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Subject: Re: Pawn hashing without Zobrist keys

Author: Gerd Isenberg

Date: 13:49:09 09/12/03

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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.

Gerd

>
>>
>>--
>>GCP



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