CHIP-8 Emulator — C compiled to WebAssembly

A CHIP-8 emulator written in C, compiled to WebAssembly using Emscripten. Rendering is done via SDL2 on an HTML5 canvas.

Controls (Pong)

Action	Key
Player 1 up	1
Player 1 down	4
Player 2 up	D
Player 2 down	C

Prerequisites

• Node.js
• Emscripten (emsdk)

Install Emscripten

git clone https://github.com/emscripten-core/emsdk.git
cd emsdk
./emsdk install latest
./emsdk activate latest
source ./emsdk_env.sh        # Linux / macOS
# or on Windows:
.\emsdk_env.bat

emcc must be available in your PATH before running any build command. Re-run emsdk_env in each new terminal session, or use --permanent to add it to your system PATH.

Build & Run

# Production build
npm run build

# Debug build (assertions + heap checking)
npm run build-debug

# Build then start local server (requires: npm install -g http-server)
npm start

# Start server only, no build
npm run server

# Alternative server using Python (no install needed)
python3 -m http.server 8080

Open http://localhost:8080 in your browser.

The game must be served over HTTP — opening index.html directly via file:// will not work due to browser WASM restrictions.

Project Structure

chip8.c / chip8.h     — Emulator core (opcodes, display, input)
html_template/        — Emscripten HTML shell template
rom/pong.c8           — Bundled ROM
index.html            — Generated output (from emcc build)
index.js / index.wasm — Generated WebAssembly bundle

Implementation

• Full CHIP-8 instruction set (35 opcodes)
• 64×32 display scaled to 640×320 via SDL2 streaming texture
• Keyboard mapped to CHIP-8 hex keypad (0–F)
• Delay and sound timers decrement at 60 Hz
• 10 CPU cycles executed per frame

Credits

• Emulator logic inspired by arnsa/Chip-8-Emulator
• General architecture inspired by ColinEberhardt