C++ Chess Engine that analyzes a chess position and determines the best possible moves based off of evaluation of the current position, as well as the analysis of different positions that can occur N moves ahead. In chess programming, chess engines can evaluate billions of positions depending on the depth of moves calculated, which requires code to be as efficient as possible.
The chessboard is represented by a 64-bit unsigned integer (bitboard) where each bit represents a square on the chessboard. A set bit in the bitboard corresponds to a square being occupied by a piece. Multiple bitboards are required to represent a chessboard, one bitboard per piece for each colour, and 3 bitboards representing if a square is occupied by a white piece, black piece, or either. Bitboards are useful as multiple bit manipulation techniques/algorithms can be used to optimize the code.
In order to generate legal moves, the engine needs to know what moves for each piece are actually possible. To avoid recalculating the moves of a piece in the same position multiple times, precalculated move/attack lookup tables are generated for each piece and square beforehand so possible moves takes O(1) time.
https://www.chessprogramming.org/Main_Page https://web.archive.org/web/20071026090003/http://www.brucemo.com/compchess/programming/index.htm https://www.youtube.com/@chessprogramming591/featured https://www.youtube.com/@BlueFeverSoft https://www.codeproject.com/Articles/5313417/Worlds-Fastest-Bitboard-Chess-Movegenerator