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