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439 lines
12 KiB
ArmAsm
439 lines
12 KiB
ArmAsm
;
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; Driver for a "joystick mouse".
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;
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; Ullrich von Bassewitz, 2004-03-29, 2009-09-26
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; 2010-02-08, Greg King
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;
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; The driver prevents the keyboard from interfering by changing the
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; keyboard's output port into an input port while the driver reads its
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; controller device. That disables a wire that is left active by the
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; Kernal. That wire is used by the STOP-key to break out of BASIC
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; programs -- CC65 programs don't use that feature. The wire is shared
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; by these keys: STOP, "Q", Commodore, Space, "2", CTRL, Left-Arrow, and
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; "1". I listed them, in order, from bit 7 over to bit 0. The
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; rightmost five keys can look like joystick switches.
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;
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; The driver prevents the mouse/joystick from interfering by "blinding"
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; the keyboard scanner while any button/switch is active. It changes
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; the input port into an output port, then stores all zero-bits in that
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; port's latch. Reading from an output port sees the bitwise-AND of the
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; latch and the input signals. Therefore, the scanner thinks that eight
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; keys are being pushed at the same time. It doesn't know what to do
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; about that condition; so, it does nothing. The driver lets the
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; scanner see normally, again, when no buttons/switches are active.
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;
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.include "zeropage.inc"
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.include "mouse-kernel.inc"
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.include "c64.inc"
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.macpack generic
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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.segment "JUMPTABLE"
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HEADER:
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; Driver signature
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.byte $6d, $6f, $75 ; "mou"
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.byte MOUSE_API_VERSION ; Mouse driver API version number
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; Jump table.
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.addr INSTALL
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.addr UNINSTALL
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.addr HIDE
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.addr SHOW
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.addr SETBOX
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.addr GETBOX
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.addr MOVE
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.addr BUTTONS
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.addr POS
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.addr INFO
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.addr IOCTL
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.addr IRQ
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; Mouse driver flags
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.byte MOUSE_FLAG_LATE_IRQ
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; Callback table, set by the kernel before INSTALL is called
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CHIDE: jmp $0000 ; Hide the cursor
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CSHOW: jmp $0000 ; Show the cursor
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CMOVEX: jmp $0000 ; Move the cursor to X coord
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CMOVEY: jmp $0000 ; Move the cursor to Y coord
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;----------------------------------------------------------------------------
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; Constants
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SCREEN_HEIGHT = 200
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SCREEN_WIDTH = 320
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.enum JOY
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UP = $01
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DOWN = $02
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LEFT = $04
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RIGHT = $08
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FIRE = $10
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.endenum
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;----------------------------------------------------------------------------
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; Global variables. The bounding box values are sorted so that they can be
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; written with the least effort in the SETBOX and GETBOX routines, so don't
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; reorder them.
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.bss
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Vars:
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YPos: .res 2 ; Current mouse position, Y
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XPos: .res 2 ; Current mouse position, X
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XMin: .res 2 ; X1 value of bounding box
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YMin: .res 2 ; Y1 value of bounding box
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XMax: .res 2 ; X2 value of bounding box
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YMax: .res 2 ; Y2 value of bounding box
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Buttons: .res 1 ; Button mask
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; Temporary value used in the int handler
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Temp: .res 1
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; Default values for above variables
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.rodata
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.proc DefVars
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.word SCREEN_HEIGHT/2 ; YPos
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.word SCREEN_WIDTH/2 ; XPos
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.word 0 ; XMin
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.word 0 ; YMin
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.word SCREEN_WIDTH ; XMax
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.word SCREEN_HEIGHT ; YMax
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.byte 0 ; Buttons
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.endproc
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.code
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;----------------------------------------------------------------------------
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; INSTALL routine. Is called after the driver is loaded into memory. If
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; possible, check if the hardware is present.
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; Must return an MOUSE_ERR_xx code in a/x.
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INSTALL:
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; Initialize variables. Just copy the default stuff over
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ldx #.sizeof(DefVars)-1
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@L1: lda DefVars,x
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sta Vars,x
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dex
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bpl @L1
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; Be sure the mouse cursor is invisible and at the default location. We
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; need to do that here, because our mouse interrupt handler doesn't set the
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; mouse position if it hasn't changed.
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sei
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jsr CHIDE
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lda XPos
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ldx XPos+1
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jsr CMOVEX
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lda YPos
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ldx YPos+1
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jsr CMOVEY
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cli
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; Done, return zero (= MOUSE_ERR_OK)
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ldx #$00
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txa
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rts
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;----------------------------------------------------------------------------
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; UNINSTALL routine. Is called before the driver is removed from memory.
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; No return code required (the driver is removed from memory on return).
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UNINSTALL = HIDE ; Hide cursor on exit
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;----------------------------------------------------------------------------
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; HIDE routine. Is called to hide the mouse pointer. The mouse kernel manages
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; a counter for calls to show/hide, and the driver entry point is only called
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; if the mouse is currently visible and should get hidden. For most drivers,
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; no special action is required besides hiding the mouse cursor.
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; No return code required.
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HIDE: sei
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jsr CHIDE
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cli
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rts
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;----------------------------------------------------------------------------
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; SHOW routine. Is called to show the mouse pointer. The mouse kernel manages
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; a counter for calls to show/hide, and the driver entry point is only called
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; if the mouse is currently hidden and should become visible. For most drivers,
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; no special action is required besides enabling the mouse cursor.
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; No return code required.
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SHOW: sei
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jsr CSHOW
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cli
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rts
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;----------------------------------------------------------------------------
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; SETBOX: Set the mouse bounding box. The parameters are passed as they come
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; from the C program, that is, a pointer to a mouse_box struct in a/x.
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; No checks are done if the mouse is currently inside the box, this is the job
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; of the caller. It is not necessary to validate the parameters, trust the
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; caller and save some code here. No return code required.
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SETBOX: sta ptr1
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stx ptr1+1 ; Save data pointer
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ldy #.sizeof (MOUSE_BOX)-1
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sei
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@L1: lda (ptr1),y
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sta XMin,y
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dey
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bpl @L1
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cli
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rts
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;----------------------------------------------------------------------------
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; GETBOX: Return the mouse bounding box. The parameters are passed as they
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; come from the C program, that is, a pointer to a mouse_box struct in a/x.
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GETBOX: sta ptr1
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stx ptr1+1 ; Save data pointer
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ldy #.sizeof (MOUSE_BOX)-1
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@L1: lda XMin,y
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sta (ptr1),y
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dey
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bpl @L1
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rts
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;----------------------------------------------------------------------------
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; MOVE: Move the mouse to a new position. The position is passed as it comes
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; from the C program, that is: X on the stack and Y in a/x. The C wrapper will
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; remove the parameter from the stack on return.
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; No checks are done if the new position is valid (within the bounding box or
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; the screen). No return code required.
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;
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MOVE: sei ; No interrupts
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sta YPos
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stx YPos+1 ; New Y position
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jsr CMOVEY ; Set it
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ldy #$01
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lda (sp),y
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sta XPos+1
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tax
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dey
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lda (sp),y
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sta XPos ; New X position
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jsr CMOVEX ; Move the cursor
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cli ; Allow interrupts
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rts
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;----------------------------------------------------------------------------
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; BUTTONS: Return the button mask in a/x.
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BUTTONS:
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lda Buttons
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ldx #$00
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rts
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;----------------------------------------------------------------------------
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; POS: Return the mouse position in the MOUSE_POS struct pointed to by ptr1.
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; No return code required.
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POS: ldy #MOUSE_POS::XCOORD ; Structure offset
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sei ; Disable interrupts
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lda XPos ; Transfer the position
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sta (ptr1),y
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lda XPos+1
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iny
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sta (ptr1),y
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lda YPos
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iny
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sta (ptr1),y
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lda YPos+1
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cli ; Enable interrupts
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iny
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sta (ptr1),y ; Store last byte
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rts ; Done
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;----------------------------------------------------------------------------
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; INFO: Returns mouse position and current button mask in the MOUSE_INFO
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; struct pointed to by ptr1. No return code required.
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;
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; We're cheating here to keep the code smaller: The first fields of the
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; mouse_info struct are identical to the mouse_pos struct, so we will just
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; call _mouse_pos to initialize the struct pointer and fill the position
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; fields.
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INFO: jsr POS
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; Fill in the button state
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lda Buttons
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ldy #MOUSE_INFO::BUTTONS
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sta (ptr1),y
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rts
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;----------------------------------------------------------------------------
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; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
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; specific data in ptr1, and the ioctl code in A.
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; Must return an error code in a/x.
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;
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IOCTL: lda #<MOUSE_ERR_INV_IOCTL ; We don't support ioclts for now
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ldx #>MOUSE_ERR_INV_IOCTL
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rts
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;----------------------------------------------------------------------------
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; IRQ: Irq handler entry point. Called as a subroutine but in IRQ context
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; (so be careful). The routine MUST return carry set if the interrupt has been
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; 'handled' - which means that the interrupt source is gone. Otherwise it
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; MUST return carry clear.
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;
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; Avoid crosstalk between the keyboard and a joystick.
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IRQ: ldy #%00000000 ; Set ports A and B to input
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sty CIA1_DDRB
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sty CIA1_DDRA ; Keyboard won't look like joystick
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lda CIA1_PRB ; Read Control-Port 1
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dec CIA1_DDRA ; Set port A back to output
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eor #%11111111 ; Bit goes up when switch goes down
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beq @Save ;(bze)
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dec CIA1_DDRB ; Joystick won't look like keyboard
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sty CIA1_PRB ; Set "all keys pushed"
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@Save: sta Temp
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; Check for a pressed button and place the result into Buttons
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ldx #$00 ; Assume no button pressed
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and #JOY::FIRE ; Check fire button
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beq @L0 ; Jump if not pressed
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ldx #MOUSE_BTN_LEFT ; Left (only) button is pressed
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@L0: stx Buttons
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; Check left/right
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lda Temp ; Read joystick #0
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and #(JOY::LEFT | JOY::RIGHT)
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beq @SkipX ;
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; We will cheat here and rely on the fact that either the left, OR the right
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; bit can be active
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and #JOY::RIGHT ; Check RIGHT bit
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bne @Right
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lda #$FF
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tax
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bne @AddX ; Branch always
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@Right: lda #$01
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ldx #$00
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; Calculate the new X coordinate (--> a/y)
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@AddX: add XPos
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tay ; Remember low byte
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txa
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adc XPos+1
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tax
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; Limit the X coordinate to the bounding box
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cpy XMin
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sbc XMin+1
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bpl @L1
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ldy XMin
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ldx XMin+1
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jmp @L2
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@L1: txa
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cpy XMax
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sbc XMax+1
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bmi @L2
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ldy XMax
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ldx XMax+1
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@L2: sty XPos
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stx XPos+1
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; Move the mouse pointer to the new X pos
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tya
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jsr CMOVEX
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; Calculate the Y movement vector
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@SkipX: lda Temp ; Read joystick #0
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and #(JOY::UP | JOY::DOWN) ; Check up/down
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beq @SkipY ;
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; We will cheat here and rely on the fact that either the up, OR the down
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; bit can be active
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lsr a ; Check UP bit
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bcc @Down
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lda #$FF
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tax
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bne @AddY
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@Down: lda #$01
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ldx #$00
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; Calculate the new Y coordinate (--> a/y)
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@AddY: add YPos
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tay ; Remember low byte
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txa
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adc YPos+1
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tax
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; Limit the Y coordinate to the bounding box
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cpy YMin
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sbc YMin+1
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bpl @L3
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ldy YMin
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ldx YMin+1
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jmp @L4
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@L3: txa
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cpy YMax
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sbc YMax+1
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bmi @L4
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ldy YMax
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ldx YMax+1
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@L4: sty YPos
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stx YPos+1
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; Move the mouse pointer to the new X pos
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tya
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jsr CMOVEY
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; Done
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@SkipY: clc ; Interrupt not handled
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rts
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