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26 lines
831 B
Plaintext
26 lines
831 B
Plaintext
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;Paddle Controller Constants and Functions for Apple II
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PADDLS EQU #4 ;Maximum Numbers of Paddles
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;Read Paddle
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PADDLE: LDY #0 ;Set Result to 0
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CMP #PADDLS ;If Paddle# >= Max
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BCS PADDLZ ; Return # of Paddles & Carry Set
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TAX ;Copy Paddle# to X Register
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JSR $FB1E ;Execute Monitor PREAD Routine
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PADDLZ: TYA ;Copy Result to Accumulator
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RTS
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BUTTNS EQU #2 ;Maximum Numbers of Buttons
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;Read Paddle Button
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BUTTON: LDY #0 ;Set Result to 0
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CMP #BUTTNS ;If Button# >= Max
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BCS BUTTOZ ; Return Zero & Carry Set
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TAX ;Copy Paddle# to X Register
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LDA $C061,X ;Load Button Register
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BPL BUTTOZ ;If Bit 7 Set
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DEY ; Change Result to $FF
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BUTTOZ: TYA ;Copy Result to Accumulator
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RTS
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