CHIP-8 Emulator

Overview

A basic emulator for the CHIP-8 virtual machine written in C++ with Simple DirectMedia Layer (SDL) for graphics rendering.

This is my first C++ project and I used this as an opportunity to learn modern C++ practices. This includes the use of high level C++ abstractions as well utilising automated memory management. However, my limited experience with C++ will definitely show with less than ideal solutions at times.

Please feel free to pull request any improvements you see.

Features

• Replication of the CHIP-8 instruction set architecture.
• Cross-platform rendering of graphics using SDL.

Image of Program

Quick Start

Dependencies

This project relies on the SDL graphics library. Run the following commands (or your distro's equivalent) to download these dependencies:

1. sudo apt-get install libsdl2-dev
2. sudo apt-get install libsdl2-image-dev
3. sudo apt-get install libsdl2-ttf-dev
4. sudo apt-get install libsdl2-mixer-dev

Note: requiring manual installation of dependencies is clunky. This project will eventually be updated to grab all dependencies during the build process.

Building

This project relies on the Bazel build system. To build, simply run:

$ bazel build //main

The program can then be started by running:

$ ./bazel-bin/main/main <rom>

Project Structure

• main/main.cpp - Main entry point to the program. Contains minimal logic other than the main loop.

• lib/Emulator - Core emulation logic. Composed of all other classes and is responsible for delegating work between classes. Also contains the implementation of the CHIP-8 instruction set and fetch-execute cycle.

• lib/GUI - C++ class wrapper for functions in the SDL library. Encapsulates the graphics rendering logic and provides a simplified interface specifically for CHIP-8 emulation.

• lib/Memory - Simple class that provides an abstraction for the CHIP-8 memory.

• lib/Stack - Simple class that provides an abstraction for the CHIP-8 stack. Note: is implemented separately from the emulated memory.

• lib/DecodedInstruction - Simple data class that converts an 16 bit opcode into its constituent parts.

• lib/Parser - Simple helper function to convert a raw binary ROM into a byte vector.

• lib/Keyboard - Mapping between QWERTY keyboard and the CHIP-8 keyboard.

• lib/Display - Simple class to encapsulate the logic for pixels on the CHIP-8 display. Note: does NOT contain any graphics rendering logic.

• lib/Fonts - Sprite data for basic fonts which is to be stored in the CHIP-8 memory.