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comparison include/SDL_endian.h @ 0:74212992fb08

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Initial revision
author Sam Lantinga <slouken@lokigames.com>
date Thu, 26 Apr 2001 16:45:43 +0000
parents
children b8688cfdc232
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-1:000000000000 0:74212992fb08
1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997, 1998, 1999, 2000, 2001 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@devolution.com
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 /* The macros used to swap values */
58 /* Try to use superfast macros on systems that support them */
59 #ifdef linux
60 #include <asm/byteorder.h>
61 #ifdef __arch__swab16
62 #define SDL_Swap16 __arch__swab16
63 #endif
64 #ifdef __arch__swab32
65 #define SDL_Swap32 __arch__swab32
66 #endif
67 #endif /* linux */
68 /* Use inline functions for compilers that support them, and static
69 functions for those that do not. Because these functions become
70 static for compilers that do not support inline functions, this
71 header should only be included in files that actually use them.
72 */
73 #ifndef SDL_Swap16
74 static __inline__ Uint16 SDL_Swap16(Uint16 D) {
75 return((D<<8)|(D>>8));
76 }
77 #endif
78 #ifndef SDL_Swap32
79 static __inline__ Uint32 SDL_Swap32(Uint32 D) {
80 return((D<<24)|((D<<8)&0x00FF0000)|((D>>8)&0x0000FF00)|(D>>24));
81 }
82 #endif
83 #ifdef SDL_HAS_64BIT_TYPE
84 #ifndef SDL_Swap64
85 static __inline__ Uint64 SDL_Swap64(Uint64 val) {
86 Uint32 hi, lo;
87
88 /* Separate into high and low 32-bit values and swap them */
89 lo = (Uint32)(val&0xFFFFFFFF);
90 val >>= 32;
91 hi = (Uint32)(val&0xFFFFFFFF);
92 val = SDL_Swap32(lo);
93 val <<= 32;
94 val |= SDL_Swap32(hi);
95 return(val);
96 }
97 #endif
98 #else
99 #ifndef SDL_Swap64
100 /* This is mainly to keep compilers from complaining in SDL code.
101 If there is no real 64-bit datatype, then compilers will complain about
102 the fake 64-bit datatype that SDL provides when it compiles user code.
103 */
104 #define SDL_Swap64(X) (X)
105 #endif
106 #endif /* SDL_HAS_64BIT_TYPE */
107
108
109 /* Byteswap item from the specified endianness to the native endianness */
110 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
111 #define SDL_SwapLE16(X) (X)
112 #define SDL_SwapLE32(X) (X)
113 #define SDL_SwapLE64(X) (X)
114 #define SDL_SwapBE16(X) SDL_Swap16(X)
115 #define SDL_SwapBE32(X) SDL_Swap32(X)
116 #define SDL_SwapBE64(X) SDL_Swap64(X)
117 #else
118 #define SDL_SwapLE16(X) SDL_Swap16(X)
119 #define SDL_SwapLE32(X) SDL_Swap32(X)
120 #define SDL_SwapLE64(X) SDL_Swap64(X)
121 #define SDL_SwapBE16(X) (X)
122 #define SDL_SwapBE32(X) (X)
123 #define SDL_SwapBE64(X) (X)
124 #endif
125
126 /* Read an item of the specified endianness and return in native format */
127 extern DECLSPEC Uint16 SDL_ReadLE16(SDL_RWops *src);
128 extern DECLSPEC Uint16 SDL_ReadBE16(SDL_RWops *src);
129 extern DECLSPEC Uint32 SDL_ReadLE32(SDL_RWops *src);
130 extern DECLSPEC Uint32 SDL_ReadBE32(SDL_RWops *src);
131 extern DECLSPEC Uint64 SDL_ReadLE64(SDL_RWops *src);
132 extern DECLSPEC Uint64 SDL_ReadBE64(SDL_RWops *src);
133
134 /* Write an item of native format to the specified endianness */
135 extern DECLSPEC int SDL_WriteLE16(SDL_RWops *dst, Uint16 value);
136 extern DECLSPEC int SDL_WriteBE16(SDL_RWops *dst, Uint16 value);
137 extern DECLSPEC int SDL_WriteLE32(SDL_RWops *dst, Uint32 value);
138 extern DECLSPEC int SDL_WriteBE32(SDL_RWops *dst, Uint32 value);
139 extern DECLSPEC int SDL_WriteLE64(SDL_RWops *dst, Uint64 value);
140 extern DECLSPEC int SDL_WriteBE64(SDL_RWops *dst, Uint64 value);
141
142
143 /* Ends C function definitions when using C++ */
144 #ifdef __cplusplus
145 }
146 #endif
147 #include "close_code.h"
148
149 #endif /* _SDL_endian_h */