1fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 2fe6060f1SDimitry Andric // 3fe6060f1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4fe6060f1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 5fe6060f1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6fe6060f1SDimitry Andric // 7fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 8fe6060f1SDimitry Andric 9fe6060f1SDimitry Andric #ifndef _LIBCPP___ALGORITHM_HALF_POSITIVE_H 10fe6060f1SDimitry Andric #define _LIBCPP___ALGORITHM_HALF_POSITIVE_H 11fe6060f1SDimitry Andric 12fe6060f1SDimitry Andric #include <__config> 1306c3fb27SDimitry Andric #include <__type_traits/enable_if.h> 1406c3fb27SDimitry Andric #include <__type_traits/is_integral.h> 1506c3fb27SDimitry Andric #include <__type_traits/make_unsigned.h> 16fe6060f1SDimitry Andric 17fe6060f1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18fe6060f1SDimitry Andric # pragma GCC system_header 19fe6060f1SDimitry Andric #endif 20fe6060f1SDimitry Andric 21fe6060f1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 22fe6060f1SDimitry Andric 23fe6060f1SDimitry Andric // Perform division by two quickly for positive integers (llvm.org/PR39129) 24fe6060f1SDimitry Andric 255f757f3fSDimitry Andric template <typename _Integral, __enable_if_t<is_integral<_Integral>::value, int> = 0> __half_positive(_Integral __value)26*cb14a3feSDimitry Andric_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Integral __half_positive(_Integral __value) { 27bdd1243dSDimitry Andric return static_cast<_Integral>(static_cast<__make_unsigned_t<_Integral> >(__value) / 2); 28fe6060f1SDimitry Andric } 29fe6060f1SDimitry Andric 305f757f3fSDimitry Andric template <typename _Tp, __enable_if_t<!is_integral<_Tp>::value, int> = 0> __half_positive(_Tp __value)31*cb14a3feSDimitry Andric_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Tp __half_positive(_Tp __value) { 32fe6060f1SDimitry Andric return __value / 2; 33fe6060f1SDimitry Andric } 34fe6060f1SDimitry Andric 35fe6060f1SDimitry Andric _LIBCPP_END_NAMESPACE_STD 36fe6060f1SDimitry Andric 37fe6060f1SDimitry Andric #endif // _LIBCPP___ALGORITHM_HALF_POSITIVE_H 38