CPU Scheduling Algorithms

This project is a C implementation of common CPU scheduling algorithms used in Operating Systems. It calculates the Waiting Time and Turnaround Time for a set of processes based on the selected algorithm.

Supported Algorithms

1. FCFS (First Come First Served)

   • Executes processes in the exact order they arrive.
   • Non-preemptive.

2. SJF (Shortest Job First)

   • Selects the process with the shortest burst time available.
   • Non-preemptive (once a process starts, it finishes).

3. RR (Round Robin)

   • Allocates a fixed time slice (Quantum) to each process.
   • Preemptive (switches between processes cyclically).

Project Structure

• src/: Contains the source code files (.c).
• include/: Contains the header files (.h).
• main.c: The main entry point with the user menu.
• input.txt: The file containing process data.
• output.txt: The file where results are saved.
• Makefile: Script to compile the project easily.

How to Build and Run

Option 1: Using Make (Recommended)

1. Open your terminal in the project folder.
2. Compile the project: make
3. Run the executable: ./scheduler
4. To clean up build files: make clean

Option 2: Manual Compilation

If you do not have Make installed, you can compile using gcc: gcc main.c src/utils.c src/fcfs.c src/sjf.c src/rr.c -o scheduler -I./include

Input File Format (input.txt)

The program reads process data from "input.txt". IMPORTANT: The file must contain numbers only. Do not write text headers like "ID" or "Arrival".

The format for each line is:

[Process ID] [Arrival Time] [Burst Time]

Example content for input.txt:

1 0 7
2 2 4
3 4 1
4 5 4

Usage

1. Fill "input.txt" with your process data.
2. Run the program.
3. Select an algorithm from the menu:
   • Enter 1 for FCFS.
   • Enter 2 for SJF.
   • Enter 3 for Round Robin (you will be asked to enter the Time Quantum).
4. The output table will be displayed in the terminal and saved to "output.txt".