https://github.com/paulsonkoly/chess-2

Chess engine
https://github.com/paulsonkoly/chess-2

chess chess-ai chess-ai-engine chess-engine chess-game

Last synced: 3 months ago
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Chess engine

• Host: GitHub
• URL: https://github.com/paulsonkoly/chess-2
• Owner: paulsonkoly
• Created: 2021-12-22T13:26:00.000Z (over 4 years ago)
• Default Branch: main
• Last Pushed: 2025-03-04T15:26:30.000Z (about 1 year ago)
• Last Synced: 2025-03-04T16:34:54.902Z (about 1 year ago)
• Topics: chess, chess-ai, chess-ai-engine, chess-engine, chess-game
• Language: C
• Homepage:
• Size: 337 KB
• Stars: 7
• Watchers: 2
• Forks: 0
• Open Issues: 5
• Metadata Files:
  • Readme: README.md

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README

          
# chess-2

**update: This program is now superseded by [chess-3](https://github.com/paulsonkoly/chess-3).**

Hi, I am a UCI chess engine. I'm the second chess engine my author has written, thus the really unimaginative name, following the first program [chess](https://github.com/phaul/chess). You can find my [lichess profile](https://lichess.org/@/chess-2-bot). Challenge me to a game if you fancy.

# Running the engine

Normally a UCI chess engines requires a GUI. Arena and Banksia are tested with chess-2, but all UCI compatible UIs should work.

You can also run the engine in the console, issuing [UCI](http://wbec-ridderkerk.nl/html/UCIProtocol.html) commands.

# Build

On a linux/unix compatible system with the GNU C compiler and GNU make the engine should build without any tweaks required:

     % cd chess-2

     % make

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I./src main.c -o main.o

      make[1]: Entering directory '/home/phaul/chess-2/src'

      flex -o uci.yy.c uci.fl

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src uci.yy.c -o uci.yy.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src attacks.c -o attacks.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src board.c -o board.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src evaluate.c -o evaluate.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src killer.c -o killer.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src move.c -o move.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src moveexec.c -o moveexec.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src movegen.c -o movegen.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src movelist.c -o movelist.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src pawns.c -o pawns.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src perft.c -o perft.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src pv.c -o pv.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src search.c -o search.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src see.c -o see.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src uci.c -o uci.o

      cc -c -Wall -Werror -pedantic -O2 -g -DNDEBUG -I/src zobrist.c -o zobrist.o

      make[1]: Leaving directory '/home/phaul/chess-2/src'

      cc -Wall -Werror -pedantic -O2 -g -DNDEBUG -I./src -o chess2 main.o src/*.o

# Testing

To build the CI tests install the [cmocka](https://cmocka.org/) testing framework.

     % cd chess-2/test

     % make

      make[1]: Entering directory '/home/phaul/chess-2/src'

      make[1]: Nothing to be done for 'build'.

      make[1]: Leaving directory '/home/phaul/chess-2/src'

      touch .engineobjs

      cc -o test main.o uci_tests.o zobrist_tests.o .engineobjs ../src/*.o -lcmocka 

     % ./test

      [==========] Running 30 test(s).

      [ RUN      ] perft_unit_test1

      [       OK ] perft_unit_test1

      [       OK ] uci_parser_test13

      ...

      [ RUN      ] uci_parser_test14

      [       OK ] uci_parser_test14

      [ RUN      ] zobrist_test1

      [       OK ] zobrist_test1

      [ RUN      ] zobrist_test2

      [       OK ] zobrist_test2

      [==========] 30 test(s) run.

      [  PASSED  ] 30 test(s).

      

# Contributing

New features are created on feature branches. Before a merge to main can happen the feature branch has to run against main using [cutechess-cli](https://github.com/cutechess/cutechess).

     cutechess-cli -each tc=5+3 proto=uci -engine cmd=./chess2_new -engine cmd=./chess2_old -games 128 -concurrency 8 -openings file=../OpenBench/Books/Pohl.epd -sprt alpha=0.05 beta=0.05 elo0=100 elo1=200

The branch should not be merged if there is a significant ELO drop.

## Performance

The `scripts/bench.sh` can be run against a feature branch which runs the engine with the `bench` argument. The script provides statistical analysis of performance improvements.