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___BIT_COUNTR_H 10 #define _LIBCPP___BIT_COUNTR_H 11 12 #include <__bit/rotate.h> 13 #include <__concepts/arithmetic.h> 14 #include <__config> 15 #include <limits> 16 17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18 # pragma GCC system_header 19 #endif 20 21 _LIBCPP_PUSH_MACROS 22 #include <__undef_macros> 23 24 _LIBCPP_BEGIN_NAMESPACE_STD 25 26 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_ctz(unsigned __x) _NOEXCEPT { 27 return __builtin_ctz(__x); 28 } 29 30 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_ctz(unsigned long __x) _NOEXCEPT { 31 return __builtin_ctzl(__x); 32 } 33 34 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { 35 return __builtin_ctzll(__x); 36 } 37 38 #if _LIBCPP_STD_VER >= 20 39 40 template <__libcpp_unsigned_integer _Tp> 41 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr int countr_zero(_Tp __t) noexcept { 42 if (__t == 0) 43 return numeric_limits<_Tp>::digits; 44 45 if (sizeof(_Tp) <= sizeof(unsigned int)) 46 return std::__libcpp_ctz(static_cast<unsigned int>(__t)); 47 else if (sizeof(_Tp) <= sizeof(unsigned long)) 48 return std::__libcpp_ctz(static_cast<unsigned long>(__t)); 49 else if (sizeof(_Tp) <= sizeof(unsigned long long)) 50 return std::__libcpp_ctz(static_cast<unsigned long long>(__t)); 51 else { 52 int __ret = 0; 53 const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits; 54 while (static_cast<unsigned long long>(__t) == 0uLL) { 55 __ret += __ulldigits; 56 __t >>= __ulldigits; 57 } 58 return __ret + std::__libcpp_ctz(static_cast<unsigned long long>(__t)); 59 } 60 } 61 62 template <__libcpp_unsigned_integer _Tp> 63 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr int countr_one(_Tp __t) noexcept { 64 return __t != numeric_limits<_Tp>::max() ? std::countr_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits; 65 } 66 67 #endif // _LIBCPP_STD_VER >= 20 68 69 _LIBCPP_END_NAMESPACE_STD 70 71 _LIBCPP_POP_MACROS 72 73 #endif // _LIBCPP___BIT_COUNTR_H 74