cc65/libsrc/apple2/diosectcount.s

;
; Oliver Schmidt, 31.03.2005
;
; unsigned __fastcall__ dio_query_sectcount (dhandle_t handle);
;

        .export 	_dio_query_sectcount
        .import 	_dio_query_sectsize, _malloc, _free

        .include	"zeropage.inc"
        .include	"errno.inc"
        .include	"mli.inc"

_dio_query_sectcount:

        ; Set handle
        sta	mliparam + MLI::ON_LINE::UNIT_NUM

        ; Get ProDOS 8 block size (clears __oserror)
        jsr	_dio_query_sectsize

        ; Alloc buffer
        jsr	_malloc
        sta	ptr4
        stx	ptr4+1

        ; Set buffer
        sta	mliparam + MLI::ON_LINE::DATA_BUFFER
        stx	mliparam + MLI::ON_LINE::DATA_BUFFER+1

        ; Check buffer (hibyte is enough)
        txa
        beq	nomem

        ; Get device state
        lda	#ON_LINE_CALL
        ldx	#ON_LINE_COUNT
        jsr	callmli
        bcs	check

        ; UNIT_NUM already set
        .assert MLI::RW_BLOCK::UNIT_NUM = MLI::ON_LINE::UNIT_NUM, error

        ; DATA_BUFFER already set
        .assert MLI::RW_BLOCK::DATA_BUFFER = MLI::ON_LINE::DATA_BUFFER, error

        ; Read volume directory key block
        tax			; A = 0
        lda	#$02
        sta	mliparam + MLI::RW_BLOCK::BLOCK_NUM
        stx	mliparam + MLI::RW_BLOCK::BLOCK_NUM+1
        lda	#READ_BLOCK_CALL
        ldx	#RW_BLOCK_COUNT
        jsr	callmli
        bcs	oserr

        ; Get and save total blocks from volume directory header
        ldy	#$29
        lda	(ptr4),y
        pha
        iny
        lda	(ptr4),y
        pha

        ; Cleanup buffer
done:   lda	ptr4
        ldx	ptr4+1
        jsr	_free

        ; Restore total blocks and return
        pla
        tax
        pla
        rts

nomem:  lda	#$FF		; Error code for sure not used by MLI
oserr:  sta	__oserror

        ; Save total blocks for failure
        lda	#$00
        pha
        pha
        beq	done		; Branch always

        ; Check for non-ProDOS disk
check:  cmp	#$52		; "Not a ProDOS volume"
        bne	oserr
        sta	__oserror

        ; Save total blocks for a 16-sector disk
        lda	#<280
        pha
        lda	#>280
        pha
        bne	done		; Branch always