2 ; Driver for a "joystick mouse".
4 ; Ullrich von Bassewitz, 2004-03-29, 2009-09-26
5 ; 2014-03-17, 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"
34 ; ------------------------------------------------------------------------
35 ; Header. Includes jump table
37 module_header _c64_joy_mou
43 .byte $6d, $6f, $75 ; "mou"
44 .byte MOUSE_API_VERSION ; Mouse driver API version number
67 .byte MOUSE_FLAG_LATE_IRQ
69 ; Callback table, set by the kernel before INSTALL is called
71 CHIDE: jmp $0000 ; Hide the cursor
72 CSHOW: jmp $0000 ; Show the cursor
73 CPREP: jmp $0000 ; Prepare to move the cursor
74 CDRAW: jmp $0000 ; Draw the cursor
75 CMOVEX: jmp $0000 ; Move the cursor to X coord
76 CMOVEY: jmp $0000 ; Move the cursor to Y coord
79 ;----------------------------------------------------------------------------
93 ;----------------------------------------------------------------------------
94 ; Global variables. The bounding box values are sorted so that they can be
95 ; written with the least effort in the SETBOX and GETBOX routines, so don't
101 YPos: .res 2 ; Current mouse position, Y
102 XPos: .res 2 ; Current mouse position, X
103 XMin: .res 2 ; X1 value of bounding box
104 YMin: .res 2 ; Y1 value of bounding box
105 XMax: .res 2 ; X2 value of bounding box
106 YMax: .res 2 ; Y2 value of bounding box
107 Buttons: .res 1 ; Button mask
109 ; Temporary value used in the int handler
115 ; Default values for above variables
116 ; (We use ".proc" because we want to define both a label and a scope.)
119 .word SCREEN_HEIGHT/2 ; YPos
120 .word SCREEN_WIDTH/2 ; XPos
123 .word SCREEN_WIDTH - 1 ; XMax
124 .word SCREEN_HEIGHT - 1 ; YMax
130 ;----------------------------------------------------------------------------
131 ; INSTALL routine. Is called after the driver is loaded into memory. If
132 ; possible, check if the hardware is present.
133 ; Must return an MOUSE_ERR_xx code in a/x.
137 ; Initialize variables. Just copy the default stuff over
139 ldx #.sizeof(DefVars)-1
145 ; Be sure the mouse cursor is invisible and at the default location. We
146 ; need to do that here, because our mouse interrupt handler doesn't set the
147 ; mouse position if it hasn't changed.
159 ; Done, return zero (= MOUSE_ERR_OK)
165 ;----------------------------------------------------------------------------
166 ; UNINSTALL routine. Is called before the driver is removed from memory.
167 ; No return code required (the driver is removed from memory on return).
169 UNINSTALL = HIDE ; Hide cursor on exit
171 ;----------------------------------------------------------------------------
172 ; HIDE routine. Is called to hide the mouse pointer. The mouse kernel manages
173 ; a counter for calls to show/hide, and the driver entry point is only called
174 ; if the mouse is currently visible and should get hidden. For most drivers,
175 ; no special action is required besides hiding the mouse cursor.
176 ; No return code required.
183 ;----------------------------------------------------------------------------
184 ; SHOW routine. Is called to show the mouse pointer. The mouse kernel manages
185 ; a counter for calls to show/hide, and the driver entry point is only called
186 ; if the mouse is currently hidden and should become visible. For most drivers,
187 ; no special action is required besides enabling the mouse cursor.
188 ; No return code required.
195 ;----------------------------------------------------------------------------
196 ; SETBOX: Set the mouse bounding box. The parameters are passed as they come
197 ; from the C program, that is, a pointer to a mouse_box struct in a/x.
198 ; No checks are done if the mouse is currently inside the box, this is the job
199 ; of the caller. It is not necessary to validate the parameters, trust the
200 ; caller and save some code here. No return code required.
203 stx ptr1+1 ; Save data pointer
205 ldy #.sizeof (MOUSE_BOX)-1
216 ;----------------------------------------------------------------------------
217 ; GETBOX: Return the mouse bounding box. The parameters are passed as they
218 ; come from the C program, that is, a pointer to a mouse_box struct in a/x.
221 stx ptr1+1 ; Save data pointer
223 ldy #.sizeof (MOUSE_BOX)-1
232 ;----------------------------------------------------------------------------
233 ; MOVE: Move the mouse to a new position. The position is passed as it comes
234 ; from the C program, that is: X on the stack and Y in a/x. The C wrapper will
235 ; remove the parameter from the stack on return.
236 ; No checks are done if the new position is valid (within the bounding box or
237 ; the screen). No return code required.
240 MOVE: sei ; No interrupts
243 stx YPos+1 ; New Y position
252 sta XPos ; New X position
254 jsr CMOVEX ; Move the cursor
256 cli ; Allow interrupts
259 ;----------------------------------------------------------------------------
260 ; BUTTONS: Return the button mask in a/x.
267 ;----------------------------------------------------------------------------
268 ; POS: Return the mouse position in the MOUSE_POS struct pointed to by ptr1.
269 ; No return code required.
271 POS: ldy #MOUSE_POS::XCOORD ; Structure offset
273 sei ; Disable interrupts
274 lda XPos ; Transfer the position
283 cli ; Enable interrupts
286 sta (ptr1),y ; Store last byte
290 ;----------------------------------------------------------------------------
291 ; INFO: Returns mouse position and current button mask in the MOUSE_INFO
292 ; struct pointed to by ptr1. No return code required.
294 ; We're cheating here to keep the code smaller: The first fields of the
295 ; mouse_info struct are identical to the mouse_pos struct, so we will just
296 ; call _mouse_pos to initialize the struct pointer and fill the position
301 ; Fill in the button state
304 ldy #MOUSE_INFO::BUTTONS
309 ;----------------------------------------------------------------------------
310 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
311 ; specific data in ptr1, and the ioctl code in A.
312 ; Must return an error code in a/x.
315 IOCTL: lda #<MOUSE_ERR_INV_IOCTL ; We don't support ioclts for now
316 ldx #>MOUSE_ERR_INV_IOCTL
319 ;----------------------------------------------------------------------------
320 ; IRQ: Irq handler entry point. Called as a subroutine but in IRQ context
321 ; (so be careful). The routine MUST return carry set if the interrupt has been
322 ; 'handled' - which means that the interrupt source is gone. Otherwise it
323 ; MUST return carry clear.
328 ; Avoid crosstalk between the keyboard and a joystick.
330 ldy #%00000000 ; Set ports A and B to input
332 sty CIA1_DDRA ; Keyboard won't look like joystick
333 lda CIA1_PRB ; Read Control-Port 1
334 dec CIA1_DDRA ; Set port A back to output
335 eor #%11111111 ; Bit goes up when switch goes down
337 dec CIA1_DDRB ; Joystick won't look like keyboard
338 sty CIA1_PRB ; Set "all keys pushed"
341 ; Check for a pressed button and place the result into Buttons
343 ldx #$00 ; Assume no button pressed
344 and #JOY::FIRE ; Check fire button
345 beq @L0 ; Jump if not pressed
346 ldx #MOUSE_BTN_LEFT ; Left (only) button is pressed
351 lda Temp ; Read joystick #0
352 and #(JOY::LEFT | JOY::RIGHT)
355 ; We will cheat here and rely on the fact that either the left, OR the right
358 and #JOY::RIGHT ; Check RIGHT bit
362 bne @AddX ; Branch always
366 ; Calculate the new X coordinate (--> a/y)
369 tay ; Remember low byte
374 ; Limit the X coordinate to the bounding box
392 ; Move the mouse pointer to the new X pos
397 ; Calculate the Y movement vector
399 @SkipX: lda Temp ; Read joystick #0
400 and #(JOY::UP | JOY::DOWN) ; Check up/down
403 ; We will cheat here and rely on the fact that either the up, OR the down
414 ; Calculate the new Y coordinate (--> a/y)
417 tay ; Remember low byte
422 ; Limit the Y coordinate to the bounding box
440 ; Move the mouse pointer to the new X pos
448 clc ; Interrupt not "handled"