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// Saturation arithmetic -*- C++ -*-
// Copyright The GNU Toolchain Authors.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file include/bits/sat_arith.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{numeric}
*/
#ifndef _GLIBCXX_SAT_ARITH_H
#define _GLIBCXX_SAT_ARITH_H 1
#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif
#include <bits/version.h>
#ifdef __glibcxx_saturation_arithmetic // C++ >= 26
#include <concepts>
#include <ext/numeric_traits.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Add two integers, with saturation in case of overflow.
template<typename _Tp> requires __is_standard_integer<_Tp>::value
constexpr _Tp
add_sat(_Tp __x, _Tp __y) noexcept
{
_Tp __z;
if (!__builtin_add_overflow(__x, __y, &__z))
return __z;
if constexpr (is_unsigned_v<_Tp>)
return __gnu_cxx::__int_traits<_Tp>::__max;
else if (__x < 0)
return __gnu_cxx::__int_traits<_Tp>::__min;
else
return __gnu_cxx::__int_traits<_Tp>::__max;
}
/// Subtract one integer from another, with saturation in case of overflow.
template<typename _Tp> requires __is_standard_integer<_Tp>::value
constexpr _Tp
sub_sat(_Tp __x, _Tp __y) noexcept
{
_Tp __z;
if (!__builtin_sub_overflow(__x, __y, &__z))
return __z;
if constexpr (is_unsigned_v<_Tp>)
return __gnu_cxx::__int_traits<_Tp>::__min;
else if (__x < 0)
return __gnu_cxx::__int_traits<_Tp>::__min;
else
return __gnu_cxx::__int_traits<_Tp>::__max;
}
/// Multiply two integers, with saturation in case of overflow.
template<typename _Tp> requires __is_standard_integer<_Tp>::value
constexpr _Tp
mul_sat(_Tp __x, _Tp __y) noexcept
{
_Tp __z;
if (!__builtin_mul_overflow(__x, __y, &__z))
return __z;
if constexpr (is_unsigned_v<_Tp>)
return __gnu_cxx::__int_traits<_Tp>::__max;
else if (__x < 0 != __y < 0)
return __gnu_cxx::__int_traits<_Tp>::__min;
else
return __gnu_cxx::__int_traits<_Tp>::__max;
}
/// Divide one integer by another, with saturation in case of overflow.
template<typename _Tp> requires __is_standard_integer<_Tp>::value
constexpr _Tp
div_sat(_Tp __x, _Tp __y) noexcept
{
__glibcxx_assert(__y != 0);
if constexpr (is_signed_v<_Tp>)
if (__x == __gnu_cxx::__int_traits<_Tp>::__min && __y == _Tp(-1))
return __gnu_cxx::__int_traits<_Tp>::__max;
return __x / __y;
}
/// Divide one integer by another, with saturation in case of overflow.
template<typename _Res, typename _Tp>
requires __is_standard_integer<_Res>::value
&& __is_standard_integer<_Tp>::value
constexpr _Res
saturate_cast(_Tp __x) noexcept
{
constexpr int __digits_R = __gnu_cxx::__int_traits<_Res>::__digits;
constexpr int __digits_T = __gnu_cxx::__int_traits<_Tp>::__digits;
constexpr _Res __max_Res = __gnu_cxx::__int_traits<_Res>::__max;
if constexpr (is_signed_v<_Res> == is_signed_v<_Tp>)
{
if constexpr (__digits_R < __digits_T)
{
constexpr _Res __min_Res = __gnu_cxx::__int_traits<_Res>::__min;
if (__x < static_cast<_Tp>(__min_Res))
return __min_Res;
else if (__x > static_cast<_Tp>(__max_Res))
return __max_Res;
}
}
else if constexpr (is_signed_v<_Tp>) // Res is unsigned
{
if (__x < 0)
return 0;
else if (make_unsigned_t<_Tp>(__x) > __max_Res)
return __gnu_cxx::__int_traits<_Res>::__max;
}
else // Tp is unsigned, Res is signed
{
if (__x > make_unsigned_t<_Res>(__max_Res))
return __max_Res;
}
return static_cast<_Res>(__x);
}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // __glibcxx_saturation_arithmetic
#endif /* _GLIBCXX_SAT_ARITH_H */
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