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Atmosphere/libraries/libvapours/include/vapours/util/util_int_util.hpp

159 lines
5.2 KiB
C++

/*
* Copyright (c) Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <vapours/common.hpp>
#include <vapours/assert.hpp>
namespace ams::util {
namespace impl {
template<std::signed_integral To, std::signed_integral From>
constexpr ALWAYS_INLINE bool IsIntValueRepresentableImpl(From v) {
using ToLimit = std::numeric_limits<To>;
using FromLimit = std::numeric_limits<From>;
if constexpr (ToLimit::min() <= FromLimit::min() && FromLimit::max() <= ToLimit::max()) {
return true;
} else {
return ToLimit::min() <= v && v <= ToLimit::max();
}
}
template<std::unsigned_integral To, std::unsigned_integral From>
constexpr ALWAYS_INLINE bool IsIntValueRepresentableImpl(From v) {
using ToLimit = std::numeric_limits<To>;
using FromLimit = std::numeric_limits<From>;
if constexpr (ToLimit::min() <= FromLimit::min() && FromLimit::max() <= ToLimit::max()) {
return true;
} else {
return ToLimit::min() <= v && v <= ToLimit::max();
}
}
template<std::unsigned_integral To, std::signed_integral From>
constexpr ALWAYS_INLINE bool IsIntValueRepresentableImpl(From v) {
using UnsignedFrom = typename std::make_unsigned<From>::type;
if (v < 0) {
return false;
} else {
return IsIntValueRepresentableImpl<To, UnsignedFrom>(static_cast<UnsignedFrom>(v));
}
}
template<std::signed_integral To, std::unsigned_integral From>
constexpr ALWAYS_INLINE bool IsIntValueRepresentableImpl(From v) {
using UnsignedTo = typename std::make_unsigned<To>::type;
return v <= static_cast<UnsignedTo>(std::numeric_limits<To>::max());
}
}
template<std::integral To, std::integral From>
constexpr ALWAYS_INLINE bool IsIntValueRepresentable(From v) {
return ::ams::util::impl::IsIntValueRepresentableImpl<To, From>(v);
}
template<std::integral T>
constexpr ALWAYS_INLINE bool CanAddWithoutOverflow(T x, T y) {
if constexpr (std::unsigned_integral<T>) {
return x <= std::numeric_limits<T>::max() - y;
} else {
if (y >= 0) {
return x <= std::numeric_limits<T>::max() - y;
} else {
return x >= std::numeric_limits<T>::min() - y;
}
}
}
template<std::integral T>
constexpr ALWAYS_INLINE bool CanSubtractWithoutOverflow(T x, T y) {
if constexpr (std::unsigned_integral<T>) {
return x >= std::numeric_limits<T>::min() + y;
} else {
if (y >= 0) {
return x >= std::numeric_limits<T>::min() + y;
} else {
return x <= std::numeric_limits<T>::max() + y;
}
}
}
template<std::integral T>
constexpr ALWAYS_INLINE bool CanMultiplyWithoutOverflow(T x, T y) {
if (x == 0 || y == 0) {
return true;
}
if constexpr (std::unsigned_integral<T>) {
return y <= std::numeric_limits<T>::max() / x;
} else {
if (x > 0) {
if (y > 0) {
return y <= std::numeric_limits<T>::max() / x;
} else /*if (y < 0) */ {
return y >= std::numeric_limits<T>::min() / x;
}
} else /* if (x < 0) */ {
if (y > 0) {
return x >= std::numeric_limits<T>::min() / y;
} else /*if (y < 0) */ {
return y >= std::numeric_limits<T>::max() / x;
}
}
}
}
template<std::integral T>
constexpr inline bool TryAddWithoutOverflow(T *out, T x, T y) {
AMS_ASSERT(out != nullptr);
if (CanAddWithoutOverflow(x, y)) {
*out = x + y;
return true;
} else {
return false;
}
}
template<std::integral T>
constexpr inline bool TrySubtractWithoutOverflow(T *out, T x, T y) {
AMS_ASSERT(out != nullptr);
if (CanSubtractWithoutOverflow(x, y)) {
*out = x - y;
return true;
} else {
return false;
}
}
template<std::integral T>
constexpr inline bool TryMultiplyWithoutOverflow(T *out, T x, T y) {
AMS_ASSERT(out != nullptr);
if (CanMultiplyWithoutOverflow(x, y)) {
*out = x * y;
return true;
} else {
return false;
}
}
}