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55 lines
786 B
ArmAsm
55 lines
786 B
ArmAsm
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; Ullrich von Bassewitz, 09.06.1998
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;
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; int memcmp (const void* p1, const void* p2, size_t count);
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;
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.export _memcmp
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.import popax, return0
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.importzp ptr1, ptr2, ptr3
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_memcmp:
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sta ptr3 ; Save count
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sta ptr3+1
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jsr popax ; get p2
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sta ptr2
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stx ptr2+1
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jsr popax ; get p1
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sta ptr1
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stx ptr1+1
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ldy #0
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ldx ptr3 ; use X as low counter byte
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beq L3
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L1: lda (ptr1),y
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cmp (ptr2),y
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bne L5
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iny
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bne L2
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inc ptr1+1
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inc ptr2+1
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L2: txa
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beq L3
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dex
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jmp L1
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L3: lda ptr3+1 ; check high byte
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beq L4
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dec ptr3+1
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dex ; X = $FF
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bne L1 ; branch always
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; Memory areas are equal
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L4: jmp return0
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; Not equal, check which one is greater
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L5: bcs L6
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ldx #$FF
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rts
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L6: ldx #$01
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rts
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