Author: Dieter Buerssner
Date: 09:23:47 12/19/03
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On December 19, 2003 at 09:31:33, Uri Blass wrote: >12 bits for the squares of the kings [...] >castling rights is 4 bits 12 bits are enough to store 2 kings icnlusive castling rights: just one additional precalculated table is needed to translate kk and castling rights to a 12 bit number. There are 3612 legal kk positions without castling. Only few of those can have castling rights, and 4096 is enough to store them all. I think, it is not really worth the effort. In my perft HT, I use 4 bit per square -> 32 bytes for storing the pos (+ep etc.). So you can save about 10 bytes. I also store 2 depth and 2 8 bit counters (for really large perft 3 depths might be better). For fast lookup before going through the array, another 32 bit Zorbrist key. So, the relative size you can save does not look too attractive to me. You may get perhaps 20% more hash entries in the same RAM. Regards, Dieter
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