CMPS 105 Fall04: Systems Programming

Programming Assignment #7: IPC Simultaneous Tic-Tac-Toe

Remember: your programming assignment must be turned in online.

The Basics

The goal of this assignment is to get familiar with the Interprocess Communication using pipes.

In this assignment, you are to report the moves and the result of 10 tic-tac-toe matches between the parent and its three children.

The Details

You first need to create three child processes of the main process, call them 'ch1', 'ch2' and 'ch3' such that the parent can communicate with each of the children using half-duplex pipes. Now parent plays tic-tac-toe simultaneously with each of its children (in parallel). The rules of the game are as follows :

Child always makes the first move.
Move made by each child is 'random', i.e. it moves in any randomly chosen blank spot.
Parent always makes an intelligent move, i.e. it always moves such that the move would help him win the game or lose the game your choice. So, ideally parent is suppose to win all the games or lose all games :-).
If there is a winner in a game, it declares the 'Win' after making the winning move. Else the player to make the last move declares the 'Draw'.

Both the parent and the child communicate their moves to each other through a pipe. Each child also outputs all moves of its games to a file as they occur(both the parent moves and its own moves). There are to be three files for this output: ch1games, ch2games and ch3games. The structure of the report of each move has the following syntax.

Match number and players. For example : Match 1 : Ch1 Vs Parent
Number of current move and the player who made the move. For example : Move 2 by Parent
Board layout. Here you need to show the current status of all the 9 blocks.
Status of the game. This is either 'Draw' or announcement of the winner, and is reported only on the last move of each game.

You need to report 10 matches between the parent and each child. So a total of 30 matches should be reported, 10 in the file corresponding to each child. You are free to use any valid 'C' standard library or UNIX system function calls for this assignment.

Extra Credit

For extra credit, instead of using the three children files for reporting moves, have each player besides sending its move to its opponent over a pipe also output its move to the standard output. You can see that there would be synchronization issues among the players while reporting the moves to the standard output. You don't want the contents of two or more move reports inter-mixed. You might like to use Semaphores to avoid it. ;-)

What to turn in

Your code, a working makefile, output files of the two children and your design document. In addition, include a README file to explain anything unusual to the TA — testing procedures, etc.

REMEMBER: Do not submit object files, assembler files, or executables. Every file in the submit directory that could be generated automatically by the compiler or assembler will result in a deduction from your programming assignment grade.