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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-exception6//7//===----------------------------------------------------------------------===//8 9#ifndef _LIBCPP___ALGORITHM_HALF_POSITIVE_H10#define _LIBCPP___ALGORITHM_HALF_POSITIVE_H11 12#include <__config>13#include <__type_traits/enable_if.h>14#include <__type_traits/is_integral.h>15#include <__type_traits/make_unsigned.h>16 17#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)18# pragma GCC system_header19#endif20 21_LIBCPP_BEGIN_NAMESPACE_STD22 23// Perform division by two quickly for positive integers (llvm.org/PR39129)24 25template <typename _Integral, __enable_if_t<is_integral<_Integral>::value, int> = 0>26_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Integral __half_positive(_Integral __value) {27 return static_cast<_Integral>(static_cast<__make_unsigned_t<_Integral> >(__value) / 2);28}29 30template <typename _Tp, __enable_if_t<!is_integral<_Tp>::value, int> = 0>31_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Tp __half_positive(_Tp __value) {32 return __value / 2;33}34 35_LIBCPP_END_NAMESPACE_STD36 37#endif // _LIBCPP___ALGORITHM_HALF_POSITIVE_H38