Event-driven finite-state machine


In computation, a finite-state machine is event driven if the transition from one state to another is triggered by an event or a message. This is in contrast to the parsing-theory origins of the term finite-state machine where the machine is described as consuming characters or tokens.
Often these machines are implemented as threads or processes communicating with one another as part of a larger application. For example, a telecommunication protocol is most of the time implemented as an event-driven finite-state machine.

Example in C

This code describes the state machine for a very basic car radio system. It is basically an infinite loop that reads incoming events. The state machine is only 2 states: radio mode, or CD mode. The event is either a mode change from radio to cd back and forth, or a go to next.

/********************************************************************/
  1. include
/********************************************************************/
typedef enum STATES;
typedef enum EVENTS;
EVENTS readEventFromMessageQueue;
/********************************************************************/
int main