-## Overview
+<div align="center">
+
+ [![Stockfish][stockfish128-logo]][website-link]
+
+ [![Build][build-badge]][build-link]
+ [![License][license-badge]][license-link]
+ <br>
+ [![Release][release-badge]][release-link]
+ [![Commits][commits-badge]][commits-link]
+ <br>
+ [![Website][website-badge]][website-link]
+ [![Fishtest][fishtest-badge]][fishtest-link]
+ [![Discord][discord-badge]][discord-link]
-[](https://github.com/official-stockfish/Stockfish/actions)
+</div>
+
+## Overview
-[Stockfish](https://stockfishchess.org) is a free, powerful UCI chess engine
-derived from Glaurung 2.1. Stockfish is not a complete chess program and requires a
-UCI-compatible graphical user interface (GUI) (e.g. XBoard with PolyGlot, Scid,
-Cute Chess, eboard, Arena, Sigma Chess, Shredder, Chess Partner or Fritz) in order
-to be used comfortably. Read the documentation for your GUI of choice for information
-about how to use Stockfish with it.
+[Stockfish][website-link] is a free, powerful UCI chess engine derived from
+Glaurung 2.1. Stockfish is not a complete chess program and requires a UCI-compatible
+graphical user interface (GUI) (e.g. XBoard with PolyGlot, Scid, Cute Chess, eboard,
+Arena, Sigma Chess, Shredder, Chess Partner or Fritz) in order to be used comfortably.
+Read the documentation for your GUI of choice for information about how to use
+Stockfish with it.
-The Stockfish engine features two evaluation functions for chess. The efficiently
+The Stockfish engine features two evaluation functions for chess. The efficiently
updatable neural network (NNUE) based evaluation is the default and by far the strongest.
-The classical evaluation based on handcrafted terms remains available. The strongest
+The classical evaluation based on handcrafted terms remains available. The strongest
network is integrated in the binary and downloaded automatically during the build process.
-The NNUE evaluation benefits from the vector intrinsics available on most CPUs (sse2,
+The NNUE evaluation benefits from the vector intrinsics available on most CPUs (sse2,
avx2, neon, or similar).
## Files
This distribution of Stockfish consists of the following files:
- * [README.md](https://github.com/official-stockfish/Stockfish/blob/master/README.md),
- the file you are currently reading.
+ * [README.md][readme-link], the file you are currently reading.
- * [Copying.txt](https://github.com/official-stockfish/Stockfish/blob/master/Copying.txt),
- a text file containing the GNU General Public License version 3.
+ * [Copying.txt][license-link], a text file containing the GNU General Public License
+ version 3.
- * [AUTHORS](https://github.com/official-stockfish/Stockfish/blob/master/AUTHORS),
- a text file with the list of authors for the project
+ * [AUTHORS][authors-link], a text file with the list of authors for the project.
- * [src](https://github.com/official-stockfish/Stockfish/tree/master/src),
- a subdirectory containing the full source code, including a Makefile
+ * [src][src-link], a subdirectory containing the full source code, including a Makefile
that can be used to compile Stockfish on Unix-like systems.
- * a file with the .nnue extension, storing the neural network for the NNUE
- evaluation. Binary distributions will have this file embedded.
+ * a file with the .nnue extension, storing the neural network for the NNUE evaluation.
+ Binary distributions will have this file embedded.
## The UCI protocol and available options
The Universal Chess Interface (UCI) is a standard protocol used to communicate with
a chess engine, and is the recommended way to do so for typical graphical user interfaces
(GUI) or chess tools. Stockfish implements the majority of its options as described
-in [the UCI protocol](https://www.shredderchess.com/download/div/uci.zip).
+in [the UCI protocol][uci-link].
Developers can see the default values for UCI options available in Stockfish by typing
`./stockfish uci` in a terminal, but the majority of users will typically see them and
For developers the following non-standard commands might be of interest, mainly useful for debugging:
* #### bench *ttSize threads limit fenFile limitType evalType*
- Performs a standard benchmark using various options. The signature of a version
- (standard node count) is obtained using all defaults. `bench` is currently
+ Performs a standard benchmark using various options. The signature of a version
+ (standard node count) is obtained using all defaults. `bench` is currently
`bench 16 1 13 default depth mixed`.
* #### compiler
The NNUE evaluation was first introduced in shogi, and ported to Stockfish afterward.
It can be evaluated efficiently on CPUs, and exploits the fact that only parts
of the neural network need to be updated after a typical chess move.
-[The nodchip repository](https://github.com/nodchip/Stockfish) provided the first
-version of the needed tools to train and develop the NNUE networks. Today, more
-advanced training tools are available in
-[the nnue-pytorch repository](https://github.com/glinscott/nnue-pytorch/),
-while data generation tools are available in
-[a dedicated branch](https://github.com/official-stockfish/Stockfish/tree/tools).
+[The nodchip repository][nodchip-link] provided the first version of the needed tools
+to train and develop the NNUE networks. Today, more advanced training tools are
+available in [the nnue-pytorch repository][pytorch-link], while data generation tools
+are available in [a dedicated branch][tools-link].
On CPUs supporting modern vector instructions (avx2 and similar), the NNUE evaluation
results in much stronger playing strength, even if the nodes per second computed by
Notes:
-1) the NNUE evaluation depends on the Stockfish binary and the network parameter file
+1) the NNUE evaluation depends on the Stockfish binary and the network parameter file
(see the EvalFile UCI option). Not every parameter file is compatible with a given
-Stockfish binary, but the default value of the EvalFile UCI option is the name of a
+Stockfish binary, but the default value of the EvalFile UCI option is the name of a
network that is guaranteed to be compatible with that binary.
2) to use the NNUE evaluation, the additional data file with neural network parameters
### Support on Windows
The use of large pages requires "Lock Pages in Memory" privilege. See
-[Enable the Lock Pages in Memory Option (Windows)](https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/enable-the-lock-pages-in-memory-option-windows)
-on how to enable this privilege, then run [RAMMap](https://docs.microsoft.com/en-us/sysinternals/downloads/rammap)
+[Enable the Lock Pages in Memory Option (Windows)][lockpages-link]
+on how to enable this privilege, then run [RAMMap][rammap-link]
to double-check that large pages are used. We suggest that you reboot
your computer after you have enabled large pages, because long Windows
sessions suffer from memory fragmentation, which may prevent Stockfish
### Donating hardware
Improving Stockfish requires a massive amount of testing. You can donate
-your hardware resources by installing the [Fishtest Worker](https://github.com/glinscott/fishtest/wiki/Running-the-worker:-overview)
-and view the current tests on [Fishtest](https://tests.stockfishchess.org/tests).
+your hardware resources by installing the [Fishtest Worker][worker-link]
+and view the current tests on [Fishtest][fishtest-link].
### Improving the code
If you want to help improve the code, there are several valuable resources:
-* [In this wiki,](https://www.chessprogramming.org) many techniques used in
+* [In this wiki,][programming-link] many techniques used in
Stockfish are explained with a lot of background information.
-* [The section on Stockfish](https://www.chessprogramming.org/Stockfish)
+* [The section on Stockfish][programmingsf-link]
describes many features and techniques used by Stockfish. However, it is
generic rather than being focused on Stockfish's precise implementation.
Nevertheless, a helpful resource.
-* The latest source can always be found on [GitHub](https://github.com/official-stockfish/Stockfish).
-Discussions about Stockfish take place these days mainly in the [FishCooking](https://groups.google.com/forum/#!forum/fishcooking)
-group and on the [Stockfish Discord channel](https://discord.gg/nv8gDtt).
-The engine testing is done on [Fishtest](https://tests.stockfishchess.org/tests).
-If you want to help improve Stockfish, please read this [guideline](https://github.com/glinscott/fishtest/wiki/Creating-my-first-test)
+* The latest source can always be found on [GitHub][github-link].
+Discussions about Stockfish take place these days mainly in the [FishCooking][fishcooking-link]
+group and on the [Stockfish Discord channel][discord-link].
+The engine testing is done on [Fishtest][fishtest-link].
+If you want to help improve Stockfish, please read this [guideline][guideline-link]
first, where the basics of Stockfish development are explained.
The only real limitation is that whenever you distribute Stockfish in
some way, you MUST always include the license and the full source code
-(or a pointer to where the source code can be found) to generate the
+(or a pointer to where the source code can be found) to generate the
exact binary you are distributing. If you make any changes to the
source code, these changes must also be made available under the GPL v3.
For full details, read the copy of the GPL v3 found in the file named
-[*Copying.txt*](https://github.com/official-stockfish/Stockfish/blob/master/Copying.txt).
+[*Copying.txt*][license-link].
+
+
+[authors-link]: https://github.com/official-stockfish/Stockfish/blob/master/AUTHORS
+[build-link]: https://github.com/official-stockfish/Stockfish/actions/workflows/stockfish.yml
+[commits-link]: https://github.com/official-stockfish/Stockfish/commits/master
+[discord-link]: https://discord.gg/GWDRS3kU6R
+[fishcooking-link]: https://groups.google.com/g/fishcooking
+[fishtest-link]: https://tests.stockfishchess.org/tests
+[github-link]: https://github.com/official-stockfish/Stockfish
+[guideline-link]: https://github.com/glinscott/fishtest/wiki/Creating-my-first-test
+[license-link]: https://github.com/official-stockfish/Stockfish/blob/master/Copying.txt
+[lockpages-link]: https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/enable-the-lock-pages-in-memory-option-windows
+[nodchip-link]: https://github.com/nodchip/Stockfish
+[programming-link]: https://www.chessprogramming.org/Main_Page
+[programmingsf-link]: https://www.chessprogramming.org/Stockfish
+[pytorch-link]: https://github.com/glinscott/nnue-pytorch
+[rammap-link]: https://docs.microsoft.com/en-us/sysinternals/downloads/rammap
+[readme-link]: https://github.com/official-stockfish/Stockfish/blob/master/README.md
+[release-link]: https://github.com/official-stockfish/Stockfish/releases/latest
+[src-link]: https://github.com/official-stockfish/Stockfish/tree/master/src
+[stockfish128-logo]: https://stockfishchess.org/images/logo/icon_128x128.png
+[tools-link]: https://github.com/official-stockfish/Stockfish/tree/tools
+[uci-link]: https://www.shredderchess.com/download/div/uci.zip
+[website-link]: https://stockfishchess.org
+[worker-link]: https://github.com/glinscott/fishtest/wiki/Running-the-worker:-overview
+
+[build-badge]: https://img.shields.io/github/actions/workflow/status/official-stockfish/Stockfish/stockfish.yml?branch=master&style=for-the-badge&label=stockfish&logo=github
+[commits-badge]: https://img.shields.io/github/commits-since/official-stockfish/Stockfish/latest?style=for-the-badge
+[discord-badge]: https://img.shields.io/discord/435943710472011776?style=for-the-badge&label=discord&logo=Discord
+[fishtest-badge]: https://img.shields.io/website?style=for-the-badge&down_color=red&down_message=Offline&label=Fishtest&up_color=success&up_message=Online&url=https%3A%2F%2Ftests.stockfishchess.org%2Ftests%2Ffinished
+[license-badge]: https://img.shields.io/github/license/official-stockfish/Stockfish?style=for-the-badge&label=license&color=success
+[release-badge]: https://img.shields.io/github/v/release/official-stockfish/Stockfish?style=for-the-badge&label=official%20release
+[website-badge]: https://img.shields.io/website?style=for-the-badge&down_color=red&down_message=Offline&label=website&up_color=success&up_message=Online&url=https%3A%2F%2Fstockfishchess.org
projects / stockfish / blobdiff