mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-11-22 16:34:15 +00:00
34 lines
1.1 KiB
Plaintext
34 lines
1.1 KiB
Plaintext
|
;Paddle Controller Constants and Functions for Atari 400 & 800
|
||
|
|
|
||
|
|
PADDLS EQU #$08 ;Maximum Numbers of Paddles
|
||
|
|
|
||
|
|
;Read Paddle
|
||
|
|
;Args: A = Paddle #
|
||
|
|
;Affects: X
|
||
|
|
;Returns: A = Paddle Value
|
||
|
|
; 0 and Carry Set if Paddle # Invalid
|
||
|
|
PADDLE: CMP #PADDLS ;If Invalid Paddle #
|
||
|
|
BCS BUTTOZ ; Return 0 & Carry Set
|
||
|
|
TAX ;Copy Paddle # to X
|
||
|
|
LDA $0270,X ;Read Paddle Shadow Register
|
||
|
|
RTS
|
||
|
|
|
||
|
|
BUTTNS EQU #$04 ;Maximum Numbers of Paddle Buttons
|
||
|
|
|
||
|
|
;Read Paddle Button
|
||
|
|
;Args: A = Button #
|
||
|
|
;Affects: X,Y
|
||
|
|
;Returns: A = $FF if Paddle Button Pressed
|
||
|
|
; $00 if Paddle Button Not Pressed
|
||
|
|
; Carry Set if Button Number Invalid
|
||
|
|
BUTTON: CMP #BUTTNS ;If Button# >= # of Buttons
|
||
|
|
BCS BUTTOZ ; Return FALSE & Carry Set
|
||
|
|
TAX ;and Copy to X Register
|
||
|
|
LDA $027C,Y ;Read Button Shadow Register
|
||
|
|
AND #$01 ;Mask off Relevant Bit
|
||
|
|
BNE BUTTOZ ;If Bit is 0
|
||
|
|
LDA #$FF ; Return TRUE
|
||
|
|
RTS ;Else
|
||
|
|
BUTTOZ: LDA #$00 ; Return FALSE
|
||
|
|
RTS
|