src/image/sublib/SDL_rwops.h

   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: SDL_rwops.h,v 1.1.1.1 2003/01/04 11:37:22 leo Exp $";
  26 #endif
  27
  28 /* This file provides a general interface for SDL to read and write
  29    data sources.  It can easily be extended to files, memory, etc.
  30 */
  31
  32 #ifndef _SDL_RWops_h
  33 #define _SDL_RWops_h
  34
  35 #include <stdio.h>
  36
  37 #include "SDL_types.h"
  38
  39 #include "begin_code.h"
  40 /* Set up for C function definitions, even when using C++ */
  41 #ifdef __cplusplus
  42 extern "C" {
  43 #endif
  44
  45 /* This is the read/write operation structure -- very basic */
  46
  47 typedef struct SDL_RWops {
  48         /* Seek to 'offset' relative to whence, one of stdio's whence values:
  49                 SEEK_SET, SEEK_CUR, SEEK_END
  50            Returns the final offset in the data source.
  51          */
  52         int (*seek)(struct SDL_RWops *context, int offset, int whence);
  53
  54         /* Read up to 'num' objects each of size 'objsize' from the data
  55            source to the area pointed at by 'ptr'.
  56            Returns the number of objects read, or -1 if the read failed.
  57          */
  58         int (*read)(struct SDL_RWops *context, void *ptr, int size, int maxnum);
  59
  60         /* Write exactly 'num' objects each of size 'objsize' from the area
  61            pointed at by 'ptr' to data source.
  62            Returns 'num', or -1 if the write failed.
  63          */
  64         int (*write)(struct SDL_RWops *context, const void *ptr, int size, int num);
  65
  66         /* Close and free an allocated SDL_FSops structure */
  67         int (*close)(struct SDL_RWops *context);
  68
  69         Uint32 type;
  70         union {
  71             struct {
  72                 int autoclose;
  73                 FILE *fp;
  74             } stdio;
  75             struct {
  76                 Uint8 *base;
  77                 Uint8 *here;
  78                 Uint8 *stop;
  79             } mem;
  80             struct {
  81                 void *data1;
  82             } unknown;
  83         } hidden;
  84
  85 } SDL_RWops;
  86
  87
  88 /* Functions to create SDL_RWops structures from various data sources */
  89
  90 extern DECLSPEC SDL_RWops * SDL_RWFromFile(const char *file, const char *mode);
  91
  92 extern DECLSPEC SDL_RWops * SDL_RWFromFP(FILE *fp, int autoclose);
  93
  94 extern DECLSPEC SDL_RWops * SDL_RWFromMem(void *mem, int size);
  95
  96 extern DECLSPEC SDL_RWops * SDL_AllocRW(void);
  97 extern DECLSPEC void SDL_FreeRW(SDL_RWops *area);
  98
  99 /* Macros to easily read and write from an SDL_RWops structure */
 100 #define SDL_RWseek(ctx, offset, whence) (ctx)->seek(ctx, offset, whence)
 101 #define SDL_RWtell(ctx)                 (ctx)->seek(ctx, 0, SEEK_CUR)
 102 #define SDL_RWread(ctx, ptr, size, n)   (ctx)->read(ctx, ptr, size, n)
 103 #define SDL_RWwrite(ctx, ptr, size, n)  (ctx)->write(ctx, ptr, size, n)
 104 #define SDL_RWclose(ctx)                (ctx)->close(ctx)
 105
 106
 107 /* Ends C function definitions when using C++ */
 108 #ifdef __cplusplus
 109 }
 110 #endif
 111 #include "close_code.h"
 112
 113 #endif /* _SDL_RWops_h */