;*
;* GRAPHICS TABLET DEVICE DRIVER
;*
TEM	EQU	$280
XFLL	EQU	$281
XFLH	EQU	$282
YFLL	EQU	$283
YFLH	EQU	$284
MSLOT	EQU	$7F8
ROMREAD	EQU	$CBF4
ROMOFFSC	EQU	$CBC6
ROMSWCHK	EQU	$CBD0
ROMSW	EQU	$CFFF

GT_INIT:	LDA	#IOCTL_CLOSE
	BNE	GT_CTRL
GT_DRIVER:
GT_DRVR_SZ:	.WORD	GT_DRVR_END - GT_DRVR_START
GT_READ_OFS:	.WORD	GT_READ     - GT_DRVR_START
GT_WRITE_OFS:	.WORD	GT_WRITE    - GT_DRVR_START
GT_CTRL_OFS:	.WORD	GT_CTRL     - GT_DRVR_START
GT_IRQ_OFS:	.WORD	GT_IRQ      - GT_DRVR_START
GT_DRVR_START:
GT_READ:
GT_WRITE:	SEC
	RTS
GT_CTRL:	TYA
	AND	#$F8		; MASK OFF SLOT #
	CMP	#GTCTL_CALLFW
	BNE	:+
	TYA
	AND	#$07
	ORA	#$C0
	SEI
	STA	MSLOT
	STA	TMPTR+1
	BIT	ROMSW
	LDY	#$00
	STY	TMPTR
	LDA	(TMPTR),Y
	JSR	ROMREAD
	CLI
	BCC	GTSWCHK
	JMP	ROMOFFSC
GTSWCHK:	JMP	ROMSWCHK
:	CMP	#IOCTL_OPEN
	BNE	:+
	TYA
	AND	#$07
	ASL
	TAX
	CLC
	RTS
:	CMP	#IOCTL_CLOSE
	BNE	:+
	CLC
	RTS
:	CMP	#IOCTL_ID
	BNE	:+
	LDA	#$2F		; GRAPHICS TABLET ID
	CLC
	RTS
GT_IRQ:
:	SEC
	RTS
GT_DRVR_END	EQU	*