Difference between revisions of "Rotated Indices"
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'''[[Main Page|Home]] * [[Board Representation]] * [[Bitboards]] * [[Sliding Piece Attacks]] * Rotated Indices''' | '''[[Main Page|Home]] * [[Board Representation]] * [[Bitboards]] * [[Sliding Piece Attacks]] * Rotated Indices''' | ||
| − | [[FILE:Mittman_Yellow_Cherries.jpg|border|right|thumb|link=http://www.barbaramittman.com/Site/Yellow_Cherries.html| [[ | + | [[FILE:Mittman_Yellow_Cherries.jpg|border|right|thumb|link=http://www.barbaramittman.com/Site/Yellow_Cherries.html| [[:Category:Barbara Mittman|Barbara Mittman]] - Yellow Cherries <ref>[http://www.barbaramittman.com/Site/Still_Lifes.html Still Lifes] by [[:Category:Barbara Mittman|Barbara Mittman]]</ref> ]] |
'''Rotated indices''',<br/> | '''Rotated indices''',<br/> | ||
Latest revision as of 15:40, 19 December 2018
Home * Board Representation * Bitboards * Sliding Piece Attacks * Rotated Indices
Rotated indices,
a deconcentrated version of rotated bitboards, proposed by Alessandro Damiani [2] as used in his engine Fortress. 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..
See also
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
- ↑ Still Lifes by Barbara Mittman
- ↑ Re: Rotated bitboards by Alessandro Damiani, rgcc, October 31, 1997
