Author: Andrew Dados
Date: 17:36:36 09/16/99
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On September 16, 1999 at 20:24:45, Robert Hyatt wrote: >On September 16, 1999 at 12:38:41, Andrew Dados wrote: > >>On September 16, 1999 at 12:19:24, Tom Kerrigan wrote: >> >>>The overhead of separating 24 bits is trivial: >>> >>>(hash_key >> 40) >>> >>>-Tom >> >> Well.. you have to detect pawn moves/captures exactly as in 'normal, 2-key >>way', separate that, xor, mask topmost bits and finally combine back. No real >>gain when you think of that. (otherwise xor would screw both 'parts' of key). >>But that of course only for xor way... >> -Andrew- > > >You probably wouldn't have to do this... you would just put bits in the right >part of each of the random numbers you xor in/out. IE pawns only have bits on >the right end, pieces only on the left.. then you would ignore which is which. If I did that, I would end up with a pawn signature dependant on what pieces was moved and where... because even xoring with all zeroes would change pawn signature part bits (talking 24 pawn bits here). > >However, on a PC, if I did this, I would just do two 32 bit values separately >to avoid the overhead... That's only way to make this efficiency idea efficient, imo (or 64/32 separate signatures, but then 96 bit divide (or modulo) operation is needed - so I'll wait for merced with that :)
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