Atmosphere/libraries/libvapours/include/vapours/util/util_endian.hpp
2020-02-23 17:34:30 -08:00

122 lines
3.7 KiB
C++

/*
* Copyright (c) 2018-2020 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 {
/* TODO: C++20 std::endian */
constexpr bool IsLittleEndian() {
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
return true;
#else
return false;
#endif
}
constexpr bool IsBigEndian() {
#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
return true;
#else
return false;
#endif
}
static_assert(IsLittleEndian() ^ IsBigEndian());
template<typename U> /* requires unsigned_integral<U> */
constexpr ALWAYS_INLINE U SwapBytes(const U u) {
static_assert(BITSIZEOF(u8) == 8);
constexpr U ByteMask = 0xFFu;
if constexpr (std::is_same<U, u64>::value) {
return ((u & (ByteMask << 56)) >> 56) |
((u & (ByteMask << 48)) >> 40) |
((u & (ByteMask << 40)) >> 24) |
((u & (ByteMask << 32)) >> 8) |
((u & (ByteMask << 24)) << 8) |
((u & (ByteMask << 16)) << 24) |
((u & (ByteMask << 8)) << 40) |
((u & (ByteMask << 0)) << 56);
} else if constexpr (std::is_same<U, u32>::value) {
return ((u & (ByteMask << 24)) >> 24) |
((u & (ByteMask << 16)) >> 8) |
((u & (ByteMask << 8)) << 8) |
((u & (ByteMask << 0)) << 24);
} else if constexpr (std::is_same<U, u16>::value) {
return ((u & (ByteMask << 8)) >> 8) |
((u & (ByteMask << 0)) << 8);
} else if constexpr (std::is_same<U, u8>::value) {
return u;
} else {
static_assert(!std::is_same<U, U>::value);
}
}
template<typename T> /* requires integral<T> */
constexpr ALWAYS_INLINE void SwapBytes(T *ptr) {
using U = typename std::make_unsigned<T>::type;
*ptr = static_cast<T>(SwapBytes(static_cast<U>(*ptr)));
}
template<typename T>
constexpr ALWAYS_INLINE T ConvertToBigEndian(const T val) {
if constexpr (IsBigEndian()) {
return val;
} else {
static_assert(IsLittleEndian());
return SwapBytes(val);
}
}
template<typename T>
constexpr ALWAYS_INLINE T ConvertToLittleEndian(const T val) {
if constexpr (IsBigEndian()) {
return SwapBytes(val);
} else {
static_assert(IsLittleEndian());
return val;
}
}
template<typename T> /* requires integral<T> */
constexpr ALWAYS_INLINE T LoadBigEndian(T *ptr) {
return ConvertToBigEndian(*ptr);
}
template<typename T> /* requires integral<T> */
constexpr ALWAYS_INLINE T LoadLittleEndian(T *ptr) {
return ConvertToLittleEndian(*ptr);
}
template<typename T>
constexpr ALWAYS_INLINE void StoreBigEndian(T *ptr, T val) {
*ptr = ConvertToBigEndian(val);
}
template<typename T>
constexpr ALWAYS_INLINE void StoreLittleEndian(T *ptr, T val) {
*ptr = ConvertToLittleEndian(val);
}
}