Author: Robert Hyatt
Date: 07:49:48 12/06/01
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On December 06, 2001 at 04:57:03, David Rasmussen wrote: >On December 06, 2001 at 00:20:24, Robert Hyatt wrote: > >>I ran the test and you are absolutely correct. 32 bit pawn hash keys >>are not usable. I am not sure when I went to this, but I did look back >>thru my test results in my file at the office, and the last time I did any >>hash sanity testing was when I did use 64 bits. Since I made the change to >>32 I apparently didn't test well enough. >> >>It is a trivial change to fix, and Crafty is now back to 64 bit signatures. >> >>Glad you took the time to test and kept the idea "alive". You were >>certainly correct about the number of collisions... and it has to be >>unacceptable. > >Thanks! Finally... I was beginning to think I was insane or that my computer had >faulty RAM or something :) > >We agree then. Do you think 48 bits could do it? Probably. But it's not worth >the effort, now that you (and I) already have a 64-bit type. The PawnHashTable >doesn't need to be "big" anyway. > >You are saying that Bruce uses 32-bit keys. Is this true? He has the problem >too, then. > >/David I am not sure. I _think_ he said he was using three 32 bit hash values. One to store in the real hash table, one to index the real hash table, and one (pawns only) for pawn hashing. But I might well have not remembered correctly here. My only question right now is how I chose to go to 32 bits without checking it properly. It shows up too easily. Which suggests that I simply "did it" after someone reported that it worked for them. And that is not something I usually do. Which leaves a mystery. why would I go to 32 bits without testing? Or did I simply use a broken test? No idea...
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