Author: Mathieu Pagé
Date: 06:51:50 10/22/04
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On October 22, 2004 at 07:14:49, Thorsten Greiner wrote: >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). Thank you, I'll look at it
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