Project 1: Pong Command Integration for FogOS
Name: Michael H. Smith
Project: Terminal-Based Pong Game
Description:
This project implements a text-based version of the classic Atari game, Pong. A single-player version of the game, the user controls a paddle and attempts to prevent the ball from passing their paddle while the ball bounces back from the opposite wall.
The Pong command is designed to integrate with the existing OS and utilizes several system calls for input handling and screen manipulation. The implementation faced challenges with real-time user input, and while it is functional, some areas—such as non-blocking input—still require further refinement.
Features:
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Real-Time Input: The game relies on custom system calls to handle user input in real time, although there are still challenges in making this fully non-blocking.
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Basic Game Mechanics: The player controls a paddle using the arrow keys, and the ball bounces back and forth in the terminal window.
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Game Logic: The game ends when the player fails to prevent the ball from passing the paddle, and the score is displayed in the terminal.
Files Modified/Created:
Modified:
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Makefile: Updated to compile pong.c along with the rest of the user programs and link the necessary system calls.
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kernel/console.c: Adjustments made for raw mode and real-time input handling in conjunction with the new system calls.
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kernel/defs.h: Updated with new function prototypes related to input handling for the Pong game.
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kernel/syscall.c: Integrated new system calls for cursor movement, clearing the screen, and handling non-blocking input.
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kernel/syscall.h: Added definitions for new system calls required for the Pong command.
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kernel/sysproc.c: Additional system calls implemented to handle user input and terminal manipulations.
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user/ulib.c: System calls integrated here to allow the Pong game to interact with the terminal (e.g., moving the cursor and clearing the screen).
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user/user.h: Function prototypes updated to include new system calls and utilities needed for the Pong game.
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user/usys.pl: System call numbers updated to accommodate new functions.
Created:
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kernel/rawmode.c: Created to handle raw input mode for the terminal, enabling real-time input during the Pong game.
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kernel/vga.c & kernel/vga.h: Implemented to support VGA-like cursor movement and screen clearing features in the terminal.
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user/pong.c: Main game logic and implementation of the Pong game, handling game mechanics, input, and rendering.
Challenges:
The main challenge encountered in this project was implementing non-blocking input. Due to the complexities involved in handling user input within a terminal environment, input is still partially blocking. Furthermore, due to the issues with input handling, the initially planned difficulty modes (easy, medium, hard) were not implemented, as the underlying game mechanics were not yet fully stable.
Future Enhancements:
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Non-Blocking Input: Further work is needed to ensure that the game can process input without stalling, allowing for smoother and more responsive gameplay.
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Difficulty Modes: Once the input handling is refined, flags can be added to adjust the difficulty by altering the ball's speed and the game's refresh rate.
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Multiplayer Mode: A future enhancement could include adding a multiplayer mode, allowing two players to control separate paddles.
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Game Logic Improvements: The ball's trajectory and speed could be adjusted to make the gameplay more dynamic and challenging.
Lessons Learned:
Through the process of developing the Pong command, I gained a deeper understanding of how to implement system calls in the xv6 OS. Specifically, I learned how to manipulate the terminal by moving the cursor and clearing the screen via system calls, as well as enabling and disabling raw input mode for real-time user interaction.
Additional Notes:
The repository includes a fully-functional C template of the Pong game logic in the docs folder, which was used as a reference during this development.