AVOIDING ROTATED BITBOARDS WITH DIRECT LOOKUP

Article type: Research Article

Authors: Tannous, S.¹

Affiliations: Durham, North Carolina, USA

Note: [1] Durham, North Carolina, USA. Email: [email protected].

Abstract: This paper describes an approach for obtaining direct access to the attacked squares of sliding pieces without resorting to rotated bitboards. The technique involves creating four hash tables using the built-in hash arrays from an interpreted, high-level language. The rank, file, and diagonal occupancy are first isolated by masking the desired portion of the board. The attacked squares are then directly retrieved from the hash tables. Maintaining incrementally updated rotated bitboards becomes unnecessary as does all the updating, mapping, and shifting required to access the attacked squares. Finally, rotated-bitboard move-generation speed is compared with that of the direct hash-table lookup method.

DOI: 10.3233/ICG-2007-30204

Journal: ICGA Journal, vol. 30, no. 2, pp. 85-91, 2007