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