chip8-rust

This is a CHIP8 emulator written in Rust (first time using it). It was developed in VS Code on Windows 11 using WSL.

Types

Rom

The bytecode for a chip8 rom. This is just an array of unsigned bytes.

Cpu

This is the actual chip8 cpu emulator. It mirrors the hardware of the actual chip8:

• 4096 bytes of RAM
• 16 general purpose 8-bit registers
• 1 16-bit memory register for referring to addresses in RAM
• 1 8-bit delay timer
• 1 8-bit sound timer

I keep the current keyboard state and screen state outside of the actual emulated hardware.

Program

A composition of a Cpu, Rom, program counter, and stack pointer. Also has a frequency parameter that controls how many opcodes are executed per second.

Platform

The Chip8 has a 16 key keyboard and a 64x32 pixel screen. The Platform is the implementation of these 2 pieces of hardware.
It could theoretically be implemented using any number of windowing libraries, but I supplied 1 implementation using SDL 2.

PlatformContext & CpuContext

The Emulator and the Platform are run concurrently in 2 threads. The Emulator runs in the main thread of the program while the Platform is responsible for spawning a separate thread for managing keyboard input and display rendering. The Emulator and Platform communicate via a set of 4 Channels.

• Keyboard Channel
• Display Channel
• Sound Channel
• Single-Key Channel

The PlatformContext needs:

• Keyboard Sender
• Display Receiver
• Sound Receiver
• Single-Key Sender

While the CpuContext needs:

• Keyboard Receiver
• Display Sender
• Sound Sender
• Single-Key Receiver

Platform implementations should use the non-blocking try_send and try_recv.