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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_UNIFORM_INT_DISTRIBUTION_H
10#define _LIBCPP___RANDOM_UNIFORM_INT_DISTRIBUTION_H
11
12#include <__bit/countl.h>
13#include <__config>
14#include <__cstddef/size_t.h>
15#include <__random/is_valid.h>
16#include <__random/log2.h>
17#include <__type_traits/conditional.h>
18#include <__type_traits/make_unsigned.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 _Engine, class _UIntType>
33class __independent_bits_engine {
34public:
35 // types
36 typedef _UIntType result_type;
37
38private:
39 typedef typename _Engine::result_type _Engine_result_type;
40 typedef __conditional_t<sizeof(_Engine_result_type) <= sizeof(result_type), result_type, _Engine_result_type>
41 _Working_result_type;
42
43 _Engine& __e_;
44 size_t __w_;
45 size_t __w0_;
46 size_t __n_;
47 size_t __n0_;
48 _Working_result_type __y0_;
49 _Working_result_type __y1_;
50 _Engine_result_type __mask0_;
51 _Engine_result_type __mask1_;
52
53#ifdef _LIBCPP_CXX03_LANG
54 static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min + _Working_result_type(1);
55#else
56 static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min() + _Working_result_type(1);
57#endif
58 static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
59 static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
60 static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
61
62public:
63 // constructors and seeding functions
64 _LIBCPP_HIDE_FROM_ABI __independent_bits_engine(_Engine& __e, size_t __w);
65
66 // generating functions
67 _LIBCPP_HIDE_FROM_ABI result_type operator()() { return __eval(integral_constant<bool, _Rp != 0>()); }
68
69private:
70 _LIBCPP_HIDE_FROM_ABI result_type __eval(false_type);
71 _LIBCPP_HIDE_FROM_ABI result_type __eval(true_type);
72};
73
74template <class _Engine, class _UIntType>
75__independent_bits_engine<_Engine, _UIntType>::__independent_bits_engine(_Engine& __e, size_t __w)
76 : __e_(__e), __w_(__w) {
77 __n_ = __w_ / __m + (__w_ % __m != 0);
78 __w0_ = __w_ / __n_;
79 if (_Rp == 0)
80 __y0_ = _Rp;
81 else if (__w0_ < _WDt)
82 __y0_ = (_Rp >> __w0_) << __w0_;
83 else
84 __y0_ = 0;
85 if (_Rp - __y0_ > __y0_ / __n_) {
86 ++__n_;
87 __w0_ = __w_ / __n_;
88 if (__w0_ < _WDt)
89 __y0_ = (_Rp >> __w0_) << __w0_;
90 else
91 __y0_ = 0;
92 }
93 __n0_ = __n_ - __w_ % __n_;
94 if (__w0_ < _WDt - 1)
95 __y1_ = (_Rp >> (__w0_ + 1)) << (__w0_ + 1);
96 else
97 __y1_ = 0;
98 __mask0_ = __w0_ > 0 ? _Engine_result_type(~0) >> (_EDt - __w0_) : _Engine_result_type(0);
99 __mask1_ = __w0_ < _EDt - 1 ? _Engine_result_type(~0) >> (_EDt - (__w0_ + 1)) : _Engine_result_type(~0);
100}
101
102template <class _Engine, class _UIntType>
103inline _UIntType __independent_bits_engine<_Engine, _UIntType>::__eval(false_type) {
104 return static_cast<result_type>(__e_() & __mask0_);
105}
106
107template <class _Engine, class _UIntType>
108_UIntType __independent_bits_engine<_Engine, _UIntType>::__eval(true_type) {
109 const size_t __w_rt = numeric_limits<result_type>::digits;
110 result_type __sp = 0;
111 for (size_t __k = 0; __k < __n0_; ++__k) {
112 _Engine_result_type __u;
113 do {
114 __u = __e_() - _Engine::min();
115 } while (__u >= __y0_);
116 if (__w0_ < __w_rt)
117 __sp <<= __w0_;
118 else
119 __sp = 0;
120 __sp += __u & __mask0_;
121 }
122 for (size_t __k = __n0_; __k < __n_; ++__k) {
123 _Engine_result_type __u;
124 do {
125 __u = __e_() - _Engine::min();
126 } while (__u >= __y1_);
127 if (__w0_ < __w_rt - 1)
128 __sp <<= __w0_ + 1;
129 else
130 __sp = 0;
131 __sp += __u & __mask1_;
132 }
133 return __sp;
134}
135
136template <class _IntType = int>
137class uniform_int_distribution {
138 static_assert(__libcpp_random_is_valid_inttype<_IntType>::value, "IntType must be a supported integer type");
139
140public:
141 // types
142 typedef _IntType result_type;
143
144 class param_type {
145 result_type __a_;
146 result_type __b_;
147
148 public:
149 typedef uniform_int_distribution distribution_type;
150
151 _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __a = 0, result_type __b = numeric_limits<result_type>::max())
152 : __a_(__a), __b_(__b) {}
153
154 _LIBCPP_HIDE_FROM_ABI result_type a() const { return __a_; }
155 _LIBCPP_HIDE_FROM_ABI result_type b() const { return __b_; }
156
157 _LIBCPP_HIDE_FROM_ABI friend bool operator==(const param_type& __x, const param_type& __y) {
158 return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;
159 }
160 _LIBCPP_HIDE_FROM_ABI friend bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
161 };
162
163private:
164 param_type __p_;
165
166public:
167 // constructors and reset functions
168#ifndef _LIBCPP_CXX03_LANG
169 _LIBCPP_HIDE_FROM_ABI uniform_int_distribution() : uniform_int_distribution(0) {}
170 _LIBCPP_HIDE_FROM_ABI explicit uniform_int_distribution(
171 result_type __a, result_type __b = numeric_limits<result_type>::max())
172 : __p_(param_type(__a, __b)) {}
173#else
174 explicit uniform_int_distribution(result_type __a = 0, result_type __b = numeric_limits<result_type>::max())
175 : __p_(param_type(__a, __b)) {}
176#endif
177 _LIBCPP_HIDE_FROM_ABI explicit uniform_int_distribution(const param_type& __p) : __p_(__p) {}
178 _LIBCPP_HIDE_FROM_ABI void reset() {}
179
180 // generating functions
181 template <class _URNG>
182 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
183 return (*this)(__g, __p_);
184 }
185 template <class _URNG>
186 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
187
188 // property functions
189 _LIBCPP_HIDE_FROM_ABI result_type a() const { return __p_.a(); }
190 _LIBCPP_HIDE_FROM_ABI result_type b() const { return __p_.b(); }
191
192 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
193 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
194
195 _LIBCPP_HIDE_FROM_ABI result_type min() const { return a(); }
196 _LIBCPP_HIDE_FROM_ABI result_type max() const { return b(); }
197
198 _LIBCPP_HIDE_FROM_ABI friend bool
199 operator==(const uniform_int_distribution& __x, const uniform_int_distribution& __y) {
200 return __x.__p_ == __y.__p_;
201 }
202 _LIBCPP_HIDE_FROM_ABI friend bool
203 operator!=(const uniform_int_distribution& __x, const uniform_int_distribution& __y) {
204 return !(__x == __y);
205 }
206};
207
208template <class _IntType>
209template <class _URNG>
210typename uniform_int_distribution<_IntType>::result_type uniform_int_distribution<_IntType>::operator()(
211 _URNG& __g, const param_type& __p) _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK {
212 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
213 typedef __conditional_t<sizeof(result_type) <= sizeof(uint32_t), uint32_t, __make_unsigned_t<result_type> > _UIntType;
214 const _UIntType __rp = _UIntType(__p.b()) - _UIntType(__p.a()) + _UIntType(1);
215 if (__rp == 1)
216 return __p.a();
217 const size_t __dt = numeric_limits<_UIntType>::digits;
218 typedef __independent_bits_engine<_URNG, _UIntType> _Eng;
219 if (__rp == 0)
220 return static_cast<result_type>(_Eng(__g, __dt)());
221 size_t __w = __dt - std::__countl_zero(__rp) - 1;
222 if ((__rp & (numeric_limits<_UIntType>::max() >> (__dt - __w))) != 0)
223 ++__w;
224 _Eng __e(__g, __w);
225 _UIntType __u;
226 do {
227 __u = __e();
228 } while (__u >= __rp);
229 return static_cast<result_type>(__u + __p.a());
230}
231
232template <class _CharT, class _Traits, class _IT>
233_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
234operator<<(basic_ostream<_CharT, _Traits>& __os, const uniform_int_distribution<_IT>& __x) {
235 __save_flags<_CharT, _Traits> __lx(__os);
236 typedef basic_ostream<_CharT, _Traits> _Ostream;
237 __os.flags(_Ostream::dec | _Ostream::left);
238 _CharT __sp = __os.widen(' ');
239 __os.fill(__sp);
240 return __os << __x.a() << __sp << __x.b();
241}
242
243template <class _CharT, class _Traits, class _IT>
244_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
245operator>>(basic_istream<_CharT, _Traits>& __is, uniform_int_distribution<_IT>& __x) {
246 typedef uniform_int_distribution<_IT> _Eng;
247 typedef typename _Eng::result_type result_type;
248 typedef typename _Eng::param_type param_type;
249 __save_flags<_CharT, _Traits> __lx(__is);
250 typedef basic_istream<_CharT, _Traits> _Istream;
251 __is.flags(_Istream::dec | _Istream::skipws);
252 result_type __a;
253 result_type __b;
254 __is >> __a >> __b;
255 if (!__is.fail())
256 __x.param(param_type(__a, __b));
257 return __is;
258}
259
260_LIBCPP_END_NAMESPACE_STD
261
262_LIBCPP_POP_MACROS
263
264#endif // _LIBCPP___RANDOM_UNIFORM_INT_DISTRIBUTION_H
265

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source code of libcxx/include/__random/uniform_int_distribution.h