4 Stockfish is a free UCI chess engine derived from Glaurung 2.1. It is
5 not a complete chess program and requires some UCI-compatible GUI
6 (e.g. XBoard with PolyGlot, eboard, Arena, Sigma Chess, Shredder, Chess
7 Partner or Fritz) in order to be used comfortably. Read the
8 documentation for your GUI of choice for information about how to use
11 This version of Stockfish supports up to 32 CPUs, but has not been
12 tested thoroughly with more than 4. The program tries to detect the
13 number of CPUs on your computer and sets the number of search threads
14 accordingly, but please be aware that the detection is not always
15 correct. It is therefore recommended to inspect the value of the
16 "Threads" UCI parameter, and to make sure it equals the number of CPU
17 cores on your computer. If you are using more than eight threads, it is
18 recommended to raise the value of the "Min Split Depth" UCI parameter to
25 This distribution of Stockfish consists of the following files:
27 * Readme.txt, the file you are currently reading.
29 * Copying.txt, a text file containing the GNU General Public License.
31 * src/, a subdirectory containing the full source code, including a
32 Makefile that can be used to compile Stockfish on Unix-like systems.
33 For further information about how to compile Stockfish yourself read
36 * polyglot.ini, for using Stockfish with Fabien Letouzey's PolyGlot
43 This version of Stockfish has support for PolyGlot opening books. For
44 information about how to create such books, consult the PolyGlot
45 documentation. The book file can be selected by setting the "Book File"
49 4. Compiling it yourself
50 ------------------------
52 On Unix-like systems, it should be possible to compile Stockfish
53 directly from the source code with the included Makefile.
55 Stockfish has support for 32 or 64-bit CPUs, the hardware POPCNT
56 instruction, big-endian machines such as Power PC, and other platforms.
58 In general it is recommended to run 'make help' to see a list of make
59 targets with corresponding descriptions. When not using Makefile to
60 compile (for instance with Microsoft MSVC) you need to manually
61 set/unset some switches in the compiler command line; see file "types.h"
62 for a quick reference.
68 Stockfish is free, and distributed under the GNU General Public License
69 (GPL). Essentially, this means that you are free to do almost exactly
70 what you want with the program, including distributing it among your
71 friends, making it available for download from your web site, selling
72 it (either by itself or as part of some bigger software package), or
73 using it as the starting point for a software project of your own.
75 The only real limitation is that whenever you distribute Stockfish in
76 some way, you must always include the full source code, or a pointer
77 to where the source code can be found. If you make any changes to the
78 source code, these changes must also be made available under the GPL.
80 For full details, read the copy of the GPL found in the file named