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cc65/libsrc/vic20/joy/vic20-ptvjoy.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

156 lines
4.4 KiB
ArmAsm

;
; PTV-3 Player joystick driver for the VIC20
;
; Stefan Haubenthal, 2005-05-25
; Groepaz/Hitmen, 2002-12-23
; obviously based on Ullrichs driver :)
; Using code from Steve Schmidtke
;
.include "zeropage.inc"
.include "joy-kernel.inc"
.include "joy-error.inc"
.include "vic20.inc"
.macpack module
; ------------------------------------------------------------------------
; Header. Includes jump table
module_header _vic20_ptvjoy_joy
; 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
VIA1_PRB := VIA1 ; User port register
JOY_COUNT = 3 ; 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 #$7F ; mask for VIA2 JOYBIT: sw3
ldx #$C3 ; mask for VIA1 JOYBITS: sw0,sw1,sw2,sw4
sei ; necessary?
ldy VIA2_DDRB ; remember the date of DDRB
sta VIA2_DDRB ; set JOYBITS on this VIA for input
lda VIA2_JOY ; read JOYBIT: sw3
sty VIA2_DDRB ; restore the state of DDRB
asl ; Shift sw3 into carry
ldy VIA1_DDRA ; remember the state of DDRA
stx VIA1_DDRA ; set JOYBITS on this VIA for input
lda VIA1_JOY ; read JOYBITS: sw0,sw1,sw2,sw4
sty VIA1_DDRA ; restore the state of DDRA
cli ; necessary?
ror ; Shift sw3 into bit 7
and #$9E ; Mask relevant bits
eor #$9E ; Active states are inverted
rts
; Read joystick 2
joy2: lda #%10000000 ; via port B Data-Direction
sta VIA1_DDRB ; bit 7: out bit 6-0: in
dex
bne joy3
lda #$80 ; via port B read/write
sta VIA1_PRB ; (output one at PB7)
lda VIA1_PRB ; via port B read/write
and #$1f ; get bit 4-0 (PB4-PB0)
eor #$1f
rts
; Read joystick 3
joy3: lda #$00 ; via port B read/write
sta VIA1_PRB ; (output zero at PB7)
lda VIA1_PRB ; via port B read/write
and #$0f ; get bit 3-0 (PB3-PB0)
sta tmp1 ; joy 4 directions
lda VIA1_PRB ; via port B read/write
and #%00100000 ; get bit 5 (PB5)
lsr
ora tmp1
eor #$1f
ldx #0
rts