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Subject: Re: Pawn hashing without Zobrist keys

Author: Gerd Isenberg

Date: 08:22:39 09/13/03

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On September 13, 2003 at 10:10:17, Vincent Diepeveen wrote:

>On September 12, 2003 at 16:59:13, Dieter Buerssner wrote:
>
>>On September 12, 2003 at 16:53:44, Omid David Tabibi wrote:
>>
>>>assuming 'table_size' is a power of 2, the following two expressions are
>>>equivalent:
>>>
>>>address = key % table_size;
>>>address = key & (table_size - 1);
>>
>>Omid, read over this thread, again. I think, there is no doubt, that Gerd is
>>very well aware of the above. It seems, you are not aware of all the
>>consequences (GCP gave you a hint).
>>
>>Regards,
>>Dieter
>
>I seriously doubt Gerd is aware how slow bitboards are and how difficult they
>are to use in complex software to improve for example ones evaluation function.
>
>Also i seriously doubt Gerd knows the penalty for % at the opteron.
>
>Regards,
>Vincent

Vincent! You are playing games with me :-)
I seriously doubt thet you read my initial post.

About opterons %:

Athlon
DIV  mreg16/32    VectorPath 24/40
MUL  mreg32       VectorPath 6

Opteron
DIV  mreg16/32/64 VectorPath 23/39/71
MUL  mreg64       Double!    5!
MUL  mreg32       Double!    3!

so doing some (32bit) muls instead of one 64-bit mod seems
not to be a bad idea on opteron - if your tables are not power of two sized.
See you in Leiden, where we may discuss about eval topics with bitboards ;-)

Gerd



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