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https://github.com/cc65/cc65.git
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e6530d68dd
Note that the joystick driver doesn't support combined movements (like left/up or right/down). This should be fixed.
194 lines
5.3 KiB
ArmAsm
194 lines
5.3 KiB
ArmAsm
;
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; Standard joystick driver for the Creativision.
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;
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; Christian Groessler, 2017-02-06
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;
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.include "zeropage.inc"
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.include "joy-kernel.inc"
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.include "joy-error.inc"
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.include "creativision.inc"
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.macpack module
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; ------------------------------------------------------------------------
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; Header. Includes jump table
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module_header _creativisionstd_joy
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; Driver signature
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.byte $6A, $6F, $79 ; "joy"
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.byte JOY_API_VERSION ; Driver API version number
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; Library reference
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.addr $0000
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; Button state masks (8 values)
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.byte $10 ; JOY_UP
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.byte $04 ; JOY_DOWN
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.byte $20 ; JOY_LEFT
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.byte $08 ; JOY_RIGHT
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.byte $01 ; JOY_FIRE (button #1)
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.byte $02 ; JOY_FIRE2 (button #2)
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.byte $00 ; Future expansion
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.byte $00 ; Future expansion
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; Jump table.
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.addr INSTALL
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.addr UNINSTALL
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.addr COUNT
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.addr READJOY
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.addr 0 ; IRQ entry not used
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; ------------------------------------------------------------------------
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; Constants
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JOY_COUNT = 2 ; Number of joysticks we support
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; ------------------------------------------------------------------------
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; Code
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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 and determine the amount of
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; memory available.
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; Must return an JOY_ERR_xx code in a/x.
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;
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INSTALL:
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lda #JOY_ERR_OK
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ldx #0
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; rts ; Fall through
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; ------------------------------------------------------------------------
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; UNINSTALL routine. Is called before the driver is removed from memory.
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; Can do cleanup or whatever. Must not return anything.
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;
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UNINSTALL:
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rts
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; ------------------------------------------------------------------------
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; COUNT: Return the total number of available joysticks in a/x.
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;
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COUNT:
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lda #<JOY_COUNT
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ldx #>JOY_COUNT
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rts
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; ------------------------------------------------------------------------
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; READ: Read a particular joystick passed in A.
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;
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READJOY:
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and #1 ; fix joystick number
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bne READJOY_1 ; read right joystick
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; Read left joystick
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ldx ZP_JOY0_DIR
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lda ZP_JOY0_BUTTONS
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jmp convert ; convert joystick state to sane cc65 values
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; Read right joystick
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READJOY_1:
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ldx ZP_JOY1_DIR
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lda ZP_JOY1_BUTTONS
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lsr a
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lsr a
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;jmp convert ; convert joystick state to sane cc65 values
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; fall thru...
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; ------------------------------------------------------------------------
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; convert: make runtime lib compatible values
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; A - buttons
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; X - direction
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;
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convert:
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ldy #0
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sty retval ; initialize return value
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; ------
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; buttons:
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; Port values are for the left hand joystick (right hand joystick
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; values were shifted to the right to be identical).
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; Why are there two bits indicating a pressed trigger?
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; According to the "Second book of programs for the Dick Smith Wizard"
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; (pg. 88ff), the left hand fire button gives the value of
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; %00010001 and the right hand button gives %00100010
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; Why two bits? Am I missing something? Can there be cases that just
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; one of those bits is set?
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; We just test if any of those two bits is not zero...
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tay
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and #%00010001
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beq cnv_1
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inc retval ; left button pressed
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cnv_1: tya
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and #%00100010
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beq cnv_2
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lda #$02
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ora retval
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sta retval ; right button pressed
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; ------
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; direction:
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cnv_2: txa
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; tested with https://sourceforge.net/projects/creativisionemulator
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; $49 - %01001001 - up
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; $41 - %01000001 - down
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; $4D - %01001101 - left
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; $45 - %01000101 - right
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;
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; are these correct? "Second book of programs for the Dick Smith Wizard" pg. 85 says something different
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; ignored for now...
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; $85 - %10000101 - up + right
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; $8D - %10001101 - down + left
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; $89 - %10001001 - up + left
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; $85 - %10000101 - down + right (emulator bug?)
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bit testbit ; bit #0 set?
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beq done ; no, no direction
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and #%00001100 ; mask out other bits
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lsr a
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lsr a
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tax
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lda #%00000100 ; init bitmask
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loop: dex
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bmi done2
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asl a
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bne loop
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done2: ora retval
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rts
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done: lda retval
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rts
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; ------------------------------------------------------------------------
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;
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.data
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testbit:.byte $01
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; ------------------------------------------------------------------------
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;
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.bss
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retval: .res 0
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