sdl_endian.h

sdl开发库

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 Sam Lantinga

    This library 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 2.1 of the License, or (at your option) any later version.

    This library 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 this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    [e-mail]
*/

/* Functions for reading and writing endian-specific values */

#ifndef _SDL_endian_h
#define _SDL_endian_h

#include "SDL_stdinc.h"

/* The two types of endianness */
#define SDL_LIL_ENDIAN	1234
#define SDL_BIG_ENDIAN	4321

#ifndef SDL_BYTEORDER	/* Not defined in SDL_config.h? */
#if defined(__hppa__) || \
    defined(__m68k__) || defined(mc68000) || defined(_M_M68K) || \
    (defined(__MIPS__) && defined(__MISPEB__)) || \
    defined(__ppc__) || defined(__POWERPC__) || defined(_M_PPC) || \
    defined(__sparc__)
#define SDL_BYTEORDER	SDL_BIG_ENDIAN
#else
#define SDL_BYTEORDER	SDL_LIL_ENDIAN
#endif
#endif /* !SDL_BYTEORDER */


#include "begin_code.h"
/* Set up for C function definitions, even when using C++ */
#ifdef __cplusplus
extern "C" {
#endif

/* Use inline functions for compilers that support them, and static
   functions for those that do not.  Because these functions become
   static for compilers that do not support inline functions, this
   header should only be included in files that actually use them.
*/
#if defined(__GNUC__) && defined(__i386__) && \
   !(__GNUC__ == 2 && __GNUC_MINOR__ <= 95 /* broken gcc version */)
static __inline__ Uint16 SDL_Swap16(Uint16 x)
{
	__asm__("xchgb %b0,%h0" : "=q" (x) :  "0" (x));
	return x;
}
#elif defined(__GNUC__) && defined(__x86_64__)
static __inline__ Uint16 SDL_Swap16(Uint16 x)
{
	__asm__("xchgb %b0,%h0" : "=Q" (x) :  "0" (x));
	return x;
}
#elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
static __inline__ Uint16 SDL_Swap16(Uint16 x)
{
	Uint16 result;

	__asm__("rlwimi %0,%2,8,16,23" : "=&r" (result) : "0" (x >> 8), "r" (x));
	return result;
}
#elif defined(__GNUC__) && (defined(__M68000__) || defined(__M68020__))
static __inline__ Uint16 SDL_Swap16(Uint16 x)
{
	__asm__("rorw #8,%0" : "=d" (x) :  "0" (x) : "cc");
	return x;
}
#else
static __inline__ Uint16 SDL_Swap16(Uint16 x) {
	return((x<<8)|(x>>8));
}
#endif

#if defined(__GNUC__) && defined(__i386__) && \
   !(__GNUC__ == 2 && __GNUC_MINOR__ <= 95 /* broken gcc version */)
static __inline__ Uint32 SDL_Swap32(Uint32 x)
{
	__asm__("bswap %0" : "=r" (x) : "0" (x));
	return x;
}
#elif defined(__GNUC__) && defined(__x86_64__)
static __inline__ Uint32 SDL_Swap32(Uint32 x)
{
	__asm__("bswapl %0" : "=r" (x) : "0" (x));
	return x;
}
#elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
static __inline__ Uint32 SDL_Swap32(Uint32 x)
{
	Uint32 result;

	__asm__("rlwimi %0,%2,24,16,23" : "=&r" (result) : "0" (x>>24), "r" (x));
	__asm__("rlwimi %0,%2,8,8,15"   : "=&r" (result) : "0" (result),    "r" (x));
	__asm__("rlwimi %0,%2,24,0,7"   : "=&r" (result) : "0" (result),    "r" (x));
	return result;
}
#elif defined(__GNUC__) && (defined(__M68000__) || defined(__M68020__))
static __inline__ Uint32 SDL_Swap32(Uint32 x)
{
	__asm__("rorw #8,%0\n\tswap %0\n\trorw #8,%0" : "=d" (x) :  "0" (x) : "cc");
	return x;
}
#else
static __inline__ Uint32 SDL_Swap32(Uint32 x) {
	return((x<<24)|((x<<8)&0x00FF0000)|((x>>8)&0x0000FF00)|(x>>24));
}
#endif

#ifdef SDL_HAS_64BIT_TYPE
#if defined(__GNUC__) && defined(__i386__) && \
   !(__GNUC__ == 2 && __GNUC_MINOR__ <= 95 /* broken gcc version */)
static __inline__ Uint64 SDL_Swap64(Uint64 x)
{
	union { 
		struct { Uint32 a,b; } s;
		Uint64 u;
	} v;
	v.u = x;
	__asm__("bswapl %0 ; bswapl %1 ; xchgl %0,%1" 
	        : "=r" (v.s.a), "=r" (v.s.b) 
	        : "0" (v.s.a), "1" (v.s.b)); 
	return v.u;
}
#elif defined(__GNUC__) && defined(__x86_64__)
static __inline__ Uint64 SDL_Swap64(Uint64 x)
{
	__asm__("bswapq %0" : "=r" (x) : "0" (x));
	return x;
}
#else
static __inline__ Uint64 SDL_Swap64(Uint64 x)
{
	Uint32 hi, lo;

	/* Separate into high and low 32-bit values and swap them */
	lo = (Uint32)(x&0xFFFFFFFF);
	x >>= 32;
	hi = (Uint32)(x&0xFFFFFFFF);
	x = SDL_Swap32(lo);
	x <<= 32;
	x |= SDL_Swap32(hi);
	return(x);
}
#endif
#else
/* This is mainly to keep compilers from complaining in SDL code.
   If there is no real 64-bit datatype, then compilers will complain about
   the fake 64-bit datatype that SDL provides when it compiles user code.
*/
#define SDL_Swap64(X)	(X)
#endif /* SDL_HAS_64BIT_TYPE */


/* Byteswap item from the specified endianness to the native endianness */
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
#define SDL_SwapLE16(X)	(X)
#define SDL_SwapLE32(X)	(X)
#define SDL_SwapLE64(X)	(X)
#define SDL_SwapBE16(X)	SDL_Swap16(X)
#define SDL_SwapBE32(X)	SDL_Swap32(X)
#define SDL_SwapBE64(X)	SDL_Swap64(X)
#else
#define SDL_SwapLE16(X)	SDL_Swap16(X)
#define SDL_SwapLE32(X)	SDL_Swap32(X)
#define SDL_SwapLE64(X)	SDL_Swap64(X)
#define SDL_SwapBE16(X)	(X)
#define SDL_SwapBE32(X)	(X)
#define SDL_SwapBE64(X)	(X)
#endif

/* Ends C function definitions when using C++ */
#ifdef __cplusplus
}
#endif
#include "close_code.h"

#endif /* _SDL_endian_h */