cc65/libsrc/atari/ucase_fn.s

;
; Christian Groessler, Dec-2001
;
; ucase_fn
; helper routine to convert a string (file name) to uppercase
; used by open.s and remove.s
;
; Calling parameters:
;	AX   - points to filename
; Return parameters:
;	C    - 0/1 for OK/Error (filename too long)
;	AX   - points to uppercased version of the filename on the stack
;	tmp3 - amount of bytes used on the stack (needed for cleanup)
; Uses:
;       ptr4 - scratch pointer used to remember original AX pointer
;
;

	.include	"atari.inc"

.ifdef	DEFAULT_DEVICE
	.importzp tmp2
	.import	__defdev
.endif
	.importzp tmp3,ptr4,sp
	.import	subysp,addysp
	.export	ucase_fn

.proc   ucase_fn

	; we make sure that the filename doesn't contain lowercase letters
	; we copy the filename we got onto the stack, uppercase it and use this
	; one to open the iocb
	; we're using tmp3, ptr4

	; save the original pointer
	sta	ptr4
	stx	ptr4+1

.ifdef	DEFAULT_DEVICE
	ldy	#1
	sty	tmp2		; initialize flag: device present in passed string
	lda	#':'
	cmp	(ptr4),y
	beq	hasdev
	iny
	cmp	(ptr4),y
	beq	hasdev
	sta	tmp2		; set flag: no device in passed string
hasdev:
.endif

	ldy	#128
	sty	tmp3		; save size
	jsr	subysp		; make room on the stack

	; copy filename to the temp. place on the stack, also uppercasing it
	ldy	#0

loop2:	lda	(ptr4),y
	sta	(sp),y
	beq	copy_end
	bmi	L1		; Not lowercase (also, invalid, should reject)
	cmp	#'a'
	bcc	L1		; Not lowercase
	and	#$DF		; make upper case char, assume ASCII chars
	sta	(sp),y		; store back
L1:
	iny
	bpl	loop2		; bpl: this way we only support a max. length of 127

	; Filename too long
	jsr	addysp		; restore the stack
	sec			; indicate error
	rts

copy_end:

.ifdef	DEFAULT_DEVICE
	lda	tmp2
	cmp	#1		; was device present in passed string?
	beq	hasdev2		; yes, don't prepend something

	ldy	#128+3		; no, prepend "D:" (or other device)
	sty	tmp3		; adjust stack size used
	ldy	#3
	jsr	subysp		; adjust stack pointer
	dey
cpdev:	lda	__defdev,y
	sta	(sp),y		; insert device name, number and ':'
	dey
	bpl	cpdev
hasdev2:
.endif

	; leave A and X pointing to the modified filename
	lda	sp
	ldx	sp+1
	clc			; indicate success
	rts

.endproc