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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___NUMERIC_SATURATION_ARITHMETIC_H
#define _LIBCPP___NUMERIC_SATURATION_ARITHMETIC_H
#include <__concepts/arithmetic.h>
#include <__config>
#include <__utility/cmp.h>
#include <limits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 26
template <__libcpp_integer _Tp>
_LIBCPP_HIDE_FROM_ABI constexpr _Tp add_sat(_Tp __x, _Tp __y) noexcept {
if (_Tp __sum; !__builtin_add_overflow(__x, __y, &__sum))
return __sum;
// Handle overflow
if constexpr (__libcpp_unsigned_integer<_Tp>) {
return std::numeric_limits<_Tp>::max();
} else {
// Signed addition overflow
if (__x > 0)
// Overflows if (x > 0 && y > 0)
return std::numeric_limits<_Tp>::max();
else
// Overflows if (x < 0 && y < 0)
return std::numeric_limits<_Tp>::min();
}
}
template <__libcpp_integer _Tp>
_LIBCPP_HIDE_FROM_ABI constexpr _Tp sub_sat(_Tp __x, _Tp __y) noexcept {
if (_Tp __sub; !__builtin_sub_overflow(__x, __y, &__sub))
return __sub;
// Handle overflow
if constexpr (__libcpp_unsigned_integer<_Tp>) {
// Overflows if (x < y)
return std::numeric_limits<_Tp>::min();
} else {
// Signed subtration overflow
if (__x >= 0)
// Overflows if (x >= 0 && y < 0)
return std::numeric_limits<_Tp>::max();
else
// Overflows if (x < 0 && y > 0)
return std::numeric_limits<_Tp>::min();
}
}
template <__libcpp_integer _Tp>
_LIBCPP_HIDE_FROM_ABI constexpr _Tp mul_sat(_Tp __x, _Tp __y) noexcept {
if (_Tp __mul; !__builtin_mul_overflow(__x, __y, &__mul))
return __mul;
// Handle overflow
if constexpr (__libcpp_unsigned_integer<_Tp>) {
return std::numeric_limits<_Tp>::max();
} else {
// Signed multiplication overflow
if ((__x > 0 && __y > 0) || (__x < 0 && __y < 0))
return std::numeric_limits<_Tp>::max();
// Overflows if (x < 0 && y > 0) || (x > 0 && y < 0)
return std::numeric_limits<_Tp>::min();
}
}
template <__libcpp_integer _Tp>
_LIBCPP_HIDE_FROM_ABI constexpr _Tp div_sat(_Tp __x, _Tp __y) noexcept {
_LIBCPP_ASSERT_UNCATEGORIZED(__y != 0, "Division by 0 is undefined");
if constexpr (__libcpp_unsigned_integer<_Tp>) {
return __x / __y;
} else {
// Handle signed division overflow
if (__x == std::numeric_limits<_Tp>::min() && __y == _Tp{-1})
return std::numeric_limits<_Tp>::max();
return __x / __y;
}
}
template <__libcpp_integer _Rp, __libcpp_integer _Tp>
_LIBCPP_HIDE_FROM_ABI constexpr _Rp saturate_cast(_Tp __x) noexcept {
// Saturation is impossible edge case when ((min _Rp) < (min _Tp) && (max _Rp) > (max _Tp)) and it is expected to be
// optimized out by the compiler.
// Handle overflow
if (std::cmp_less(__x, std::numeric_limits<_Rp>::min()))
return std::numeric_limits<_Rp>::min();
if (std::cmp_greater(__x, std::numeric_limits<_Rp>::max()))
return std::numeric_limits<_Rp>::max();
// No overflow
return static_cast<_Rp>(__x);
}
#endif // _LIBCPP_STD_VER >= 26
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___NUMERIC_SATURATION_ARITHMETIC_H
|
