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35377b5807
commit ed00e1d1b5a9783a72dade3f3676b161a9cfe287
Author: Curtis F Kaylor <revcurtis@gmail.com>
Date: Sun Sep 9 22:20:49 2018 -0400
Documented joystk, paddle, and lgtpen modules
commit ec0a5ede8d1b043fcf0094ea653255a808dbf8d3
Author: Curtis F Kaylor <revcurtis@gmail.com>
Date: Sun Sep 9 20:31:11 2018 -0400
Added joystick, paddle, and lightpen test programs
commit 7b787f432e2f4f7ae5d7f0053ade1d3586a4fad1
Author: Curtis F Kaylor <revcurtis@gmail.com>
Date: Sun Sep 9 20:30:03 2018 -0400
Updated Apple II and VIC-20 Batch Files
commit 50568294349d7e3c6b7d0d364aeaece73c9e4ab6
Author: Curtis F Kaylor <revcurtis@gmail.com>
Date: Sun Sep 9 20:28:09 2018 -0400
Separated light pen code into separate files
commit d45e59f73d55eef1d30c591d19a043ad79cfd81a
Author: Curtis F Kaylor <revcurtis@gmail.com>
Date: Sun Sep 9 19:28:56 2018 -0400
Moved code for paddles into separate include files
commit fc5c5472d758c960332ea14105d5ec4a7c8cbbfb
Author: Curtis F Kaylor <revcurtis@gmail.com>
Date: Sun Sep 9 16:15:32 2018 -0400
Added system specific module 'joystk'
36 lines
1.2 KiB
Plaintext
36 lines
1.2 KiB
Plaintext
;Joystick Assembly Language Library for VIC-20
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JYSTKS EQU $01 ;Number of Joysticks
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;Joystick Bit Masks
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JOYUP EQU $04 ;Bit 2 - Up
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JOYDN EQU $08 ;Bit 3 - Down
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JOYLF EQU $10 ;Bit 4 - Left
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JOYRT EQU $01 ;Bit 1 - Right
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JOYB0 EQU $20 ;Bit 5 - Button
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;Read Joystick
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JOYSTK: LDX #$FF ;Preset X with 255
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ORA #0 ;Check Parameter
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BNE JOYSTZ ;If Not Zero, Return Error
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TAX ;Set X to 0
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LDA $9113 ;Get DDR for Port A Status
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PHA ;and Save It
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LDA $9122 ;Set DDR for Port B Status
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PHA ;amd Save It
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STX $9113 ;Set DDR for Port A to All Inputs
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STX $9122 ;Set DDR for Port B to All Inputs
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LDA $9120 ;Read Port B (Right)
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ASL ;Shift Bit 7 into Carry
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LDA $9111 ;Read Port A
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AND #$3C ;Mask Bits
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ADC #0 ;Move Carry into Bit 0
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EOR #$3D ;Invert Bits
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TAX ;and Save in X Register
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PLA ;Restore Port B DDDR
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STA $9122
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PLA ;Restore Port A DDDR
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STA $9113
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JOYSTZ: TXA ;Copy Status Back into Accumulator
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RTS
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