define horizontalMovementRight $1
define verticalMovementDown $2
updateBallNoClip:
  lda #horizontalMovementRight
  bit ballDirection           ;check if direction to the right
  bne right
left:
  dec ballX
  jmp verticalCheck
right:
  inc ballX
verticalCheck:
  lda #verticalMovementDown
  bit ballDirection           ;check if going down
  bne down
up:
  dec ballY
  jmp endUpdateBallNoClip
down:
  inc ballY
endUpdateBallNoClip:
  rts

;check if the ball should bounce off walls
checkBallWallCollision:
leftWallCheck:
  lda ballX
  bpl rightWallCheck
  ;hit left wall
  jsr toggleHorizontalDirection
  ;move right two places
  inc ballX
  inc ballX
rightWallCheck:
  cmp #$20   ;over the right wall
  bne topWallCheck
  ;hit right wall
  jsr toggleHorizontalDirection
  dec ballX
  dec ballX
topWallCheck:
  lda ballY
  bpl bottomWallCheck
  ;hit top wall
  jsr toggleVerticalDirection
  inc ballY
  inc ballY
bottomWallCheck:
  cmp #$20
  bne endCheckBallWallCollision
  jsr toggleVerticalDirection
  dec ballY
  dec ballY
endCheckBallWallCollision:
  rts

toggleHorizontalDirection:
  lda ballDirection           ; toggle horizontal bit
  eor #horizontalMovementRight
  sta ballDirection
  rts

toggleVerticalDirection:
  lda ballDirection           ; toggle vertical bit
  eor #verticalMovementDown
  sta ballDirection
  rts