0ad/source/lib/byte_order.h
2022-01-31 06:53:30 +00:00

167 lines
5.4 KiB
C

/* Copyright (C) 2022 Wildfire Games.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/*
* byte order (endianness) support routines.
*/
#ifndef INCLUDED_BYTE_ORDER
#define INCLUDED_BYTE_ORDER
#include "lib/sysdep/cpu.h"
// detect byte order via predefined macros.
#ifndef BYTE_ORDER
# define LITTLE_ENDIAN 0x4321
# define BIG_ENDIAN 0x1234
# if ARCH_IA32 || ARCH_IA64 || ARCH_AMD64 || ARCH_ALPHA || ARCH_ARM || ARCH_AARCH64 || ARCH_MIPS || ARCH_E2K || ARCH_PPC64 || defined(__LITTLE_ENDIAN__)
# define BYTE_ORDER LITTLE_ENDIAN
# else
# define BYTE_ORDER BIG_ENDIAN
# endif
#endif
/**
* convert 4 characters to u32 (at compile time) for easy comparison.
* output is in native byte order; e.g. FOURCC_LE can be used instead.
**/
#define FOURCC(a,b,c,d) // real definition is below
#undef FOURCC
// implementation rationale:
// - can't pass code as string, and use s[0]..s[3], because
// VC6/7 don't realize the macro is constant
// (it should be usable as a switch{} expression)
// - the casts are ugly but necessary. u32 is required because u8 << 8 == 0;
// the additional u8 cast ensures each character is treated as unsigned
// (otherwise, they'd be promoted to signed int before the u32 cast,
// which would break things).
/// big-endian version of FOURCC
#define FOURCC_BE(a,b,c,d) ( ((u32)(u8)a) << 24 | ((u32)(u8)b) << 16 | \
((u32)(u8)c) << 8 | ((u32)(u8)d) << 0 )
/// little-endian version of FOURCC
#define FOURCC_LE(a,b,c,d) ( ((u32)(u8)a) << 0 | ((u32)(u8)b) << 8 | \
((u32)(u8)c) << 16 | ((u32)(u8)d) << 24 )
#if BYTE_ORDER == BIG_ENDIAN
# define FOURCC FOURCC_BE
#else
# define FOURCC FOURCC_LE
#endif
#if BYTE_ORDER == BIG_ENDIAN
// convert a little-endian number to/from native byte order.
# define to_le16(x) swap16(x)
# define to_le32(x) swap32(x)
# define to_le64(x) swap64(x)
// convert a big-endian number to/from native byte order.
# define to_be16(x) (x)
# define to_be32(x) (x)
# define to_be64(x) (x)
#else // LITTLE_ENDIAN
// convert a little-endian number to/from native byte order.
# define to_le16(x) (x)
# define to_le32(x) (x)
# define to_le64(x) (x)
// convert a big-endian number to/from native byte order.
# define to_be16(x) swap16(x)
# define to_be32(x) swap32(x)
# define to_be64(x) swap64(x)
#endif
/// read a little-endian number from memory into native byte order.
u16 read_le16(const void* p);
u32 read_le32(const void* p); /// see read_le16
u64 read_le64(const void* p); /// see read_le16
/// read a big-endian number from memory into native byte order.
u16 read_be16(const void* p);
u32 read_be32(const void* p); /// see read_be16
u64 read_be64(const void* p); /// see read_be16
/// write a little-endian number to memory in native byte order.
void write_le16(void* p, u16 x);
void write_le32(void* p, u32 x); /// see write_le16
void write_le64(void* p, u64 x); /// see write_le16
/// write a big-endian number to memory in native byte order.
void write_be16(void* p, u16 x);
void write_be32(void* p, u32 x); /// see write_be16
void write_be64(void* p, u64 x); /// see write_be16
/**
* zero-extend \<size\> (truncated to 8) bytes of little-endian data to u64,
* starting at address \<p\> (need not be aligned).
**/
u64 movzx_le64(const u8* p, size_t size);
u64 movzx_be64(const u8* p, size_t size);
/**
* sign-extend \<size\> (truncated to 8) bytes of little-endian data to i64,
* starting at address \<p\> (need not be aligned).
**/
i64 movsx_le64(const u8* p, size_t size);
i64 movsx_be64(const u8* p, size_t size);
#if ICC_VERSION
#define swap32 _bswap
#define swap64 _bswap64
#elif MSC_VERSION
extern unsigned short _byteswap_ushort(unsigned short);
extern unsigned long _byteswap_ulong(unsigned long);
extern unsigned __int64 _byteswap_uint64(unsigned __int64);
#pragma intrinsic(_byteswap_ushort)
#pragma intrinsic(_byteswap_ulong)
#pragma intrinsic(_byteswap_uint64)
# define swap16 _byteswap_ushort
# define swap32 _byteswap_ulong
# define swap64 _byteswap_uint64
#elif defined(linux)
# include <asm/byteorder.h>
# if defined(__arch__swab16) && !defined(swap16)
# define swap16 __arch__swab16
# endif
# if defined(__arch__swab32) && !defined(swap32)
# define swap32 __arch__swab32
# endif
# if defined(__arch__swab64) && !defined(swap64)
# define swap64 __arch__swab64
# endif
#endif
#ifndef swap16
u16 swap16(const u16 x);
#endif
#ifndef swap32
u32 swap32(const u32 x);
#endif
#ifndef swap64
u64 swap64(const u64 x);
#endif
#endif // #ifndef INCLUDED_BYTE_ORDER