;Paddle Controller Constants and Functions for Apple II

PADDLS  EQU 4       ;Maximum Numbers of Paddles

;paddle(n) - Read Paddle n
;Args: A = Paddle Number (0-3)
;Returns: A, Y = Paddle Value (0-255)
;         Carry Set if P
PADDLE: LDY #0      ;Set Result to 0
        CMP #PADDLS ;If Paddle# >= Max 
        BCS PADDLZ  ;  Return 0 & Carry Set
        TAX         ;Copy Paddle# to X Register
        JSR $FB1E   ;Execute Monitor PREAD Routine
PADDLZ: TYA         ;Copy Result to Accumulator
        RTS

BUTTNS  EQU 2       ;Maximum Numbers of Buttons

;button(n) - Read Paddle Button n
;Args: A = Button Number (0-1)
;Returns: A, Y = Button State
;                0 = Not Pressed
;                $FF = Pressed
;         X = Button Number
;         Carry Set if P
BUTTON: LDY #0      ;Set Result to 0
        CMP #BUTTNS ;If Button# >= Max
        BCS BUTTOZ  ;  Return Zero & Carry Set
        TAX         ;Copy Paddle# to X Register
        LDA $C061,X ;Load Button Register
        BPL BUTTOZ  ;If Bit 7 Set
        DEY         ;  Change Result to $FF
BUTTOZ: TYA         ;Copy Result to Accumulator
        RTS