Assignment 2: Finite State Machines

Due by: Friday, January 31, 2025 at 11:59 p.m.

In this assignment, you'll build a table of transitions and function pointers to implement the following finite state machine in C, modeling the states a Linux process can be in:

State diagram showing states of a Linux process

As with all the assignments and projects in this course, it's recommended that you do the stages in the order given. Get the MIN unit tests passing before moving on to the FULL ones. Likewise, get the MIN integration tests passing before moving on to the FULL ones.

First, download the archive given below and unzip it into an appropriate directory.

Stage 1: States and Transitions

Complete the following to set up the states and transitions and to update main() to send events.

  • Edit the transition table defined in statemodel.c to match the model above. The row of transitions from NEW state is already complete in the table. Correctly set up the fields of the fsm_t struct in initialize_fsm().
  • Fill in an implementation of transition(), the function that transitions the states inside fsm. Don't worry about the effect and entry functions yet.
  • Complete the implementation of handle_event(). Be sure to perform robust error handling for invalid events and transitions. Use an assert() to ensure that the passed fsm parameter is never NULL. Change state only if the table indicates that the next state is valid (something other than NST).
  • Update main.c to loop through command-line arguments, treating each as an event. Note that you will need to convert these arguments (which are strings) to their equivalent integer values. Return EXIT_FAILURE for any bad arguments.

Stage 2: Entry and Effect Functions

Complete the following to add function pointers for when a state is entered and when a transition happens.

  • Add a 2D array of function pointers for effect functions. Use NULL for invalid transitions as well as valid transitions with no effects. If used, effect functions are listed next to the transitions in the state diagram.
  • Add an array of entry function pointers, one per state. If used, entry functions are listed below the name of each state.
  • Extend the functionality of transition() to store effects and entry actions into parameters as appropriate.
  • Update handle_event() to call the updated effect and entry action function pointers if they're not NULL.
  • Complete the implementations of the effect functions in effects.c. These functions should manipulate the other fields of the fsm_t based on the function name.
  • Eliminate all compiler warnings and memory leaks.

Turn In

First, run make clean to remove all of the executable and object files from your directory structure. Then, zip up the contents of your project directory in either a .zip or a .tar.xz file. Upload this archive to Brightspace. Your assignment must be submitted by Friday, January 31, 2025 at 11:59 p.m. Grace days are not available for assignments.

All work must be done within assigned teams, though you may discuss general concepts with your classmates. Please refer to the course policies if you have any questions about academic integrity. If you have trouble with the assignment, I am always available for assistance.

Under no circumstances should any member of one team look at the code written by another team. Tools will be used to detect code similarity automatically.

Code that does not compile will automatically score zero points.

Grading

Your grade will be determined by the following categories.

Category Description Weight
Compiling Code Free points! 10%
Unit Tests Your solution passes the 10 unit tests. 30%
Integration Tests Your solution passes the six integration tests. 60%

Credits

This assignment is based on material from CS 361 by Michael S. Kirkpatrick. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.