;
; Standard joystick driver for the Atari 7800.
; This version tries to use 7800 and 2600 joysticks.
; But assumes that both joysticks are of same type.
;
; Modified by Karri Kaksonen, 2022-02-27
; Ullrich von Bassewitz, 2002-12-20
; Using code from Steve Schmidtke
;

        .include        "zeropage.inc"

        .include        "joy-kernel.inc"
        .include        "joy-error.inc"
        .include        "atari7800.inc"

        .macpack        generic
        .macpack        module


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

        module_header   _atari7800_stdjoy_joy

; Driver signature

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

; Library reference

        .addr   $0000

; Jump table.

        .addr   INSTALL
        .addr   UNINSTALL
        .addr   COUNT
        .addr   READ

; ------------------------------------------------------------------------
; 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:
        ; Assume 7800 2-button controller, can change
        ; to 2600 1-button later
        lda #$14
        sta CTLSWB ; enable 2-button 7800 controller 1: set pin 6 to output
        ldy #$00
        sty SWCHB ; enable 2-button 7800 controller 2: pull pin 6 (INPT4) high

reset:
        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 for 2 fire buttons. 

readbuttons:
	; Y has joystick of interest 0/1
        ; return value:
	;  $00: no button,
	;  $80: left/B button,
	;  $40: right/A button,
	;  $c0: both buttons
        ; preserves X
	tya
	beq L5
	; Joystick 1 processing
	; 7800 joystick 1 buttons
	ldy #0		; ........
	bit INPT2	; Check for right button
	bpl L1
	ldy #2		; ......2.
L1:	bit INPT3	;Check for left button
	bpl L2
	iny		; ......21
L2:	tya
	bne L4		; Joystick worked
	; 2600 Joystick 1
	bit INPT5
	bpl L4
L3:	iny		; .......1
	lda #0		; Fallback to 2600 joystick mode
	sta CTLSWB
L4:	tya
	ror		; .......2 1
	ror		; 1....... 2
	ror		; 21......
	rts

L5:	; Joystick 0 processing
	; 7800 joystick 0 buttons
	ldy #0		; ........
	bit INPT0	; Check for right button
	bpl L6
	ldy #2		; ......2.
L6:	bit INPT1	;Check for left button
	bpl L7
	iny		; ......21
L7:	tya
	bne L4		; Joystick worked
	; 2600 Joystick 0
	bit INPT4
	bpl L4
	bmi L3

READ:
	tay			; Store joystick 0/1 in Y
	beq	L8
	lda	SWCHA
	rol			; ...RLDU.
	rol			; ..RLDU..
	rol			; .RLDU... - joystick 1
	jmp	L9
L8:	lda     SWCHA           ; Read joystick
	ror			; .RLDU... - joystick 0
L9:	tax
	jsr readbuttons		; A = 21......, X = .RLDU...
	rol			; A = 1 .......2
	tay			; Y = .......2
	txa			; A = .RLDU...
	ror			; A = 1.RLDU..
	tax			; X = 1.RLDU..
	tya			; A = .......2
	ror			; A = ........ 2
	txa			; A = 1.RLDU..
	rol			; A = .RLDU..2 1
	rol			; A = RLDU..21
	eor	#$F0		; The direction buttons were inversed
	and	#$F3
	rts