]> git.ipfire.org Git - thirdparty/gcc.git/blame - libstdc++-v3/include/std/ratio
PR libstdc++/36104 part four
[thirdparty/gcc.git] / libstdc++-v3 / include / std / ratio
CommitLineData
5b9daa7e 1// ratio -*- C++ -*-
4acedca1 2
ab65a4c7 3// Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.
4acedca1
CF
4//
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
748086b7 8// Free Software Foundation; either version 3, or (at your option)
4acedca1
CF
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
748086b7
JJ
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
4acedca1 19
748086b7
JJ
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
4acedca1 24
f910786b 25/** @file include/ratio
4acedca1
CF
26 * This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_RATIO
30#define _GLIBCXX_RATIO 1
31
32#pragma GCC system_header
33
34#ifndef __GXX_EXPERIMENTAL_CXX0X__
ab65a4c7 35# include <bits/c++0x_warning.h>
4acedca1
CF
36#else
37
38#include <type_traits>
39#include <cstdint>
40
41#ifdef _GLIBCXX_USE_C99_STDINT_TR1
42
12ffa228
BK
43namespace std _GLIBCXX_VISIBILITY(default)
44{
45_GLIBCXX_BEGIN_NAMESPACE_VERSION
53dc5044 46
5b9daa7e
BK
47 /**
48 * @defgroup ratio Rational Arithmetic
49 * @ingroup utilities
50 *
79e2c7b0 51 * Compile time representation of finite rational numbers.
5b9daa7e
BK
52 * @{
53 */
54
4acedca1
CF
55 template<intmax_t _Pn>
56 struct __static_sign
57 : integral_constant<intmax_t, (_Pn < 0) ? -1 : 1>
58 { };
59
60 template<intmax_t _Pn>
61 struct __static_abs
62 : integral_constant<intmax_t, _Pn * __static_sign<_Pn>::value>
63 { };
64
65 template<intmax_t _Pn, intmax_t _Qn>
66 struct __static_gcd;
67
68 template<intmax_t _Pn, intmax_t _Qn>
69 struct __static_gcd
70 : __static_gcd<_Qn, (_Pn % _Qn)>
71 { };
72
73 template<intmax_t _Pn>
74 struct __static_gcd<_Pn, 0>
75 : integral_constant<intmax_t, __static_abs<_Pn>::value>
76 { };
77
78 template<intmax_t _Qn>
79 struct __static_gcd<0, _Qn>
80 : integral_constant<intmax_t, __static_abs<_Qn>::value>
81 { };
82
83 // Let c = 2^(half # of bits in an intmax_t)
84 // then we find a1, a0, b1, b0 s.t. N = a1*c + a0, M = b1*c + b0
85 // The multiplication of N and M becomes,
86 // N * M = (a1 * b1)c^2 + (a0 * b1 + b0 * a1)c + a0 * b0
87 // Multiplication is safe if each term and the sum of the terms
88 // is representable by intmax_t.
89 template<intmax_t _Pn, intmax_t _Qn>
90 struct __safe_multiply
91 {
92 private:
93 static const uintmax_t __c = uintmax_t(1) << (sizeof(intmax_t) * 4);
94
95 static const uintmax_t __a0 = __static_abs<_Pn>::value % __c;
96 static const uintmax_t __a1 = __static_abs<_Pn>::value / __c;
97 static const uintmax_t __b0 = __static_abs<_Qn>::value % __c;
98 static const uintmax_t __b1 = __static_abs<_Qn>::value / __c;
99
100 static_assert(__a1 == 0 || __b1 == 0,
101 "overflow in multiplication");
102 static_assert(__a0 * __b1 + __b0 * __a1 < (__c >> 1),
103 "overflow in multiplication");
ea31932d 104 static_assert(__b0 * __a0 <= __INTMAX_MAX__,
4acedca1
CF
105 "overflow in multiplication");
106 static_assert((__a0 * __b1 + __b0 * __a1) * __c <=
ea31932d 107 __INTMAX_MAX__ - __b0 * __a0, "overflow in multiplication");
4acedca1
CF
108
109 public:
110 static const intmax_t value = _Pn * _Qn;
111 };
112
113 // Helpers for __safe_add
114 template<intmax_t _Pn, intmax_t _Qn, bool>
115 struct __add_overflow_check_impl
ea31932d 116 : integral_constant<bool, (_Pn <= __INTMAX_MAX__ - _Qn)>
4acedca1
CF
117 { };
118
119 template<intmax_t _Pn, intmax_t _Qn>
120 struct __add_overflow_check_impl<_Pn, _Qn, false>
ea31932d 121 : integral_constant<bool, (_Pn >= -__INTMAX_MAX__ - _Qn)>
4acedca1
CF
122 { };
123
124 template<intmax_t _Pn, intmax_t _Qn>
125 struct __add_overflow_check
126 : __add_overflow_check_impl<_Pn, _Qn, (_Qn >= 0)>
127 { };
128
129 template<intmax_t _Pn, intmax_t _Qn>
130 struct __safe_add
131 {
132 static_assert(__add_overflow_check<_Pn, _Qn>::value != 0,
133 "overflow in addition");
134
135 static const intmax_t value = _Pn + _Qn;
136 };
137
ea31932d
PC
138 /**
139 * @brief Provides compile-time rational arithmetic.
5b9daa7e 140 *
ea31932d
PC
141 * This class template represents any finite rational number with a
142 * numerator and denominator representable by compile-time constants of
143 * type intmax_t. The ratio is simplified when instantiated.
144 *
145 * For example:
146 * @code
147 * std::ratio<7,-21>::num == -1;
148 * std::ratio<7,-21>::den == 3;
149 * @endcode
150 *
151 */
4acedca1
CF
152 template<intmax_t _Num, intmax_t _Den = 1>
153 struct ratio
154 {
155 static_assert(_Den != 0, "denominator cannot be zero");
ea31932d
PC
156 static_assert(_Num >= -__INTMAX_MAX__ && _Den >= -__INTMAX_MAX__,
157 "out of range");
158
4acedca1 159 // Note: sign(N) * abs(N) == N
94a86be0 160 static constexpr intmax_t num =
4acedca1
CF
161 _Num * __static_sign<_Den>::value / __static_gcd<_Num, _Den>::value;
162
94a86be0 163 static constexpr intmax_t den =
4acedca1 164 __static_abs<_Den>::value / __static_gcd<_Num, _Den>::value;
e1d4e035
PC
165
166 typedef ratio<num, den> type;
4acedca1
CF
167 };
168
169 template<intmax_t _Num, intmax_t _Den>
94a86be0 170 constexpr intmax_t ratio<_Num, _Den>::num;
4acedca1
CF
171
172 template<intmax_t _Num, intmax_t _Den>
94a86be0 173 constexpr intmax_t ratio<_Num, _Den>::den;
4acedca1 174
ad68e9fc 175 /// ratio_add
4acedca1
CF
176 template<typename _R1, typename _R2>
177 struct ratio_add
178 {
179 private:
180 static const intmax_t __gcd =
181 __static_gcd<_R1::den, _R2::den>::value;
182
183 public:
184 typedef ratio<
185 __safe_add<
186 __safe_multiply<_R1::num, (_R2::den / __gcd)>::value,
187 __safe_multiply<_R2::num, (_R1::den / __gcd)>::value>::value,
188 __safe_multiply<_R1::den, (_R2::den / __gcd)>::value> type;
e1d4e035 189
76d0be83
PC
190 static constexpr intmax_t num = type::num;
191 static constexpr intmax_t den = type::den;
4acedca1
CF
192 };
193
e1d4e035 194 template<typename _R1, typename _R2>
76d0be83 195 constexpr intmax_t ratio_add<_R1, _R2>::num;
e1d4e035
PC
196
197 template<typename _R1, typename _R2>
76d0be83 198 constexpr intmax_t ratio_add<_R1, _R2>::den;
e1d4e035 199
ad68e9fc 200 /// ratio_subtract
4acedca1
CF
201 template<typename _R1, typename _R2>
202 struct ratio_subtract
203 {
204 typedef typename ratio_add<
205 _R1,
206 ratio<-_R2::num, _R2::den>>::type type;
e1d4e035 207
76d0be83
PC
208 static constexpr intmax_t num = type::num;
209 static constexpr intmax_t den = type::den;
4acedca1
CF
210 };
211
e1d4e035 212 template<typename _R1, typename _R2>
76d0be83 213 constexpr intmax_t ratio_subtract<_R1, _R2>::num;
e1d4e035
PC
214
215 template<typename _R1, typename _R2>
76d0be83 216 constexpr intmax_t ratio_subtract<_R1, _R2>::den;
e1d4e035 217
ad68e9fc 218 /// ratio_multiply
4acedca1
CF
219 template<typename _R1, typename _R2>
220 struct ratio_multiply
221 {
222 private:
223 static const intmax_t __gcd1 =
224 __static_gcd<_R1::num, _R2::den>::value;
225 static const intmax_t __gcd2 =
226 __static_gcd<_R2::num, _R1::den>::value;
227
228 public:
229 typedef ratio<
230 __safe_multiply<(_R1::num / __gcd1),
231 (_R2::num / __gcd2)>::value,
232 __safe_multiply<(_R1::den / __gcd2),
233 (_R2::den / __gcd1)>::value> type;
e1d4e035 234
76d0be83
PC
235 static constexpr intmax_t num = type::num;
236 static constexpr intmax_t den = type::den;
4acedca1
CF
237 };
238
e1d4e035 239 template<typename _R1, typename _R2>
76d0be83 240 constexpr intmax_t ratio_multiply<_R1, _R2>::num;
e1d4e035
PC
241
242 template<typename _R1, typename _R2>
76d0be83 243 constexpr intmax_t ratio_multiply<_R1, _R2>::den;
e1d4e035 244
ad68e9fc 245 /// ratio_divide
4acedca1
CF
246 template<typename _R1, typename _R2>
247 struct ratio_divide
248 {
249 static_assert(_R2::num != 0, "division by 0");
250
251 typedef typename ratio_multiply<
252 _R1,
253 ratio<_R2::den, _R2::num>>::type type;
e1d4e035 254
76d0be83
PC
255 static constexpr intmax_t num = type::num;
256 static constexpr intmax_t den = type::den;
4acedca1
CF
257 };
258
e1d4e035 259 template<typename _R1, typename _R2>
76d0be83 260 constexpr intmax_t ratio_divide<_R1, _R2>::num;
e1d4e035
PC
261
262 template<typename _R1, typename _R2>
76d0be83 263 constexpr intmax_t ratio_divide<_R1, _R2>::den;
e1d4e035 264
ad68e9fc 265 /// ratio_equal
4acedca1
CF
266 template<typename _R1, typename _R2>
267 struct ratio_equal
268 : integral_constant<bool, _R1::num == _R2::num && _R1::den == _R2::den>
269 { };
270
ad68e9fc 271 /// ratio_not_equal
4acedca1
CF
272 template<typename _R1, typename _R2>
273 struct ratio_not_equal
274 : integral_constant<bool, !ratio_equal<_R1, _R2>::value>
275 { };
cd6b4a4b
PC
276
277 template<typename _R1>
278 struct __ratio_less_impl_1
279 : integral_constant<bool, _R1::num < _R1::den>
280 { };
281
282 template<typename _R1, typename _R2,
283 bool = (_R1::num == 0 || _R2::num == 0
284 || (__static_sign<_R1::num>::value
285 != __static_sign<_R2::num>::value)),
286 bool = (__static_sign<_R1::num>::value == -1
287 && __static_sign<_R2::num>::value == -1)>
288 struct __ratio_less_impl
289 : __ratio_less_impl_1<typename ratio_divide<_R1, _R2>::type>::type
290 { };
291
4acedca1 292 template<typename _R1, typename _R2>
cd6b4a4b
PC
293 struct __ratio_less_impl<_R1, _R2, true, false>
294 : integral_constant<bool, _R1::num < _R2::num>
ea31932d
PC
295 { };
296
ea31932d 297 template<typename _R1, typename _R2>
cd6b4a4b
PC
298 struct __ratio_less_impl<_R1, _R2, false, true>
299 : __ratio_less_impl_1<typename ratio_divide<_R2, _R1>::type>::type
ea31932d
PC
300 { };
301
ad68e9fc 302 /// ratio_less
ea31932d
PC
303 template<typename _R1, typename _R2>
304 struct ratio_less
305 : __ratio_less_impl<_R1, _R2>::type
4acedca1
CF
306 { };
307
ad68e9fc 308 /// ratio_less_equal
4acedca1
CF
309 template<typename _R1, typename _R2>
310 struct ratio_less_equal
311 : integral_constant<bool, !ratio_less<_R2, _R1>::value>
312 { };
313
ad68e9fc 314 /// ratio_greater
4acedca1
CF
315 template<typename _R1, typename _R2>
316 struct ratio_greater
317 : integral_constant<bool, ratio_less<_R2, _R1>::value>
318 { };
319
ad68e9fc 320 /// ratio_greater_equal
4acedca1
CF
321 template<typename _R1, typename _R2>
322 struct ratio_greater_equal
323 : integral_constant<bool, !ratio_less<_R1, _R2>::value>
324 { };
325
326 typedef ratio<1, 1000000000000000000> atto;
327 typedef ratio<1, 1000000000000000> femto;
328 typedef ratio<1, 1000000000000> pico;
329 typedef ratio<1, 1000000000> nano;
330 typedef ratio<1, 1000000> micro;
331 typedef ratio<1, 1000> milli;
332 typedef ratio<1, 100> centi;
333 typedef ratio<1, 10> deci;
334 typedef ratio< 10, 1> deca;
335 typedef ratio< 100, 1> hecto;
336 typedef ratio< 1000, 1> kilo;
337 typedef ratio< 1000000, 1> mega;
338 typedef ratio< 1000000000, 1> giga;
339 typedef ratio< 1000000000000, 1> tera;
340 typedef ratio< 1000000000000000, 1> peta;
341 typedef ratio< 1000000000000000000, 1> exa;
5b9daa7e
BK
342
343 // @} group ratio
12ffa228
BK
344_GLIBCXX_END_NAMESPACE_VERSION
345} // namespace
4acedca1
CF
346
347#endif //_GLIBCXX_USE_C99_STDINT_TR1
348
349#endif //__GXX_EXPERIMENTAL_CXX0X__
350
351#endif //_GLIBCXX_RATIO