SDL_endian.h

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2010 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
    slouken@libsdl.org
*/

/**
 *  \file SDL_endian.h
 *  
 *  Functions for reading and writing endian-specific values
 */

#ifndef _SDL_endian_h
#define _SDL_endian_h

#include "SDL_stdinc.h"

/**
 *  \name 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
/* *INDENT-OFF* */
extern "C" {
/* *INDENT-ON* */
#endif

/**
 *  \file SDL_endian.h
 *  
 *  Uses 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__)) && !defined(__mcoldfire__)
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__)
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__)) && !defined(__mcoldfire__)
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__)
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 = SDL_static_cast(Uint32, x & 0xFFFFFFFF);
    x >>= 32;
    hi = SDL_static_cast(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 */


static __inline__ float
SDL_SwapFloat(float x)
{
    union
    {
        float f;
        Uint32 ui32;
    } swapper;
    swapper.f = x;
    swapper.ui32 = SDL_Swap32(swapper.ui32);
    return swapper.f;
}


/**
 *  \name Swap to native
 *  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_SwapFloatLE(X)	(X)
#define SDL_SwapBE16(X)	SDL_Swap16(X)
#define SDL_SwapBE32(X)	SDL_Swap32(X)
#define SDL_SwapBE64(X)	SDL_Swap64(X)
#define SDL_SwapFloatBE(X)	SDL_SwapFloat(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_SwapFloatLE(X)	SDL_SwapFloat(X)
#define SDL_SwapBE16(X)	(X)
#define SDL_SwapBE32(X)	(X)
#define SDL_SwapBE64(X)	(X)
#define SDL_SwapFloatBE(X)	(X)
#endif
/*@}*//*Swap to native*/

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

#endif /* _SDL_endian_h */

/* vi: set ts=4 sw=4 expandtab: */