include/SDL_endian.h
author Sam Lantinga <slouken@libsdl.org>
Tue, 25 Jan 2005 17:58:44 +0000
changeset 1033 aebfa3ce2a53
parent 1031 3cf036d8861f
child 1044 d36ea7925763
permissions -rw-r--r--
The fix is going back in. :)
     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 #elif defined(__GNUC__) && defined(__M68000__)
    83 static __inline__ Uint16 SDL_Swap16(Uint16 x)
    84 {
    85 	__asm__("rorw #8,%0" : "=d" (x) :  "0" (x) : "cc");
    86 	return x;
    87 }
    88 #else
    89 static __inline__ Uint16 SDL_Swap16(Uint16 x) {
    90 	return((x<<8)|(x>>8));
    91 }
    92 #endif
    93 
    94 #if defined(__GNUC__) && defined(__i386__)
    95 static __inline__ Uint32 SDL_Swap32(Uint32 x)
    96 {
    97 	__asm__("bswap %0" : "=r" (x) : "0" (x));
    98 	return x;
    99 }
   100 #elif defined(__GNUC__) && defined(__x86_64__)
   101 static __inline__ Uint32 SDL_Swap32(Uint32 x)
   102 {
   103 	__asm__("bswapl %0" : "=r" (x) : "0" (x));
   104 	return x;
   105 }
   106 #elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
   107 static __inline__ Uint32 SDL_Swap32(Uint32 x)
   108 {
   109 	Uint32 result;
   110 
   111 	__asm__("rlwimi %0,%2,24,16,23" : "=&r" (result) : "0" (x>>24), "r" (x));
   112 	__asm__("rlwimi %0,%2,8,8,15"   : "=&r" (result) : "0" (result),    "r" (x));
   113 	__asm__("rlwimi %0,%2,24,0,7"   : "=&r" (result) : "0" (result),    "r" (x));
   114 	return result;
   115 }
   116 #elif defined(__GNUC__) && defined(__M68000__)
   117 static __inline__ Uint32 SDL_Swap32(Uint32 x)
   118 {
   119 	__asm__("rorw	#8,%0\n\tswap	%0\n\tror	#8,%0" : "=d" (x) :  "0" (x) : "cc");
   120 	return x;
   121 }
   122 #else
   123 static __inline__ Uint32 SDL_Swap32(Uint32 x) {
   124 	return((x<<24)|((x<<8)&0x00FF0000)|((x>>8)&0x0000FF00)|(x>>24));
   125 }
   126 #endif
   127 
   128 #ifdef SDL_HAS_64BIT_TYPE
   129 #if defined(__GNUC__) && defined(__i386__)
   130 static __inline__ Uint64 SDL_Swap64(Uint64 x)
   131 {
   132 	union { 
   133 		struct { Uint32 a,b; } s;
   134 		Uint64 u;
   135 	} v;
   136 	v.u = x;
   137 	__asm__("bswapl %0 ; bswapl %1 ; xchgl %0,%1" 
   138 	        : "=r" (v.s.a), "=r" (v.s.b) 
   139 	        : "0" (v.s.a), "1" (v.s.b)); 
   140 	return v.u;
   141 }
   142 #elif defined(__GNUC__) && defined(__x86_64__)
   143 static __inline__ Uint64 SDL_Swap64(Uint64 x)
   144 {
   145 	__asm__("bswapq %0" : "=r" (x) : "0" (x));
   146 	return x;
   147 }
   148 #else
   149 static __inline__ Uint64 SDL_Swap64(Uint64 x)
   150 {
   151 	Uint32 hi, lo;
   152 
   153 	/* Separate into high and low 32-bit values and swap them */
   154 	lo = (Uint32)(x&0xFFFFFFFF);
   155 	x >>= 32;
   156 	hi = (Uint32)(x&0xFFFFFFFF);
   157 	x = SDL_Swap32(lo);
   158 	x <<= 32;
   159 	x |= SDL_Swap32(hi);
   160 	return(x);
   161 }
   162 #endif
   163 #else
   164 /* This is mainly to keep compilers from complaining in SDL code.
   165    If there is no real 64-bit datatype, then compilers will complain about
   166    the fake 64-bit datatype that SDL provides when it compiles user code.
   167 */
   168 #define SDL_Swap64(X)	(X)
   169 #endif /* SDL_HAS_64BIT_TYPE */
   170 
   171 
   172 /* Byteswap item from the specified endianness to the native endianness */
   173 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
   174 #define SDL_SwapLE16(X)	(X)
   175 #define SDL_SwapLE32(X)	(X)
   176 #define SDL_SwapLE64(X)	(X)
   177 #define SDL_SwapBE16(X)	SDL_Swap16(X)
   178 #define SDL_SwapBE32(X)	SDL_Swap32(X)
   179 #define SDL_SwapBE64(X)	SDL_Swap64(X)
   180 #else
   181 #define SDL_SwapLE16(X)	SDL_Swap16(X)
   182 #define SDL_SwapLE32(X)	SDL_Swap32(X)
   183 #define SDL_SwapLE64(X)	SDL_Swap64(X)
   184 #define SDL_SwapBE16(X)	(X)
   185 #define SDL_SwapBE32(X)	(X)
   186 #define SDL_SwapBE64(X)	(X)
   187 #endif
   188 
   189 /* Read an item of the specified endianness and return in native format */
   190 extern DECLSPEC Uint16 SDLCALL SDL_ReadLE16(SDL_RWops *src);
   191 extern DECLSPEC Uint16 SDLCALL SDL_ReadBE16(SDL_RWops *src);
   192 extern DECLSPEC Uint32 SDLCALL SDL_ReadLE32(SDL_RWops *src);
   193 extern DECLSPEC Uint32 SDLCALL SDL_ReadBE32(SDL_RWops *src);
   194 extern DECLSPEC Uint64 SDLCALL SDL_ReadLE64(SDL_RWops *src);
   195 extern DECLSPEC Uint64 SDLCALL SDL_ReadBE64(SDL_RWops *src);
   196 
   197 /* Write an item of native format to the specified endianness */
   198 extern DECLSPEC int SDLCALL SDL_WriteLE16(SDL_RWops *dst, Uint16 value);
   199 extern DECLSPEC int SDLCALL SDL_WriteBE16(SDL_RWops *dst, Uint16 value);
   200 extern DECLSPEC int SDLCALL SDL_WriteLE32(SDL_RWops *dst, Uint32 value);
   201 extern DECLSPEC int SDLCALL SDL_WriteBE32(SDL_RWops *dst, Uint32 value);
   202 extern DECLSPEC int SDLCALL SDL_WriteLE64(SDL_RWops *dst, Uint64 value);
   203 extern DECLSPEC int SDLCALL SDL_WriteBE64(SDL_RWops *dst, Uint64 value);
   204 
   205 
   206 /* Ends C function definitions when using C++ */
   207 #ifdef __cplusplus
   208 }
   209 #endif
   210 #include "close_code.h"
   211 
   212 #endif /* _SDL_endian_h */