src/include/SDL_endian.h

   1 /*
   2     SDL - Simple DirectMedia Layer
   3     Copyright (C) 1997-2006 Sam Lantinga
   4
   5     This library is free software; you can redistribute it and/or
   6     modify it under the terms of the GNU Lesser General Public
   7     License as published by the Free Software Foundation; either
   8     version 2.1 of the License, or (at your option) any later version.
   9
  10     This library is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13     Lesser General Public License for more details.
  14
  15     You should have received a copy of the GNU Lesser General Public
  16     License along with this library; if not, write to the Free Software
  17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18
  19     Sam Lantinga
  20     slouken@libsdl.org
  21 */
  22
  23 /* Functions for reading and writing endian-specific values */
  24
  25 #ifndef _SDL_endian_h
  26 #define _SDL_endian_h
  27
  28 #include "SDL_stdinc.h"
  29
  30 /* The two types of endianness */
  31 #define SDL_LIL_ENDIAN  1234
  32 #define SDL_BIG_ENDIAN  4321
  33
  34 #ifndef SDL_BYTEORDER   /* Not defined in SDL_config.h? */
  35 #if defined(__hppa__) || \
  36     defined(__m68k__) || defined(mc68000) || defined(_M_M68K) || \
  37     (defined(__MIPS__) && defined(__MISPEB__)) || \
  38     defined(__ppc__) || defined(__POWERPC__) || defined(_M_PPC) || \
  39     defined(__sparc__)
  40 #define SDL_BYTEORDER   SDL_BIG_ENDIAN
  41 #else
  42 #define SDL_BYTEORDER   SDL_LIL_ENDIAN
  43 #endif
  44 #endif /* !SDL_BYTEORDER */
  45
  46
  47 #include "begin_code.h"
  48 /* Set up for C function definitions, even when using C++ */
  49 #ifdef __cplusplus
  50 extern "C" {
  51 #endif
  52
  53 /* Use inline functions for compilers that support them, and static
  54    functions for those that do not.  Because these functions become
  55    static for compilers that do not support inline functions, this
  56    header should only be included in files that actually use them.
  57 */
  58 #if defined(__GNUC__) && defined(__i386__) && \
  59    !(__GNUC__ == 2 && __GNUC_MINOR__ <= 95 /* broken gcc version */)
  60 static __inline__ Uint16 SDL_Swap16(Uint16 x)
  61 {
  62         __asm__("xchgb %b0,%h0" : "=q" (x) :  "0" (x));
  63         return x;
  64 }
  65 #elif defined(__GNUC__) && defined(__x86_64__)
  66 static __inline__ Uint16 SDL_Swap16(Uint16 x)
  67 {
  68         __asm__("xchgb %b0,%h0" : "=Q" (x) :  "0" (x));
  69         return x;
  70 }
  71 #elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
  72 static __inline__ Uint16 SDL_Swap16(Uint16 x)
  73 {
  74         Uint16 result;
  75
  76         __asm__("rlwimi %0,%2,8,16,23" : "=&r" (result) : "0" (x >> 8), "r" (x));
  77         return result;
  78 }
  79 #elif defined(__GNUC__) && (defined(__M68000__) || defined(__M68020__))
  80 static __inline__ Uint16 SDL_Swap16(Uint16 x)
  81 {
  82         __asm__("rorw #8,%0" : "=d" (x) :  "0" (x) : "cc");
  83         return x;
  84 }
  85 #else
  86 static __inline__ Uint16 SDL_Swap16(Uint16 x) {
  87         return((x<<8)|(x>>8));
  88 }
  89 #endif
  90
  91 #if defined(__GNUC__) && defined(__i386__) && \
  92    !(__GNUC__ == 2 && __GNUC_MINOR__ <= 95 /* broken gcc version */)
  93 static __inline__ Uint32 SDL_Swap32(Uint32 x)
  94 {
  95         __asm__("bswap %0" : "=r" (x) : "0" (x));
  96         return x;
  97 }
  98 #elif defined(__GNUC__) && defined(__x86_64__)
  99 static __inline__ Uint32 SDL_Swap32(Uint32 x)
 100 {
 101         __asm__("bswapl %0" : "=r" (x) : "0" (x));
 102         return x;
 103 }
 104 #elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
 105 static __inline__ Uint32 SDL_Swap32(Uint32 x)
 106 {
 107         Uint32 result;
 108
 109         __asm__("rlwimi %0,%2,24,16,23" : "=&r" (result) : "0" (x>>24), "r" (x));
 110         __asm__("rlwimi %0,%2,8,8,15"   : "=&r" (result) : "0" (result),    "r" (x));
 111         __asm__("rlwimi %0,%2,24,0,7"   : "=&r" (result) : "0" (result),    "r" (x));
 112         return result;
 113 }
 114 #elif defined(__GNUC__) && (defined(__M68000__) || defined(__M68020__))
 115 static __inline__ Uint32 SDL_Swap32(Uint32 x)
 116 {
 117         __asm__("rorw #8,%0\n\tswap %0\n\trorw #8,%0" : "=d" (x) :  "0" (x) : "cc");
 118         return x;
 119 }
 120 #else
 121 static __inline__ Uint32 SDL_Swap32(Uint32 x) {
 122         return((x<<24)|((x<<8)&0x00FF0000)|((x>>8)&0x0000FF00)|(x>>24));
 123 }
 124 #endif
 125
 126 #ifdef SDL_HAS_64BIT_TYPE
 127 #if defined(__GNUC__) && defined(__i386__) && \
 128    !(__GNUC__ == 2 && __GNUC_MINOR__ <= 95 /* broken gcc version */)
 129 static __inline__ Uint64 SDL_Swap64(Uint64 x)
 130 {
 131         union {
 132                 struct { Uint32 a,b; } s;
 133                 Uint64 u;
 134         } v;
 135         v.u = x;
 136         __asm__("bswapl %0 ; bswapl %1 ; xchgl %0,%1"
 137                 : "=r" (v.s.a), "=r" (v.s.b)
 138                 : "0" (v.s.a), "1" (v.s.b));
 139         return v.u;
 140 }
 141 #elif defined(__GNUC__) && defined(__x86_64__)
 142 static __inline__ Uint64 SDL_Swap64(Uint64 x)
 143 {
 144         __asm__("bswapq %0" : "=r" (x) : "0" (x));
 145         return x;
 146 }
 147 #else
 148 static __inline__ Uint64 SDL_Swap64(Uint64 x)
 149 {
 150         Uint32 hi, lo;
 151
 152         /* Separate into high and low 32-bit values and swap them */
 153         lo = (Uint32)(x&0xFFFFFFFF);
 154         x >>= 32;
 155         hi = (Uint32)(x&0xFFFFFFFF);
 156         x = SDL_Swap32(lo);
 157         x <<= 32;
 158         x |= SDL_Swap32(hi);
 159         return(x);
 160 }
 161 #endif
 162 #else
 163 /* This is mainly to keep compilers from complaining in SDL code.
 164    If there is no real 64-bit datatype, then compilers will complain about
 165    the fake 64-bit datatype that SDL provides when it compiles user code.
 166 */
 167 #define SDL_Swap64(X)   (X)
 168 #endif /* SDL_HAS_64BIT_TYPE */
 169
 170
 171 /* Byteswap item from the specified endianness to the native endianness */
 172 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
 173 #define SDL_SwapLE16(X) (X)
 174 #define SDL_SwapLE32(X) (X)
 175 #define SDL_SwapLE64(X) (X)
 176 #define SDL_SwapBE16(X) SDL_Swap16(X)
 177 #define SDL_SwapBE32(X) SDL_Swap32(X)
 178 #define SDL_SwapBE64(X) SDL_Swap64(X)
 179 #else
 180 #define SDL_SwapLE16(X) SDL_Swap16(X)
 181 #define SDL_SwapLE32(X) SDL_Swap32(X)
 182 #define SDL_SwapLE64(X) SDL_Swap64(X)
 183 #define SDL_SwapBE16(X) (X)
 184 #define SDL_SwapBE32(X) (X)
 185 #define SDL_SwapBE64(X) (X)
 186 #endif
 187
 188 /* Ends C function definitions when using C++ */
 189 #ifdef __cplusplus
 190 }
 191 #endif
 192 #include "close_code.h"
 193
 194 #endif /* _SDL_endian_h */