Author: Ed Schröder
Date: 12:17:03 01/20/03
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On January 20, 2003 at 00:15:31, Scott Gasch wrote: >Hi all, > >I'm pondering a major code overhaul of the engine to implement some ideas I've >been thinking about for a while. One of these is attack tables. So I wanted to >seek the advice of those of you who have attack tables in your engines already. > >First, I assume attack tables are things you want to do incrementally. This >seems really expensive though -- not only do you have to update the squares >attacked by the moving piece but also you have to look for attacks exposed by >the vacated square and attacks blocked by the destination square. I'm not >missing any more clever way to handle this incrementally am I? >Next, on Ed's page he talks a little about attack tables in Rebel. He said he >generates them non-incrementally (in eval from scratch) and he says he only uses >a few bits per side. Like a single P, N, B, R, Q, K bit and a count. I wonder >why not burn a few extra bits and have P, P, N, N, B, R, R, Q, K (10 total): it >would make the square control lookup table much more accurate and not too big (I >get 1M entries)? Doing it in one byte is just a matter of speed, extending the system to 16 or 32 bit would slowdown the process as the processor while indexing must do an expensive SHL instruction every time. Ed >Any feedback / advice appreciated. >Scott
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