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cfa322fa9a
The `__log2i` function template in `<algorithm/sort.h>` is basically equivalent to `__bit_log2` in `<__bit/bit_log2.h>`. It seems better to avoid duplication.
32 lines
1013 B
C++
32 lines
1013 B
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_BIT_LOG2_H
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#define _LIBCPP___BIT_BIT_LOG2_H
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#include <__bit/countl.h>
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#include <__config>
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#include <__type_traits/is_unsigned_integer.h>
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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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template <class _Tp>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Tp __bit_log2(_Tp __t) _NOEXCEPT {
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static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__bit_log2 requires an unsigned integer type");
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return numeric_limits<_Tp>::digits - 1 - std::__countl_zero(__t);
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}
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___BIT_BIT_LOG2_H
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