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86 lines
1.6 KiB
ArmAsm
86 lines
1.6 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 2003-02-01
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;
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; Return the size of the largest free block on the heap.
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;
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; size_t _heapmaxavail (void);
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;
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;
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.importzp ptr1, ptr2
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.export __heapmaxavail
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.include "_heap.inc"
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.macpack generic
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;-----------------------------------------------------------------------------
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; Code
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__heapmaxavail:
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; size_t Size = (_heapend - _heapptr) * sizeof (*_heapend);
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lda __heapend
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sub __heapptr
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sta ptr2
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lda __heapend+1
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sbc __heapptr+1
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sta ptr2+1
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; struct freeblock* F = _heapfirst;
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lda __heapfirst
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sta ptr1
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lda __heapfirst+1
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@L1: sta ptr1+1
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; while (F) {
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ora ptr1
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beq @L3 ; Jump if end of free list reached
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; if (Size < F->size) {
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ldy #freeblock::size
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lda ptr2
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sub (ptr1),y
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iny
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lda ptr2+1
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sbc (ptr1),y
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bcs @L2
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; Size = F->size;
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ldy #freeblock::size
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lda (ptr1),y
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sta ptr2
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iny
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lda (ptr1),y
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sta ptr2+1
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; F = F->next;
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@L2: iny ; Points to F->next
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lda (ptr1),y
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tax
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iny
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lda (ptr1),y
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stx ptr1
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jmp @L1
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; if (Size < HEAP_ADMIN_SPACE) return 0;
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@L3: lda ptr2
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sub #HEAP_ADMIN_SPACE
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ldx ptr2+1
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bcs @L5
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bne @L4
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txa
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rts
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; return Size - HEAP_ADMIN_SPACE;
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@L4: dex
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@L5: rts
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