A reimplementation of Zelda 3.
This is a reverse engineered clone of Zelda 3 - A Link to the Past.
It's around 70-80kLOC of C code, and reimplements all parts of the original game. The game is playable from start to end.
You need a copy of the ROM to extract game resources (levels, images). Then once that's done, the ROM is no longer needed.
It uses the PPU and DSP implementation from LakeSnes. Additionally, it can be configured to also run the original machine code side by side. Then the RAM state is compared after each frame, to verify that the C implementation is correct.
I got much assistance from spannierism's Zelda 3 JP disassembly and the other ones that documented loads of function names and variables.
- the
libsdl2-devlibrary (ubuntu:apt install libsdl2-dev, macOS:brew install sdl2). On Windows, it's installed automatically with NuGet. - a
tables/zelda3.sfcUS ROM file (for asset extraction step only) with SHA256 hash66871d66be19ad2c34c927d6b14cd8eb6fc3181965b6e517cb361f7316009cfb. - The
pillowandpyyamlpython dependencies used by the assets extractor.pip install pillow pyyaml
cd tables
Run python3 extract_resources.py to extract resources from the ROM into a more human readable format.
Run python3 compile_resources.py to produce .h files that get included by the C code.
First extract and compile resources, see above. Then build the .sln file with Visual Studio.
Linux: apt install libsdl2-dev
macOS: brew install sdl2
First extract and compile resources, see above. Then make sure you are in the root directory.
clang++ `sdl2-config --cflags` -O2 -ozelda3 *.c snes/*.c `sdl2-config --libs`
or
make -j$(nproc)
The game supports snapshots. The joypad input history is also saved in the snapshot. It's thus possible to replay a playthrough in turbo mode to verify that the game behaves correctly.
The game is run with ./zelda3 and takes an optional path to the ROM-file, which will verify for each frame that the C code matches the original behavior.
| Button | Key |
|---|---|
| Up | Up arrow |
| Down | Down arrow |
| Left | Left arrow |
| Right | Right arrow |
| Start | Enter |
| Select | Right shift |
| A | X |
| B | Z |
| X | S |
| Y | A |
| L | D |
| R | C |
Additionally, the following commands are available:
| Key | Action |
|---|---|
| W | Fill health/magic |
| E | Hard reset |
| P | Pause |
| T | Toggle replay turbo |
| K | Clear all input history from current snapshot |
| F1-F10 | Load snapshot |
| Alt+Enter | Toggle Fullscreen |
| Shift+F1-F10 | Save snapshot |
| Ctrl+F1-F10 | Replay the snapshot |
Additionally, there are a bunch of included playthrough snapshots that play all dungeons of the game. You access them with the digit keys. If you want to replay the stage in turbo mode, press Ctrl+Digit (eg Ctrl-5).
This project is licensed under the MIT license. See 'LICENSE.txt' for details.