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 27 int __libcpp_ctz(unsigned __x) _NOEXCEPT { return __builtin_ctz(__x); } 28 29 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR 30 int __libcpp_ctz(unsigned long __x) _NOEXCEPT { return __builtin_ctzl(__x); } 31 32 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR 33 int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); } 34 35 #if _LIBCPP_STD_VER >= 20 36 37 template <__libcpp_unsigned_integer _Tp> 38 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr int countr_zero(_Tp __t) noexcept { 39 if (__t == 0) 40 return numeric_limits<_Tp>::digits; 41 42 if (sizeof(_Tp) <= sizeof(unsigned int)) 43 return std::__libcpp_ctz(static_cast<unsigned int>(__t)); 44 else if (sizeof(_Tp) <= sizeof(unsigned long)) 45 return std::__libcpp_ctz(static_cast<unsigned long>(__t)); 46 else if (sizeof(_Tp) <= sizeof(unsigned long long)) 47 return std::__libcpp_ctz(static_cast<unsigned long long>(__t)); 48 else { 49 int __ret = 0; 50 const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits; 51 while (static_cast<unsigned long long>(__t) == 0uLL) { 52 __ret += __ulldigits; 53 __t >>= __ulldigits; 54 } 55 return __ret + std::__libcpp_ctz(static_cast<unsigned long long>(__t)); 56 } 57 } 58 59 template <__libcpp_unsigned_integer _Tp> 60 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr int countr_one(_Tp __t) noexcept { 61 return __t != numeric_limits<_Tp>::max() ? std::countr_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits; 62 } 63 64 #endif // _LIBCPP_STD_VER >= 20 65 66 _LIBCPP_END_NAMESPACE_STD 67 68 _LIBCPP_POP_MACROS 69 70 #endif // _LIBCPP___BIT_COUNTR_H 71