Author: Omid David Tabibi
Date: 13:53:44 09/12/03
Go up one level in this thread
On September 12, 2003 at 16:49:09, Gerd Isenberg wrote: >On September 12, 2003 at 16:39:33, Omid David Tabibi wrote: > >>On September 12, 2003 at 16:34:48, Gian-Carlo Pascutto wrote: >> >>>On September 12, 2003 at 16:33:13, Omid David Tabibi wrote: >>> >>>>I still don't understand why modulus is needed, and >>>>I have a pawn hash of 2^17 entries. What is so special >>>>about pawn hash that you need the modulus operation >>>>there while you don't need it in the normal hash table? >>> >>>You don't? >>> >>>I assume you have 32 or 64 bit hash keys. >> >>64 bit. >> >>> >>>How do you map 2^64 -> 2^17 ? >> >>Please, don't tell me that you guys are mapping the hash key as following: >> >>address = key % table_size; > > >Yes, unless you use zobrist keys and power of two table sizes for pawn hashing, >which is probably smarter. Do you have a smarter way of getting a hashkey from >white/black pawn bitboards? > >> >>??? >> >>Do you know how many cycles does the modolus operation take??? >> > >Yes, that's the reason for my initial posting. > assuming 'table_size' is a power of 2, the following two expressions are equivalent: address = key % table_size; address = key & (table_size - 1); >Gerd > >> >>> >>>-- >>>GCP
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