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cc65/libsrc/pet/joy/pet-stdjoy.s
2013-06-01 00:36:08 +02:00

130 lines
2.9 KiB
ArmAsm

;
; Standard PET userport joystick driver for the PET
;
; Marco van den Heuvel, 2010-01-23
;
.include "zeropage.inc"
.include "joy-kernel.inc"
.include "joy-error.inc"
.include "pet.inc"
; ------------------------------------------------------------------------
; Header. Includes jump table
.segment "JUMPTABLE"
; 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 $01 ; JOY_UP
.byte $02 ; JOY_DOWN
.byte $04 ; JOY_LEFT
.byte $08 ; JOY_RIGHT
.byte $10 ; JOY_FIRE
.byte $00 ; JOY_FIRE2 unavailable
.byte $00 ; Future expansion
.byte $00 ; Future expansion
; Jump table.
.addr INSTALL
.addr UNINSTALL
.addr COUNT
.addr READ
.addr 0 ; IRQ entry unused
; ------------------------------------------------------------------------
; Constants
JOY_COUNT = 2 ; Number of joysticks we support
.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
; rts ; Run into UNINSTALL instead
; ------------------------------------------------------------------------
; 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 #<JOY_COUNT
ldx #>JOY_COUNT
rts
; ------------------------------------------------------------------------
; READ: Read a particular joystick passed in A.
;
READ:
tax ; Joystick number into X
bne joy2
; Read joystick 1
joy1:
lda #0
sta VIA_DDRA
lda VIA_PRA
and #$0f
cmp #$0c
bne @notc1
lda #$0f
bne @end1
@notc1:
ora #$10
@end1:
eor #$1f
rts
; Read joystick 2
joy2:
lda #0
sta VIA_DDRA
lda VIA_PRA
lsr
lsr
lsr
lsr
cmp #$0c
bne @notc2
lda #$0f
bne @end2
@notc2:
ora #$10
@end2:
eor #$1f
ldx #0
rts