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/*
* Copyright (C) 2011-2015 Max Kellermann <max.kellermann@gmail.com>,
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef BYTE_ORDER_HXX
#define BYTE_ORDER_HXX
#include "Compiler.h"
#include <stdint.h>
#if defined(__i386__) || defined(__x86_64__) || defined(__ARMEL__)
/* well-known little-endian */
# define IS_LITTLE_ENDIAN true
# define IS_BIG_ENDIAN false
#elif defined(__MIPSEB__)
/* well-known big-endian */
# define IS_LITTLE_ENDIAN false
# define IS_BIG_ENDIAN true
#elif defined(__APPLE__) || defined(__NetBSD__)
/* compile-time check for MacOS */
# include <machine/endian.h>
# if BYTE_ORDER == LITTLE_ENDIAN
# define IS_LITTLE_ENDIAN true
# define IS_BIG_ENDIAN false
# else
# define IS_LITTLE_ENDIAN false
# define IS_BIG_ENDIAN true
# endif
#elif defined(__BYTE_ORDER__)
/* GCC-specific macros */
# if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
# define IS_LITTLE_ENDIAN true
# define IS_BIG_ENDIAN false
# else
# define IS_LITTLE_ENDIAN false
# define IS_BIG_ENDIAN true
# endif
#else
/* generic compile-time check */
# include <endian.h>
# if __BYTE_ORDER == __LITTLE_ENDIAN
# define IS_LITTLE_ENDIAN true
# define IS_BIG_ENDIAN false
# else
# define IS_LITTLE_ENDIAN false
# define IS_BIG_ENDIAN true
# endif
#endif
constexpr bool
IsLittleEndian() noexcept
{
return IS_LITTLE_ENDIAN;
}
constexpr bool
IsBigEndian() noexcept
{
return IS_BIG_ENDIAN;
}
constexpr uint16_t
GenericByteSwap16(uint16_t value) noexcept
{
return (value >> 8) | (value << 8);
}
constexpr uint32_t
GenericByteSwap32(uint32_t value) noexcept
{
return (value >> 24) | ((value >> 8) & 0x0000ff00) |
((value << 8) & 0x00ff0000) | (value << 24);
}
constexpr uint64_t
GenericByteSwap64(uint64_t value) noexcept
{
return uint64_t(GenericByteSwap32(uint32_t(value >> 32)))
| (uint64_t(GenericByteSwap32(value)) << 32);
}
constexpr uint16_t
ByteSwap16(uint16_t value) noexcept
{
#if CLANG_OR_GCC_VERSION(4,8)
return __builtin_bswap16(value);
#else
return GenericByteSwap16(value);
#endif
}
constexpr uint32_t
ByteSwap32(uint32_t value) noexcept
{
#if CLANG_OR_GCC_VERSION(4,3)
return __builtin_bswap32(value);
#else
return GenericByteSwap32(value);
#endif
}
constexpr uint64_t
ByteSwap64(uint64_t value) noexcept
{
#if CLANG_OR_GCC_VERSION(4,3)
return __builtin_bswap64(value);
#else
return GenericByteSwap64(value);
#endif
}
/**
* Converts a 16bit value from big endian to the system's byte order
*/
constexpr uint16_t
FromBE16(uint16_t value) noexcept
{
return IsBigEndian() ? value : ByteSwap16(value);
}
/**
* Converts a 32bit value from big endian to the system's byte order
*/
constexpr uint32_t
FromBE32(uint32_t value) noexcept
{
return IsBigEndian() ? value : ByteSwap32(value);
}
/**
* Converts a 64bit value from big endian to the system's byte order
*/
constexpr uint64_t
FromBE64(uint64_t value) noexcept
{
return IsBigEndian() ? value : ByteSwap64(value);
}
/**
* Converts a 16bit value from little endian to the system's byte order
*/
constexpr uint16_t
FromLE16(uint16_t value) noexcept
{
return IsLittleEndian() ? value : ByteSwap16(value);
}
/**
* Converts a 32bit value from little endian to the system's byte order
*/
constexpr uint32_t
FromLE32(uint32_t value) noexcept
{
return IsLittleEndian() ? value : ByteSwap32(value);
}
/**
* Converts a 64bit value from little endian to the system's byte order
*/
constexpr uint64_t
FromLE64(uint64_t value) noexcept
{
return IsLittleEndian() ? value : ByteSwap64(value);
}
/**
* Converts a 16bit value from the system's byte order to big endian
*/
constexpr uint16_t
ToBE16(uint16_t value) noexcept
{
return IsBigEndian() ? value : ByteSwap16(value);
}
/**
* Converts a 32bit value from the system's byte order to big endian
*/
constexpr uint32_t
ToBE32(uint32_t value) noexcept
{
return IsBigEndian() ? value : ByteSwap32(value);
}
/**
* Converts a 64bit value from the system's byte order to big endian
*/
constexpr uint64_t
ToBE64(uint64_t value) noexcept
{
return IsBigEndian() ? value : ByteSwap64(value);
}
/**
* Converts a 16bit value from the system's byte order to little endian
*/
constexpr uint16_t
ToLE16(uint16_t value) noexcept
{
return IsLittleEndian() ? value : ByteSwap16(value);
}
/**
* Converts a 32bit value from the system's byte order to little endian
*/
constexpr uint32_t
ToLE32(uint32_t value) noexcept
{
return IsLittleEndian() ? value : ByteSwap32(value);
}
/**
* Converts a 64bit value from the system's byte order to little endian
*/
constexpr uint64_t
ToLE64(uint64_t value) noexcept
{
return IsLittleEndian() ? value : ByteSwap64(value);
}
/**
* Converts a 16 bit integer from little endian to the host byte order
* and returns it as a signed integer.
*/
constexpr int16_t
FromLE16S(uint16_t value) noexcept
{
/* assuming two's complement representation */
return static_cast<int16_t>(FromLE16(value));
}
#endif
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