How to Design Efficient and Robust State Machines in C?

C State Machine Design: Implementing Tried-and-Tested Techniques

This SO inquiry delves into the realm of designing state machines in C. With a focus on practical and time-proven implementation techniques, we explore various approaches shared by experienced developers.

Event Integrator and Dispatcher Architecture

After gathering extensive feedback, the question author settled on an architecture featuring an event pump, event integrator, dispatcher, and actions. The event pump identifies events, which are passed to the event integrator. The integrator then routes them to the dispatcher, which triggers specific actions based on a transition table. This versatile design enables the creation of robust state machines.

Struct Array and Loop Approach

Another widely used technique involves employing a structure array and loop. Each structure holds state and event information along with a function pointer that calculates the new state. A transition array defines all possible transitions, assigning functions to specific events and states. Global variables facilitate data sharing among state functions.

This approach offers simplicity, ease of debugging, and flexibility in modifying transitions.

Passing Structure Pointer to Functions

An alternative strategy involves passing a structure pointer to all state functions instead of relying on globals. This allows multiple state machines to operate concurrently without interfering with each other. A structure is created to encapsulate machine-specific data, including the current state.

Conclusion

By leveraging these tried-and-tested techniques, developers can craft reliable and efficient state machines in C. From the event integrator architecture to the struct array approach and pointer-passing strategy, each approach provides unique benefits.

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