2 ; Standard joystick driver for the VIC20. May be used multiple times when linked
3 ; to the statically application.
5 ; Ullrich von Bassewitz, 2002-12-20
6 ; Using code from Steve Schmidtke
9 .include "zeropage.inc"
11 .include "joy-kernel.inc"
12 .include "joy-error.inc"
18 ; ------------------------------------------------------------------------
19 ; Header. Includes jump table
25 .byte $6A, $6F, $79 ; "joy"
26 .byte JOY_API_VERSION ; Driver API version number
32 ; Button state masks (8 values)
39 .byte $00 ; JOY_FIRE2 unavailable
40 .byte $00 ; Future expansion
41 .byte $00 ; Future expansion
49 .addr 0 ; IRQ entry unused
51 ; ------------------------------------------------------------------------
54 JOY_COUNT = 1 ; Number of joysticks we support
57 ; ------------------------------------------------------------------------
63 ; ------------------------------------------------------------------------
64 ; INSTALL routine. Is called after the driver is loaded into memory. If
65 ; possible, check if the hardware is present and determine the amount of
67 ; Must return an JOY_ERR_xx code in a/x.
73 ; rts ; Run into UNINSTALL instead
75 ; ------------------------------------------------------------------------
76 ; UNINSTALL routine. Is called before the driver is removed from memory.
77 ; Can do cleanup or whatever. Must not return anything.
84 ; ------------------------------------------------------------------------
85 ; COUNT: Return the total number of available joysticks in a/x.
93 ; ------------------------------------------------------------------------
94 ; READ: Read a particular joystick passed in A.
95 ; The current implemenation will ignore the joystick number because we do only
98 READ: lda #$7F ; mask for VIA2 JOYBIT: sw3
99 ldx #$C3 ; mask for VIA1 JOYBITS: sw0,sw1,sw2,sw4
102 ldy VIA2_DDRB ; remember the date of DDRB
103 sta VIA2_DDRB ; set JOYBITS on this VIA for input
104 lda VIA2_JOY ; read JOYBIT: sw3
105 sty VIA2_DDRB ; restore the state of DDRB
106 asl ; Shift sw3 into carry
108 ldy VIA1_DDRA ; remember the state of DDRA
109 stx VIA1_DDRA ; set JOYBITS on this VIA for input
110 lda VIA1_JOY ; read JOYBITS: sw0,sw1,sw2,sw4
111 sty VIA1_DDRA ; restore the state of DDRA
114 ror ; Shift sw3 into bit 7
115 and #$9E ; Mask relevant bits
116 eor #$9E ; Active states are inverted