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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___CXX03___RANDOM_UNIFORM_INT_DISTRIBUTION_H
10#define _LIBCPP___CXX03___RANDOM_UNIFORM_INT_DISTRIBUTION_H
11
12#include <__cxx03/__bit/countl.h>
13#include <__cxx03/__config>
14#include <__cxx03/__random/is_valid.h>
15#include <__cxx03/__random/log2.h>
16#include <__cxx03/__type_traits/conditional.h>
17#include <__cxx03/__type_traits/make_unsigned.h>
18#include <__cxx03/cstddef>
19#include <__cxx03/cstdint>
20#include <__cxx03/iosfwd>
21#include <__cxx03/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 <__cxx03/__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 static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min + _Working_result_type(1);
54 static const size_t __m = __log2<_Working_result_type, _Rp>::value;
55 static const size_t _WDt = numeric_limits<_Working_result_type>::digits;
56 static const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
57
58public:
59 // constructors and seeding functions
60 _LIBCPP_HIDE_FROM_ABI __independent_bits_engine(_Engine& __e, size_t __w);
61
62 // generating functions
63 _LIBCPP_HIDE_FROM_ABI result_type operator()() { return __eval(integral_constant<bool, _Rp != 0>()); }
64
65private:
66 _LIBCPP_HIDE_FROM_ABI result_type __eval(false_type);
67 _LIBCPP_HIDE_FROM_ABI result_type __eval(true_type);
68};
69
70template <class _Engine, class _UIntType>
71__independent_bits_engine<_Engine, _UIntType>::__independent_bits_engine(_Engine& __e, size_t __w)
72 : __e_(__e), __w_(__w) {
73 __n_ = __w_ / __m + (__w_ % __m != 0);
74 __w0_ = __w_ / __n_;
75 if (_Rp == 0)
76 __y0_ = _Rp;
77 else if (__w0_ < _WDt)
78 __y0_ = (_Rp >> __w0_) << __w0_;
79 else
80 __y0_ = 0;
81 if (_Rp - __y0_ > __y0_ / __n_) {
82 ++__n_;
83 __w0_ = __w_ / __n_;
84 if (__w0_ < _WDt)
85 __y0_ = (_Rp >> __w0_) << __w0_;
86 else
87 __y0_ = 0;
88 }
89 __n0_ = __n_ - __w_ % __n_;
90 if (__w0_ < _WDt - 1)
91 __y1_ = (_Rp >> (__w0_ + 1)) << (__w0_ + 1);
92 else
93 __y1_ = 0;
94 __mask0_ = __w0_ > 0 ? _Engine_result_type(~0) >> (_EDt - __w0_) : _Engine_result_type(0);
95 __mask1_ = __w0_ < _EDt - 1 ? _Engine_result_type(~0) >> (_EDt - (__w0_ + 1)) : _Engine_result_type(~0);
96}
97
98template <class _Engine, class _UIntType>
99inline _UIntType __independent_bits_engine<_Engine, _UIntType>::__eval(false_type) {
100 return static_cast<result_type>(__e_() & __mask0_);
101}
102
103template <class _Engine, class _UIntType>
104_UIntType __independent_bits_engine<_Engine, _UIntType>::__eval(true_type) {
105 const size_t __w_rt = numeric_limits<result_type>::digits;
106 result_type __sp = 0;
107 for (size_t __k = 0; __k < __n0_; ++__k) {
108 _Engine_result_type __u;
109 do {
110 __u = __e_() - _Engine::min();
111 } while (__u >= __y0_);
112 if (__w0_ < __w_rt)
113 __sp <<= __w0_;
114 else
115 __sp = 0;
116 __sp += __u & __mask0_;
117 }
118 for (size_t __k = __n0_; __k < __n_; ++__k) {
119 _Engine_result_type __u;
120 do {
121 __u = __e_() - _Engine::min();
122 } while (__u >= __y1_);
123 if (__w0_ < __w_rt - 1)
124 __sp <<= __w0_ + 1;
125 else
126 __sp = 0;
127 __sp += __u & __mask1_;
128 }
129 return __sp;
130}
131
132template <class _IntType = int>
133class uniform_int_distribution {
134 static_assert(__libcpp_random_is_valid_inttype<_IntType>::value, "IntType must be a supported integer type");
135
136public:
137 // types
138 typedef _IntType result_type;
139
140 class param_type {
141 result_type __a_;
142 result_type __b_;
143
144 public:
145 typedef uniform_int_distribution distribution_type;
146
147 _LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __a = 0, result_type __b = numeric_limits<result_type>::max())
148 : __a_(__a), __b_(__b) {}
149
150 _LIBCPP_HIDE_FROM_ABI result_type a() const { return __a_; }
151 _LIBCPP_HIDE_FROM_ABI result_type b() const { return __b_; }
152
153 _LIBCPP_HIDE_FROM_ABI friend bool operator==(const param_type& __x, const param_type& __y) {
154 return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;
155 }
156 _LIBCPP_HIDE_FROM_ABI friend bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
157 };
158
159private:
160 param_type __p_;
161
162public:
163 // constructors and reset functions
164 explicit uniform_int_distribution(result_type __a = 0, result_type __b = numeric_limits<result_type>::max())
165 : __p_(param_type(__a, __b)) {}
166 _LIBCPP_HIDE_FROM_ABI explicit uniform_int_distribution(const param_type& __p) : __p_(__p) {}
167 _LIBCPP_HIDE_FROM_ABI void reset() {}
168
169 // generating functions
170 template <class _URNG>
171 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
172 return (*this)(__g, __p_);
173 }
174 template <class _URNG>
175 _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
176
177 // property functions
178 _LIBCPP_HIDE_FROM_ABI result_type a() const { return __p_.a(); }
179 _LIBCPP_HIDE_FROM_ABI result_type b() const { return __p_.b(); }
180
181 _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
182 _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
183
184 _LIBCPP_HIDE_FROM_ABI result_type min() const { return a(); }
185 _LIBCPP_HIDE_FROM_ABI result_type max() const { return b(); }
186
187 _LIBCPP_HIDE_FROM_ABI friend bool
188 operator==(const uniform_int_distribution& __x, const uniform_int_distribution& __y) {
189 return __x.__p_ == __y.__p_;
190 }
191 _LIBCPP_HIDE_FROM_ABI friend bool
192 operator!=(const uniform_int_distribution& __x, const uniform_int_distribution& __y) {
193 return !(__x == __y);
194 }
195};
196
197template <class _IntType>
198template <class _URNG>
199typename uniform_int_distribution<_IntType>::result_type uniform_int_distribution<_IntType>::operator()(
200 _URNG& __g, const param_type& __p) _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK {
201 static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
202 typedef __conditional_t<sizeof(result_type) <= sizeof(uint32_t), uint32_t, __make_unsigned_t<result_type> > _UIntType;
203 const _UIntType __rp = _UIntType(__p.b()) - _UIntType(__p.a()) + _UIntType(1);
204 if (__rp == 1)
205 return __p.a();
206 const size_t __dt = numeric_limits<_UIntType>::digits;
207 typedef __independent_bits_engine<_URNG, _UIntType> _Eng;
208 if (__rp == 0)
209 return static_cast<result_type>(_Eng(__g, __dt)());
210 size_t __w = __dt - std::__countl_zero(__rp) - 1;
211 if ((__rp & (numeric_limits<_UIntType>::max() >> (__dt - __w))) != 0)
212 ++__w;
213 _Eng __e(__g, __w);
214 _UIntType __u;
215 do {
216 __u = __e();
217 } while (__u >= __rp);
218 return static_cast<result_type>(__u + __p.a());
219}
220
221template <class _CharT, class _Traits, class _IT>
222_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
223operator<<(basic_ostream<_CharT, _Traits>& __os, const uniform_int_distribution<_IT>& __x) {
224 __save_flags<_CharT, _Traits> __lx(__os);
225 typedef basic_ostream<_CharT, _Traits> _Ostream;
226 __os.flags(_Ostream::dec | _Ostream::left);
227 _CharT __sp = __os.widen(' ');
228 __os.fill(__sp);
229 return __os << __x.a() << __sp << __x.b();
230}
231
232template <class _CharT, class _Traits, class _IT>
233_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
234operator>>(basic_istream<_CharT, _Traits>& __is, uniform_int_distribution<_IT>& __x) {
235 typedef uniform_int_distribution<_IT> _Eng;
236 typedef typename _Eng::result_type result_type;
237 typedef typename _Eng::param_type param_type;
238 __save_flags<_CharT, _Traits> __lx(__is);
239 typedef basic_istream<_CharT, _Traits> _Istream;
240 __is.flags(_Istream::dec | _Istream::skipws);
241 result_type __a;
242 result_type __b;
243 __is >> __a >> __b;
244 if (!__is.fail())
245 __x.param(param_type(__a, __b));
246 return __is;
247}
248
249_LIBCPP_END_NAMESPACE_STD
250
251_LIBCPP_POP_MACROS
252
253#endif // _LIBCPP___CXX03___RANDOM_UNIFORM_INT_DISTRIBUTION_H
254

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source code of libcxx/include/__cxx03/__random/uniform_int_distribution.h