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130 lines
3.3 KiB
ArmAsm
130 lines
3.3 KiB
ArmAsm
;
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; Standard joystick driver for the Apple ][. May be used multiple times
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; when statically linked to the application.
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;
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; Ullrich von Bassewitz, 2003-05-02
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; Oliver Schmidt, 2008-02-25
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; Using the readjoy code from Stefan Haubenthal
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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 "apple2.inc"
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; ------------------------------------------------------------------------
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; Constants
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THRESHOLD = 20 ; Deviation from center triggering movement
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; ------------------------------------------------------------------------
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; ROM entry points
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PREAD := $FB1E ; Read paddle in X, return AD conv. value in Y
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; ------------------------------------------------------------------------
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; Header. Includes jump table.
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.segment "JUMPTABLE"
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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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; Button state masks (8 values)
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.byte $10
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.byte $20
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.byte $04
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.byte $08
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.byte $40
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.byte $80
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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 not used
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; ------------------------------------------------------------------------
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.code
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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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INSTALL:
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lda #<JOY_ERR_OK
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ldx #>JOY_ERR_OK
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; Fall through
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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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UNINSTALL:
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rts
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; COUNT: Return the total number of available joysticks in a/x.
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COUNT:
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lda #$02 ; Number of joysticks we support
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ldx #$00
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rts
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; READ: Read a particular joystick passed in A.
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READJOY:
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bit $C082 ; Switch in ROM
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and #$01 ; Restrict joystick number
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; Read horizontal paddle
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asl ; Joystick number -> paddle number
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tax ; Set paddle number (0, 2)
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jsr PREAD ; Read paddle value
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lda #$00 ; 0 0 0 0 0 0 0 0
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cpy #127 - THRESHOLD
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ror ; !LEFT 0 0 0 0 0 0 0
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cpy #127 + THRESHOLD
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ror ; RIGHT !LEFT 0 0 0 0 0 0
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; Read vertical paddle
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pha
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inx ; Set paddle number (1, 3)
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jsr PREAD ; Read paddle value
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pla
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cpy #127 - THRESHOLD
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ror ; !UP RIGHT !LEFT 0 0 0 0 0
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cpy #127 + THRESHOLD
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ror ; DOWN !UP RIGHT !LEFT 0 0 0 0
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; Read primary button
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tay
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lda BUTN0-1,x ; Check button (1, 3)
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asl
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tya
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ror ; FIRE DOWN !UP RIGHT !LEFT 0 0 0
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; Read secondary button
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tay
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inx
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txa
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and #$03 ; IIgs has fourth button at TAPEIN
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tax
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lda BUTN0-1,x ; Check button (2, 0)
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asl
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tya
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ror ; FIRE2 FIRE DOWN !UP RIGHT !LEFT 0 0
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; Finalize
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eor #%00010100 ; FIRE2 FIRE DOWN UP RIGHT LEFT 0 0
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ldx #$00
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bit $C080 ; Switch in LC bank 2 for R/O
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rts
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