2 ; PTV-3 Player joystick driver for the VIC20
4 ; Stefan Haubenthal, 2005-05-25
5 ; Groepaz/Hitmen, 2002-12-23
6 ; obviously based on Ullrichs driver :)
7 ; Using code from Steve Schmidtke
10 .include "zeropage.inc"
12 .include "joy-kernel.inc"
13 .include "joy-error.inc"
19 ; ------------------------------------------------------------------------
20 ; Header. Includes jump table
22 module_header _vic20_ptvjoy_joy
26 .byte $6A, $6F, $79 ; "joy"
27 .byte JOY_API_VERSION ; Driver API version number
40 ; ------------------------------------------------------------------------
43 JOY_COUNT = 3 ; Number of joysticks we support
48 ; ------------------------------------------------------------------------
49 ; INSTALL routine. Is called after the driver is loaded into memory. If
50 ; possible, check if the hardware is present and determine the amount of
52 ; Must return an JOY_ERR_xx code in a/x.
58 ; rts ; Run into UNINSTALL instead
60 ; ------------------------------------------------------------------------
61 ; UNINSTALL routine. Is called before the driver is removed from memory.
62 ; Can do cleanup or whatever. Must not return anything.
69 ; ------------------------------------------------------------------------
70 ; COUNT: Return the total number of available joysticks in a/x.
78 ; ------------------------------------------------------------------------
79 ; READ: Read a particular joystick passed in A.
82 READ: tax ; Joystick number into X
87 joy1: lda #$7F ; mask for VIA2 JOYBIT: sw3
88 ldx #$C3 ; mask for VIA1 JOYBITS: sw0,sw1,sw2,sw4
91 ldy VIA2_DDRB ; remember the date of DDRB
92 sta VIA2_DDRB ; set JOYBITS on this VIA for input
93 lda VIA2_PB ; read JOYBIT: sw3
94 sty VIA2_DDRB ; restore the state of DDRB
95 asl ; Shift sw3 into carry
97 ldy VIA1_DDRA ; remember the state of DDRA
98 stx VIA1_DDRA ; set JOYBITS on this VIA for input
99 lda VIA1_PA1 ; read JOYBITS: sw0,sw1,sw2,sw4
100 sty VIA1_DDRA ; restore the state of DDRA
103 php ; Save sw3 in carry
104 lsr ; Shift sw0,sw1,sw2,sw4 into bits 1-4
105 tax ; Save sw0,sw1,sw2
106 and #$10 ; Extract sw4 in bit 4
107 sta tmp1 ; Save sw4 in bit 4
108 txa ; Restore sw0,sw1,sw2
109 lsr ; Shift sw0,sw1,sw2 into bits 0-2
110 and #$07 ; Mask bits 0-2
111 plp ; Restore sw3 in carry
112 bcc @L0 ; Is sw3 set?
113 ora #$08 ; Yes: Add sw3 in bit 3
114 @L0: ora tmp1 ; Add sw4 in bit 4
115 eor #$1F ; Active states are inverted
122 joy2: lda #%10000000 ; via port B Data-Direction
123 sta VIA1_DDRB ; bit 7: out bit 6-0: in
128 lda #$80 ; via port B read/write
129 sta VIA1_PB ; (output one at PB7)
131 lda VIA1_PB ; via port B read/write
132 and #$1F ; get bit 4-0 (PB4-PB0)
138 joy3: lda #$00 ; via port B read/write
139 sta VIA1_PB ; (output zero at PB7)
141 lda VIA1_PB ; via port B read/write
142 and #$0F ; get bit 3-0 (PB3-PB0)
143 sta tmp1 ; joy 4 directions
145 lda VIA1_PB ; via port B read/write
146 and #%00100000 ; get bit 5 (PB5)