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_INDEPENDENT_BITS_ENGINE_H
10 #define _LIBCPP___CXX03___RANDOM_INDEPENDENT_BITS_ENGINE_H
11
12 #include <__cxx03/__config>
13 #include <__cxx03/__fwd/istream.h>
14 #include <__cxx03/__fwd/ostream.h>
15 #include <__cxx03/__random/is_seed_sequence.h>
16 #include <__cxx03/__random/log2.h>
17 #include <__cxx03/__type_traits/conditional.h>
18 #include <__cxx03/__type_traits/enable_if.h>
19 #include <__cxx03/__type_traits/is_convertible.h>
20 #include <__cxx03/__utility/move.h>
21 #include <__cxx03/cstddef>
22 #include <__cxx03/limits>
23
24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
25 # pragma GCC system_header
26 #endif
27
28 _LIBCPP_PUSH_MACROS
29 #include <__cxx03/__undef_macros>
30
31 _LIBCPP_BEGIN_NAMESPACE_STD
32
33 template <class _Engine, size_t __w, class _UIntType>
34 class _LIBCPP_TEMPLATE_VIS independent_bits_engine {
35 template <class _UInt, _UInt _R0, size_t _Wp, size_t _Mp>
36 class __get_n {
37 static const size_t _Dt = numeric_limits<_UInt>::digits;
38 static const size_t _Np = _Wp / _Mp + (_Wp % _Mp != 0);
39 static const size_t _W0 = _Wp / _Np;
40 static const _UInt _Y0 = _W0 >= _Dt ? 0 : (_R0 >> _W0) << _W0;
41
42 public:
43 static const size_t value = _R0 - _Y0 > _Y0 / _Np ? _Np + 1 : _Np;
44 };
45
46 public:
47 // types
48 typedef _UIntType result_type;
49
50 private:
51 _Engine __e_;
52
53 static const result_type _Dt = numeric_limits<result_type>::digits;
54 static_assert(0 < __w, "independent_bits_engine invalid parameters");
55 static_assert(__w <= _Dt, "independent_bits_engine invalid parameters");
56
57 typedef typename _Engine::result_type _Engine_result_type;
58 typedef __conditional_t<sizeof(_Engine_result_type) <= sizeof(result_type), result_type, _Engine_result_type>
59 _Working_result_type;
60 static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min + _Working_result_type(1);
61 static const size_t __m = __log2<_Working_result_type, _Rp>::value;
62 static const size_t __n = __get_n<_Working_result_type, _Rp, __w, __m>::value;
63 static const size_t __w0 = __w / __n;
64 static const size_t __n0 = __n - __w % __n;
65 static const size_t _WDt = numeric_limits<_Working_result_type>::digits;
66 static const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
67 static const _Working_result_type __y0 = __w0 >= _WDt ? 0 : (_Rp >> __w0) << __w0;
68 static const _Working_result_type __y1 = __w0 >= _WDt - 1 ? 0 : (_Rp >> (__w0 + 1)) << (__w0 + 1);
69 static const _Engine_result_type
70 __mask0 = __w0 > 0 ? _Engine_result_type(~0) >> (_EDt - __w0) : _Engine_result_type(0);
71 static const _Engine_result_type
72 __mask1 = __w0 < _EDt - 1 ? _Engine_result_type(~0) >> (_EDt - (__w0 + 1)) : _Engine_result_type(~0);
73
74 public:
75 static const result_type _Min = 0;
76 static const result_type _Max = __w == _Dt ? result_type(~0) : (result_type(1) << __w) - result_type(1);
77 static_assert(_Min < _Max, "independent_bits_engine invalid parameters");
78
79 // engine characteristics
min()80 _LIBCPP_HIDE_FROM_ABI static result_type min() { return _Min; }
max()81 _LIBCPP_HIDE_FROM_ABI static result_type max() { return _Max; }
82
83 // constructors and seeding functions
independent_bits_engine()84 _LIBCPP_HIDE_FROM_ABI independent_bits_engine() {}
independent_bits_engine(const _Engine & __e)85 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(const _Engine& __e) : __e_(__e) {}
independent_bits_engine(result_type __sd)86 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(result_type __sd) : __e_(__sd) {}
87 template <
88 class _Sseq,
89 __enable_if_t<__is_seed_sequence<_Sseq, independent_bits_engine>::value && !is_convertible<_Sseq, _Engine>::value,
90 int> = 0>
independent_bits_engine(_Sseq & __q)91 _LIBCPP_HIDE_FROM_ABI explicit independent_bits_engine(_Sseq& __q) : __e_(__q) {}
seed()92 _LIBCPP_HIDE_FROM_ABI void seed() { __e_.seed(); }
seed(result_type __sd)93 _LIBCPP_HIDE_FROM_ABI void seed(result_type __sd) { __e_.seed(__sd); }
94 template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, independent_bits_engine>::value, int> = 0>
seed(_Sseq & __q)95 _LIBCPP_HIDE_FROM_ABI void seed(_Sseq& __q) {
96 __e_.seed(__q);
97 }
98
99 // generating functions
operator()100 _LIBCPP_HIDE_FROM_ABI result_type operator()() { return __eval(integral_constant<bool, _Rp != 0>()); }
discard(unsigned long long __z)101 _LIBCPP_HIDE_FROM_ABI void discard(unsigned long long __z) {
102 for (; __z; --__z)
103 operator()();
104 }
105
106 // property functions
base()107 _LIBCPP_HIDE_FROM_ABI const _Engine& base() const _NOEXCEPT { return __e_; }
108
109 template <class _Eng, size_t _Wp, class _UInt>
110 friend bool operator==(const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
111 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);
112
113 template <class _Eng, size_t _Wp, class _UInt>
114 friend bool operator!=(const independent_bits_engine<_Eng, _Wp, _UInt>& __x,
115 const independent_bits_engine<_Eng, _Wp, _UInt>& __y);
116
117 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>
118 friend basic_ostream<_CharT, _Traits>&
119 operator<<(basic_ostream<_CharT, _Traits>& __os, const independent_bits_engine<_Eng, _Wp, _UInt>& __x);
120
121 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>
122 friend basic_istream<_CharT, _Traits>&
123 operator>>(basic_istream<_CharT, _Traits>& __is, independent_bits_engine<_Eng, _Wp, _UInt>& __x);
124
125 private:
126 _LIBCPP_HIDE_FROM_ABI result_type __eval(false_type);
127 _LIBCPP_HIDE_FROM_ABI result_type __eval(true_type);
128
129 template <size_t __count,
130 __enable_if_t<__count< _Dt, int> = 0> _LIBCPP_HIDE_FROM_ABI static result_type __lshift(result_type __x) {
131 return __x << __count;
132 }
133
134 template <size_t __count, __enable_if_t<(__count >= _Dt), int> = 0>
__lshift(result_type)135 _LIBCPP_HIDE_FROM_ABI static result_type __lshift(result_type) {
136 return result_type(0);
137 }
138 };
139
140 template <class _Engine, size_t __w, class _UIntType>
__eval(false_type)141 inline _UIntType independent_bits_engine<_Engine, __w, _UIntType>::__eval(false_type) {
142 return static_cast<result_type>(__e_() & __mask0);
143 }
144
145 template <class _Engine, size_t __w, class _UIntType>
__eval(true_type)146 _UIntType independent_bits_engine<_Engine, __w, _UIntType>::__eval(true_type) {
147 result_type __sp = 0;
148 for (size_t __k = 0; __k < __n0; ++__k) {
149 _Engine_result_type __u;
150 do {
151 __u = __e_() - _Engine::min();
152 } while (__u >= __y0);
153 __sp = static_cast<result_type>(__lshift<__w0>(__sp) + (__u & __mask0));
154 }
155 for (size_t __k = __n0; __k < __n; ++__k) {
156 _Engine_result_type __u;
157 do {
158 __u = __e_() - _Engine::min();
159 } while (__u >= __y1);
160 __sp = static_cast<result_type>(__lshift<__w0 + 1>(__sp) + (__u & __mask1));
161 }
162 return __sp;
163 }
164
165 template <class _Eng, size_t _Wp, class _UInt>
166 inline _LIBCPP_HIDE_FROM_ABI bool
167 operator==(const independent_bits_engine<_Eng, _Wp, _UInt>& __x, const independent_bits_engine<_Eng, _Wp, _UInt>& __y) {
168 return __x.base() == __y.base();
169 }
170
171 template <class _Eng, size_t _Wp, class _UInt>
172 inline _LIBCPP_HIDE_FROM_ABI bool
173 operator!=(const independent_bits_engine<_Eng, _Wp, _UInt>& __x, const independent_bits_engine<_Eng, _Wp, _UInt>& __y) {
174 return !(__x == __y);
175 }
176
177 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>
178 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
179 operator<<(basic_ostream<_CharT, _Traits>& __os, const independent_bits_engine<_Eng, _Wp, _UInt>& __x) {
180 return __os << __x.base();
181 }
182
183 template <class _CharT, class _Traits, class _Eng, size_t _Wp, class _UInt>
184 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
185 operator>>(basic_istream<_CharT, _Traits>& __is, independent_bits_engine<_Eng, _Wp, _UInt>& __x) {
186 _Eng __e;
187 __is >> __e;
188 if (!__is.fail())
189 __x.__e_ = __e;
190 return __is;
191 }
192
193 _LIBCPP_END_NAMESPACE_STD
194
195 _LIBCPP_POP_MACROS
196
197 #endif // _LIBCPP___CXX03___RANDOM_INDEPENDENT_BITS_ENGINE_H
198