cc65/libsrc/atari/atari-stdjoy.s

;
; Standard joystick driver for the Atari. May be used multiple times when linked
; to the statically application.
;
; Ullrich von Bassewitz, 2002-12-21
; Using the readjoy code from Christian Groessler
;

	.include	"zeropage.inc"

	.include	"joy-kernel.inc"
	.include	"joy-error.inc"
	.include	"atari.inc"

	.macpack	generic


; ------------------------------------------------------------------------
; 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 not available
	.byte	$00			; Future expansion
	.byte	$00			; Future expansion

; Jump table.

	.addr	INSTALL
	.addr	UNINSTALL
	.addr	COUNT
	.addr	READJOY
	.addr	0			; IRQ entry not used

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

JOY_COUNT	= 4		; Number of joysticks we support


; ------------------------------------------------------------------------
; Data.


.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	#0
;	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	$fcd8
	cpx	#$a2
	beq	_400800
	lsr	a		; XL and newer machines only have 2 ports
_400800:
	ldx	#0
	rts

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

READJOY:
	and	#3		; fix joystick number
	tax			; Joystick number (0-3) into X

; Read joystick

	lda	STRIG0,x	; get button
	asl	a
	asl	a
	asl	a
	asl	a
	ora	STICK0,x	; add position information
	eor	#$1F
	ldx	#0		; fix X
	rts