; probably not work.
.struct freeblock
size .word
- next .word
- prev .word
+ next .addr
+ prev .addr
+.endstruct
+
+; Struct usedblock
+; See notes above
+.struct usedblock
+ size .word
+ start .addr
.endstruct
-HEAP_ADMIN_SPACE = 2
HEAP_MIN_BLOCKSIZE = .sizeof (freeblock) ; Minimum size of an allocated block
+HEAP_ADMIN_SPACE = .sizeof (usedblock) ; Additional space for used bocks
; Variables
.global __heaporg
/*
* _heap.h
*
- * Ullrich von Bassewitz, 03.06.1998
+ * Ullrich von Bassewitz, 1998-06-03, 2004-12-19
*
*/
+/* Structure that preceeds a user block in most cases.
+ * The aligned_malloc function may generate blocks where the start pointer
+ * and size are splitted to handle a memory hole that is needed for
+ * alignment.
+ */
+struct usedblock {
+ unsigned size;
+ struct usedblock* start;
+};
+
/* Space needed for administering used blocks */
-#define HEAP_ADMIN_SPACE sizeof (unsigned)
+#define HEAP_ADMIN_SPACE sizeof (struct usedblock)
/* The data type used to implement the free list.
* Beware: Field order is significant!
- */
+ */
struct freeblock {
unsigned size;
struct freeblock* next;
_free: sta ptr2
stx ptr2+1 ; Save block
-; Is the argument NULL?
+; Is the argument NULL? If so, bail out.
ora ptr2+1 ; Is the argument NULL?
- beq @L9 ; Jump if yes
+ bne @L0 ; Jump if no
+ rts ; Bail out if yes
-; Decrement the given pointer by the admin space amount, so it points to the
-; real block allocated. The size of the block is stored in the admin space.
+; There's a pointer below the user space that points to the real start of the
+; raw block. The first word of the raw block is the total size of the block.
; Remember the block size in ptr1.
- lda ptr2
- sub #HEAP_ADMIN_SPACE
+@L0: lda ptr2
+ sub #2
sta ptr2
bcs @L1
dec ptr2+1
-@L1: ldy #freeblock::size+1
+@L1: ldy #1
+ lda (ptr2),y ; High byte of real block address
+ tax
+ dey
+ lda (ptr2),y
+ stx ptr2+1
+ sta ptr2 ; Set ptr2 to start of real block
+
+ ldy #usedblock::size+1
lda (ptr2),y ; High byte of size
- sta ptr1+1 ; Save it
+ sta ptr1+1 ; Save it
dey
lda (ptr2),y
sta ptr1
; }
; } else {
; f->prev = 0;
-; /* Special case: This is the new freelist start */
+; /* Special case: This is the new freelist start */
; _hfirst = f;
; }
; }
+
stx ptr2
sta ptr2+1
-; Fill the size into the admin space of the block and return the user pointer
+; Fill the size and start address into the admin space of the block
+; (struct usedblock) and return the user pointer
FillSizeAndRet:
- ldy #freeblock::size ; *p = size;
- lda ptr1 ; Low byte of block size
+ ldy #usedblock::size ; p->size = size;
+ lda ptr1 ; Low byte of block size
sta (ptr2),y
- iny ; Points to freeblock::size+1
+ iny ; Points to freeblock::size+1
lda ptr1+1
sta (ptr2),y
RetUserPtr:
+ ldy #usedblock::start ; p->start = p
+ lda ptr2
+ sta (ptr2),y
+ iny
+ lda ptr2+1
+ sta (ptr2),y
+
+; Return the user pointer, which points behind the struct usedblock
+
lda ptr2 ; return ++p;
ldx ptr2+1
add #HEAP_ADMIN_SPACE
/* */
/* */
/* */
-/* (C) 1998-2002 Ullrich von Bassewitz */
+/* (C) 1998-2004 Ullrich von Bassewitz */
/* Wacholderweg 14 */
/* D-70597 Stuttgart */
/* EMail: uz@musoftware.de */
void* __fastcall__ realloc (void* block, size_t size)
{
- unsigned* b;
- unsigned* newblock;
+ struct usedblock* b;
+ struct usedblock* newblock;
unsigned oldsize;
+ unsigned newhptr;
int diff;
/* Check the block parameter */
if (size == 0) {
/* Block is not NULL, but size is: free the block */
free (block);
- return 0;
+ return 0;
}
/* Make the internal used size from the given size */
size = sizeof (struct freeblock);
}
- /* Get a pointer to the real block, get the old block size */
- b = (unsigned*) (((int) block) - 2);
- oldsize = *b;
+ /* The word below the user block contains a pointer to the start of the
+ * raw memory block. The first word of this raw memory block is the full
+ * size of the block. Get a pointer to the real block, get the old block
+ * size.
+ */
+ b = (((struct usedblock*) block) - 1)->start;
+ oldsize = b->size;
/* Get the size difference as a signed quantity */
diff = size - oldsize;
/* Is the block at the current heap top? */
- if (((int) b) + oldsize == ((int) _heapptr)) {
+ if (((unsigned) b) + oldsize == ((unsigned) _heapptr)) {
/* Check if we've enough memory at the heap top */
- int newhptr;
- newhptr = ((int) _heapptr) + diff;
- if (newhptr <= ((int) _heapend)) {
+ newhptr = ((unsigned) _heapptr) + diff;
+ if (newhptr <= ((unsigned) _heapend)) {
/* Ok, there's space enough */
_heapptr = (unsigned*) newhptr;
- *b = size;
+ b->size = size;
+ b->start = b;
return block;
}
}
*/
if (newblock = malloc (size)) {
- /* Adjust the old size to the user visible portion */
- oldsize -= sizeof (unsigned);
+ /* Adjust the old size to the user visible portion */
+ oldsize -= HEAP_ADMIN_SPACE;
- /* If the new block is larger than the old one, copy the old
- * data only
- */
- if (size > oldsize) {
- size = oldsize;
- }
+ /* If the new block is larger than the old one, copy the old
+ * data only
+ */
+ if (size > oldsize) {
+ size = oldsize;
+ }
- /* Copy the block data */
+ /* Copy the block data */
memcpy (newblock, block, size);
free (block);
}
-
+
projects / cc65 / commitdiff