cc65/libsrc/common/strlower.s

48 lines
1.3 KiB
ArmAsm

;
; 1998-06-02, Ullrich von Bassewitz
; 2013-08-28, Greg King
;
; char* __fastcall__ strlower (char* s);
; char* __fastcall__ strlwr (char* s);
;
; Non-ANSI
;
.export _strlower, _strlwr
.import popax
.importzp ptr1, ptr2
.import ctype_preprocessor_no_check
.include "ctype.inc"
_strlower:
_strlwr:
sta ptr1 ; Save s (working copy)
stx ptr1+1
sta ptr2
stx ptr2+1 ; save function result
ldy #0
loop: lda (ptr1),y ; get character
beq L9 ; jump if done
; get character classification
jsr ctype_preprocessor_no_check
and #CT_UPPER ; upper case char?
beq L1 ; jump if no
lda (ptr1),y ; fetch character again
sec
sbc #<('A'-'a') ; make lower case char
sta (ptr1),y ; store back
L1: iny ; next char
bne loop
inc ptr1+1 ; handle offset overflow
bne loop ; branch always
; Done, return the argument string
L9: lda ptr2
ldx ptr2+1
rts