2 ; Driver for a "joystick mouse".
4 ; Ullrich von Bassewitz, 2004-03-29, 2009-09-26
5 ; 2010-02-08, Greg King
7 ; The driver prevents the keyboard from interfering by changing the
8 ; keyboard's output port into an input port while the driver reads its
9 ; controller device. That disables a wire that is left active by the
10 ; Kernal. That wire is used by the STOP-key to break out of BASIC
11 ; programs -- CC65 programs don't use that feature. The wire is shared
12 ; by these keys: STOP, "Q", Commodore, Space, "2", CTRL, Left-Arrow, and
13 ; "1". I listed them, in order, from bit 7 over to bit 0. The
14 ; rightmost five keys can look like joystick switches.
16 ; The driver prevents the mouse/joystick from interfering by "blinding"
17 ; the keyboard scanner while any button/switch is active. It changes
18 ; the input port into an output port, then stores all zero-bits in that
19 ; port's latch. Reading from an output port sees the bitwise-AND of the
20 ; latch and the input signals. Therefore, the scanner thinks that eight
21 ; keys are being pushed at the same time. It doesn't know what to do
22 ; about that condition; so, it does nothing. The driver lets the
23 ; scanner see normally, again, when no buttons/switches are active.
26 .include "zeropage.inc"
27 .include "mouse-kernel.inc"
32 ; ------------------------------------------------------------------------
33 ; Header. Includes jump table
41 .byte $6d, $6f, $75 ; "mou"
42 .byte MOUSE_API_VERSION ; Mouse driver API version number
65 .byte MOUSE_FLAG_LATE_IRQ
67 ; Callback table, set by the kernel before INSTALL is called
69 CHIDE: jmp $0000 ; Hide the cursor
70 CSHOW: jmp $0000 ; Show the cursor
71 CMOVEX: jmp $0000 ; Move the cursor to X coord
72 CMOVEY: jmp $0000 ; Move the cursor to Y coord
75 ;----------------------------------------------------------------------------
89 ;----------------------------------------------------------------------------
90 ; Global variables. The bounding box values are sorted so that they can be
91 ; written with the least effort in the SETBOX and GETBOX routines, so don't
97 YPos: .res 2 ; Current mouse position, Y
98 XPos: .res 2 ; Current mouse position, X
99 XMin: .res 2 ; X1 value of bounding box
100 YMin: .res 2 ; Y1 value of bounding box
101 XMax: .res 2 ; X2 value of bounding box
102 YMax: .res 2 ; Y2 value of bounding box
103 Buttons: .res 1 ; Button mask
105 ; Temporary value used in the int handler
111 ; Default values for below variables
112 ; (We use ".proc" because we want to define both a label and a scope.)
115 .word SCREEN_HEIGHT/2 ; YPos
116 .word SCREEN_WIDTH/2 ; XPos
119 .word SCREEN_WIDTH ; XMax
120 .word SCREEN_HEIGHT ; YMax
126 ;----------------------------------------------------------------------------
127 ; INSTALL routine. Is called after the driver is loaded into memory. If
128 ; possible, check if the hardware is present.
129 ; Must return an MOUSE_ERR_xx code in a/x.
133 ; Initialize variables. Just copy the default stuff over
135 ldx #.sizeof(DefVars)-1
141 ; Be sure the mouse cursor is invisible and at the default location. We
142 ; need to do that here, because our mouse interrupt handler doesn't set the
143 ; mouse position if it hasn't changed.
155 ; Done, return zero (= MOUSE_ERR_OK)
161 ;----------------------------------------------------------------------------
162 ; UNINSTALL routine. Is called before the driver is removed from memory.
163 ; No return code required (the driver is removed from memory on return).
165 UNINSTALL = HIDE ; Hide cursor on exit
167 ;----------------------------------------------------------------------------
168 ; HIDE routine. Is called to hide the mouse pointer. The mouse kernel manages
169 ; a counter for calls to show/hide, and the driver entry point is only called
170 ; if the mouse is currently visible and should get hidden. For most drivers,
171 ; no special action is required besides hiding the mouse cursor.
172 ; No return code required.
179 ;----------------------------------------------------------------------------
180 ; SHOW routine. Is called to show the mouse pointer. The mouse kernel manages
181 ; a counter for calls to show/hide, and the driver entry point is only called
182 ; if the mouse is currently hidden and should become visible. For most drivers,
183 ; no special action is required besides enabling the mouse cursor.
184 ; No return code required.
191 ;----------------------------------------------------------------------------
192 ; SETBOX: Set the mouse bounding box. The parameters are passed as they come
193 ; from the C program, that is, a pointer to a mouse_box struct in a/x.
194 ; No checks are done if the mouse is currently inside the box, this is the job
195 ; of the caller. It is not necessary to validate the parameters, trust the
196 ; caller and save some code here. No return code required.
199 stx ptr1+1 ; Save data pointer
201 ldy #.sizeof (MOUSE_BOX)-1
212 ;----------------------------------------------------------------------------
213 ; GETBOX: Return the mouse bounding box. The parameters are passed as they
214 ; come from the C program, that is, a pointer to a mouse_box struct in a/x.
217 stx ptr1+1 ; Save data pointer
219 ldy #.sizeof (MOUSE_BOX)-1
228 ;----------------------------------------------------------------------------
229 ; MOVE: Move the mouse to a new position. The position is passed as it comes
230 ; from the C program, that is: X on the stack and Y in a/x. The C wrapper will
231 ; remove the parameter from the stack on return.
232 ; No checks are done if the new position is valid (within the bounding box or
233 ; the screen). No return code required.
236 MOVE: sei ; No interrupts
239 stx YPos+1 ; New Y position
248 sta XPos ; New X position
250 jsr CMOVEX ; Move the cursor
252 cli ; Allow interrupts
255 ;----------------------------------------------------------------------------
256 ; BUTTONS: Return the button mask in a/x.
263 ;----------------------------------------------------------------------------
264 ; POS: Return the mouse position in the MOUSE_POS struct pointed to by ptr1.
265 ; No return code required.
267 POS: ldy #MOUSE_POS::XCOORD ; Structure offset
269 sei ; Disable interrupts
270 lda XPos ; Transfer the position
279 cli ; Enable interrupts
282 sta (ptr1),y ; Store last byte
286 ;----------------------------------------------------------------------------
287 ; INFO: Returns mouse position and current button mask in the MOUSE_INFO
288 ; struct pointed to by ptr1. No return code required.
290 ; We're cheating here to keep the code smaller: The first fields of the
291 ; mouse_info struct are identical to the mouse_pos struct, so we will just
292 ; call _mouse_pos to initialize the struct pointer and fill the position
297 ; Fill in the button state
300 ldy #MOUSE_INFO::BUTTONS
305 ;----------------------------------------------------------------------------
306 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
307 ; specific data in ptr1, and the ioctl code in A.
308 ; Must return an error code in a/x.
311 IOCTL: lda #<MOUSE_ERR_INV_IOCTL ; We don't support ioclts for now
312 ldx #>MOUSE_ERR_INV_IOCTL
315 ;----------------------------------------------------------------------------
316 ; IRQ: Irq handler entry point. Called as a subroutine but in IRQ context
317 ; (so be careful). The routine MUST return carry set if the interrupt has been
318 ; 'handled' - which means that the interrupt source is gone. Otherwise it
319 ; MUST return carry clear.
322 ; Avoid crosstalk between the keyboard and a joystick.
324 IRQ: ldy #%00000000 ; Set ports A and B to input
326 sty CIA1_DDRA ; Keyboard won't look like joystick
327 lda CIA1_PRB ; Read Control-Port 1
328 dec CIA1_DDRA ; Set port A back to output
329 eor #%11111111 ; Bit goes up when switch goes down
331 dec CIA1_DDRB ; Joystick won't look like keyboard
332 sty CIA1_PRB ; Set "all keys pushed"
335 ; Check for a pressed button and place the result into Buttons
337 ldx #$00 ; Assume no button pressed
338 and #JOY::FIRE ; Check fire button
339 beq @L0 ; Jump if not pressed
340 ldx #MOUSE_BTN_LEFT ; Left (only) button is pressed
345 lda Temp ; Read joystick #0
346 and #(JOY::LEFT | JOY::RIGHT)
349 ; We will cheat here and rely on the fact that either the left, OR the right
352 and #JOY::RIGHT ; Check RIGHT bit
356 bne @AddX ; Branch always
360 ; Calculate the new X coordinate (--> a/y)
363 tay ; Remember low byte
368 ; Limit the X coordinate to the bounding box
386 ; Move the mouse pointer to the new X pos
391 ; Calculate the Y movement vector
393 @SkipX: lda Temp ; Read joystick #0
394 and #(JOY::UP | JOY::DOWN) ; Check up/down
397 ; We will cheat here and rely on the fact that either the up, OR the down
408 ; Calculate the new Y coordinate (--> a/y)
411 tay ; Remember low byte
416 ; Limit the Y coordinate to the bounding box
434 ; Move the mouse pointer to the new X pos
441 @SkipY: clc ; Interrupt not handled