Author: Robert Hyatt
Date: 14:01:44 05/31/01
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On May 31, 2001 at 10:47:27, Bas Hamstra wrote: >>I'm not a factor of 3 slower. That is your imagination working. Somethings >>are faster in bitmaps, some slower. You want to harp on the move generation. >>That is less than 10% of my execution time, so it doesn't count. Evaluation >>is very good in bitmaps. > >For most things, yes, but not everything. If you want to use AttacksTo info >heavily, like some tactical programs do, you have a problem doing that with >bitboards. You could do it either "on the fly" using a couple of dozens >AttacksTo()'s and end up with a *very* low nps. The alternative would be to >calculate AttackTo tables (or even keep them incrementally). Now that is a >problem with bitboards too. It *can* be done, of course, but as a result for >instance Crafty could then divide it's nps by 4 (if not more). > >(and remember I use bitboards myself) I used to incrementally update the attacks_to and attacks_from. It made my program not quite twice as slow, NPS-wise, once I used rotated bitmaps to do the updates. In fact, it was something on the order of 50-60% faster when I stopped the incremental update. But _if_ I wanted that information, I would certainly go back to doing it that way. I just happen to not like using that info in the evaluation. I did for a while and didn't like the result. After taking it out, getting rid of the incremental update was the next natural step. > > >Best regards, >Bas.
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