cc65/libsrc/c64/c64-potmouse.s

;
; Driver for a potentiometer "mouse" e.g. Koala Pad
;
; Ullrich von Bassewitz, 2004-03-29
; Stefan Haubenthal, 2006-08-20
;

	.include	"zeropage.inc"
	.include	"mouse-kernel.inc"
	.include	"c64.inc"

	.macpack	generic

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

.segment	"JUMPTABLE"

HEADER:

; Driver signature

	.byte	$6d, $6f, $75		; "mou"
	.byte	MOUSE_API_VERSION	; Mouse driver API version number

; Jump table.

	.addr	INSTALL
	.addr	UNINSTALL
	.addr	HIDE
	.addr	SHOW
	.addr	BOX
	.addr	MOVE
	.addr	BUTTONS
	.addr	POS
	.addr	INFO
	.addr	IOCTL
	.addr	IRQ

; Callback table, set by the kernel before INSTALL is called

CHIDE:	jmp	$0000			; Hide the cursor
CSHOW:	jmp	$0000			; Show the cursor
CMOVEX: jmp	$0000			; Move the cursor to X coord
CMOVEY: jmp	$0000			; Move the cursor to Y coord


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

SCREEN_HEIGHT	= 200
SCREEN_WIDTH	= 320

.enum	JOY
	UP	= $01
	DOWN	= $02
	LEFT	= $04
	RIGHT	= $08
	FIRE	= $10
.endenum

;----------------------------------------------------------------------------
; Global variables. The bounding box values are sorted so that they can be
; written with the least effort in the BOX routine, so don't reorder them.

.bss

Vars:
YPos:		.res	2		; Current mouse position, Y
XPos:		.res	2		; Current mouse position, X
YMax:		.res	2		; Y2 value of bounding box
XMax:		.res	2		; X2 value of bounding box
YMin:		.res	2		; Y1 value of bounding box
XMin:		.res	2		; X1 value of bounding box
Buttons:	.res	1		; Button mask

; Temporary value used in the int handler

Temp:		.res	1

; Default values for above variables

.rodata

.proc	DefVars
	.word	SCREEN_HEIGHT/2		; YPos
	.word	SCREEN_WIDTH/2		; XPos
	.word	SCREEN_HEIGHT		; YMax
	.word	SCREEN_WIDTH		; XMax
	.word	0			; YMin
	.word	0			; XMin
	.byte	0			; Buttons
.endproc

.code

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

INSTALL:

; Initialize variables. Just copy the default stuff over

	ldx	#.sizeof(DefVars)-1
@L1:	lda	DefVars,x
	sta	Vars,x
	dex
	bpl	@L1

; Be sure the mouse cursor is invisible and at the default location. We
; need to do that here, because our mouse interrupt handler doesn't set the
; mouse position if it hasn't changed.

	sei
	jsr	CHIDE
	lda	XPos
	ldx	XPos+1
	jsr	CMOVEX
	lda	YPos
	ldx	YPos+1
	jsr	CMOVEY
	cli

; Done, return zero (= MOUSE_ERR_OK)

	ldx	#$00
	txa
	rts

;----------------------------------------------------------------------------
; UNINSTALL routine. Is called before the driver is removed from memory.
; No return code required (the driver is removed from memory on return).

UNINSTALL	= HIDE			; Hide cursor on exit

;----------------------------------------------------------------------------
; HIDE routine. Is called to hide the mouse pointer. The mouse kernel manages
; a counter for calls to show/hide, and the driver entry point is only called
; if the mouse is currently visible and should get hidden. For most drivers,
; no special action is required besides hiding the mouse cursor.
; No return code required.

HIDE:	sei
	jsr	CHIDE
	cli
	rts

;----------------------------------------------------------------------------
; SHOW routine. Is called to show the mouse pointer. The mouse kernel manages
; a counter for calls to show/hide, and the driver entry point is only called
; if the mouse is currently hidden and should become visible. For most drivers,
; no special action is required besides enabling the mouse cursor.
; No return code required.

SHOW:	sei
	jsr	CSHOW
	cli
	rts

;----------------------------------------------------------------------------
; BOX: Set the mouse bounding box. The parameters are passed as they come from
; the C program, that is, maxy in a/x and the other parameters on the stack.
; The C wrapper will remove the parameters from the stack when the driver
; routine returns.
; No checks are done if the mouse is currently inside the box, this is the job
; of the caller. It is not necessary to validate the parameters, trust the
; caller and save some code here. No return code required.

BOX:	ldy	#5
	sei
	sta	YMax
	stx	YMax+1

@L1:	lda	(sp),y
	sta	XMax,y
	dey
	bpl	@L1

	cli
	rts

;----------------------------------------------------------------------------
; MOVE: Move the mouse to a new position. The position is passed as it comes
; from the C program, that is: X on the stack and Y in a/x. The C wrapper will
; remove the parameter from the stack on return.
; No checks are done if the new position is valid (within the bounding box or
; the screen). No return code required.
;

MOVE:	sei				; No interrupts

	sta	YPos
	stx	YPos+1			; New Y position
	jsr	CMOVEY			; Set it

	ldy	#$01
	lda	(sp),y
	sta	XPos+1
	tax
	dey
	lda	(sp),y
	sta	XPos			; New X position

	jsr	CMOVEX			; Move the cursor

	cli				; Allow interrupts
	rts

;----------------------------------------------------------------------------
; BUTTONS: Return the button mask in a/x.

BUTTONS:
	lda	Buttons
	ldx	#$00
	rts

;----------------------------------------------------------------------------
; POS: Return the mouse position in the MOUSE_POS struct pointed to by ptr1.
; No return code required.

POS:	ldy	#MOUSE_POS::XCOORD	; Structure offset

	sei				; Disable interrupts
	lda	XPos			; Transfer the position
	sta	(ptr1),y
	lda	XPos+1
	iny
	sta	(ptr1),y
	lda	YPos
	iny
	sta	(ptr1),y
	lda	YPos+1
	cli				; Enable interrupts

	iny
	sta	(ptr1),y		; Store last byte

	rts				; Done

;----------------------------------------------------------------------------
; INFO: Returns mouse position and current button mask in the MOUSE_INFO
; struct pointed to by ptr1. No return code required.
;
; We're cheating here to keep the code smaller: The first fields of the
; mouse_info struct are identical to the mouse_pos struct, so we will just
; call _mouse_pos to initialize the struct pointer and fill the position
; fields.

INFO:	jsr	POS

; Fill in the button state

	lda	Buttons
	ldy	#MOUSE_INFO::BUTTONS
	sta	(ptr1),y

	rts

;----------------------------------------------------------------------------
; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
; specific data in ptr1, and the ioctl code in A.
; Must return an error code in a/x.
;

IOCTL:	lda	#<MOUSE_ERR_INV_IOCTL	  ; We don't support ioclts for now
	ldx	#>MOUSE_ERR_INV_IOCTL
	rts

;----------------------------------------------------------------------------
; IRQ: Irq handler entry point. Called as a subroutine but in IRQ context
; (so be careful).
;

IRQ:	lda	#$7F
	sta	CIA1_PRA
	lda	CIA1_PRB		; Read port #1
	and	#%00001100
	eor	#%00001100		; Make all bits active high
	asl
	sta	Buttons
	lsr
	lsr
	lsr
	and	#%00000001
	ora	Buttons
	sta	Buttons
	ldx	#%01000000
	stx	CIA1_PRA
	ldy	#0
:	dey
	bne	:-
	ldx	SID_ADConv1
	stx	XPos
	ldx	SID_ADConv2
	stx	YPos

	lda	#$FF
	tax
	bne	@AddX			; Branch always
	lda	#$01
	ldx	#$00

; Calculate the new X coordinate (--> a/y)

@AddX:	add	XPos
	tay				; Remember low byte
	txa
	adc	XPos+1
	tax

; Limit the X coordinate to the bounding box

	cpy	XMin
	sbc	XMin+1
	bpl	@L1
	ldy	XMin
	ldx	XMin+1
	jmp	@L2
@L1:	txa

	cpy	XMax
	sbc	XMax+1
	bmi	@L2
	ldy	XMax
	ldx	XMax+1
@L2:	sty	XPos
	stx	XPos+1

; Move the mouse pointer to the new X pos

	tya
	jsr	CMOVEX

	lda	#$FF
	tax
	bne	@AddY
@Down:	lda	#$01
	ldx	#$00

; Calculate the new Y coordinate (--> a/y)

@AddY:	add	YPos
	tay				; Remember low byte
	txa
	adc	YPos+1
	tax

; Limit the Y coordinate to the bounding box

	cpy	YMin
	sbc	YMin+1
	bpl	@L3
	ldy	YMin
	ldx	YMin+1
	jmp	@L4
@L3:	txa

	cpy	YMax
	sbc	YMax+1
	bmi	@L4
	ldy	YMax
	ldx	YMax+1
@L4:	sty	YPos
	stx	YPos+1

; Move the mouse pointer to the new X pos

	tya
	jmp	CMOVEY