include/SDL_rwops.h
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     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 /* 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 */