Author: Sune Fischer
Date: 02:48:16 09/13/03
Go up one level in this thread
On September 13, 2003 at 05:32:29, Gerd Isenberg wrote: >>>I guess a 32-bit key, >>>incremental updated if pawn structure changed, is good enough to address the >>>pawn hash table. >> >>Why consider 32 bit? >>You have the 64 bit zobrist table already in cache. > >I use the pawn-bitboard signature anyway to make sure that there is no >collision. So i only need a 15- or 16-bit key as table index. > >> >>You're a bitboarder, think 64 bit and drop the 32 bit kludges.. ;) >> > >Sure, but if i need less than 33 bits it seems a waste of space and time to use >64 bits - even on opteron. You still have the 32-bit gp-registers with one byte >shorter opcode. Note that "int" is still 32-bit in msc for AMD64. You have already loaded this data (into registers?) when updating the normal key, you just repeat the process for the pawn key while you're at it. No table access needed for the second update. >It is even possible to pack two 32-bit ints inside one 64-bit word and do >simd-like processing. On the other hand one (or compiler) should avoid memory >size mismatches. Yes, make life easier - stick to 64 bit ;-) -S. >Gerd > >>-S. >>>Gerd
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