- Rust 97.7%
- Python 2.3%
c31a703db4
Retain the supplied image PC+8 snapshot after successful ARM BIOS instructions. CPU data reads from outside BIOS use its byte lanes; reads inside BIOS and host inspection remain mapped reads. Keep nominal timing and diagnostic atomicity. Unknown history, Thumb BIOS execution, and missing lookahead remain explicit limits rather than guessed values. Add original regressions for ARM/Thumb callers, all CPU modes, widths and rotation, synthetic SWI/IRQ returns, original boot provenance, context isolation, history invalidation, and device progress. No Nintendo firmware or opcode constants are used to synthesize results. Darwin arm64 validation: 861 workspace tests and 792 core/demo tests in debug and release; 39 Python tests; native ROM windows; all ten demo smoke tests; fmt, clippy, rustdoc, and docs links. Public ARM, Thumb, and memory ROMs still pass. The public BIOS ROM still fails firmware-specific test 1, now reading its actual replacement-BIOS prefetch rather than raw vector bytes. |
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|---|---|---|
| crates | ||
| docs | ||
| tools | ||
| .envrc | ||
| .gitignore | ||
| AGENTS.md | ||
| Cargo.lock | ||
| Cargo.toml | ||
| CLAUDE.md | ||
| flake.lock | ||
| flake.nix | ||
| README.md | ||
gameboy-rust
Game Boy family emulation in Rust, written from scratch. The Game Boy Advance (GBA) is the first and currently only system.
This cannot run Pokémon Emerald or other commercial games yet. It is an emulator foundation: an ARM7TDMI interpreter, memory bus, timers, DMA, Mode 0–5 video, and an original BIOS replacement. The included demos run original ARM test programs through the emulated hardware. Raw ROM files can run in terminal sessions or a window with keyboard input. Audio and saves are not implemented.
Layout
| Crate | Purpose |
|---|---|
crates/gba-core |
Platform-independent GBA emulator. No external Rust dependencies. |
crates/gba-demos |
Original test programs that drive the core. |
crates/desktop |
Native window frontend on minifb. Builds the gameboy-rust executable. |
Quick start
macOS on Apple Silicon is the verified platform. Install Nix (with flakes) and direnv, then:
direnv allow .
direnv exec . cargo run --locked --release -- --tile-demo
direnv exec . cargo test --locked
Arrows scroll, Q rotates, W zooms, Z flips, X changes priority, Enter resets, and Escape exits.
Run direnv exec . cargo run --locked -- --help to list all modes.
For original ROM files, use --rom path/to/original.gba --window, or --steps 100000 instead of --window for terminal diagnostics.
See cartridge loading for limits and report meanings.
Use --test-suite suite.json for repeatable headless ROM assertions.
Documentation
| Document | Contents |
|---|---|
| docs/status.md | What works today, deliberate limits, and next steps |
| docs/demos.md | Every demo, its command, and its controls |
| docs/development.md | Nix, direnv, and macOS build notes |
| docs/testing.md | Validation commands and what the test suites cover |
| docs/rom-tests.md | Headless ROM suites, completion checks, assertions, and JSON reports |
| docs/public-arm-tests.md | Pinned public ARM test, preparation command, results, and limits |
| docs/public-thumb-tests.md | Pinned public Thumb test, result protocol, and compatibility baseline |
| docs/public-memory-tests.md | Pinned public memory test, results, and video-byte coverage limits |
| docs/public-bios-tests.md | Pinned BIOS read-protection test and firmware-specific failure |
| docs/architecture.md | Crate boundaries and a file-by-file map |
| docs/hardware/cpu.md | ARM/Thumb execution rules, modes, exceptions, and timing |
| docs/hardware/cartridge.md | ROM loading, window/input controls, original ROM generator, and diagnostics |
| docs/hardware/bios.md | The original BIOS replacement and each supported service |
| docs/hardware/timers-irq.md | Timers, interrupt registers, HALT/STOP, and power control |
| docs/hardware/dma.md | DMA channels, triggers, and timing |
| docs/hardware/display-timing.md | Display clock, status, IRQs, and scanline capture |
| docs/hardware/video.md | Backgrounds, sprites, mosaic, windows, color effects, and input |
| docs/references.md | External hardware references and emulator sources consulted |
Coding agents should start with AGENTS.md.
Legal
All demo content and the BIOS replacement are original. No Nintendo code or assets are included. Only use game ROMs that you may lawfully use. Do not commit game ROMs, BIOS files, or game assets.