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cc65/libsrc/common/strlen.s
2021-05-08 19:36:37 +02:00

40 lines
852 B
ArmAsm

;
; Ullrich von Bassewitz, 31.05.1998
;
; Note: strspn & strcspn call internally this function and rely on
; the usage of only ptr2 here! Keep in mind when appling changes
; and check the other implementations too!
;
; size_t __fastcall__ strlen (const char* s);
;
.export _strlen
.importzp ptr2
.macpack cpu
_strlen:
sta ptr2 ; Save s
stx ptr2+1
.if (.cpu .bitand ::CPU_ISET_HUC6280)
clx
cly
.else
ldx #0 ; YX used as counter
.if (.cpu .bitand ::CPU_ISET_65816)
txy
.else
ldy #0
.endif
.endif
L1: lda (ptr2),y
beq L9
iny
bne L1
inc ptr2+1
inx
bne L1
L9: tya ; get low byte of counter, hi's all set
rts