Design, using an ASM chart, a traffic signal controller for a crossroads. The signals change only when a car is detected in the direction with a red signal. The signals change in the (British) sequence: Red, Red and Amber, Green, Amber, Red. Note that while the signals in one direction are Green, Amber, or Red and Amber, the signals in the other direction are Red (i.e. you need more than four states). Design an implementation that uses a minimal number of D flip-flops.