Author: Thorsten Greiner
Date: 04:14:49 10/22/04
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On October 21, 2004 at 22:49:28, Mathieu Pagé wrote: >I just read this paper by Robert Hyatt on rotated bitmap: > >http://www.cis.uab.edu/info/faculty/hyatt/bitmaps.html > >It describe how to generate attack_to[] and attack_from[] bitmaps. I think those >tables are not updated incrementaly and are computed from scratch at each node. >Am I right, or is there a efficient way to do it incrementaly ? I think crafty computes this information 'from scratch'. If you want to see how to update these tables incrementally you may want to look at the source code of my chess program Amy. Amy updates attack_to[] and attack_from[] incrementally in true CHESS 4.x fashion. >Moreover, it seem to me that attack_to should be computed "on demand" only, >since we will probably not use every square of it. So it could be a function : >attack_to(int sq). Does this make sense ? For non-sliding pieces, attack_to is constant. For sliding pieces, attack_to can be efficiently calculated using rotated bitboards. Actually, that is the whole point of rotated bitboards (at least most of it).
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