cc65/libsrc/atari/dosdetect.s

;
; Freddy Offenga, Stefan Haubenthal, Christian Groessler, March 2007
;
; detect the DOS version we're running on
;

        .include        "atari.inc"
        .constructor    detect, 26
        .export         __dos_type

; ------------------------------------------------------------------------
; DOS type detection

.segment        "ONCE"

detect: lda     DOS
        cmp     #'S'            ; SpartaDOS
        beq     spdos
        cmp     #'M'            ; MyDOS
        beq     mydos
        cmp     #'X'            ; XDOS
        beq     xdos
        cmp     #'R'            ; RealDOS
        beq     rdos

        lda     #$4C            ; probably default
        ldy     #COMTAB
        cmp     (DOSVEC),y
        bne     done
        ldy     #ZCRNAME
        cmp     (DOSVEC),y
        bne     done

        ldy     #6              ; OS/A+ has a jmp here
        cmp     (DOSVEC),y
        beq     done
        lda     #OSADOS
        bne     set

spdos:  lda     DOS+3           ; 'B' in BW-DOS
        cmp     #'B'
        bne     spdos_real
        lda     DOS+4           ; 'W' in BW-DOS
        cmp     #'W'
        bne     spdos_real

        lda     #BWDOS
        .byte   $2C             ; BIT <abs>

spdos_real:
        lda     #SPARTADOS
        .byte   $2C             ; BIT <abs>

mydos:  lda     #MYDOS
        .byte   $2C             ; BIT <abs>

rdos:   lda     #REALDOS
        .byte   $2C             ; BIT <abs>

xdos:   lda     #XDOS
set:    sta     __dos_type
done:   rts

; ------------------------------------------------------------------------
; Data

        .data

__dos_type:     .byte   ATARIDOS; default to ATARIDOS