cc65/libsrc/pet/pet-ptvjoy.s

;
; PTV-2 Player joystick driver for the PET
;
; Stefan Haubenthal, 2005-05-25
; Groepaz/Hitmen, 2002-12-23
; obviously based on Ullrichs driver :)
;

	.include "zeropage.inc"

	.include "joy-kernel.inc"
	.include "joy-error.inc"
;	.include "pet.inc"
VIA_PRA		:= $E841		; Port register A
VIA_DDRA	:= $E843		; Data direction register A

; ------------------------------------------------------------------------
; Header. Includes jump table

	.segment "JUMPTABLE"

; Driver signature

	.byte	$6A, $6F, $79	; "joy"
	.byte	JOY_API_VERSION ; Driver API version number

; Button state masks (8 values)

	.byte	$01			; JOY_UP
	.byte	$02			; JOY_DOWN
	.byte	$04			; JOY_LEFT
	.byte	$08			; JOY_RIGHT
	.byte	$10			; JOY_FIRE
	.byte	$00			; JOY_FIRE2 unavailable
	.byte	$00			; Future expansion
	.byte	$00			; Future expansion

; Jump table.

	.addr	INSTALL
	.addr	UNINSTALL
	.addr	COUNT
	.addr	READ
	.addr	0			; IRQ entry unused

; ------------------------------------------------------------------------
; Constants

JOY_COUNT	= 2		; Number of joysticks we support


.code

; ------------------------------------------------------------------------
; INSTALL routine. Is called after the driver is loaded into memory. If
; possible, check if the hardware is present and determine the amount of
; memory available.
; Must return an JOY_ERR_xx code in a/x.
;

INSTALL:
	lda	#<JOY_ERR_OK
	ldx	#>JOY_ERR_OK
;	rts			; Run into UNINSTALL instead

; ------------------------------------------------------------------------
; UNINSTALL routine. Is called before the driver is removed from memory.
; Can do cleanup or whatever. Must not return anything.
;

UNINSTALL:
	rts


; ------------------------------------------------------------------------
; COUNT: Return the total number of available joysticks in a/x.
;

COUNT:
	lda	#<JOY_COUNT
	ldx	#>JOY_COUNT
	rts

; ------------------------------------------------------------------------
; READ: Read a particular joystick passed in A.
;

READ:	lda	#%10000000	; via port A Data-Direction
	sta	VIA_DDRA	; bit 7: out	bit 6-0: in

	tax			; Joystick number into X
	bne	joy2

; Read joystick 1

joy1:	lda	#$80		; via port A read/write
	sta	VIA_PRA		; (output one at PA7)

	lda	VIA_PRA		; via port A read/write
	and	#$1f		; get bit 4-0 (PA4-PA0)
	eor	#$1f
	rts

; Read joystick 2

joy2:	lda	#$00		; via port A read/write
	sta	VIA_PRA		; (output zero at PA7)

	lda	VIA_PRA		; via port A read/write
	and	#$0f		; get bit 3-0 (PA3-PA0)
	sta	tmp1		; joy 4 directions

	lda	VIA_PRA		; via port A read/write
	and	#%00100000	; get bit 5 (PA5)
	lsr
	ora	tmp1
	eor	#$1f

	ldx	#0
	rts