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cc65/libsrc/common/_heapmemavail.s
2022-08-29 19:55:48 +02:00

79 lines
1.4 KiB
ArmAsm

;
; Ullrich von Bassewitz, 2003-02-01
;
; Return the amount of free memory on the heap.
;
; size_t _heapmemavail (void);
;
;
.importzp ptr1, ptr2
.export ___heapmemavail
.include "_heap.inc"
.macpack generic
;-----------------------------------------------------------------------------
; Code
___heapmemavail:
; size_t Size = 0;
lda #0
sta ptr2
sta ptr2+1
; struct freeblock* F = _heapfirst;
lda ___heapfirst
sta ptr1
lda ___heapfirst+1
@L1: sta ptr1+1
; while (F) {
ora ptr1
beq @L2 ; Jump if end of free list reached
; Size += F->size;
ldy #freeblock::size
lda (ptr1),y
add ptr2
sta ptr2
iny
lda (ptr1),y
adc ptr2+1
sta ptr2+1
; F = F->next;
iny ; Points to F->next
lda (ptr1),y
tax
iny
lda (ptr1),y
stx ptr1
jmp @L1
; return Size + (_heapend - _heapptr) * sizeof (*_heapend);
@L2: lda ptr2
add ___heapend
sta ptr2
lda ptr2+1
adc ___heapend+1
tax
lda ptr2
sub ___heapptr
sta ptr2
txa
sbc ___heapptr+1
tax
lda ptr2
rts