gbe_fork/overlay_experimental/System/Endianness.hpp

128 lines
3.9 KiB
C++
Raw Normal View History

2022-08-05 14:06:42 +08:00
/*
* Copyright (C) Nemirtingas
* This file is part of System.
*
* System is free software; you can redistribute it
* and/or modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* System 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with System; if not, see
* <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <cstddef> // size_t
#include <cstdint> // uint*_t
namespace System {
class Endian
{
private:
template<typename T, size_t byte_count>
struct ByteSwapImpl
{
constexpr static inline T swap(T v)
{
for (int i = 0; i < (byte_count/2); ++i)
{
uint8_t tmp = reinterpret_cast<uint8_t*>(&v)[i];
reinterpret_cast<uint8_t*>(&v)[i] = reinterpret_cast<uint8_t*>(&v)[byte_count - i - 1];
reinterpret_cast<uint8_t*>(&v)[byte_count - i - 1] = tmp;
}
return v;
}
};
template<typename T>
struct ByteSwapImpl<T, 1>
{
constexpr static inline T swap(T v) { return v; }
};
template<typename T>
struct ByteSwapImpl<T, 2>
{
constexpr static inline T swap(T v)
{
uint16_t& tmp = *reinterpret_cast<uint16_t*>(&v);
tmp = ((tmp & 0x00ffu) << 8)
| ((tmp & 0xff00u) >> 8);
return v;
}
};
template<typename T>
struct ByteSwapImpl<T, 4>
{
constexpr static inline T swap(T v)
{
uint32_t& tmp = *reinterpret_cast<uint32_t*>(&v);
tmp = ((tmp & 0x000000fful) << 24)
| ((tmp & 0x0000ff00ul) << 8)
| ((tmp & 0x00ff0000ul) >> 8)
| ((tmp & 0xff000000ul) >> 24);
return v;
}
};
template<typename T>
struct ByteSwapImpl<T, 8>
{
constexpr static inline T swap(T v)
{
uint64_t& tmp = *reinterpret_cast<uint64_t*>(&v);
tmp = ((tmp & 0x00000000000000ffull) << 56)
| ((tmp & 0x000000000000ff00ull) << 40)
| ((tmp & 0x0000000000ff0000ull) << 24)
| ((tmp & 0x00000000ff000000ull) << 8)
| ((tmp & 0x000000ff00000000ull) >> 8)
| ((tmp & 0x0000ff0000000000ull) >> 24)
| ((tmp & 0x00ff000000000000ull) >> 40)
| ((tmp & 0xff00000000000000ull) >> 56);
return v;
}
};
public:
static inline bool little()
{
const uint32_t endian_magic = 0x01020304;
return reinterpret_cast<const uint8_t*>(&endian_magic)[0] == 0x04;
}
static inline bool big()
{
const uint32_t endian_magic = 0x01020304;
return reinterpret_cast<const uint8_t*>(&endian_magic)[0] == 0x01;
}
template<typename T, size_t Size = sizeof(T)>
constexpr static inline T net_swap(T v)
{
if(Endian::little())
{
return ByteSwapImpl<T, Size>::swap(v);
}
return v;
}
template<typename T, size_t Size = sizeof(T)>
constexpr static inline T swap(T v)
{
return ByteSwapImpl<T, Size>::swap(v);
}
private:
Endian() = delete;
};
}