mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
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159 lines
5.2 KiB
C++
159 lines
5.2 KiB
C++
/*
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* Copyright (c) Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <vapours/common.hpp>
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#include <vapours/assert.hpp>
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namespace ams::util {
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namespace impl {
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template<std::signed_integral To, std::signed_integral From>
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constexpr ALWAYS_INLINE bool IsIntValueRepresentableImpl(From v) {
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using ToLimit = std::numeric_limits<To>;
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using FromLimit = std::numeric_limits<From>;
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if constexpr (ToLimit::min() <= FromLimit::min() && FromLimit::max() <= ToLimit::max()) {
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return true;
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} else {
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return ToLimit::min() <= v && v <= ToLimit::max();
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}
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}
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template<std::unsigned_integral To, std::unsigned_integral From>
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constexpr ALWAYS_INLINE bool IsIntValueRepresentableImpl(From v) {
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using ToLimit = std::numeric_limits<To>;
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using FromLimit = std::numeric_limits<From>;
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if constexpr (ToLimit::min() <= FromLimit::min() && FromLimit::max() <= ToLimit::max()) {
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return true;
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} else {
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return ToLimit::min() <= v && v <= ToLimit::max();
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}
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}
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template<std::unsigned_integral To, std::signed_integral From>
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constexpr ALWAYS_INLINE bool IsIntValueRepresentableImpl(From v) {
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using UnsignedFrom = typename std::make_unsigned<From>::type;
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if (v < 0) {
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return false;
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} else {
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return IsIntValueRepresentableImpl<To, UnsignedFrom>(static_cast<UnsignedFrom>(v));
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}
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}
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template<std::signed_integral To, std::unsigned_integral From>
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constexpr ALWAYS_INLINE bool IsIntValueRepresentableImpl(From v) {
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using UnsignedTo = typename std::make_unsigned<To>::type;
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return v <= static_cast<UnsignedTo>(std::numeric_limits<To>::max());
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}
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}
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template<std::integral To, std::integral From>
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constexpr ALWAYS_INLINE bool IsIntValueRepresentable(From v) {
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return ::ams::util::impl::IsIntValueRepresentableImpl<To, From>(v);
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}
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template<std::integral T>
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constexpr ALWAYS_INLINE bool CanAddWithoutOverflow(T x, T y) {
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if constexpr (std::unsigned_integral<T>) {
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return x <= std::numeric_limits<T>::max() - y;
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} else {
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if (y >= 0) {
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return x <= std::numeric_limits<T>::max() - y;
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} else {
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return x >= std::numeric_limits<T>::min() - y;
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}
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}
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}
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template<std::integral T>
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constexpr ALWAYS_INLINE bool CanSubtractWithoutOverflow(T x, T y) {
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if constexpr (std::unsigned_integral<T>) {
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return x >= std::numeric_limits<T>::min() + y;
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} else {
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if (y >= 0) {
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return x >= std::numeric_limits<T>::min() + y;
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} else {
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return x <= std::numeric_limits<T>::max() + y;
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}
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}
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}
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template<std::integral T>
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constexpr ALWAYS_INLINE bool CanMultiplyWithoutOverflow(T x, T y) {
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if (x == 0 || y == 0) {
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return true;
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}
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if constexpr (std::unsigned_integral<T>) {
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return y <= std::numeric_limits<T>::max() / x;
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} else {
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if (x > 0) {
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if (y > 0) {
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return y <= std::numeric_limits<T>::max() / x;
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} else /*if (y < 0) */ {
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return y >= std::numeric_limits<T>::min() / x;
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}
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} else /* if (x < 0) */ {
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if (y > 0) {
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return x >= std::numeric_limits<T>::min() / y;
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} else /*if (y < 0) */ {
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return y >= std::numeric_limits<T>::max() / x;
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}
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}
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}
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}
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template<std::integral T>
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constexpr inline bool TryAddWithoutOverflow(T *out, T x, T y) {
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AMS_ASSERT(out != nullptr);
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if (CanAddWithoutOverflow(x, y)) {
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*out = x + y;
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return true;
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} else {
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return false;
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}
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}
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template<std::integral T>
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constexpr inline bool TrySubtractWithoutOverflow(T *out, T x, T y) {
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AMS_ASSERT(out != nullptr);
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if (CanSubtractWithoutOverflow(x, y)) {
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*out = x - y;
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return true;
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} else {
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return false;
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}
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}
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template<std::integral T>
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constexpr inline bool TryMultiplyWithoutOverflow(T *out, T x, T y) {
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AMS_ASSERT(out != nullptr);
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if (CanMultiplyWithoutOverflow(x, y)) {
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*out = x * y;
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return true;
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} else {
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return false;
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}
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}
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}
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