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56 lines
720 B
ArmAsm
56 lines
720 B
ArmAsm
;
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; Ullrich von Bassewitz, 31.05.1998
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;
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; char* strcat (char* dest, const char* src);
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;
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.export _strcat
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.import popax
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.importzp ptr1, ptr2, tmp3
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_strcat:
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sta ptr1 ; Save src
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stx ptr1+1
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jsr popax ; Get dest
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sta ptr2
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stx ptr2+1
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sta tmp3 ; Remember for function return
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ldy #0
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; find end of dest
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sc1: lda (ptr2),y
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beq sc2
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iny
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bne sc1
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inc ptr2+1
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bne sc1
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; end found, get offset in y into pointer
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sc2: tya
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clc
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adc ptr2
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sta ptr2
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bcc sc3
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inc ptr2+1
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; copy src
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sc3: ldy #0
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sc4: lda (ptr1),y
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sta (ptr2),y
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beq sc5
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iny
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bne sc4
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inc ptr1+1
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inc ptr2+1
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bne sc4
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; done, return pointer to dest
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sc5: lda tmp3 ; X does still contain high byte
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rts
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