Author: Dieter Buerssner
Date: 11:18:38 06/20/02
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On June 20, 2002 at 14:08:52, Tom Kerrigan wrote: >I can't imagine Crafty adds or subtracts bitboards much...? So this wouldn't be >a big problem. Sorry, I perhaps don't understand your comment. I think, I have rather clearly written: "I mean cases with |,&,^" BTW. A usage of + and - for chess engines could be hash tables. Instead of "xoring" the new piece on the new "to-square", one could add it. Research and theoretical insight on lagged Fibonacci pseudo random number generators (which are somewhat related to calculating a hash index for a chess position) has shown, that add/subtract is much preferable to xor. But still in this case, adding two unsigned 32 bit number pairs, and ignoring the carry/overflow flag would be essentially the same, and could be done efficiently from high level language without a native 64 bit type. Regards, Dieter
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