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;
; Standard joystick driver for the Apple ][. May be used multiple times
; when statically linked to the application.
;
; Ullrich von Bassewitz, 2003-05-02
; Oliver Schmidt, 2008-02-25
; Using the readjoy code from Stefan Haubenthal
;
.include "zeropage.inc"
.include "joy-kernel.inc"
.include "joy-error.inc"
.include "apple2.inc"
.macpack module
; ------------------------------------------------------------------------
; Constants
THRESHOLD = 20 ; Deviation from center triggering movement
; ------------------------------------------------------------------------
; ROM entry points
PREAD := $FB1E ; Read paddle in X, return AD conv. value in Y
; ------------------------------------------------------------------------
; Header. Includes jump table.
.ifdef __APPLE2ENH__
module_header _a2e_stdjoy_joy
.else
module_header _a2_stdjoy_joy
.endif
; Driver signature
.byte $6A, $6F, $79 ; "joy"
.byte JOY_API_VERSION ; Driver API version number
; Library reference
.addr $0000
; Jump table
.addr INSTALL
.addr UNINSTALL
.addr COUNT
.addr READJOY
; ------------------------------------------------------------------------
.code
; INSTALL routine. Is called after the driver is loaded into memory. If
; possible, check if the hardware is present and determine the amount of
; memory available.
; Must return an JOY_ERR_xx code in a/x.
INSTALL:
lda #<JOY_ERR_OK
ldx #>JOY_ERR_OK
; Fall through
; UNINSTALL routine. Is called before the driver is removed from memory.
; Can do cleanup or whatever. Must not return anything.
UNINSTALL:
rts
; COUNT: Return the total number of available joysticks in a/x.
COUNT:
lda #$02 ; Number of joysticks we support
ldx #$00
rts
; READ: Read a particular joystick passed in A.
READJOY:
bit $C082 ; Switch in ROM
and #$01 ; Restrict joystick number
; Read horizontal paddle
asl ; Joystick number -> paddle number
tax ; Set paddle number (0, 2)
jsr PREAD ; Read paddle value
lda #$00 ; 0 0 0 0 0 0 0 0
cpy #127 - THRESHOLD
ror ; !LEFT 0 0 0 0 0 0 0
cpy #127 + THRESHOLD
ror ; RIGHT !LEFT 0 0 0 0 0 0
; Read vertical paddle
pha
inx ; Set paddle number (1, 3)
jsr PREAD ; Read paddle value
pla
cpy #127 - THRESHOLD
ror ; !UP RIGHT !LEFT 0 0 0 0 0
cpy #127 + THRESHOLD
ror ; DOWN !UP RIGHT !LEFT 0 0 0 0
; Read primary button
tay
lda BUTN0-1,x ; Check button (1, 3)
asl
tya
ror ; BTN DOWN !UP RIGHT !LEFT 0 0 0
; Read secondary button
tay
inx
txa
and #$03 ; IIgs has fourth button at TAPEIN
tax
lda BUTN0-1,x ; Check button (2, 0)
asl
tya
ror ; BTN2 BTN DOWN !UP RIGHT !LEFT 0 0
; Finalize
eor #%00010100 ; BTN2 BTN DOWN UP RIGHT LEFT 0 0
ldx #$00
bit $C080 ; Switch in LC bank 2 for R/O
rts
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