include/SDL_endian.h
author Sam Lantinga <slouken@libsdl.org>
Fri, 20 Aug 2004 22:32:05 +0000
changeset 932 66761191fc11
parent 859 6b28c91bf3d2
child 985 cec525374267
permissions -rw-r--r--
Use the canonical glext.h on MacOS X as well (#define NO_SDL_GLEXT if you don't want this)
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2004 Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Library General Public
     7     License as published by the Free Software Foundation; either
     8     version 2 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     Library General Public License for more details.
    14 
    15     You should have received a copy of the GNU Library General Public
    16     License along with this library; if not, write to the Free
    17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 
    23 #ifdef SAVE_RCSID
    24 static char rcsid =
    25  "@(#) $Id$";
    26 #endif
    27 
    28 /* Functions for reading and writing endian-specific values */
    29 
    30 #ifndef _SDL_endian_h
    31 #define _SDL_endian_h
    32 
    33 /* These functions read and write data of the specified endianness, 
    34    dynamically translating to the host machine endianness.
    35 
    36    e.g.: If you want to read a 16 bit value on big-endian machine from
    37          an open file containing little endian values, you would use:
    38 		value = SDL_ReadLE16(rp);
    39          Note that the read/write functions use SDL_RWops pointers
    40          instead of FILE pointers.  This allows you to read and write
    41          endian values from large chunks of memory as well as files 
    42          and other data sources.
    43 */
    44 
    45 #include <stdio.h>
    46 
    47 #include "SDL_types.h"
    48 #include "SDL_rwops.h"
    49 #include "SDL_byteorder.h"
    50 
    51 #include "begin_code.h"
    52 /* Set up for C function definitions, even when using C++ */
    53 #ifdef __cplusplus
    54 extern "C" {
    55 #endif
    56 
    57 /* Use inline functions for compilers that support them, and static
    58    functions for those that do not.  Because these functions become
    59    static for compilers that do not support inline functions, this
    60    header should only be included in files that actually use them.
    61 */
    62 #if defined(__GNUC__) && defined(__i386__)
    63 static __inline__ Uint16 SDL_Swap16(Uint16 x)
    64 {
    65 	__asm__("xchgb %b0,%h0" : "=q" (x) :  "0" (x));
    66 	return x;
    67 }
    68 #elif defined(__GNUC__) && defined(__x86_64__)
    69 static __inline__ Uint16 SDL_Swap16(Uint16 x)
    70 {
    71 	__asm__("xchgb %b0,%h0" : "=q" (x) :  "0" (x));
    72 	return x;
    73 }
    74 #elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
    75 static __inline__ Uint16 SDL_Swap16(Uint16 x)
    76 {
    77 	Uint16 result;
    78 
    79 	__asm__("rlwimi %0,%2,8,16,23" : "=&r" (result) : "0" (x >> 8), "r" (x));
    80 	return result;
    81 }
    82 #else
    83 static __inline__ Uint16 SDL_Swap16(Uint16 x) {
    84 	return((x<<8)|(x>>8));
    85 }
    86 #endif
    87 
    88 #if defined(__GNUC__) && defined(__i386__)
    89 static __inline__ Uint32 SDL_Swap32(Uint32 x)
    90 {
    91 	__asm__("bswap %0" : "=r" (x) : "0" (x));
    92 	return x;
    93 }
    94 #elif defined(__GNUC__) && defined(__x86_64__)
    95 static __inline__ Uint32 SDL_Swap32(Uint32 x)
    96 {
    97 	__asm__("bswapl %0" : "=r" (x) : "0" (x));
    98 	return x;
    99 }
   100 #elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
   101 static __inline__ Uint32 SDL_Swap32(Uint32 x)
   102 {
   103 	Uint32 result;
   104 
   105 	__asm__("rlwimi %0,%2,24,16,23" : "=&r" (result) : "0" (x>>24), "r" (x));
   106 	__asm__("rlwimi %0,%2,8,8,15"   : "=&r" (result) : "0" (result),    "r" (x));
   107 	__asm__("rlwimi %0,%2,24,0,7"   : "=&r" (result) : "0" (result),    "r" (x));
   108 	return result;
   109 }
   110 #else
   111 static __inline__ Uint32 SDL_Swap32(Uint32 x) {
   112 	return((x<<24)|((x<<8)&0x00FF0000)|((x>>8)&0x0000FF00)|(x>>24));
   113 }
   114 #endif
   115 
   116 #ifdef SDL_HAS_64BIT_TYPE
   117 #if defined(__GNUC__) && defined(__i386__)
   118 static __inline__ Uint64 SDL_Swap64(Uint64 x)
   119 {
   120 	union { 
   121 		struct { Uint32 a,b; } s;
   122 		Uint64 u;
   123 	} v;
   124 	v.u = x;
   125 	__asm__("bswapl %0 ; bswapl %1 ; xchgl %0,%1" 
   126 	        : "=r" (v.s.a), "=r" (v.s.b) 
   127 	        : "0" (v.s.a), "1" (v.s.b)); 
   128 	return v.u;
   129 }
   130 #elif defined(__GNUC__) && defined(__x86_64__)
   131 static __inline__ Uint64 SDL_Swap64(Uint64 x)
   132 {
   133 	__asm__("bswapq %0" : "=r" (x) : "0" (x));
   134 	return x;
   135 }
   136 #else
   137 static __inline__ Uint64 SDL_Swap64(Uint64 x)
   138 {
   139 	Uint32 hi, lo;
   140 
   141 	/* Separate into high and low 32-bit values and swap them */
   142 	lo = (Uint32)(x&0xFFFFFFFF);
   143 	x >>= 32;
   144 	hi = (Uint32)(x&0xFFFFFFFF);
   145 	x = SDL_Swap32(lo);
   146 	x <<= 32;
   147 	x |= SDL_Swap32(hi);
   148 	return(x);
   149 }
   150 #endif
   151 #else
   152 /* This is mainly to keep compilers from complaining in SDL code.
   153    If there is no real 64-bit datatype, then compilers will complain about
   154    the fake 64-bit datatype that SDL provides when it compiles user code.
   155 */
   156 #define SDL_Swap64(X)	(X)
   157 #endif /* SDL_HAS_64BIT_TYPE */
   158 
   159 
   160 /* Byteswap item from the specified endianness to the native endianness */
   161 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
   162 #define SDL_SwapLE16(X)	(X)
   163 #define SDL_SwapLE32(X)	(X)
   164 #define SDL_SwapLE64(X)	(X)
   165 #define SDL_SwapBE16(X)	SDL_Swap16(X)
   166 #define SDL_SwapBE32(X)	SDL_Swap32(X)
   167 #define SDL_SwapBE64(X)	SDL_Swap64(X)
   168 #else
   169 #define SDL_SwapLE16(X)	SDL_Swap16(X)
   170 #define SDL_SwapLE32(X)	SDL_Swap32(X)
   171 #define SDL_SwapLE64(X)	SDL_Swap64(X)
   172 #define SDL_SwapBE16(X)	(X)
   173 #define SDL_SwapBE32(X)	(X)
   174 #define SDL_SwapBE64(X)	(X)
   175 #endif
   176 
   177 /* Read an item of the specified endianness and return in native format */
   178 extern DECLSPEC Uint16 SDLCALL SDL_ReadLE16(SDL_RWops *src);
   179 extern DECLSPEC Uint16 SDLCALL SDL_ReadBE16(SDL_RWops *src);
   180 extern DECLSPEC Uint32 SDLCALL SDL_ReadLE32(SDL_RWops *src);
   181 extern DECLSPEC Uint32 SDLCALL SDL_ReadBE32(SDL_RWops *src);
   182 extern DECLSPEC Uint64 SDLCALL SDL_ReadLE64(SDL_RWops *src);
   183 extern DECLSPEC Uint64 SDLCALL SDL_ReadBE64(SDL_RWops *src);
   184 
   185 /* Write an item of native format to the specified endianness */
   186 extern DECLSPEC int SDLCALL SDL_WriteLE16(SDL_RWops *dst, Uint16 value);
   187 extern DECLSPEC int SDLCALL SDL_WriteBE16(SDL_RWops *dst, Uint16 value);
   188 extern DECLSPEC int SDLCALL SDL_WriteLE32(SDL_RWops *dst, Uint32 value);
   189 extern DECLSPEC int SDLCALL SDL_WriteBE32(SDL_RWops *dst, Uint32 value);
   190 extern DECLSPEC int SDLCALL SDL_WriteLE64(SDL_RWops *dst, Uint64 value);
   191 extern DECLSPEC int SDLCALL SDL_WriteBE64(SDL_RWops *dst, Uint64 value);
   192 
   193 
   194 /* Ends C function definitions when using C++ */
   195 #ifdef __cplusplus
   196 }
   197 #endif
   198 #include "close_code.h"
   199 
   200 #endif /* _SDL_endian_h */