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C02/include/oric/joystk.a02
2018-09-17 19:41:51 -04:00

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;Joystick Assembly Language Library for Oric-1
;Untested
JYSTKS EQU $02 ;Number of Joysticks
;Joystick Bit Masks
JOYUP EQU $10 ;Bit 4 - Up
JOYDN EQU $08 ;Bit 3 - Down
JOYLF EQU $01 ;Bit 0 - Left
JOYRT EQU $02 ;Bit 1 - Right
JOYB0 EQU $20 ;Bit 5 - Button
;Read Joystick (ALTAI)
;http://wiki.defence-force.org/doku.php?id=oric:hardware:altai_drivers
JOYSTK: CMP #JYSTKS ;If Joystick# >= Maximum
BCS JOYSTZ ; Return Error
TAX ;Copy Joystick# to X
LDY JOYSTT,X ;Load Y from Table
LDA #%11000000
STA $0303 ;Set Data Direction Register A
STY $0301 ;Select Joystick
LDA $0301 ;Read Joystick
LDY #%11111111
STY $0303 ;Restore Data Direction Register A
AND #%00111111 ;Mask Bits
EOR #%00111111 ;and Invert Them
RTS
JOYSTZ: LDA #$FF ;Return Error
RTS
JOYSTT: DC #%10000000,#%01000000