bitbit
======
A bitboard based chess engine written in c.

Building bitbit
---------------
Run

	$ make

in the root directory. Make can be run with the following additional variables

	$ make TT={n} SIMD={simd} NNUE={file}

to specify a transposition table size, available SIMD instructions and an NNUE
filename respectively. TT={n} gives a transposition table of n MiB. The default
value of n is 256. The only available target for SIMD={simd} is avx2.

Training data
-------------
Every single binary file, evaluation constant and training data set that has
been used to tune bitbit, has been generated by programs from this repository
alone. No external programs nor files have been used as aid, with the exception
of Syzygy tablebases and the Syzygy probing tool Fathom, available at
<https://github.com/jdart1/Fathom>. The tournament manager fastchess has been
used to run games between bitbit and itself. It is available at
<https://github.com/Disservin/fastchess>.

Testing
-------
bitbit is tested using the test server testbit. It is available at
<https://github.com/spinojara/testbit>.

Copying
-------
Copyright (C) 2022-2025 Isak Ellmer

All source files are distributed under the GNU General Public License, version 2
(GPLv2). In addition, all files that use this license begin with a license
notice. A copy of GPLv2 is available in the file COPYING and at
<https://www.gnu.org/licenses/>.

All other files are licensed under the Creative Commons Attribution-ShareAlike
4.0 license (CC BY-SA 4.0). That includes this file, the various binary files
and any files that do not have a license notice for GPLv2. A copy of CC BY-SA
4.0 is available at <https://creativecommons.org/licenses/by-sa/4.0/>.