include/SDL_endian.h
author Sam Lantinga <slouken@libsdl.org>
Mon, 06 Feb 2006 08:28:51 +0000
changeset 1330 450721ad5436
parent 1312 c9b51268668f
child 1353 7ba544e2888d
permissions -rw-r--r--
It's now possible to build SDL without any C runtime at all on Windows,
using Visual C++ 2005
     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 /* These functions read and write data of the specified endianness, 
    29    dynamically translating to the host machine endianness.
    30 
    31    e.g.: If you want to read a 16 bit value on big-endian machine from
    32          an open file containing little endian values, you would use:
    33 		value = SDL_ReadLE16(rp);
    34          Note that the read/write functions use SDL_RWops pointers
    35          instead of FILE pointers.  This allows you to read and write
    36          endian values from large chunks of memory as well as files 
    37          and other data sources.
    38 */
    39 
    40 #include "SDL_types.h"
    41 #include "SDL_rwops.h"
    42 #include "SDL_byteorder.h"
    43 
    44 #include "begin_code.h"
    45 /* Set up for C function definitions, even when using C++ */
    46 #ifdef __cplusplus
    47 extern "C" {
    48 #endif
    49 
    50 /* Use inline functions for compilers that support them, and static
    51    functions for those that do not.  Because these functions become
    52    static for compilers that do not support inline functions, this
    53    header should only be included in files that actually use them.
    54 */
    55 #if defined(__GNUC__) && defined(__i386__)
    56 static __inline__ Uint16 SDL_Swap16(Uint16 x)
    57 {
    58 	__asm__("xchgb %b0,%h0" : "=q" (x) :  "0" (x));
    59 	return x;
    60 }
    61 #elif defined(__GNUC__) && defined(__x86_64__)
    62 static __inline__ Uint16 SDL_Swap16(Uint16 x)
    63 {
    64 	__asm__("xchgb %b0,%h0" : "=Q" (x) :  "0" (x));
    65 	return x;
    66 }
    67 #elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
    68 static __inline__ Uint16 SDL_Swap16(Uint16 x)
    69 {
    70 	Uint16 result;
    71 
    72 	__asm__("rlwimi %0,%2,8,16,23" : "=&r" (result) : "0" (x >> 8), "r" (x));
    73 	return result;
    74 }
    75 #elif defined(__GNUC__) && (defined(__M68000__) || defined(__M68020__))
    76 static __inline__ Uint16 SDL_Swap16(Uint16 x)
    77 {
    78 	__asm__("rorw #8,%0" : "=d" (x) :  "0" (x) : "cc");
    79 	return x;
    80 }
    81 #else
    82 static __inline__ Uint16 SDL_Swap16(Uint16 x) {
    83 	return((x<<8)|(x>>8));
    84 }
    85 #endif
    86 
    87 #if defined(__GNUC__) && defined(__i386__)
    88 static __inline__ Uint32 SDL_Swap32(Uint32 x)
    89 {
    90 	__asm__("bswap %0" : "=r" (x) : "0" (x));
    91 	return x;
    92 }
    93 #elif defined(__GNUC__) && defined(__x86_64__)
    94 static __inline__ Uint32 SDL_Swap32(Uint32 x)
    95 {
    96 	__asm__("bswapl %0" : "=r" (x) : "0" (x));
    97 	return x;
    98 }
    99 #elif defined(__GNUC__) && (defined(__powerpc__) || defined(__ppc__))
   100 static __inline__ Uint32 SDL_Swap32(Uint32 x)
   101 {
   102 	Uint32 result;
   103 
   104 	__asm__("rlwimi %0,%2,24,16,23" : "=&r" (result) : "0" (x>>24), "r" (x));
   105 	__asm__("rlwimi %0,%2,8,8,15"   : "=&r" (result) : "0" (result),    "r" (x));
   106 	__asm__("rlwimi %0,%2,24,0,7"   : "=&r" (result) : "0" (result),    "r" (x));
   107 	return result;
   108 }
   109 #elif defined(__GNUC__) && (defined(__M68000__) || defined(__M68020__))
   110 static __inline__ Uint32 SDL_Swap32(Uint32 x)
   111 {
   112 	__asm__("rorw #8,%0\n\tswap %0\n\trorw #8,%0" : "=d" (x) :  "0" (x) : "cc");
   113 	return x;
   114 }
   115 #else
   116 static __inline__ Uint32 SDL_Swap32(Uint32 x) {
   117 	return((x<<24)|((x<<8)&0x00FF0000)|((x>>8)&0x0000FF00)|(x>>24));
   118 }
   119 #endif
   120 
   121 #ifdef SDL_HAS_64BIT_TYPE
   122 #if defined(__GNUC__) && defined(__i386__)
   123 static __inline__ Uint64 SDL_Swap64(Uint64 x)
   124 {
   125 	union { 
   126 		struct { Uint32 a,b; } s;
   127 		Uint64 u;
   128 	} v;
   129 	v.u = x;
   130 	__asm__("bswapl %0 ; bswapl %1 ; xchgl %0,%1" 
   131 	        : "=r" (v.s.a), "=r" (v.s.b) 
   132 	        : "0" (v.s.a), "1" (v.s.b)); 
   133 	return v.u;
   134 }
   135 #elif defined(__GNUC__) && defined(__x86_64__)
   136 static __inline__ Uint64 SDL_Swap64(Uint64 x)
   137 {
   138 	__asm__("bswapq %0" : "=r" (x) : "0" (x));
   139 	return x;
   140 }
   141 #else
   142 static __inline__ Uint64 SDL_Swap64(Uint64 x)
   143 {
   144 	Uint32 hi, lo;
   145 
   146 	/* Separate into high and low 32-bit values and swap them */
   147 	lo = (Uint32)(x&0xFFFFFFFF);
   148 	x >>= 32;
   149 	hi = (Uint32)(x&0xFFFFFFFF);
   150 	x = SDL_Swap32(lo);
   151 	x <<= 32;
   152 	x |= SDL_Swap32(hi);
   153 	return(x);
   154 }
   155 #endif
   156 #else
   157 /* This is mainly to keep compilers from complaining in SDL code.
   158    If there is no real 64-bit datatype, then compilers will complain about
   159    the fake 64-bit datatype that SDL provides when it compiles user code.
   160 */
   161 #define SDL_Swap64(X)	(X)
   162 #endif /* SDL_HAS_64BIT_TYPE */
   163 
   164 
   165 /* Byteswap item from the specified endianness to the native endianness */
   166 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
   167 #define SDL_SwapLE16(X)	(X)
   168 #define SDL_SwapLE32(X)	(X)
   169 #define SDL_SwapLE64(X)	(X)
   170 #define SDL_SwapBE16(X)	SDL_Swap16(X)
   171 #define SDL_SwapBE32(X)	SDL_Swap32(X)
   172 #define SDL_SwapBE64(X)	SDL_Swap64(X)
   173 #else
   174 #define SDL_SwapLE16(X)	SDL_Swap16(X)
   175 #define SDL_SwapLE32(X)	SDL_Swap32(X)
   176 #define SDL_SwapLE64(X)	SDL_Swap64(X)
   177 #define SDL_SwapBE16(X)	(X)
   178 #define SDL_SwapBE32(X)	(X)
   179 #define SDL_SwapBE64(X)	(X)
   180 #endif
   181 
   182 /* Read an item of the specified endianness and return in native format */
   183 extern DECLSPEC Uint16 SDLCALL SDL_ReadLE16(SDL_RWops *src);
   184 extern DECLSPEC Uint16 SDLCALL SDL_ReadBE16(SDL_RWops *src);
   185 extern DECLSPEC Uint32 SDLCALL SDL_ReadLE32(SDL_RWops *src);
   186 extern DECLSPEC Uint32 SDLCALL SDL_ReadBE32(SDL_RWops *src);
   187 extern DECLSPEC Uint64 SDLCALL SDL_ReadLE64(SDL_RWops *src);
   188 extern DECLSPEC Uint64 SDLCALL SDL_ReadBE64(SDL_RWops *src);
   189 
   190 /* Write an item of native format to the specified endianness */
   191 extern DECLSPEC int SDLCALL SDL_WriteLE16(SDL_RWops *dst, Uint16 value);
   192 extern DECLSPEC int SDLCALL SDL_WriteBE16(SDL_RWops *dst, Uint16 value);
   193 extern DECLSPEC int SDLCALL SDL_WriteLE32(SDL_RWops *dst, Uint32 value);
   194 extern DECLSPEC int SDLCALL SDL_WriteBE32(SDL_RWops *dst, Uint32 value);
   195 extern DECLSPEC int SDLCALL SDL_WriteLE64(SDL_RWops *dst, Uint64 value);
   196 extern DECLSPEC int SDLCALL SDL_WriteBE64(SDL_RWops *dst, Uint64 value);
   197 
   198 
   199 /* Ends C function definitions when using C++ */
   200 #ifdef __cplusplus
   201 }
   202 #endif
   203 #include "close_code.h"
   204 
   205 #endif /* _SDL_endian_h */