1// -*- C++ -*- 2//===----------------------------------------------------------------------===// 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 // [bit.cast], bit_cast 18 template<class To, class From> 19 constexpr To bit_cast(const From& from) noexcept; // C++20 20 21 // [bit.byteswap], byteswap 22 template<class T> 23 constexpr T byteswap(T value) noexcept; // C++23 24 25 // [bit.pow.two], integral powers of 2 26 template <class T> 27 constexpr bool has_single_bit(T x) noexcept; // C++20 28 template <class T> 29 constexpr T bit_ceil(T x); // C++20 30 template <class T> 31 constexpr T bit_floor(T x) noexcept; // C++20 32 template <class T> 33 constexpr int bit_width(T x) noexcept; // C++20 34 35 // [bit.rotate], rotating 36 template<class T> 37 constexpr T rotl(T x, unsigned int s) noexcept; // C++20 38 template<class T> 39 constexpr T rotr(T x, unsigned int s) noexcept; // C++20 40 41 // [bit.count], counting 42 template<class T> 43 constexpr int countl_zero(T x) noexcept; // C++20 44 template<class T> 45 constexpr int countl_one(T x) noexcept; // C++20 46 template<class T> 47 constexpr int countr_zero(T x) noexcept; // C++20 48 template<class T> 49 constexpr int countr_one(T x) noexcept; // C++20 50 template<class T> 51 constexpr int popcount(T x) noexcept; // C++20 52 53 // [bit.endian], endian 54 enum class endian { 55 little = see below, // C++20 56 big = see below, // C++20 57 native = see below // C++20 58 }; 59 60} // namespace std 61 62*/ 63 64#include <__assert> // all public C++ headers provide the assertion handler 65#include <__bit/bit_cast.h> 66#include <__bit/byteswap.h> 67#include <__bits> // __libcpp_clz 68#include <__concepts/arithmetic.h> 69#include <__config> 70#include <limits> 71#include <type_traits> 72#include <version> 73 74#if defined(__IBMCPP__) 75# include "__support/ibm/support.h" 76#endif 77#if defined(_LIBCPP_COMPILER_MSVC) 78# include <intrin.h> 79#endif 80 81#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 82# pragma GCC system_header 83#endif 84 85_LIBCPP_PUSH_MACROS 86#include <__undef_macros> 87 88_LIBCPP_BEGIN_NAMESPACE_STD 89 90template<class _Tp> 91_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11 92_Tp __rotr(_Tp __t, unsigned int __cnt) _NOEXCEPT 93{ 94 static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__rotr requires an unsigned integer type"); 95 const unsigned int __dig = numeric_limits<_Tp>::digits; 96 if ((__cnt % __dig) == 0) 97 return __t; 98 return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig))); 99} 100 101template<class _Tp> 102_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11 103int __countl_zero(_Tp __t) _NOEXCEPT 104{ 105 static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__countl_zero requires an unsigned integer type"); 106 if (__t == 0) 107 return numeric_limits<_Tp>::digits; 108 109 if (sizeof(_Tp) <= sizeof(unsigned int)) 110 return std::__libcpp_clz(static_cast<unsigned int>(__t)) 111 - (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits); 112 else if (sizeof(_Tp) <= sizeof(unsigned long)) 113 return std::__libcpp_clz(static_cast<unsigned long>(__t)) 114 - (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits); 115 else if (sizeof(_Tp) <= sizeof(unsigned long long)) 116 return std::__libcpp_clz(static_cast<unsigned long long>(__t)) 117 - (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits); 118 else 119 { 120 int __ret = 0; 121 int __iter = 0; 122 const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits; 123 while (true) { 124 __t = std::__rotr(__t, __ulldigits); 125 if ((__iter = std::__countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits) 126 break; 127 __ret += __iter; 128 } 129 return __ret + __iter; 130 } 131} 132 133#if _LIBCPP_STD_VER > 17 134 135template <__libcpp_unsigned_integer _Tp> 136_LIBCPP_HIDE_FROM_ABI constexpr _Tp rotl(_Tp __t, unsigned int __cnt) noexcept { 137 const unsigned int __dig = numeric_limits<_Tp>::digits; 138 if ((__cnt % __dig) == 0) 139 return __t; 140 return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig))); 141} 142 143template <__libcpp_unsigned_integer _Tp> 144_LIBCPP_HIDE_FROM_ABI constexpr _Tp rotr(_Tp __t, unsigned int __cnt) noexcept { 145 return std::__rotr(__t, __cnt); 146} 147 148template <__libcpp_unsigned_integer _Tp> 149_LIBCPP_HIDE_FROM_ABI constexpr int countl_zero(_Tp __t) noexcept { 150 return std::__countl_zero(__t); 151} 152 153template <__libcpp_unsigned_integer _Tp> 154_LIBCPP_HIDE_FROM_ABI constexpr int countl_one(_Tp __t) noexcept { 155 return __t != numeric_limits<_Tp>::max() ? std::countl_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits; 156} 157 158template <__libcpp_unsigned_integer _Tp> 159_LIBCPP_HIDE_FROM_ABI constexpr int countr_zero(_Tp __t) noexcept { 160 if (__t == 0) 161 return numeric_limits<_Tp>::digits; 162 163 if (sizeof(_Tp) <= sizeof(unsigned int)) 164 return std::__libcpp_ctz(static_cast<unsigned int>(__t)); 165 else if (sizeof(_Tp) <= sizeof(unsigned long)) 166 return std::__libcpp_ctz(static_cast<unsigned long>(__t)); 167 else if (sizeof(_Tp) <= sizeof(unsigned long long)) 168 return std::__libcpp_ctz(static_cast<unsigned long long>(__t)); 169 else { 170 int __ret = 0; 171 const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits; 172 while (static_cast<unsigned long long>(__t) == 0uLL) { 173 __ret += __ulldigits; 174 __t >>= __ulldigits; 175 } 176 return __ret + std::__libcpp_ctz(static_cast<unsigned long long>(__t)); 177 } 178} 179 180template <__libcpp_unsigned_integer _Tp> 181_LIBCPP_HIDE_FROM_ABI constexpr int countr_one(_Tp __t) noexcept { 182 return __t != numeric_limits<_Tp>::max() ? std::countr_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits; 183} 184 185template <__libcpp_unsigned_integer _Tp> 186_LIBCPP_HIDE_FROM_ABI constexpr int popcount(_Tp __t) noexcept { 187 if (sizeof(_Tp) <= sizeof(unsigned int)) 188 return std::__libcpp_popcount(static_cast<unsigned int>(__t)); 189 else if (sizeof(_Tp) <= sizeof(unsigned long)) 190 return std::__libcpp_popcount(static_cast<unsigned long>(__t)); 191 else if (sizeof(_Tp) <= sizeof(unsigned long long)) 192 return std::__libcpp_popcount(static_cast<unsigned long long>(__t)); 193 else { 194 int __ret = 0; 195 while (__t != 0) { 196 __ret += std::__libcpp_popcount(static_cast<unsigned long long>(__t)); 197 __t >>= numeric_limits<unsigned long long>::digits; 198 } 199 return __ret; 200 } 201} 202 203template <__libcpp_unsigned_integer _Tp> 204_LIBCPP_HIDE_FROM_ABI constexpr bool has_single_bit(_Tp __t) noexcept { 205 return __t != 0 && (((__t & (__t - 1)) == 0)); 206} 207 208// integral log base 2 209template <__libcpp_unsigned_integer _Tp> 210_LIBCPP_HIDE_FROM_ABI constexpr _Tp __bit_log2(_Tp __t) noexcept { 211 return numeric_limits<_Tp>::digits - 1 - std::countl_zero(__t); 212} 213 214template <__libcpp_unsigned_integer _Tp> 215_LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_floor(_Tp __t) noexcept { 216 return __t == 0 ? 0 : _Tp{1} << std::__bit_log2(__t); 217} 218 219template <__libcpp_unsigned_integer _Tp> 220_LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_ceil(_Tp __t) noexcept { 221 if (__t < 2) 222 return 1; 223 const unsigned __n = numeric_limits<_Tp>::digits - std::countl_zero((_Tp)(__t - 1u)); 224 _LIBCPP_ASSERT(__n != numeric_limits<_Tp>::digits, "Bad input to bit_ceil"); 225 226 if constexpr (sizeof(_Tp) >= sizeof(unsigned)) 227 return _Tp{1} << __n; 228 else { 229 const unsigned __extra = numeric_limits<unsigned>::digits - numeric_limits<_Tp>::digits; 230 const unsigned __retVal = 1u << (__n + __extra); 231 return (_Tp)(__retVal >> __extra); 232 } 233} 234 235template <__libcpp_unsigned_integer _Tp> 236_LIBCPP_HIDE_FROM_ABI constexpr int bit_width(_Tp __t) noexcept { 237 return __t == 0 ? 0 : std::__bit_log2(__t) + 1; 238} 239 240enum class endian { 241 little = 0xDEAD, 242 big = 0xFACE, 243# if defined(_LIBCPP_LITTLE_ENDIAN) 244 native = little 245# elif defined(_LIBCPP_BIG_ENDIAN) 246 native = big 247# else 248 native = 0xCAFE 249# endif 250}; 251 252#endif // _LIBCPP_STD_VER > 17 253 254_LIBCPP_END_NAMESPACE_STD 255 256_LIBCPP_POP_MACROS 257 258#endif // _LIBCPP_BIT 259