Author: Tom Kerrigan
Date: 09:07:27 09/16/99
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What if it was 32 and 32 then? And remember, with this setup, it's not like the "main" hash key is any shorter. It's just divided into two parts. -Tom On September 16, 1999 at 09:44:56, Robert Hyatt wrote: >On September 16, 1999 at 04:00:43, Tom Kerrigan wrote: > >>If you have a program with 64 bit hash keys, is it a good idea to devote n bits >>to pawns and the rest to pieces and side-to-move? >> >>I was thinking a good balance may be 24 bits for pawns, but I have no data to >>back this up. Does anybody else? >> >>-Tom > >If you are going to use them independently to probe tables (ie using the 24 >bits to probe the pawn hash table) then this won't work well. 24 bits is only >16 million possibilities... that will get more than a few collisions. And >the same for the upper 40 bits and pieces. I know that 32 bits is not enough >for normal hashing. Stanback/I ran a bunch of tests years ago in a discussion >on r.g.c.c and we got collisions by the bucketload with 32 bit keys. 64 was >totally safe back then, although speeds are way up now compared to then. I >am using a 32 bit pawn hash signature, but a full 64 bit total hash signature.
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