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Size: 625
Comment: create page, add content (Wed Mar 10 ver; changeset 4428)
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Size: 2221
Comment: update content - RWops stream
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| Deletions are marked like this. | Additions are marked like this. |
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| Use this function to ^allocate a read/write to a specific SDL_RWops structure^. ??? | Use this function to *allocate an empty, unpopulated SDL_RWops structure. * |
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| ^Reads or writes to the specified SDL_RWops structure.^ ??? | *Returns a pointer to ,,the allocated memory on success,, ^a data stream^, or NULL on error. * |
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| *<<BR>> | |
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| You can add your code example here }}} |
#include <string.h> /* for memset */ #include "SDL_error.h" /* for SDL_SetError */ #include "SDL_rwops.h" /* These functions should not be used except from pointers in a RWops */ static int myseekfunc(SDL_RWops *context, int offset, int whence) { SDL_SetError("Can't seek in this kind of RWops"); return(-1); } static int myreadfunc(SDL_RWops *context, void *ptr, int size, int maxnum) { memset(ptr,0,size*maxnum); return(maxnum); } static int mywritefunc(SDL_RWops *context, const void *ptr, int size, int num) { return(num); } static int myclosefunc(SDL_RWops *context) { if(context->type != 0xdeadbeef) { SDL_SetError("Wrong kind of RWops for myclosefunc()"); return(-1); } free(context->hidden.unknown.data1); SDL_FreeRW(context); return(0); } /* Note that this function is NOT static -- we want it directly callable from other source files */ SDL_RWops *MyCustomRWop() { SDL_RWops *c=SDL_AllocRW(); if(c==NULL) return(NULL); c->seek =myseekfunc; c->read =myreadfunc; c->write=mywritefunc; c->close=myclosefunc; c->type =0xdeadbeef; c->hidden.unknown.data1=malloc(256); return(c); } }}}<<BR>>* |
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| ''You can add useful comments here'' | *<<BR>> /!\ You must free any memory allocated ,,with,, ^using^ [[SDL_AllocRW]]() with [[SDL_FreeRW]](). Depending on your operating system and compiler, there may be a difference between the malloc() and free() your program uses and the versions SDL calls internally. Trying to mix the two can cause crashing such as segmentation faults. <<BR>>* <<Color2(green,Should malloc() and free() be formatted `malloc()` and `free()`?)>> |
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| .[[SDL_FreeRW]] ??? | .[[SDL_FreeRW]] * |
DRAFT |
SDL_AllocRW
Use this function to *allocate an empty, unpopulated SDL_RWops structure. *
Syntax
SDL_RWops* SDL_AllocRW(void)
Return Value
*Returns a pointer to the allocated memory on success a data stream, or NULL on error. *
Code Examples
*
#include <string.h> /* for memset */
#include "SDL_error.h" /* for SDL_SetError */
#include "SDL_rwops.h"
/* These functions should not be used except from pointers in a RWops */
static int myseekfunc(SDL_RWops *context, int offset, int whence)
{
SDL_SetError("Can't seek in this kind of RWops");
return(-1);
}
static int myreadfunc(SDL_RWops *context, void *ptr, int size, int maxnum)
{
memset(ptr,0,size*maxnum);
return(maxnum);
}
static int mywritefunc(SDL_RWops *context, const void *ptr, int size, int num)
{
return(num);
}
static int myclosefunc(SDL_RWops *context)
{
if(context->type != 0xdeadbeef)
{
SDL_SetError("Wrong kind of RWops for myclosefunc()");
return(-1);
}
free(context->hidden.unknown.data1);
SDL_FreeRW(context);
return(0);
}
/* Note that this function is NOT static -- we want it directly callable from other source files */
SDL_RWops *MyCustomRWop()
{
SDL_RWops *c=SDL_AllocRW();
if(c==NULL) return(NULL);
c->seek =myseekfunc;
c->read =myreadfunc;
c->write=mywritefunc;
c->close=myclosefunc;
c->type =0xdeadbeef;
c->hidden.unknown.data1=malloc(256);
return(c);
}
*
Remarks
*
![/!\](/moin_static198/fixedleft/img/alert.png "/!\"){kind=small}
You must free any memory allocated with using SDL_AllocRW() with SDL_FreeRW(). Depending on your operating system and compiler, there may be a difference between the malloc() and free() your program uses and the versions SDL calls internally. Trying to mix the two can cause crashing such as segmentation faults.
*
green
