Traffic lights FSM

fsm.c

/*
	Traffic lights finite state machine (FSM) 
	as programmed in C.
*/
#include <stdio.h> // For stdout
#include "xplatform.h" // For cross-platform xsleep() and xcls()

void goToState(void); // Prototype

// Define states (enumerated types - like ints)
enum states { RED, REDAMBER, GREEN, AMBER };
int currState = -1;

int main(void) {
	while(1) {
		xcls();
		printf("\nTraffic lights FSM\n");
		printf("Terminate with Ctrl-C\n\n");
		goToState();
	}
	return 0;
}

void goToState(void) {
	currState++;
	switch(currState) {
		case RED: // Red light
			printf("{R}\n");
			printf(" A \n");
			printf(" G \n");
			break;
			
		case REDAMBER: // Red + Amber lights
			printf("{R}\n");
			printf("{A}\n");
			printf(" G \n");
			break;
			
		case GREEN: // Green light
			printf(" R \n");
			printf(" A \n");
			printf("{G}\n");
			break;
			
		case AMBER: // Amber light
			printf(" R \n");
			printf("{A}\n");
			printf(" G \n");
			currState = -1; // Continue ad naseum...
			break;		
	}
	xsleep(4000); // Timer delay; 4 seconds
}