1 | // -*- C++ -*- |
2 | //===------------------------------ bit ----------------------------------===// |
3 | // |
4 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
5 | // See https://llvm.org/LICENSE.txt for license information. |
6 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
7 | // |
8 | //===---------------------------------------------------------------------===// |
9 | |
10 | #ifndef _LIBCPP_BIT |
11 | #define _LIBCPP_BIT |
12 | |
13 | /* |
14 | bit synopsis |
15 | |
16 | namespace std { |
17 | |
18 | template <class T> |
19 | constexpr bool ispow2(T x) noexcept; // C++20 |
20 | template <class T> |
21 | constexpr T ceil2(T x); // C++20 |
22 | template <class T> |
23 | constexpr T floor2(T x) noexcept; // C++20 |
24 | template <class T> |
25 | constexpr T log2p1(T x) noexcept; // C++20 |
26 | |
27 | // 23.20.2, rotating |
28 | template<class T> |
29 | constexpr T rotl(T x, unsigned int s) noexcept; // C++20 |
30 | template<class T> |
31 | constexpr T rotr(T x, unsigned int s) noexcept; // C++20 |
32 | |
33 | // 23.20.3, counting |
34 | template<class T> |
35 | constexpr int countl_zero(T x) noexcept; // C++20 |
36 | template<class T> |
37 | constexpr int countl_one(T x) noexcept; // C++20 |
38 | template<class T> |
39 | constexpr int countr_zero(T x) noexcept; // C++20 |
40 | template<class T> |
41 | constexpr int countr_one(T x) noexcept; // C++20 |
42 | template<class T> |
43 | constexpr int popcount(T x) noexcept; // C++20 |
44 | |
45 | // 20.15.9, endian |
46 | enum class endian { |
47 | little = see below, // C++20 |
48 | big = see below, // C++20 |
49 | native = see below // C++20 |
50 | }; |
51 | |
52 | } // namespace std |
53 | |
54 | */ |
55 | |
56 | #include <__config> |
57 | #include <limits> |
58 | #include <type_traits> |
59 | #include <version> |
60 | #include <__debug> |
61 | |
62 | #if defined(__IBMCPP__) |
63 | #include "support/ibm/support.h" |
64 | #endif |
65 | #if defined(_LIBCPP_COMPILER_MSVC) |
66 | #include <intrin.h> |
67 | #endif |
68 | |
69 | #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
70 | #pragma GCC system_header |
71 | #endif |
72 | |
73 | _LIBCPP_PUSH_MACROS |
74 | #include <__undef_macros> |
75 | |
76 | _LIBCPP_BEGIN_NAMESPACE_STD |
77 | |
78 | #ifndef _LIBCPP_COMPILER_MSVC |
79 | |
80 | inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
81 | int __libcpp_ctz(unsigned __x) _NOEXCEPT { return __builtin_ctz(__x); } |
82 | |
83 | inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
84 | int __libcpp_ctz(unsigned long __x) _NOEXCEPT { return __builtin_ctzl(__x); } |
85 | |
86 | inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
87 | int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); } |
88 | |
89 | |
90 | inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
91 | int __libcpp_clz(unsigned __x) _NOEXCEPT { return __builtin_clz(__x); } |
92 | |
93 | inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
94 | int __libcpp_clz(unsigned long __x) _NOEXCEPT { return __builtin_clzl(__x); } |
95 | |
96 | inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
97 | int __libcpp_clz(unsigned long long __x) _NOEXCEPT { return __builtin_clzll(__x); } |
98 | |
99 | |
100 | inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
101 | int __libcpp_popcount(unsigned __x) _NOEXCEPT { return __builtin_popcount(__x); } |
102 | |
103 | inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
104 | int __libcpp_popcount(unsigned long __x) _NOEXCEPT { return __builtin_popcountl(__x); } |
105 | |
106 | inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
107 | int __libcpp_popcount(unsigned long long __x) _NOEXCEPT { return __builtin_popcountll(__x); } |
108 | |
109 | #else // _LIBCPP_COMPILER_MSVC |
110 | |
111 | // Precondition: __x != 0 |
112 | inline _LIBCPP_INLINE_VISIBILITY |
113 | int __libcpp_ctz(unsigned __x) { |
114 | static_assert(sizeof(unsigned) == sizeof(unsigned long), "" ); |
115 | static_assert(sizeof(unsigned long) == 4, "" ); |
116 | unsigned long __where; |
117 | if (_BitScanForward(&__where, __x)) |
118 | return static_cast<int>(__where); |
119 | return 32; |
120 | } |
121 | |
122 | inline _LIBCPP_INLINE_VISIBILITY |
123 | int __libcpp_ctz(unsigned long __x) { |
124 | static_assert(sizeof(unsigned long) == sizeof(unsigned), "" ); |
125 | return __ctz(static_cast<unsigned>(__x)); |
126 | } |
127 | |
128 | inline _LIBCPP_INLINE_VISIBILITY |
129 | int __libcpp_ctz(unsigned long long __x) { |
130 | unsigned long __where; |
131 | #if defined(_LIBCPP_HAS_BITSCAN64) |
132 | (defined(_M_AMD64) || defined(__x86_64__)) |
133 | if (_BitScanForward64(&__where, __x)) |
134 | return static_cast<int>(__where); |
135 | #else |
136 | // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls. |
137 | if (_BitScanForward(&__where, static_cast<unsigned long>(__x))) |
138 | return static_cast<int>(__where); |
139 | if (_BitScanForward(&__where, static_cast<unsigned long>(__x >> 32))) |
140 | return static_cast<int>(__where + 32); |
141 | #endif |
142 | return 64; |
143 | } |
144 | |
145 | // Precondition: __x != 0 |
146 | inline _LIBCPP_INLINE_VISIBILITY |
147 | int __libcpp_clz(unsigned __x) { |
148 | static_assert(sizeof(unsigned) == sizeof(unsigned long), "" ); |
149 | static_assert(sizeof(unsigned long) == 4, "" ); |
150 | unsigned long __where; |
151 | if (_BitScanReverse(&__where, __x)) |
152 | return static_cast<int>(31 - __where); |
153 | return 32; // Undefined Behavior. |
154 | } |
155 | |
156 | inline _LIBCPP_INLINE_VISIBILITY |
157 | int __libcpp_clz(unsigned long __x) { |
158 | static_assert(sizeof(unsigned) == sizeof(unsigned long), "" ); |
159 | return __libcpp_clz(static_cast<unsigned>(__x)); |
160 | } |
161 | |
162 | inline _LIBCPP_INLINE_VISIBILITY |
163 | int __libcpp_clz(unsigned long long __x) { |
164 | unsigned long __where; |
165 | #if defined(_LIBCPP_HAS_BITSCAN64) |
166 | if (_BitScanReverse64(&__where, __x)) |
167 | return static_cast<int>(63 - __where); |
168 | #else |
169 | // Win32 doesn't have _BitScanReverse64 so emulate it with two 32 bit calls. |
170 | if (_BitScanReverse(&__where, static_cast<unsigned long>(__x >> 32))) |
171 | return static_cast<int>(63 - (__where + 32)); |
172 | if (_BitScanReverse(&__where, static_cast<unsigned long>(__x))) |
173 | return static_cast<int>(63 - __where); |
174 | #endif |
175 | return 64; // Undefined Behavior. |
176 | } |
177 | |
178 | inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned __x) { |
179 | static_assert(sizeof(unsigned) == 4, "" ); |
180 | return __popcnt(__x); |
181 | } |
182 | |
183 | inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long __x) { |
184 | static_assert(sizeof(unsigned long) == 4, "" ); |
185 | return __popcnt(__x); |
186 | } |
187 | |
188 | inline _LIBCPP_INLINE_VISIBILITY int __libcpp_popcount(unsigned long long __x) { |
189 | static_assert(sizeof(unsigned long long) == 8, "" ); |
190 | return __popcnt64(__x); |
191 | } |
192 | |
193 | #endif // _LIBCPP_COMPILER_MSVC |
194 | |
195 | template <class _Tp> |
196 | using __bitop_unsigned_integer _LIBCPP_NODEBUG_TYPE = integral_constant<bool, |
197 | is_integral<_Tp>::value && |
198 | is_unsigned<_Tp>::value && |
199 | _IsNotSame<typename remove_cv<_Tp>::type, bool>::value && |
200 | _IsNotSame<typename remove_cv<_Tp>::type, signed char>::value && |
201 | _IsNotSame<typename remove_cv<_Tp>::type, wchar_t>::value && |
202 | _IsNotSame<typename remove_cv<_Tp>::type, char16_t>::value && |
203 | _IsNotSame<typename remove_cv<_Tp>::type, char32_t>::value |
204 | >; |
205 | |
206 | |
207 | template<class _Tp> |
208 | _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 |
209 | _Tp __rotl(_Tp __t, unsigned int __cnt) _NOEXCEPT |
210 | { |
211 | static_assert(__bitop_unsigned_integer<_Tp>::value, "__rotl requires unsigned" ); |
212 | const unsigned int __dig = numeric_limits<_Tp>::digits; |
213 | if ((__cnt % __dig) == 0) |
214 | return __t; |
215 | return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig))); |
216 | } |
217 | |
218 | |
219 | template<class _Tp> |
220 | _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 |
221 | _Tp __rotr(_Tp __t, unsigned int __cnt) _NOEXCEPT |
222 | { |
223 | static_assert(__bitop_unsigned_integer<_Tp>::value, "__rotr requires unsigned" ); |
224 | const unsigned int __dig = numeric_limits<_Tp>::digits; |
225 | if ((__cnt % __dig) == 0) |
226 | return __t; |
227 | return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig))); |
228 | } |
229 | |
230 | |
231 | |
232 | template<class _Tp> |
233 | _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 |
234 | int __countr_zero(_Tp __t) _NOEXCEPT |
235 | { |
236 | static_assert(__bitop_unsigned_integer<_Tp>::value, "__countr_zero requires unsigned" ); |
237 | if (__t == 0) |
238 | return numeric_limits<_Tp>::digits; |
239 | |
240 | if (sizeof(_Tp) <= sizeof(unsigned int)) |
241 | return __libcpp_ctz(static_cast<unsigned int>(__t)); |
242 | else if (sizeof(_Tp) <= sizeof(unsigned long)) |
243 | return __libcpp_ctz(static_cast<unsigned long>(__t)); |
244 | else if (sizeof(_Tp) <= sizeof(unsigned long long)) |
245 | return __libcpp_ctz(static_cast<unsigned long long>(__t)); |
246 | else |
247 | { |
248 | int __ret = 0; |
249 | int __iter = 0; |
250 | const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits; |
251 | while ((__iter = __libcpp_ctz(static_cast<unsigned long long>(__t))) == __ulldigits) |
252 | { |
253 | __ret += __iter; |
254 | __t >>= __ulldigits; |
255 | } |
256 | return __ret + __iter; |
257 | } |
258 | } |
259 | |
260 | template<class _Tp> |
261 | _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 |
262 | int __countl_zero(_Tp __t) _NOEXCEPT |
263 | { |
264 | static_assert(__bitop_unsigned_integer<_Tp>::value, "__countl_zero requires unsigned" ); |
265 | if (__t == 0) |
266 | return numeric_limits<_Tp>::digits; |
267 | |
268 | if (sizeof(_Tp) <= sizeof(unsigned int)) |
269 | return __libcpp_clz(static_cast<unsigned int>(__t)) |
270 | - (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits); |
271 | else if (sizeof(_Tp) <= sizeof(unsigned long)) |
272 | return __libcpp_clz(static_cast<unsigned long>(__t)) |
273 | - (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits); |
274 | else if (sizeof(_Tp) <= sizeof(unsigned long long)) |
275 | return __libcpp_clz(static_cast<unsigned long long>(__t)) |
276 | - (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits); |
277 | else |
278 | { |
279 | int __ret = 0; |
280 | int __iter = 0; |
281 | const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits; |
282 | while (true) { |
283 | __t = __rotr(__t, __ulldigits); |
284 | if ((__iter = __countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits) |
285 | break; |
286 | __ret += __iter; |
287 | } |
288 | return __ret + __iter; |
289 | } |
290 | } |
291 | |
292 | template<class _Tp> |
293 | _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 |
294 | int __countl_one(_Tp __t) _NOEXCEPT |
295 | { |
296 | static_assert(__bitop_unsigned_integer<_Tp>::value, "__countl_one requires unsigned" ); |
297 | return __t != numeric_limits<_Tp>::max() |
298 | ? __countl_zero(static_cast<_Tp>(~__t)) |
299 | : numeric_limits<_Tp>::digits; |
300 | } |
301 | |
302 | |
303 | template<class _Tp> |
304 | _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 |
305 | int __countr_one(_Tp __t) _NOEXCEPT |
306 | { |
307 | static_assert(__bitop_unsigned_integer<_Tp>::value, "__countr_one requires unsigned" ); |
308 | return __t != numeric_limits<_Tp>::max() |
309 | ? __countr_zero(static_cast<_Tp>(~__t)) |
310 | : numeric_limits<_Tp>::digits; |
311 | } |
312 | |
313 | |
314 | template<class _Tp> |
315 | _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 |
316 | int |
317 | __popcount(_Tp __t) _NOEXCEPT |
318 | { |
319 | static_assert(__bitop_unsigned_integer<_Tp>::value, "__libcpp_popcount requires unsigned" ); |
320 | if (sizeof(_Tp) <= sizeof(unsigned int)) |
321 | return __libcpp_popcount(static_cast<unsigned int>(__t)); |
322 | else if (sizeof(_Tp) <= sizeof(unsigned long)) |
323 | return __libcpp_popcount(static_cast<unsigned long>(__t)); |
324 | else if (sizeof(_Tp) <= sizeof(unsigned long long)) |
325 | return __libcpp_popcount(static_cast<unsigned long long>(__t)); |
326 | else |
327 | { |
328 | int __ret = 0; |
329 | while (__t != 0) |
330 | { |
331 | __ret += __libcpp_popcount(static_cast<unsigned long long>(__t)); |
332 | __t >>= numeric_limits<unsigned long long>::digits; |
333 | } |
334 | return __ret; |
335 | } |
336 | } |
337 | |
338 | |
339 | // integral log base 2 |
340 | template<class _Tp> |
341 | _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 |
342 | unsigned __bit_log2(_Tp __t) _NOEXCEPT |
343 | { |
344 | static_assert(__bitop_unsigned_integer<_Tp>::value, "__bit_log2 requires unsigned" ); |
345 | return std::numeric_limits<_Tp>::digits - 1 - __countl_zero(__t); |
346 | } |
347 | |
348 | template <class _Tp> |
349 | _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR |
350 | bool __ispow2(_Tp __t) _NOEXCEPT |
351 | { |
352 | static_assert(__bitop_unsigned_integer<_Tp>::value, "__ispow2 requires unsigned" ); |
353 | return __t != 0 && (((__t & (__t - 1)) == 0)); |
354 | } |
355 | |
356 | |
357 | #if _LIBCPP_STD_VER > 17 |
358 | |
359 | template<class _Tp> |
360 | _LIBCPP_INLINE_VISIBILITY constexpr |
361 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp> |
362 | rotl(_Tp __t, unsigned int __cnt) noexcept |
363 | { |
364 | return __rotl(__t, __cnt); |
365 | } |
366 | |
367 | |
368 | // rotr |
369 | template<class _Tp> |
370 | _LIBCPP_INLINE_VISIBILITY constexpr |
371 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp> |
372 | rotr(_Tp __t, unsigned int __cnt) noexcept |
373 | { |
374 | return __rotr(__t, __cnt); |
375 | } |
376 | |
377 | |
378 | template<class _Tp> |
379 | _LIBCPP_INLINE_VISIBILITY constexpr |
380 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, int> |
381 | countl_zero(_Tp __t) noexcept |
382 | { |
383 | return __countl_zero(__t); |
384 | } |
385 | |
386 | |
387 | template<class _Tp> |
388 | _LIBCPP_INLINE_VISIBILITY constexpr |
389 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, int> |
390 | countl_one(_Tp __t) noexcept |
391 | { |
392 | return __countl_one(__t); |
393 | } |
394 | |
395 | |
396 | template<class _Tp> |
397 | _LIBCPP_INLINE_VISIBILITY constexpr |
398 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, int> |
399 | countr_zero(_Tp __t) noexcept |
400 | { |
401 | return __countr_zero(__t); |
402 | } |
403 | |
404 | |
405 | template<class _Tp> |
406 | _LIBCPP_INLINE_VISIBILITY constexpr |
407 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, int> |
408 | countr_one(_Tp __t) noexcept |
409 | { |
410 | return __countr_one(__t); |
411 | } |
412 | |
413 | |
414 | template<class _Tp> |
415 | _LIBCPP_INLINE_VISIBILITY constexpr |
416 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, int> |
417 | popcount(_Tp __t) noexcept |
418 | { |
419 | return __popcount(__t); |
420 | } |
421 | |
422 | |
423 | template <class _Tp> |
424 | _LIBCPP_INLINE_VISIBILITY constexpr |
425 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, bool> |
426 | ispow2(_Tp __t) noexcept |
427 | { |
428 | return __ispow2(__t); |
429 | } |
430 | |
431 | template <class _Tp> |
432 | _LIBCPP_INLINE_VISIBILITY constexpr |
433 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp> |
434 | floor2(_Tp __t) noexcept |
435 | { |
436 | return __t == 0 ? 0 : _Tp{1} << __bit_log2(__t); |
437 | } |
438 | |
439 | template <class _Tp> |
440 | _LIBCPP_INLINE_VISIBILITY constexpr |
441 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp> |
442 | ceil2(_Tp __t) noexcept |
443 | { |
444 | if (__t < 2) return 1; |
445 | const unsigned __n = numeric_limits<_Tp>::digits - countl_zero((_Tp)(__t - 1u)); |
446 | _LIBCPP_DEBUG_ASSERT(__libcpp_is_constant_evaluated() || __n != numeric_limits<_Tp>::digits, "Bad input to ceil2" ); |
447 | |
448 | if constexpr (sizeof(_Tp) >= sizeof(unsigned)) |
449 | return _Tp{1} << __n; |
450 | else |
451 | { |
452 | const unsigned __extra = numeric_limits<unsigned>::digits - numeric_limits<_Tp>::digits; |
453 | const unsigned __retVal = 1u << (__n + __extra); |
454 | return (_Tp) (__retVal >> __extra); |
455 | } |
456 | } |
457 | |
458 | template <class _Tp> |
459 | _LIBCPP_INLINE_VISIBILITY constexpr |
460 | enable_if_t<__bitop_unsigned_integer<_Tp>::value, _Tp> |
461 | log2p1(_Tp __t) noexcept |
462 | { |
463 | return __t == 0 ? 0 : __bit_log2(__t) + 1; |
464 | } |
465 | |
466 | |
467 | enum class endian |
468 | { |
469 | little = 0xDEAD, |
470 | big = 0xFACE, |
471 | #if defined(_LIBCPP_LITTLE_ENDIAN) |
472 | native = little |
473 | #elif defined(_LIBCPP_BIG_ENDIAN) |
474 | native = big |
475 | #else |
476 | native = 0xCAFE |
477 | #endif |
478 | }; |
479 | |
480 | #endif // _LIBCPP_STD_VER > 17 |
481 | |
482 | _LIBCPP_END_NAMESPACE_STD |
483 | |
484 | _LIBCPP_POP_MACROS |
485 | |
486 | #endif // _LIBCPP_BIT |
487 | |