
117 <
118 __is_seed_sequence<_Sseq, independent_bits_engine>::value,
119 void
120 >::type
seed(_Sseq & __q)121 seed(_Sseq& __q) {__e_.seed(__q);}
122
123 // generating functions
124 _LIBCPP_INLINE_VISIBILITY
operator()125 result_type operator()() {return __eval(integral_constant<bool, _Rp != 0>());}
126 _LIBCPP_INLINE_VISIBILITY
discard(unsigned long long __z)127 void discard(unsigned long long __z) {for (; __z; --__z) operator()();}
128
129 // property functions
130 _LIBCPP_INLINE_VISIBILITY
base()131 const _Engine& base() const _NOEXCEPT {return __e_;}
132
133 template<class _Eng, size_t _Wp, class _UInt>
134 friend
135 bool
136 operator==(
137 const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
138 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);
139
140 template<class _Eng, size_t _Wp, class _UInt>
141 friend
142 bool
143 operator!=(
144 const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
145 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);
146
147 template <class _CharT, class _Traits,
148 class _Eng, size_t _Wp, class _UInt>
149 friend
150 basic_ostream<_CharT, _Traits>&
151 operator<<(basic_ostream<_CharT, _Traits>& __os,
152 const independent_bits_engine<_Eng, _Wp, _UInt>& __x);
153
154 template <class _CharT, class _Traits,
155 class _Eng, size_t _Wp, class _UInt>
156 friend
157 basic_istream<_CharT, _Traits>&
158 operator>>(basic_istream<_CharT, _Traits>& __is,
159 independent_bits_engine<_Eng, _Wp, _UInt>& __x);
160
161 private:
162 _LIBCPP_INLINE_VISIBILITY
163 result_type __eval(false_type);
164 result_type __eval(true_type);
165
166 template <size_t __count>
167 _LIBCPP_INLINE_VISIBILITY
168 static
169 typename enable_if
170 <
171 __count < _Dt,
172 result_type
173 >::type
174 __lshift(result_type __x) {return __x << __count;}
175
176 template <size_t __count>
177 _LIBCPP_INLINE_VISIBILITY
178 static
179 typename enable_if
180 <
181 (__count >= _Dt),
182 result_type
183 >::type
__lshift(result_type)184 __lshift(result_type) {return result_type(0);}
185 };
186
187 template<class _Engine, size_t __w, class _UIntType>
188 inline
189 _UIntType
__eval(false_type)190 independent_bits_engine<_Engine, __w, _UIntType>::__eval(false_type)
191 {
192 return static_cast<result_type>(__e_() & __mask0);
193 }
194
195 template<class _Engine, size_t __w, class _UIntType>
196 _UIntType
__eval(true_type)197 independent_bits_engine<_Engine, __w, _UIntType>::__eval(true_type)
198 {
199 result_type _Sp = 0;
200 for (size_t __k = 0; __k < __n0; ++__k)
201 {
202 _Engine_result_type __u;
203 do
204 {
205 __u = __e_() - _Engine::min();
206 } while (__u >= __y0);
207 _Sp = static_cast<result_type>(__lshift<__w0>(_Sp) + (__u & __mask0));
208 }
209 for (size_t __k = __n0; __k < __n; ++__k)
210 {
211 _Engine_result_type __u;
212 do
213 {
214 __u = __e_() - _Engine::min();
215 } while (__u >= __y1);
216 _Sp = static_cast<result_type>(__lshift<__w0+1>(_Sp) + (__u & __mask1));
217 }
218 return _Sp;
219 }
220
221 template<class _Eng, size_t _Wp, class _UInt>
222 inline _LIBCPP_INLINE_VISIBILITY
223 bool
224 operator==(
225 const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
226 const independent_bits_engine<_Eng, _Wp, _UInt>& __y)
227 {
228 return __x.base() == __y.base();
229 }
230
231 template<class _Eng, size_t _Wp, class _UInt>
232 inline _LIBCPP_INLINE_VISIBILITY
233 bool
234 operator!=(
235 const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
236 const independent_bits_engine<_Eng, _Wp, _UInt>& __y)
237 {
238 return !(__x == __y);
239 }
240
241 template <class _CharT, class _Traits,
242 class _Eng, size_t _Wp, class _UInt>
243 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
244 operator<<(basic_ostream<_CharT, _Traits>& __os,
245 const independent_bits_engine<_Eng, _Wp, _UInt>& __x)
246 {
247 return __os << __x.base();
248 }
249
250 template <class _CharT, class _Traits,
251 class _Eng, size_t _Wp, class _UInt>
252 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
253 operator>>(basic_istream<_CharT, _Traits>& __is,
254 independent_bits_engine<_Eng, _Wp, _UInt>& __x)
255 {
256 _Eng __e;
257 __is >> __e;
258 if (!__is.fail())
259 __x.__e_ = __e;
260 return __is;
261 }
262
263 _LIBCPP_END_NAMESPACE_STD
264
265 _LIBCPP_POP_MACROS
266
267 #endif // _LIBCPP___RANDOM_INDEPENDENT_BITS_ENGINE_H
268