Strawberry is a from-scratch Game Boy Advance emulator in Rust: ARM7TDMI interpreter, PPU, APU, DMA, timers, cartridge backup memory and a high-level-emulated BIOS, with a pure-Rust desktop player and a headless test harness. Built against the GBATEK hardware documentation.
Kingdom Hearts: Chain of Memories, the Zelda titles (Minish Cap, A Link to the Past & Four
Swords, both Classic NES Series games), Initial D: Another Stage and twenty-three further commercial
titles (Final Fantasy, Mario, Crash, Need for Speed, Max Payne, ...) reach controllable gameplay
under scripted headless runs pinned in tests/compat.toml. A sweep of a 1,543-title library
(docs/library-compat.md) boots 1,528 to a moving picture with sound; the rest are menus the
sweep does not answer and three open bugs. The BIOS sound driver (the m4a mixer and its
track-command routines) is emulated, so no BIOS image is needed for music. The mgba test suite scores Timing
2020/2020, Memory 1552/1552, DMA 1244/1244 and Timer count-up 936/936. See PROGRESS.md for the
exact state of every subsystem.
Ready-to-run builds for Windows, macOS (Intel and Apple Silicon) and Linux x64 are on the
Releases page as
strawberry-vX.Y.Z-<os>.zip / .tar.gz, each holding the strawberry binary and
QUICKSTART.md, which covers running it, the keys and where saves are kept. The
Fruit Basket launcher also lists Strawberry (v1.7.0 and
later; builds from v1.5.0 on can be launched from it).
Requires stable Rust (1.89+). No C toolchain, cmake or SDL is needed.
cargo build --release --workspace
cargo run --release -p gba-frontend # opens the library
cargo run --release -p gba-frontend -- "path\to\game.gba" # or play straight away (.zip containing one .gba also works)The player is a small GUI in the style of a 2001 game box ("paper, ink, one red";
docs/gui/): a library of cartridges scanned from your game folders (add them in Settings or
with --library DIR; the folder of a ROM given on the command line is included), an in-game
pause menu drawn inside the frame (resume, save/load one of eight state slots, settings,
bench, quit), a save states screen with film-strip thumbnails, a settings manual
(controls with keyboard and gamepad rebinding, picture size and filters, fast-forward limit, volume, BIOS,
folders, audio device, autosave), and a bench developer view (per-layer pictures, channel
meters, scanline event timeline, CPU registers and disassembly).
Saves are written beside the ROM as <rom>.sav; save states as <rom stem>.s1.state …
.s8.state, each with its picture as <rom stem>.s<N>.png (an older single <rom>.state is
picked up as slot 1). Settings live in
%APPDATA%\strawberry\settings.toml, the library index and title pictures in
%LOCALAPPDATA%\strawberry\ (covers\<rom stem>.png is a copy for the Fruit Basket launcher). No BIOS image is required. If you have one, set
GBA_BIOS to its path (or pass --bios, or choose it in Settings) and it is used instead of the
built-in HLE.
Renders of the player at its 1280×800 design size (docs/screenshots/, written by the render
tests below).
 Library. Cartridges in a case, the chosen one in the handheld with its title picture. |
 Empty library. The Strawberry cartridge is what is in the console until you add games. |
 Pause menu. Drawn inside the frame at native 240×160, scaled with the game. |
 Save states. Eight slots on film strips, a grease-pencil ring on the chosen one. |
 Settings. An open manual: rebind keys and pad buttons, picture, sound, system, saves. |
 Bench. Developer view: layers, channel meters, a scanline timeline, CPU state. |
| GBA | Keyboard | Gamepad |
|---|---|---|
| A / B | Z / X | South / East |
| L / R | A / S | LB / RB |
| Start / Select | Enter / Right Shift | Start / Select |
| D-pad | Arrow keys | D-pad or left stick |
All of these can be rebound in Settings (every GBA button shows a keyboard keycap and a gamepad keycap; click one and press the new key or pad button); the menus navigate with the same bindings (A confirm, B back, L/R turn pages).
Hotkeys: Esc or P pause menu (on a gamepad: Guide, or Select+Start held for a
second), Tab (held) fast-forward, N frame step,
F1 / F3 save / load the current slot, F2 save states screen, F5 write the .sav
now, F10 dump IO registers to the console, F11 screenshot, F12 bench, = / - more
or less sunlight on the Boktai carts' solar sensor (also the pause menu's SUN row). The window is
resizable and the picture is always drawn at a whole-number scale on a dark letterbox;
--scale N fixes the picture at N× in a window of exactly that size, --fullscreen covers the
display with a borderless window for that run, --exit-on-quit makes the pause menu's QUIT close
Strawberry (exit code 0) instead of opening the library, --slot N (1–8) starts the
game from that save-state slot (an empty slot boots normally), --no-resume starts from power-on
(what a plain launch already does; it is there for the launcher's Start fresh), --no-audio disables
sound, --fullspeed removes pacing, --bench N runs N frames headless and prints the speed.
Strawberry is Fruit Basket No. 2. The mark is a 16×16 sprite in four colours (cream, shade, ink
and red: fifteen seeds on the outside), shown at whole-number scales only and never smoothed;
the night variant, outline in cream and seeds in red on a dark ground, is the one on the
handheld's screen in the empty library. The wordmark is Archivo ExtraBold at 72 % width; over a
game the pixel font takes its place. Everything lives in docs/branding/ (SVG mark, wordmark
and lockups with night versions, .ico and PNG icons, the design boards, and README.txt, the
designer's note). gba-frontend/src/ui/brand.rs parses the SVG mark, so the file in
docs/branding/ is the one the player draws, on the window and in the exe's icon too.
| Crate | Purpose |
|---|---|
gba-core |
The machine. No dependencies by default; the savestate feature adds serde + bincode. |
gba-test |
Headless harness (gba-test <rom> --frames N ...) and the cargo test ROM driver. |
gba-frontend |
The player (binary strawberry): window (minifb), software renderer (tiny-skia; text through basket-ui's fontdue), audio (cpal, through basket-app), gamepads (gilrs), pacing, saves, state slots, settings, icons. |
docs/ARCHITECTURE.md describes the design; docs/gbatek/ holds the spec excerpts the code
was written from; CLAUDE.md holds the project rules and commands.
The generic half of the player (UI toolkit, audio, pacing, saves, slots, library) comes from fruit-basket, pinned by git tag; its docs cover the shared dependency versions, the launcher contract and the ecosystem.
scripts/fetch-tests.ps1 # clones jsmolka/gba-tests + mgba suite, downloads portable mGBA
$env:GBA_TESTS_DIR = "$PWD\tools\tests"
cargo test --workspacecargo test runs the core unit tests (390), the frontend's unit tests (113, six of them ignored by default;
cargo test -p gba-frontend --release -- --ignored render_ additionally writes review renders of
every screen to target/ui-renders/), every ROM in tests/golden.toml (the jsmolka CPU, memory,
BIOS, PPU and save suites, all passing, and the thirteen mgba-suite sub-suites pinned at their
scores) and the 69 commercial-ROM goldens in tests/compat.toml (scripted gameplay for the
priority titles, plus 1500-frame rows for the titles whose music goes through the BIOS sound
driver, which also require a minimum number of frames with audio). Commercial rows are skipped
when the ROMs are not present under Games/, which is gitignored. The mgba suite ships as
source and needs devkitARM: tools/tests/suite/suite.gba is built with its docker-build.sh.
Every milestone of the plan is complete against its headless gate except M8, where savestates,
fast-forward, audio-clocked pacing and the game-pak prefetch buffer are in and only
per-instruction timing refinement remains deferred (no runnable gate beyond the mgba-suite
scores above, which are pinned). The BIOS is high-level emulated, including the sound driver
that six library titles need, so no BIOS image is required for anything the library does
(only the undocumented SWI 20h-24h entries are unimplemented, and no title calls them). Release speed is
about 26x real time headless (1,590 fps on KH:CoM). Live audio has been verified on a real
48 kHz device (zero underruns). Audio has been compared against libmgba with a headless capture
tool (scripts/build-mgba.ps1, scripts/compare-audio.py): our levels follow GBATEK's stated
maxima and mGBA mixes about 3 dB lower, a difference in convention rather than a bug. The player
takes launcher hooks (--slot, --no-resume, --fullscreen, --exit-on-quit, and a gamepad route to the pause
menu) for the Fruit Basket launcher's couch mode. Cartridges with a real-time clock (Pokémon
Ruby, Sapphire and Emerald, Rockman EXE 4.5, Boktai and others) read the computer's clock, and
the Boktai solar sensor takes its light from a 0-10 sun level. Still open: the three boot bugs listed in
docs/library-compat.md.