Bitboard Engine

The advantages of bitboards in computer chess spring from the fact that trivial bitwise operations on them suffice to answer interesting questions about pieces on a chess board. For example, imagine a bitboard with 1-bits representing all squares attacked by white Pawns and another bitboard with 1-bits indicating all black pieces. A bitwise AND operation combining both these bitboards yields a result bitboard with 1-bits for all black pieces attacked by white Pawns. Because computers normally excel at bitwise operations while performing them on all bits of their natural word length simultaneously, bitboard usage proves to be very efficient.

The early proponents of the bitboard approach introduced all the basic principles of bitboard-based move generation, piece-attack detection, and positional evaluation [2,60,116,191,214]. Their publications contain a wealth of information about traditional bitboard techniques that will not be repeated here. Instead, this article focusses on the bitboard infrastructure and the fundamental principles of rotated bitboards as pioneered by DARKTHOUGHT.


Created by Ernst A. Heinz, Thu Dec 16 23:28:11 EST 1999