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cc65/libsrc/apple2/joy/a2.stdjoy.s
Oliver Schmidt 2c975d3642 Create static drivers directly from source files.
Up to now static drivers were created via co65 from dynamic drivers. However there was an issue with that approach:

The dynamic drivers are "o65 simple files" which obligates that they start with the 'code' segment. However dynamic drivers need to start with the module header - which is written to. For dynamic drivers this isn't more than a conceptual issue because they are always contain a 'data' segment and may therefore only be loaded into writable memory.

However when dynamic drivers are converted to static drivers using co65 then that issue becomes a real problem as then the 'code' segment may end up in non-writable memory - and thus writing to the module header fails.

Instead of changing the way dynamic drivers work I opted to rather make static driver creation totally independent from dynamic drivers. This allows to place the module header in the 'data' segment (see 'module.mac').
2014-06-04 23:50:18 +02:00

140 lines
3.8 KiB
ArmAsm

;
; 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
; Button state masks (8 values)
.byte $10
.byte $20
.byte $04
.byte $08
.byte $40
.byte $80
.byte $00 ; Future expansion
.byte $00 ; Future expansion
; Jump table
.addr INSTALL
.addr UNINSTALL
.addr COUNT
.addr READJOY
.addr 0 ; IRQ not used
; ------------------------------------------------------------------------
.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 ; FIRE 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 ; FIRE2 FIRE DOWN !UP RIGHT !LEFT 0 0
; Finalize
eor #%00010100 ; FIRE2 FIRE DOWN UP RIGHT LEFT 0 0
ldx #$00
bit $C080 ; Switch in LC bank 2 for R/O
rts