4k.c

A chess engine designed to fit into 4kB.

The engine is a <= 4096 byte UCI engine executable, without:

• Any external dependencies (including libc)
• Minification
• On-the-fly compilation

How to contribute

For general contributions

• To get the latest bench, run make && ./build/4kc bench
• If you have a potential idea, just PR it.
• All PRs are welcome, I will sort though them.
• No need to touch the changelog. I will amend the commit and you will get credited there (as well as the git history)

For size measurements

• You must have the correct gcc version on your system in your PATH. It is a version somewhere in-between 14.2 and 15.1. See below for installation details
• You must have apultra on your PATH. https://github.com/GediminasMasaitis/apultra. Just get the source, make it, and sudo mv apultra ./usr/local/bin.
• Run make NOSTDLIB=true MINI=true loader, you will see the binary size in the console output

How to install the exact gcc version:

sudo apt install build-essential
sudo apt install libmpfr-dev libgmp3-dev libmpc-dev -y

wget -O gcc-dev.zip https://github.com/GediminasMasaitis/gcc/archive/refs/heads/master.zip
unzip gcc-dev.zip
cd gcc-dev

./configure -v --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --prefix=/usr/local/gcc-dev --enable-checking=release --enable-languages=c --disable-multilib --program-suffix=-dev
make -j 4
sudo make install

sudo update-alternatives --install /usr/bin/gcc gcc /usr/local/gcc-dev/bin/gcc-dev 99

Change -j 4 to your core count for faster building

Thanks

• Rune Stubbe & Aske Simon Christensen (Mentor & Blueberry) for Crinkler, from which the compressor and loader are derived (zlib license, see THIRD_PARTY_LICENSES)
• zamfofex for helping with initial set up of a minimal Hello World executable and helping with 64 bit compilation, reducing code size
• sqrmax for helping optimize the loader