bunnies

A fast chess library for chess engines. Currently in alpha.

Current Features

• Game state representation
• (Pseudo-legal) move generation and application (and un-application)
• FEN parsing and generation
• UCI generation
• Full PGN parsing and generation
  • Support for NAGs and variations (comments are parsed, but not generated)
  • Support for nested variations
• Perft testing
• Game termination detection (and draw detection)

Optimizations

bunnies makes use of the following optimizations:

• Bitboard-based board representation
• Pseudo-legal move generation
• Make-unmake move application (eliminating the need to copy game state)
• Magic bitboards for sliding piece attack generation
• Precomputed attacks for knights and kings
• Zobrist hashing for board state hashing

bunnies is currently able to generate ~15M moves/thread/second (as measured on an M1 Macbook Pro), which is not nearly as fast as programs like Stockfish (which is able to generate ~120M moves/thread/sec under the same conditions).

Contribution

bunnies needs the following to make 1.0.0 happen:

• Identify and remove bottlenecks
• Some more benchmarks
• Some more integration tests
• Is the public API good enough?
• Support for PGN comments
• Unit tests for draw detection
• More docs

Feedback and contributions welcome!