1e78f53d1SNikolas Klauser //===----------------------------------------------------------------------===// 2e78f53d1SNikolas Klauser // 3e78f53d1SNikolas Klauser // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4e78f53d1SNikolas Klauser // See https://llvm.org/LICENSE.txt for license information. 5e78f53d1SNikolas Klauser // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6e78f53d1SNikolas Klauser // 7e78f53d1SNikolas Klauser //===----------------------------------------------------------------------===// 8e78f53d1SNikolas Klauser 9*ce777190SNikolas Klauser #ifndef _LIBCPP___CXX03___ALGORITHM_HALF_POSITIVE_H 10*ce777190SNikolas Klauser #define _LIBCPP___CXX03___ALGORITHM_HALF_POSITIVE_H 11e78f53d1SNikolas Klauser 1273fbae83SNikolas Klauser #include <__cxx03/__config> 1373fbae83SNikolas Klauser #include <__cxx03/__type_traits/enable_if.h> 1473fbae83SNikolas Klauser #include <__cxx03/__type_traits/is_integral.h> 1573fbae83SNikolas Klauser #include <__cxx03/__type_traits/make_unsigned.h> 16e78f53d1SNikolas Klauser 17e78f53d1SNikolas Klauser #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18e78f53d1SNikolas Klauser # pragma GCC system_header 19e78f53d1SNikolas Klauser #endif 20e78f53d1SNikolas Klauser 21e78f53d1SNikolas Klauser _LIBCPP_BEGIN_NAMESPACE_STD 22e78f53d1SNikolas Klauser 23e78f53d1SNikolas Klauser // Perform division by two quickly for positive integers (llvm.org/PR39129) 24e78f53d1SNikolas Klauser 25e78f53d1SNikolas Klauser template <typename _Integral, __enable_if_t<is_integral<_Integral>::value, int> = 0> 26e78f53d1SNikolas Klauser _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Integral __half_positive(_Integral __value) { 27e78f53d1SNikolas Klauser return static_cast<_Integral>(static_cast<__make_unsigned_t<_Integral> >(__value) / 2); 28e78f53d1SNikolas Klauser } 29e78f53d1SNikolas Klauser 30e78f53d1SNikolas Klauser template <typename _Tp, __enable_if_t<!is_integral<_Tp>::value, int> = 0> 31e78f53d1SNikolas Klauser _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Tp __half_positive(_Tp __value) { 32e78f53d1SNikolas Klauser return __value / 2; 33e78f53d1SNikolas Klauser } 34e78f53d1SNikolas Klauser 35e78f53d1SNikolas Klauser _LIBCPP_END_NAMESPACE_STD 36e78f53d1SNikolas Klauser 37*ce777190SNikolas Klauser #endif // _LIBCPP___CXX03___ALGORITHM_HALF_POSITIVE_H 38