Zelda3

A reimplementation of Zelda 3.

Our discord server is: https://discord.gg/AJJbJAzNNJ

About

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, but with lots of speed optimizations. 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.

Additional features

Some features have been added that are not supported by the original game.

Secondary item slot on button X (Hold X in inventory to select).

Displays max rupees, bombs and arrows with yellow or orange color.

Extends throwing bombs to four instead of two.

Support for MSU audio tracks.

Support for enhanced aspect ratios of 16:9 or 16:10.

Switching current item with L/R keys.

Reordering of inventory by pressing Y+Arrows.

Higher quality map screen.

Disable low health beep.

Pick up items and destroy pots with Sword.

Dependencies

• the libsdl2-dev library
  • Windows: automatically installed with NuGet
  • Ubuntu: apt install libsdl2-dev
  • macOS: brew install sdl2
• a tables/zelda3.sfc US ROM file (for asset extraction step only)
  • SHA256 : 66871d66be19ad2c34c927d6b14cd8eb6fc3181965b6e517cb361f7316009cfb.
• The pillow and pyyaml python dependencies used by the assets extractor.
  • python -m pip install -r requirements.txt

Compiling

Look at the wiki at https://github.com/snesrev/zelda3/wiki for more help.

Windows

First extract and compile resources.

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 create a file called zelda3_assets.dat that gets loaded by the executable.

In case you're planning to move the .exe to a different folder, please include zelda3_assets.dat.

Then build the .sln file with Visual Studio.

Building with TCC instead of Visual Studio on Windows

You can also build and run it through TCC in case you don't have Visual Studio. Note that TCC builds without optimizations so the game will run considerably slower.

Read about how to use TCC here...

Extract the assets as detailed above.

Unzip TCC for win64 into third_party/tcc.

Unzip SDL2 into third_party/SDL2-2.24.0.

Start run_with_tcc.bat. It will perform some basic error checks and then start the game.

Linux/macOS

make

Advanced make usage ...

make -j$(nproc) # run on all core
make clean all  # clear gen+obj and rebuild
CC=clang make   # specify compiler

In case you're planning to move the executable to a different location, please include the file tables/zelda3_assets.dat.

Usage and controls

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	C
R	V

The keys can be reconfigured in zelda3.ini

Additionally, the following commands are available:

Key	Action
Tab	Turbo mode
W	Fill health/magic
Shift+W	Fill rupees/bombs/arrows
Ctrl+E	Reset
P	Pause (with dim)
Shift+P	Pause (without dim)
Ctrl+Up	Increase window size
Ctrl+Down	Decrease window size
T	Toggle replay turbo mode
O	Set dungeon key to 1
K	Clear all input history from the joypad log
L	Stop replaying a shapshot
R	Toggle between fast and slow renderer
F	Display renderer performance
F1-F10	Load snapshot
Alt+Enter	Toggle Fullscreen
Shift+F1-F10	Save snapshot
Ctrl+F1-F10	Replay the snapshot
1-9	run a dungeons playthrough snapshots
Ctrl+1-9	run a dungeons playthrough in turbo mode

License

This project is licensed under the MIT license. See 'LICENSE.txt' for details.