Author: Gerd Isenberg
Date: 11:20:38 10/01/02
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On October 01, 2002 at 12:43:41, Olaf Jenkner wrote: >Your stuff is interesting, but I think a chess playing programm can be improved >better by improving the chess algorithm. It takes too much time to get a speedup >of 2 percent by bit tricks. In this time you get a greater improvement if you do >other things. >Anyway, your ideas are interesting! > >OJe Hi Olaf, Of course you are right with the better algorithm. It was a kind of expanding my awareness, after Steffan Westcott teached me about flood fill and Kogge-Stone. And now and then i love this low level assembler stuff so much, specially with these fascinating algos, which seem to be made for mmx-registers. There are always more important things to do, but it's fun, hobby and sometimes obsession. But i think it is more than a few percent. The main feature of this routines is IMHO, that they are able to simultaniously generate all attacks for multiple pieces of one kind and color (even with 128 bit xmm for both colors in parallel). With the same effort than determing all pieces which attack one square, it is possible to get a set of all attacked squares by any piece of one side. If you pass the result of this attackGetters (slightly modified by anding with some mask) to a second call of this routine you get a set of all squares reachable in two moves... There are so many applications, king move (castle) generation, in check move generation, generating check moves, attacking heavy pieces, sorting moves, eval... One nice side-effect is that there is no need for rotated bitboards, and no need to access lookup tables. Regards, Gerd
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