FireRedLeafGreenRecomp — Pokémon FireRed + LeafGreen, Recompiled

This recompilation is a byproduct of developing gbarecomp — the games are the proving ground, the framework is the goal. These are in-development previews, not finished ports — expect rough edges, and depth will keep landing over months, not days. My time for any one title is limited, so I ask for your patience. Contributions are welcome — testing, issues, and PRs to the game or framework all help and will accelerate this game's polish. More on the why at: Recomp + AI: 5 Months Later »

Static recompilation of Pokémon FireRed and Pokémon LeafGreen (Game Boy Advance) to native PC, built on the gbarecomp framework.

One repo hosts both games as separate native targets sharing one source tree and one engine (the Sonic3AndKnucklesRecomp multi-variant pattern — an add_gba_variant() CMake function emits one executable per game). Their Gen3 siblings live in RubySapphireRecomp and EmeraldRecomp.

Status — playable bring-up (v0.0.1), and self-improving

This is a static-recompilation base + runner, not a finished port. Both games boot through the BIOS intro to the title screen and into gameplay. It is early — not every code path is statically recompiled yet, and content has not been exhaustively tested.

It gets better the more you play. Any code path the static recompiler hasn't covered runs through a built-in interpreter the first time it's hit, then is JIT-compiled to native (in-process, no toolchain needed) and remembered on disk — so the next launch runs it natively from the start. Interpreted once, native ever after; coverage grows toward fully-native as the game is played. See How it self-improves.

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Screenshots

Pokémon FireRed	Pokémon LeafGreen

Native recompiled builds (no emulator), captured running the original ROMs.

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What "static recompilation" means here

The ROM's ARM7TDMI machine code is statically translated to native C — every function the game runs becomes a real generated C function. Unlike most recomp projects, the GBA BIOS is recompiled and executed too (not HLE'd or stubbed), so the boot sequence and interrupt/SWI handlers run as real recompiled code. The rest of the console — the PPU (graphics), APU + M4A sound engine, DMA, timers, and hardware I/O — is modeled by the gbarecomp runtime.

Only symbol metadata (function names, addresses, sizes) from the pret/pokefirered decompilation enters this repo — never its C source, build output, or toolchain. The ROM is never redistributed; you supply your own legally-dumped copy.

Variants

Target	Game	ROM (USA)	SHA-1	Debug port
FireRedRecomp	Pokémon FireRed	v1.0 (rev0)	41cb23d8dccc8ebd7c649cd8fbb58eeace6e2fdc	19852
LeafGreenRecomp	Pokémon LeafGreen	v1.0 (rev0)	574fa542ffebb14be69902d1d36f1ec0a4afd71e	19862

The runtime refuses to launch on an unrecognized ROM — the SHA-1 must match.

Quick start

1. Download the latest FireRedRecomp- / LeafGreenRecomp-windows-x64 zip from Releases and extract it (or build from source — see below).
2. Run the executable for the game you built.
3. Supply your own legally-obtained FireRed / LeafGreen (USA) ROM when prompted. The path is cached next to the exe for future launches.
4. Play. Early on you may briefly see the interpreter warm up new code paths; once warmed (and cached), they run native.

Controls

GBA button	Keyboard
D-Pad	Arrow keys
A	Z
B	X
Start	Enter
Select	Backspace

Save states: Shift+F1–F9 save to a slot, F1–F9 load it.

How it self-improves

gbarecomp's coverage is honest: a path that wasn't statically recompiled is bridged through the interpreter the first time, loudly, then healed:

• First hit: the interpreter runs the missed function (correct, just not native) and the runtime records it.
• Heal: the function is JIT-compiled to native in-process via a toolchain-less backend (sljit) — no compiler required on your machine.
• Persist: the healed path is written to a per-ROM cache (recomp_cache/<rom-sha1>/), so the next launch re-JITs it up front and it runs native from the start.

The result is a game that converges toward fully-native execution the more it's played, and stays improved across launches. A handful of instruction patterns the JIT can't lower yet stay on the interpreter (precision over recall); those are emitter gaps that close over time. Self-improvement is on by default; set GBARECOMP_SELFHEAL_RECOMPILE=0 for a pure-interpreter run.

Building from source

Prerequisites (Windows): MSYS2 with the mingw64 toolchain (gcc/g++), CMake 3.16+, Ninja, and SDL2 (mingw64 package). Builds are invoked from PowerShell with the mingw64 toolchain on PATH.

1. Clone this repo next to gbarecomp (the game repo builds against the sibling engine checkout on main):

git clone https://github.com/mstan/gbarecomp.git
git clone https://github.com/mstan/FireRedLeafGreenRecomp.git
cd FireRedLeafGreenRecomp

2. Supply your ROM(s) at variants/firered/roms/firered_usa.gba and/or variants/leafgreen/roms/leafgreen_usa.gba (SHA-1s above). ROMs are gitignored and never committed.

3. Recompile + build. The committed variants/*/symbols/*.toml are the importer output, so you can regenerate the C and build directly:

# from PowerShell, mingw64 on PATH
gba_recompile --rom variants/firered/roms/firered_usa.gba \
              --config variants/firered/symbols/firered.toml \
              --out variants/firered/generated
cmake -S . -B build -G Ninja
cmake --build build --target FireRedRecomp

(gba_recompile is built from the gbarecomp checkout; see that repo's README.) The recompiled translation unit is large — expect a multi-minute compile.

Legal

This project contains no copyrighted ROM data, no Nintendo BIOS, and no decomp source — only original recompiler/runtime code and symbol metadata. You must supply your own legally-dumped ROM (and BIOS, where the runtime requires one). Pokémon, FireRed, and LeafGreen are trademarks of Nintendo / Game Freak / The Pokémon Company; this project is an unaffiliated, non-commercial preservation and research effort.

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