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cc65/libsrc/common/_heapmaxavail.s
cuz 581c12ce40 Move _heap.h to the compiler include dir.
Create heap.inc and use that from the assembler code.
Rename heap related _h... variables to _heap...
Add _heapmaxavail and _heapmemavail functions.


git-svn-id: svn://svn.cc65.org/cc65/trunk@1912 b7a2c559-68d2-44c3-8de9-860c34a00d81
2003-02-01 12:22:09 +00:00

78 lines
1.4 KiB
ArmAsm

;
; Ullrich von Bassewitz, 2003-02-01
;
; Return the size of the largest free block on the heap.
;
; size_t __fastcall__ _heapmaxavail (void);
;
;
.importzp ptr1, ptr2
.export __heapmaxavail
.include "_heap.inc"
.macpack generic
;-----------------------------------------------------------------------------
; Code
__heapmaxavail:
; size_t Size = (_heapend - _heapptr) * sizeof (*_heapend);
lda __heapend
sub __heapptr
sta ptr2
lda __heapend+1
sbc __heapptr+1
sta ptr2+1
; struct freeblock* F = _heapfirst;
lda __heapfirst
sta ptr1
lda __heapfirst+1
@L1: sta ptr1+1
; while (F) {
ora ptr1
beq @L3 ; Jump if end of free list reached
; if (Size < F->size) {
ldy #freeblock_size
lda ptr2
sub (ptr1),y
iny
lda ptr2+1
sbc (ptr1),y
bcs @L2
; Size = F->size;
ldy #freeblock_size
lda (ptr1),y
sta ptr2
iny
lda (ptr1),y
sta ptr2+1
; F = F->next;
@L2: iny ; Points to F->next
lda (ptr1),y
tax
iny
lda (ptr1),y
stx ptr1
jmp @L1
; return Size;
@L3: lda ptr2
ldx ptr2+1
rts