Author: Robert Hyatt
Date: 11:04:57 12/03/97
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On December 03, 1997 at 10:16:00, Don Dailey wrote: >Hi Bob, > >Thanks for the encouragement. I haven't tried rotated bitboards but >they sound like a good thing. How are you using them? In move >generation >evaluation or both? both. Move generation for sliding pieces becomes simple table lookups. Mobility calculations for evaluation becomes a table lookup as well... and there's no need to incrementally update attack tables any longer, because you can look them up just as fast as you can load the old incremental ones... and save all the work in make/unmake... > I have a feeling that it may take some time before >bitboard stuff is completely understood. I think it took a while >before >offset programs developed to the point they are today. There will be >some tricks and techniques that we haven't even thought of and our >techniques >will improve. Rotated bitboards may be a typical example of this kind >of thing. I only heard about them a couple of months ago but have yet >to experiment with them. I assume you keep all copies of rotated >boards >up to date during move making? yes... but there are only 3 extra ones, the normal occupied squares bitmap, and three rotations to make the files and two diagonals appear in adjacent bits... > >Keep up the good work. I will share any new things I pick up with the >whole group. > >Don be looking forward to it. :) Bob
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