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
28 ; Button state masks (8 values)
35 .byte $00 ; Future expansion
36 .byte $00 ; Future expansion
37 .byte $00 ; Future expansion
46 ; ------------------------------------------------------------------------
49 JOY_COUNT = 1 ; Number of joysticks we support
52 ; ------------------------------------------------------------------------
58 ; ------------------------------------------------------------------------
59 ; INSTALL routine. Is called after the driver is loaded into memory. If
60 ; possible, check if the hardware is present and determine the amount of
62 ; Must return an JOY_ERR_xx code in a/x.
68 ; rts ; Run into UNINSTALL instead
70 ; ------------------------------------------------------------------------
71 ; UNINSTALL routine. Is called before the driver is removed from memory.
72 ; Can do cleanup or whatever. Must not return anything.
79 ; ------------------------------------------------------------------------
80 ; COUNT: Return the total number of available joysticks in a/x.
88 ; ------------------------------------------------------------------------
89 ; READ: Read a particular joystick passed in A.
90 ; The current implemenation will ignore the joystick number because we do only
93 READ: lda #$7F ; mask for VIA2 JOYBIT: sw3
94 ldx #$C3 ; mask for VIA1 JOYBITS: sw0,sw1,sw2,sw4
97 ldy VIA2_DDRB ; remember the date of DDRB
98 sta VIA2_DDRB ; set JOYBITS on this VIA for input
99 lda VIA2_JOY ; read JOYBIT: sw3
100 sty VIA2_DDRB ; restore the state of DDRB
101 asl ; Shift sw3 into carry
103 ldy VIA1_DDRA ; remember the state of DDRA
104 stx VIA1_DDRA ; set JOYBITS on this VIA for input
105 lda VIA1_JOY ; read JOYBITS: sw0,sw1,sw2,sw4
106 sty VIA1_DDRA ; restore the state of DDRA
109 ror ; Shift sw3 into bit 7
110 and #$9E ; Mask relevant bits
111 eor #$9E ; Active states are inverted