we4k

we4k is no longer in development. New development is focused on STRO4K

we4k is a chess engine designed to fit into 4096 bytes.

Building

we4k requires nasm and the latest Zig compiler. Only Linux and cpus with AVX2 and BMI2 are supported.

cd src/asm
nasm -f elf64 combined.asm
cd ../..
zig build install -Drelease-small -Dcpu=skylake-vzeroupper

The binary could be made to fit into 4096 bytes using sstrip, vondehi, and mrbdzz's decompression script. However, this is no longer possible with newer versions of the Zig compiler. build4k.sh attempts to build we4k and pack it into 4096 bytes.

./build4k.sh we4k

Questions

Why is it called we4k?

Score of we4k-86762f9 vs 4ku-9eea311: 3 - 95 - 2  [0.040] 100
...      we4k-86762f9 playing White: 0 - 50 - 0  [0.000] 50
...      we4k-86762f9 playing Black: 3 - 45 - 2  [0.080] 50
...      White vs Black: 45 - 53 - 2  [0.460] 100
Elo difference: -552.1 +/- 257.1, LOS: 0.0 %, DrawRatio: 2.0 %
Finished match

Where was there claimed to be only one Zig function?

After compilation, only one Zig function remains after inlining and dead code elimination.

Thanks

we4k was developed with contributions from many others. In particular

• The Stockfish Team - we4k was tuned using a large number Fishtest games.
• sqrmax - for dedicating a large amount of time to reading the assembly and providing suggestions.
• mrbdzz - for creating the decompression script used.
• kanchess - for creating and donating the logo