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      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 (at) libsdl.org
     21 */
     22 
     23 /* This file provides a general interface for SDL to read and write
     24    data sources.  It can easily be extended to files, memory, etc.
     25 */
     26 
     27 #ifndef _SDL_rwops_h
     28 #define _SDL_rwops_h
     29 
     30 #include "SDL_stdinc.h"
     31 #include "SDL_error.h"
     32 
     33 #include "begin_code.h"
     34 /* Set up for C function definitions, even when using C++ */
     35 #ifdef __cplusplus
     36 extern "C" {
     37 #endif
     38 
     39 /* This is the read/write operation structure -- very basic */
     40 
     41 typedef struct SDL_RWops {
     42 	/* Seek to 'offset' relative to whence, one of stdio's whence values:
     43 		SEEK_SET, SEEK_CUR, SEEK_END
     44 	   Returns the final offset in the data source.
     45 	 */
     46 	int (SDLCALL *seek)(struct SDL_RWops *context, int offset, int whence);
     47 
     48 	/* Read up to 'num' objects each of size 'objsize' from the data
     49 	   source to the area pointed at by 'ptr'.
     50 	   Returns the number of objects read, or -1 if the read failed.
     51 	 */
     52 	int (SDLCALL *read)(struct SDL_RWops *context, void *ptr, int size, int maxnum);
     53 
     54 	/* Write exactly 'num' objects each of size 'objsize' from the area
     55 	   pointed at by 'ptr' to data source.
     56 	   Returns 'num', or -1 if the write failed.
     57 	 */
     58 	int (SDLCALL *write)(struct SDL_RWops *context, const void *ptr, int size, int num);
     59 
     60 	/* Close and free an allocated SDL_FSops structure */
     61 	int (SDLCALL *close)(struct SDL_RWops *context);
     62 
     63 	Uint32 type;
     64 	union {
     65 #if defined(__WIN32__) && !defined(__SYMBIAN32__)
     66 	    struct {
     67 		int   append;
     68 		void *h;
     69 		struct {
     70 		    void *data;
     71 		    int size;
     72 		    int left;
     73 		} buffer;
     74 	    } win32io;
     75 #endif
     76 #ifdef HAVE_STDIO_H
     77 	    struct {
     78 		int autoclose;
     79 	 	FILE *fp;
     80 	    } stdio;
     81 #endif
     82 	    struct {
     83 		Uint8 *base;
     84 	 	Uint8 *here;
     85 		Uint8 *stop;
     86 	    } mem;
     87 	    struct {
     88 		void *data1;
     89 	    } unknown;
     90 	} hidden;
     91 
     92 } SDL_RWops;
     93 
     94 
     95 /* Functions to create SDL_RWops structures from various data sources */
     96 
     97 extern DECLSPEC SDL_RWops * SDLCALL SDL_RWFromFile(const char *file, const char *mode);
     98 
     99 #ifdef HAVE_STDIO_H
    100 extern DECLSPEC SDL_RWops * SDLCALL SDL_RWFromFP(FILE *fp, int autoclose);
    101 #endif
    102 
    103 extern DECLSPEC SDL_RWops * SDLCALL SDL_RWFromMem(void *mem, int size);
    104 extern DECLSPEC SDL_RWops * SDLCALL SDL_RWFromConstMem(const void *mem, int size);
    105 
    106 extern DECLSPEC SDL_RWops * SDLCALL SDL_AllocRW(void);
    107 extern DECLSPEC void SDLCALL SDL_FreeRW(SDL_RWops *area);
    108 
    109 #define RW_SEEK_SET	0	/* Seek from the beginning of data */
    110 #define RW_SEEK_CUR	1	/* Seek relative to current read point */
    111 #define RW_SEEK_END	2	/* Seek relative to the end of data */
    112 
    113 /* Macros to easily read and write from an SDL_RWops structure */
    114 #define SDL_RWseek(ctx, offset, whence)	(ctx)->seek(ctx, offset, whence)
    115 #define SDL_RWtell(ctx)			(ctx)->seek(ctx, 0, RW_SEEK_CUR)
    116 #define SDL_RWread(ctx, ptr, size, n)	(ctx)->read(ctx, ptr, size, n)
    117 #define SDL_RWwrite(ctx, ptr, size, n)	(ctx)->write(ctx, ptr, size, n)
    118 #define SDL_RWclose(ctx)		(ctx)->close(ctx)
    119 
    120 
    121 /* Read an item of the specified endianness and return in native format */
    122 extern DECLSPEC Uint16 SDLCALL SDL_ReadLE16(SDL_RWops *src);
    123 extern DECLSPEC Uint16 SDLCALL SDL_ReadBE16(SDL_RWops *src);
    124 extern DECLSPEC Uint32 SDLCALL SDL_ReadLE32(SDL_RWops *src);
    125 extern DECLSPEC Uint32 SDLCALL SDL_ReadBE32(SDL_RWops *src);
    126 extern DECLSPEC Uint64 SDLCALL SDL_ReadLE64(SDL_RWops *src);
    127 extern DECLSPEC Uint64 SDLCALL SDL_ReadBE64(SDL_RWops *src);
    128 
    129 /* Write an item of native format to the specified endianness */
    130 extern DECLSPEC int SDLCALL SDL_WriteLE16(SDL_RWops *dst, Uint16 value);
    131 extern DECLSPEC int SDLCALL SDL_WriteBE16(SDL_RWops *dst, Uint16 value);
    132 extern DECLSPEC int SDLCALL SDL_WriteLE32(SDL_RWops *dst, Uint32 value);
    133 extern DECLSPEC int SDLCALL SDL_WriteBE32(SDL_RWops *dst, Uint32 value);
    134 extern DECLSPEC int SDLCALL SDL_WriteLE64(SDL_RWops *dst, Uint64 value);
    135 extern DECLSPEC int SDLCALL SDL_WriteBE64(SDL_RWops *dst, Uint64 value);
    136 
    137 
    138 /* Ends C function definitions when using C++ */
    139 #ifdef __cplusplus
    140 }
    141 #endif
    142 #include "close_code.h"
    143 
    144 #endif /* _SDL_rwops_h */
    145