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47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
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//===----------------------------------------------------------------------===//
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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_BIT_CEIL_H
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#define _LIBCPP___BIT_BIT_CEIL_H
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#include <__assert>
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#include <__bit/countl.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_BEGIN_NAMESPACE_STD
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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 _Tp bit_ceil(_Tp __t) noexcept {
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if (__t < 2)
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return 1;
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const unsigned __n = numeric_limits<_Tp>::digits - std::countl_zero((_Tp)(__t - 1u));
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_LIBCPP_ASSERT(__n != numeric_limits<_Tp>::digits, "Bad input to bit_ceil");
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if constexpr (sizeof(_Tp) >= sizeof(unsigned))
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return _Tp{1} << __n;
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else {
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const unsigned __extra = numeric_limits<unsigned>::digits - numeric_limits<_Tp>::digits;
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const unsigned __ret_val = 1u << (__n + __extra);
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return (_Tp)(__ret_val >> __extra);
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}
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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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#endif // _LIBCPP___BIT_BIT_CEIL_H
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