cc65/libsrc/c64/c64-ptvjoy.s

;
; PTV-4 Player joystick driver for the C64
;
; Groepaz/Hitmen, 2002-12-23
; obviously based on Ullrichs driver :)
;

        .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       = 4             ; 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:   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:   dex
        bne     joy3

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

; Read joystick 3

joy3:
        lda     #%10000000      ; cia 2 port B Data-Direction
        sta     CIA2_DDRB       ; bit 7: out    bit 6-0: in

        dex
        bne     joy4

        lda     #$80            ; cia 2 port B read/write
        sta     CIA2_PRB        ; (output one at PB7)

        lda     CIA2_PRB        ; cia 2 port B read/write
        and     #$1f            ; get bit 4-0 (PB4-PB0)
        eor     #$1f
        rts

; Read joystick 4

joy4:   lda     #$00            ; cia 2 port B read/write
        sta     CIA2_PRB        ; (output zero at PB7)

        lda     CIA2_PRB        ; cia 2 port B read/write
        and     #$0f            ; get bit 3-0 (PB3-PB0)
        sta     tmp1            ; joy 4 directions

        lda     CIA2_PRB        ; cia 2 port B read/write
        and     #%00100000      ; get bit 5 (PB5)
        lsr
        ora     tmp1
        eor     #$1f

        ldx #0
        rts