Donkey Kong Country 3 Recomp

Donkey Kong Country 3 Recomp

A native recompilation of Donkey Kong Country 3 (USA), built on snesrecomp.

Run Donkey Kong Country 3 natively on Windows.

You must legally own a copy of the game. No ROM data is distributed with this project, in the repository or in any release. The recompiled C is generated locally from your own copy and is never committed.

☕ Keep the ports coming

This project is free and always will be. Every port in this series, Donkey Kong Country 3 included, is built with many hours of AI-assisted reverse engineering, and that AI time is paid. If you enjoy playing it, a coffee at buymeacoffee.com/mpolizel keeps the AI running so more SNES games can be ported to native Recomp. Any amount helps, and thank you!

Download (ready-to-run Windows build)

Get the latest donkeykongcountry3-<version>-windows-x64.zip from the Releases page.

The zip is a setup pack: it contains the launcher, the recompiler and this source tree (with the framework patches already applied), but no game data. On first run:

1. Unzip anywhere and start DonkeyKongCountry3SNESRecomp.exe.
2. Let it download the portable build tools (one time per machine), or point it at a cmake-clang-v1 zip you already have.
3. Pick your own Donkey Kong Country 3 (USA).sfc — the North American (En,Fr) release, CRC32 448eec19.
4. Press Generate & rebuild. The playable game is built into build/ and started; run it from there afterwards.

In the launcher, Settings → Shader lists the scanline, CRT and upscaler presets; choosing one switches the renderer to OpenGL automatically. A fresh install starts with no shader (the plain picture), the lightest option for any graphics card; pick a CRT or upscaler preset there if yours has room. Your choice is saved in config.ini and kept. The upscalers include ScaleFX and the neural NNEDI3 presets.

During play, Ctrl+L (or Select+L3 on a controller) reopens the launcher: shader, window scale, volume and controls apply when you press Resume, without restarting the game. I cycles the audio interpolation between Gaussian (the console's own, the default), Cubic (crisper highs) and Sinc; it only changes what you hear, never the game, and the choice is saved in audio_interpolation.txt.

On laptops with two graphics cards (NVIDIA Optimus, AMD switchable graphics) the game asks the driver for the dedicated one. If it still runs slowly, set the game's executable to High performance in Windows Settings → System → Display → Graphics.

Updates

With Check for updates on start ticked (the default; on the launcher's main screen, next to Skip launcher on boot), the game asks GitHub for the latest release when it starts and offers to install a newer one. Accepting closes the game, downloads the new setup pack, copies it over the install folder and reopens the setup window: press Generate & rebuild. Nothing is deleted; build\ (the rebuilt game, saves\, save states, config.ini, keybinds.ini) and rom.cfg are kept. Untick the box to turn the check off (saved in update.ini). Version 0.1.0 has no updater: update from it by hand once.

Your saves are never lost or broken by an update. In-game saves and save states made by any earlier release keep working in every later one. Before installing, the updater copies build\saves\ to save-backups\<date>_before_<version>\ and never deletes those copies; save files are left out of the copy, and if they changed anyway the backup is put back. Every release is checked against the one before it with tools/check_update_compat.ps1, which builds the previous release, makes an in-game save and a save state with it, installs the new pack with the previous release's own updater and rebuilds; it fails unless every save file is byte-identical and the new build continues the old save state.

See CHANGELOG.md for what changed in each release.

Status

Boots through the Nintendo logo and copyright into the opening world-map scene. Most code still runs through the snesrecomp interpreter; levels, saves and full play-through are not yet verified. See Porting from here.

Framework patches

patches/ holds changes to the snesrecomp and recomp-ui submodules. Reapply them after updating the submodules:

git -C snesrecomp apply ../patches/snesrecomp-shader-forces-opengl.patch
git -C snesrecomp apply ../patches/snesrecomp-nmi-idle-loop-wai.patch
git -C snesrecomp apply ../patches/snesrecomp-nmi-wai-in-handler.patch
git -C snesrecomp apply ../patches/snesrecomp-raster-oam-and-hdma.patch
git -C snesrecomp apply ../patches/snesrecomp-audio-interpolation.patch
git -C snesrecomp apply ../patches/snesrecomp-glsl-passprev-and-vao.patch
git -C recomp-ui apply ../patches/recomp-ui-host-toggle.patch

The second is required for this game: DKC3's NMI handler resets the stack and falls into a WAI / BRA idle loop instead of returning with RTI, and without the patch that loop runs to the interpreter's step cap every frame (black screen at ~4 fps). The patch also lets such a handler outlast a frame: DKC1's NMI uploads sound data with NMI off for several frames, and without it the upload was cut and the game froze on the intro screen.

snesrecomp-nmi-wai-in-handler.patch makes any WAI inside an interrupt handler halt until the next interrupt, as on hardware. In Donkey Kong Country (same Rare engine) a WAI left inside NMI after saving at Candy's was skipped, the interpreter spun to its step cap and the screen stayed black; this game gets the same fix preventively. With the same input, its memory matches the previous build frame for frame (a 3-frame timing difference in the boot logos of Donkey Kong Country 2 reconverges at once).

snesrecomp-raster-oam-and-hdma.patch is the renderer fix shared with the Super Mario Kart port. The renderer draws after the CPU frame and replays the frame's display writes line by line. It now keeps each sprite table (OAM) with the line it takes effect on, initializes HDMA channels enabled in vblank before line 1, and files a write made early in a line with the line before it, but never across the start of vblank: the NMI's first writes (screen mode, brightness) belong to the next frame. Filed one line early they were applied only after that frame was drawn, which in DKC2's boot showed the Rare logo over the Nintendo screen. It also counts HDMA's first transfer, made in V=0's H-blank, as a table line, as the hardware does. Every HDMA split landed one line late without it (on Donkey Kong Country 2's island map the late layer split drew a bright line across the screen).

snesrecomp-audio-interpolation.patch adds the Cubic and Sinc audio interpolation (I key). They resample the dry output only; the echo buffer, OUTX, pitch modulation and save states stay those of the console's Gaussian filter, so the game runs identically in every mode.

snesrecomp-glsl-passprev-and-vao.patch fixes two shader bugs: a pass that reads PassPrev<n> back to the game frame got nothing (ScaleFX drew black), and switching to no shader mid-game drew a black screen because the shader path left the plain path's vertex attributes disabled.

recomp-ui-host-toggle.patch lets a title add one checkbox of its own beside "Skip launcher on boot"; this project uses it for the update check.

ROM identity

File	Donkey Kong Country 3 (USA).sfc
Publisher	—
Developer	—
Year	—
Mapping	hirom
Region	USA (North America)
Coprocessor	none
CRC32	448eec19
SHA-256	2277a2d8dddb01fe5cb0ae9a0fa225d42b3a11adccaeafa18e3c339b3794a32b

tools/regen.sh refuses to run against anything else, so a mismatched revision fails immediately instead of producing subtly wrong output.

Build

git submodule update --init --recursive
bash tools/regen.sh --rom /path/to/Donkey Kong Country 3 (USA).sfc
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j

The ROM does not have to live in the repository — keeping it on your own drive is the better habit, and SNESRECOMP_ROM sets the path once for a shell. Without either, tools/regen.sh finds Donkey Kong Country 3 (USA).sfc at the repo root, then the path the setup wizard recorded in rom.cfg; .gitignore blocks both from ever being committed.

tools/regen.sh verifies the ROM, generates src/gen/*.c, and re-syncs recomp/funcs.h. Re-run it whenever you change anything under recomp/.

Run

./build/DonkeyKongCountry3SNESRecomp                     # launcher picks the ROM
./build/DonkeyKongCountry3SNESRecomp /path/to/Donkey Kong Country 3 (USA).sfc # or name it and skip the launcher

With no ROM on the command line the build opens the recomp-ui launcher: a ROM picker with a verification badge, plus display / audio / input settings. Your choice is cached in rom.cfg beside the executable, so the next launch opens on it and "Skip launcher on boot" makes it immediate. If the launcher is not built in (--no-recomp-ui), the host falls back to a native file picker.

Either way the ROM is checked against the digests above before anything boots — a dump that could not have produced this build is refused at the door rather than mis-executing ten frames in.

Layout

Path	What lives there
recomp/	Analysis input: bank*.cfg, symbols.toml, generated funcs.h
rom_identity.txt	ROM digests — read by the build, tools/regen.sh and CI
src/	Host code you own: main.c, game_rtl.c
src/gen/	Generated C. Never committed — regenerate locally
snesrecomp/	Framework submodule (owns lib/recomp-net, lib/retcomm-rbengine)
tools/	regen.sh — the ROM → C pipeline
scripts/	package_release.sh — player-facing zip
framework_pins.txt	Exact framework commits this project was scaffolded against

Porting from here

The scaffold stops where the game-specific work starts. In rough order:

1. Make it boot. src/game_rtl.c holds the frame driver. It starts on the framework's beam-aligned driver (snesrecomp/runner/src/beam_frame_driver.h): one frame per PPU field, interrupts taken where the beam latches them, the field rasterized from the raster journal. A title whose main loop it does not fit replaces those calls with its own driver.
2. Name things. Add entries to recomp/symbols.toml as you identify routines, then re-run tools/regen.sh. Set emit = true to promote one into ahead-of-time analysis; leave it false to keep it interpreted. Regen synchronizes the marked blocks in each bank cfg, creating missing configs. Only proven variants become AOT code. See recomp/README.md.
3. Resolve dispatch misses. After every run, deal with unresolved indirect targets before anything else — they are the reason a port diverges, and they are cheap to fix early.
4. Never synthesise a result to get past uncovered code, and never edit src/gen/ by hand. Fix the config or the framework and regenerate.

Multiplayer

Two players, one controller per port.

License

This project's own source is under the MIT license in LICENSE. The framework carries its own terms (PolyForm Noncommercial 1.0.0) — see snesrecomp/LICENSE and snesrecomp/THIRD_PARTY_ATTRIBUTION.md; the change in patches/ applies to that framework and falls under its terms. The shaders under assets/shaders/_libretro/ come from libretro/glsl-shaders and keep each author's license in their file headers. None of these cover the game data, which is not distributed here.

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