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cc65/libsrc/common/strcat.s
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git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00

58 lines
704 B
ArmAsm

;
; Ullrich von Bassewitz, 31.05.1998
;
; char* strcat (char* dest, const char* src);
;
.export _strcat
.import popax
.importzp ptr1, ptr2, ptr3
_strcat:
sta ptr1 ; Save src
stx ptr1+1
jsr popax ; Get dest
sta ptr2
stx ptr2+1
sta ptr3 ; Remember for function return
stx ptr3+1
ldy #0
; find end of dest
sc1: lda (ptr2),y
beq sc2
iny
bne sc1
inc ptr2+1
bne sc1
; end found, get offset in y into pointer
sc2: tya
clc
adc ptr2
sta ptr2
bcc sc3
inc ptr2+1
; copy src
sc3: ldy #0
sc4: lda (ptr1),y
sta (ptr2),y
beq sc5
iny
bne sc4
inc ptr1+1
inc ptr2+1
bne sc4
; done, return pointer to dest
sc5: lda ptr3
ldx ptr3+1
rts