cc65/libsrc/c64/c64-stdjoy.s

;
; Standard joystick driver for the C64. May be used multiple times when linked
; to the statically application.
;
; Ullrich von Bassewitz, 2002-12-20
;

	.include 	"zeropage.inc"

      	.include 	"joy-kernel.inc"
        .include        "joy-error.inc"
        .include        "c64.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 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


; ------------------------------------------------------------------------
; 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     #>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:   tax	  		; Joystick number into X
	bne    	joy2

; Read joystick 1

joy1:	lda	#$7F
     	sei
     	sta	CIA1_PRA
     	lda	CIA1_PRB
     	cli
     	and	#$1F
     	eor	#$1F
     	rts

; Read joystick 2

joy2:	ldx	#0
	lda	#$E0
	ldy	#$FF
	sei
	sta	CIA1_DDRA
	lda	CIA1_PRA
	sty	CIA1_DDRA
	cli
	and	#$1F
	eor	#$1F
	rts