Some times I get heap overflows from the ascii C compiler. I've got no clue how I actually fix them, sometimes they simply go away by placing a routine somewhere else. What is the compiler telling me and why? Moving code shouldn't solve an error.....
Heap means free memory where it can allocate space with malloc, and heap overflow would suggest that you try to allocate more space than is available. Perhaps you can increase the amount of heap space to reserve with a command line option?
@Grauw, thanks for the explaination.
Now I have something that is puzzling. I use ldirvm and ldirmv to move pieces fro VRAM to a buffer and back and write data to this block. To make these operations fast, I use disscr() and enascr(). That works, you don't see it happening. However when I try to move this piece of the screen (restore -> store next part, draw -> restore -> store next part, draw ) my screen starts to jump like moving all characters down and then up again. I have tried di() and ei() but that doesn't make difference. Is there a know thing that can do this when accessing vram with ldirvm and ldirmv?
example of heap overflow.. I am allocating nothing. When I remove this code it compiles and functions just fine.
While trying to debug I removed every line, removed all pointers and work directly with the struct. Just this function having content causes a heap overflow.
VOID rWin( dx, dy )
int dx,dy;
{
wStruct *ptr;
char num= rtWin.active;
if ( win[num].X == 0 ) return;
ptr = &win[num];
fVRAM((int)ptr->X,(int)ptr->Y,(int)ptr->W,(int)ptr->H,(int)num);
ptr->W+=dx;
ptr->H+=dy;
if ( ((ptr->X) + (ptr->W) ) > 79 ) ptr->W-=1;
if ( ((ptr->Y) + (ptr->H) ) > 25 ) ptr->H-=1;
tVRAM((int)ptr->X,(int)ptr->Y,(int)ptr->W,(int)ptr->H,(int)num);
drawWin((int)ptr->X,(int)ptr->Y,(int)ptr->W,(int)ptr->H,(int)ptr->A);
}
The compiler says the heap overflow happens in the code below
Please copy and paste the error. The compiler should tell exactly in which line number the error occurred.
Heap overflow could also happen with complex expressions.
What is fVRAM? Is it a function or a macro definition?
In either case, why not pass just ptr as parameter instead of X, Y, W, H?
Well, that's the "not so much fun part". The compilers output points at the line with fVRAM you see above, see the code below. So you are looking at the line that caused the heap overflow because the compiler said it was that line. I solved this compilation error by moving the fVRAM function to another location in the source file and it works again. Insane yes. Passing the ptr seems logical, but in this case, the code becomes less readable.
VOID fVRAM( sx, sy, sw, sh, num )
int sx,sy,sh,sw,num;
{
int lus=0;
TINY *buffer;
unsigned base = 0x2000 + (num * 0x870);
int it=0;
if ( ( buffer = alloc(sw)) == 0 ) {
puts("memory error");
exit(0);
}
memset(buffer,(char)0,sw);
sw+=2;
sh+=2;
disscr();
for (lus= sy; lus <= (sy+sh-1) ; lus++ )
{
ldirmv(buffer,base+(it * sw),sw);
ldirvm((((lus-1)*80)+sx),buffer,sw);
it++;
}
disscr();
}
You have to free the memory after you allocate and use it. Put a free(buffer); at the end of the function. Or next time you try to allocate more, it may fail for lack of free available space.
You have to free the memory after you allocate and use it. Put a free(buffer); at the end of the function. Or next time you try to allocate more, it may fail for lack of free available space.
