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cc65/libsrc/atari/getdefdev.s

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;
; Freddy Offenga & Christian Groessler, August 2003
;
; function to get default device: char *getdefdev(void);
;
; SpartaDOS:
; the ZCRNAME routine is only used to get the default drive because
; ZCRNAME has two disadvantages:
; 1. It will convert D: into D1: instead of Dn: (n = default drive)
; 2. It will give a 'no arguments' status if it detects something
; like Dn: (without filename).
;
; OS/A+ DOS:
; ZCRNAME is slightly different from SpartaDOS. It will convert D:
; into Dn: where n is the default drive.
.include "atari.inc"
.import __dos_type
.export _getdefdev ; get default device (e.g. "D1:")
; Get default device (LBUF will be destroyed!!)
_getdefdev:
lda __dos_type ; which DOS?
cmp #ATARIDOS
beq finish
ldy #BUFOFF
lda #0
sta (DOSVEC),y ; reset buffer offset
; Store dummy argument
ldy #LBUF
lda #'X'
sta (DOSVEC),y
iny
lda #ATEOL
sta (DOSVEC),y
; One extra store to avoid the buggy sequence from OS/A+ DOS:
; <D><RETURN><:> => drive number = <RETURN>
iny
sta (DOSVEC),y
; Create crunch vector
ldy #ZCRNAME+1
lda (DOSVEC),y
sta crvec+1
iny
lda (DOSVEC),y
sta crvec+2
crvec: jsr $FFFF ; will be set to crunch vector
; Get default device
ldy #COMFNAM ; COMFNAM is always "Dn:"
lda (DOSVEC),y
sta defdev
iny
lda (DOSVEC),y
sta defdev+1
; return ointer to default device
finish: lda #<defdev
ldx #>defdev
rts
.data
; Default device
defdev:
.byte "D1:", 0