Rotated+Indices

a deconcentrated version of rotated bitboards, proposed by Alessandro Damiani as used in his engine Fortress.
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 * [[image:Yellow_Cherries.jpg link="http://www.barbaramittman.com/Site/Yellow_Cherries.html"]] ||~   || **Rotated indices**,

Instead of using rotated bitboards with packed 15 diagonals and 15 anti-diagonals each, Alessandro applies an array of 16 + 30 rotated indices for all 16 orthogonal and 30 diagonal lines on the board. Those indices are incrementally updated during make/unmake, which takes a tad more effort - but once updated, the rotated indices pay off, the more often they are used inside a node of the search. No further computation is required to look up attacks, pure indexed memory accesses.

The possible disadvantage - rotated indices, similar or slightly worse than rotated bitboards, are not as versatile as techniques relying on one occupancy bitboard only - if it is about a temporary change of the occupancy on the fly for x-rays and pinned pieces etc.. || toc =See also=
 * Barbara Mittman, Yellow Cherries ||~  ||^   ||
 * Flipping Mirroring and Rotating
 * Fortress
 * Rotated Bitboards
 * Rotated Indices in Gk

=Forum Posts=
 * [|Re: Rotated bitboards] by Alessandro Damiani, rgcc, October 31, 1997
 * [|Re: Resources about rotated bitboards] by Alessandro Damiani, CCC, January 16, 2004

=References= =What links here?= include page="Rotated Indices" component="backlinks" limit="10"
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