mirror of
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145 lines
4.3 KiB
C++
145 lines
4.3 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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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___NUMERIC_SATURATION_ARITHMETIC_H
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#define _LIBCPP___NUMERIC_SATURATION_ARITHMETIC_H
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#include <__assert>
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#include <__concepts/arithmetic.h>
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#include <__config>
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#include <__utility/cmp.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_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 20
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template <__libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Tp __add_sat(_Tp __x, _Tp __y) noexcept {
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if (_Tp __sum; !__builtin_add_overflow(__x, __y, &__sum))
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return __sum;
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// Handle overflow
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if constexpr (__libcpp_unsigned_integer<_Tp>) {
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return std::numeric_limits<_Tp>::max();
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} else {
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// Signed addition overflow
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if (__x > 0)
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// Overflows if (x > 0 && y > 0)
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return std::numeric_limits<_Tp>::max();
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else
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// Overflows if (x < 0 && y < 0)
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return std::numeric_limits<_Tp>::min();
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}
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}
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template <__libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Tp __sub_sat(_Tp __x, _Tp __y) noexcept {
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if (_Tp __sub; !__builtin_sub_overflow(__x, __y, &__sub))
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return __sub;
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// Handle overflow
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if constexpr (__libcpp_unsigned_integer<_Tp>) {
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// Overflows if (x < y)
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return std::numeric_limits<_Tp>::min();
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} else {
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// Signed subtration overflow
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if (__x >= 0)
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// Overflows if (x >= 0 && y < 0)
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return std::numeric_limits<_Tp>::max();
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else
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// Overflows if (x < 0 && y > 0)
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return std::numeric_limits<_Tp>::min();
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}
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}
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template <__libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Tp __mul_sat(_Tp __x, _Tp __y) noexcept {
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if (_Tp __mul; !__builtin_mul_overflow(__x, __y, &__mul))
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return __mul;
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// Handle overflow
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if constexpr (__libcpp_unsigned_integer<_Tp>) {
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return std::numeric_limits<_Tp>::max();
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} else {
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// Signed multiplication overflow
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if ((__x > 0 && __y > 0) || (__x < 0 && __y < 0))
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return std::numeric_limits<_Tp>::max();
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// Overflows if (x < 0 && y > 0) || (x > 0 && y < 0)
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return std::numeric_limits<_Tp>::min();
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}
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}
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template <__libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Tp __div_sat(_Tp __x, _Tp __y) noexcept {
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_LIBCPP_ASSERT_UNCATEGORIZED(__y != 0, "Division by 0 is undefined");
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if constexpr (__libcpp_unsigned_integer<_Tp>) {
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return __x / __y;
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} else {
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// Handle signed division overflow
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if (__x == std::numeric_limits<_Tp>::min() && __y == _Tp{-1})
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return std::numeric_limits<_Tp>::max();
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return __x / __y;
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}
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}
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template <__libcpp_integer _Rp, __libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Rp __saturate_cast(_Tp __x) noexcept {
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// Saturation is impossible edge case when ((min _Rp) < (min _Tp) && (max _Rp) > (max _Tp)) and it is expected to be
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// optimized out by the compiler.
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// Handle overflow
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if (std::cmp_less(__x, std::numeric_limits<_Rp>::min()))
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return std::numeric_limits<_Rp>::min();
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if (std::cmp_greater(__x, std::numeric_limits<_Rp>::max()))
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return std::numeric_limits<_Rp>::max();
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// No overflow
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return static_cast<_Rp>(__x);
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}
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#endif // _LIBCPP_STD_VER >= 20
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#if _LIBCPP_STD_VER >= 26
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template <__libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Tp add_sat(_Tp __x, _Tp __y) noexcept {
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return std::__add_sat(__x, __y);
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}
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template <__libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Tp sub_sat(_Tp __x, _Tp __y) noexcept {
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return std::__sub_sat(__x, __y);
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}
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template <__libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Tp mul_sat(_Tp __x, _Tp __y) noexcept {
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return std::__mul_sat(__x, __y);
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}
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template <__libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Tp div_sat(_Tp __x, _Tp __y) noexcept {
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return std::__div_sat(__x, __y);
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}
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template <__libcpp_integer _Rp, __libcpp_integer _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr _Rp saturate_cast(_Tp __x) noexcept {
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return std::__saturate_cast<_Rp>(__x);
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}
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#endif // _LIBCPP_STD_VER >= 26
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___NUMERIC_SATURATION_ARITHMETIC_H
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