14824e7fdSDimitry Andric // -*- C++ -*- 24824e7fdSDimitry Andric //===----------------------------------------------------------------------===// 34824e7fdSDimitry Andric // 44824e7fdSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 54824e7fdSDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 64824e7fdSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 74824e7fdSDimitry Andric // 84824e7fdSDimitry Andric //===----------------------------------------------------------------------===// 94824e7fdSDimitry Andric 104824e7fdSDimitry Andric #ifndef _LIBCPP___NUMERIC_MIDPOINT_H 114824e7fdSDimitry Andric #define _LIBCPP___NUMERIC_MIDPOINT_H 124824e7fdSDimitry Andric 134824e7fdSDimitry Andric #include <__config> 14*bdd1243dSDimitry Andric #include <__type_traits/enable_if.h> 15*bdd1243dSDimitry Andric #include <__type_traits/is_floating_point.h> 16*bdd1243dSDimitry Andric #include <__type_traits/is_integral.h> 17*bdd1243dSDimitry Andric #include <__type_traits/is_null_pointer.h> 18*bdd1243dSDimitry Andric #include <__type_traits/is_object.h> 19*bdd1243dSDimitry Andric #include <__type_traits/is_pointer.h> 20*bdd1243dSDimitry Andric #include <__type_traits/is_same.h> 21*bdd1243dSDimitry Andric #include <__type_traits/is_void.h> 22*bdd1243dSDimitry Andric #include <__type_traits/make_unsigned.h> 23*bdd1243dSDimitry Andric #include <__type_traits/remove_pointer.h> 24*bdd1243dSDimitry Andric #include <cstddef> 254824e7fdSDimitry Andric #include <limits> 264824e7fdSDimitry Andric 274824e7fdSDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 284824e7fdSDimitry Andric # pragma GCC system_header 294824e7fdSDimitry Andric #endif 304824e7fdSDimitry Andric 314824e7fdSDimitry Andric _LIBCPP_PUSH_MACROS 324824e7fdSDimitry Andric #include <__undef_macros> 334824e7fdSDimitry Andric 344824e7fdSDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 354824e7fdSDimitry Andric 364824e7fdSDimitry Andric #if _LIBCPP_STD_VER > 17 374824e7fdSDimitry Andric template <class _Tp> 384824e7fdSDimitry Andric _LIBCPP_INLINE_VISIBILITY constexpr 394824e7fdSDimitry Andric enable_if_t<is_integral_v<_Tp> && !is_same_v<bool, _Tp> && !is_null_pointer_v<_Tp>, _Tp> 404824e7fdSDimitry Andric midpoint(_Tp __a, _Tp __b) noexcept 414824e7fdSDimitry Andric _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK 424824e7fdSDimitry Andric { 434824e7fdSDimitry Andric using _Up = make_unsigned_t<_Tp>; 444824e7fdSDimitry Andric constexpr _Up __bitshift = numeric_limits<_Up>::digits - 1; 454824e7fdSDimitry Andric 464824e7fdSDimitry Andric _Up __diff = _Up(__b) - _Up(__a); 474824e7fdSDimitry Andric _Up __sign_bit = __b < __a; 484824e7fdSDimitry Andric 494824e7fdSDimitry Andric _Up __half_diff = (__diff / 2) + (__sign_bit << __bitshift) + (__sign_bit & __diff); 504824e7fdSDimitry Andric 514824e7fdSDimitry Andric return __a + __half_diff; 524824e7fdSDimitry Andric } 534824e7fdSDimitry Andric 544824e7fdSDimitry Andric 554824e7fdSDimitry Andric template <class _TPtr> 564824e7fdSDimitry Andric _LIBCPP_INLINE_VISIBILITY constexpr 574824e7fdSDimitry Andric enable_if_t<is_pointer_v<_TPtr> 584824e7fdSDimitry Andric && is_object_v<remove_pointer_t<_TPtr>> 594824e7fdSDimitry Andric && ! is_void_v<remove_pointer_t<_TPtr>> 604824e7fdSDimitry Andric && (sizeof(remove_pointer_t<_TPtr>) > 0), _TPtr> 614824e7fdSDimitry Andric midpoint(_TPtr __a, _TPtr __b) noexcept 624824e7fdSDimitry Andric { 634824e7fdSDimitry Andric return __a + _VSTD::midpoint(ptrdiff_t(0), __b - __a); 644824e7fdSDimitry Andric } 654824e7fdSDimitry Andric 664824e7fdSDimitry Andric 674824e7fdSDimitry Andric template <typename _Tp> 68*bdd1243dSDimitry Andric _LIBCPP_HIDE_FROM_ABI constexpr int __sign(_Tp __val) { 694824e7fdSDimitry Andric return (_Tp(0) < __val) - (__val < _Tp(0)); 704824e7fdSDimitry Andric } 714824e7fdSDimitry Andric 724824e7fdSDimitry Andric template <typename _Fp> 73*bdd1243dSDimitry Andric _LIBCPP_HIDE_FROM_ABI constexpr _Fp __fp_abs(_Fp __f) { return __f >= 0 ? __f : -__f; } 744824e7fdSDimitry Andric 754824e7fdSDimitry Andric template <class _Fp> 764824e7fdSDimitry Andric _LIBCPP_INLINE_VISIBILITY constexpr 774824e7fdSDimitry Andric enable_if_t<is_floating_point_v<_Fp>, _Fp> 784824e7fdSDimitry Andric midpoint(_Fp __a, _Fp __b) noexcept 794824e7fdSDimitry Andric { 804824e7fdSDimitry Andric constexpr _Fp __lo = numeric_limits<_Fp>::min()*2; 814824e7fdSDimitry Andric constexpr _Fp __hi = numeric_limits<_Fp>::max()/2; 82*bdd1243dSDimitry Andric return std::__fp_abs(__a) <= __hi && std::__fp_abs(__b) <= __hi ? // typical case: overflow is impossible 834824e7fdSDimitry Andric (__a + __b)/2 : // always correctly rounded 84*bdd1243dSDimitry Andric std::__fp_abs(__a) < __lo ? __a + __b/2 : // not safe to halve a 85*bdd1243dSDimitry Andric std::__fp_abs(__b) < __lo ? __a/2 + __b : // not safe to halve b 864824e7fdSDimitry Andric __a/2 + __b/2; // otherwise correctly rounded 874824e7fdSDimitry Andric } 884824e7fdSDimitry Andric 894824e7fdSDimitry Andric #endif // _LIBCPP_STD_VER > 17 904824e7fdSDimitry Andric 914824e7fdSDimitry Andric _LIBCPP_END_NAMESPACE_STD 924824e7fdSDimitry Andric 934824e7fdSDimitry Andric _LIBCPP_POP_MACROS 944824e7fdSDimitry Andric 954824e7fdSDimitry Andric #endif // _LIBCPP___NUMERIC_MIDPOINT_H 96