I agree with you thoroughly. I would never think it might've been other way
round!
robert
On Wednesday 24 of December 2003 17:15, Claude Sylvain wrote:
> Hello Robert,
>
> I just want to point out that malloc() do not initialize the allocated
> memory space, and nothing tell that the space used by malloc() (heap
> memory) must be initialized at startup. Heap memory have it to be
> initialized at startup ??? I don't think so, because an initialized heap
> memory is not really a heap memory.
>
> Remark:
> Some devellopment tools like the one made by Microtec Research provide C
> language extension that define function like zalloc() that allocate memory
> and initialize it to (0).
>
>
> Claude.
>
>
>
> Message: 1
> From: Robert Seczkowski <rs...@poczta.onet.pl>
> To: mspgcc-users@lists.sourceforge.net
> Date: Sun, 21 Dec 2003 19:57:16 +0100
> Subject: [Mspgcc-users] memory allocation
> Reply-To: mspgcc-users@lists.sourceforge.net
>
>
> --Boundary-00=_M0e5/fLNUyuK831
> Content-Type: text/plain;
> charset="iso-8859-2"
> Content-Transfer-Encoding: 7bit
> Content-Disposition: inline
>
> I would like to recall my problem with malloc function.
> Because I didn't receive answer even touching the problem.
> It's hard for me to understand, that so many people writing to this group
> are not using malloc function. It's like diving with tied legs and hands.
> The two things where considred:
> 1. malloc occupies space of noinit section !!
> 2. malloc collide with stack after reallocating several times.
> These faults are serious and should not be avoided.
> The problems were solved in attached code.
> Please test it and let me know how is going.
>
> --Boundary-00=_M0e5/fLNUyuK831
> Content-Type: text/x-csrc;
> charset="iso-8859-2";
> name="malloc.c"
> Content-Transfer-Encoding: 7bit
> Content-Disposition: attachment; filename="malloc.c"
>
> #include <stdlib.h>
>
> #define XSIZE(x) ((*x)>>1)
> #define FREE_P(x) (!((*x)&1))
> #define MARK_BUSY(x) ((*x)|=1)
> #define MARK_FREE(x) ((*x)&=0xfffe)
>
> //extern size_t __bss_end;
> extern size_t __noinit_end;
> #define GET_HEAP_BOTTOM(__x) __asm__ __volatile__("mov r1, %0": "=r"
> ((uint16_t)__x) :)
>
> void myfree (void *p);
> void *mymalloc (size_t size);
>
> void *mymalloc (size_t size)
> {
> static char once;
> size_t * heap_bottom;
> size_t * heap_top = &__noinit_end;
> size_t * heap_next;
> size_t xsize;
> char f = 0;
>
> if (!once)
> {
> once = 1;
> *heap_top = 0xFFFE;
> }
> GET_HEAP_BOTTOM (heap_bottom);
> heap_bottom -= 20;
> size = (size+1) >> 1; /* round to 2 */
> do
> {
> xsize = XSIZE (heap_top);
> heap_next = &heap_top[xsize + 1];
>
>
> if (xsize == 0x7ff)//(xsize<<1)+2 == 0)
> {
> f = 1;
> }else if(heap_next >= heap_bottom){
> f = -1;
> }
>
> if (FREE_P (heap_top))
> {
> if (f>0)
> {
> xsize = heap_bottom - heap_top - 1;
> }
> else if (f < 0){
> *heap_top = (heap_bottom - heap_top - 1) << 1;
> xsize = XSIZE (heap_top);
> }
> else if (FREE_P(heap_next))
> {
> *heap_top = ( (XSIZE(heap_next) == 0x7FF)//<<1) + 2 == 0
> ? 0xfffe
>
> : (xsize + XSIZE(heap_next) + 1)<<1);
>
> continue;
> }
>
>
> if (xsize >= size)
> {
>
> if (f>0)
> heap_top[size + 1] = 0xfffe;
> else if (xsize != size)
> heap_top[size + 1] = (xsize - size - 1) << 1;
> *heap_top = size << 1;
> MARK_BUSY (heap_top);
> return heap_top+1;
> }
> }
> heap_top += xsize + 1;
> }
> while (!f);
> return NULL;
> }
>
> void myfree (void *p)
> {
> size_t *t = (size_t*)p - 1;
> MARK_FREE (t);
> }
>
>
> --Boundary-00=_M0e5/fLNUyuK831--
