1

1 WHEN (X[-1] < 1 OR XS[-1] = 0) -1 WHEN (X[-1] > 799) XS[-1] OTHERWISE

1 WHEN (Y[-1] < 1 OR YS[-1] = 0) -1 WHEN (Y[-1] >= 599) YS[-1] OTHERWISE

XS + X[-1] WHEN (Enable) X[-1] OTHERWISE

YS + Y[-1] WHEN (Enable) Y[-1] OTHERWISE

50

640

X <> X[-1]

600

Y <> Y[-1]

700