mirror of
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70 lines
2.2 KiB
C++
70 lines
2.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___BIT_COUNTR_H
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#define _LIBCPP___BIT_COUNTR_H
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#include <__bit/rotate.h>
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#include <__concepts/arithmetic.h>
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#include <__config>
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#include <limits>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_ctz(unsigned __x) _NOEXCEPT { return __builtin_ctz(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_ctz(unsigned long __x) _NOEXCEPT { return __builtin_ctzl(__x); }
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inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
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int __libcpp_ctz(unsigned long long __x) _NOEXCEPT { return __builtin_ctzll(__x); }
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#if _LIBCPP_STD_VER >= 20
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template <__libcpp_unsigned_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr int countr_zero(_Tp __t) noexcept {
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if (__t == 0)
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return numeric_limits<_Tp>::digits;
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if (sizeof(_Tp) <= sizeof(unsigned int))
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return std::__libcpp_ctz(static_cast<unsigned int>(__t));
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else if (sizeof(_Tp) <= sizeof(unsigned long))
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return std::__libcpp_ctz(static_cast<unsigned long>(__t));
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else if (sizeof(_Tp) <= sizeof(unsigned long long))
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return std::__libcpp_ctz(static_cast<unsigned long long>(__t));
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else {
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int __ret = 0;
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const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
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while (static_cast<unsigned long long>(__t) == 0uLL) {
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__ret += __ulldigits;
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__t >>= __ulldigits;
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}
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return __ret + std::__libcpp_ctz(static_cast<unsigned long long>(__t));
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}
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}
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template <__libcpp_unsigned_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr int countr_one(_Tp __t) noexcept {
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return __t != numeric_limits<_Tp>::max() ? std::countr_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits;
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}
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#endif // _LIBCPP_STD_VER >= 20
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___BIT_COUNTR_H
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