var lastBallY = 0;

function nextMove(paddle, ball)

{

    var ballY = ball.middleY;

    var ballDirection = ballY > lastBallY

        ? kUpDirection 

        : kDownDirection;

    lastBallY = ballY;

    if (ballY > paddle.top)

        return kUpDirection;

    if (ballY < paddle.bottom)

        return kDownDirection;

    return ballDirection;

}