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Subject: Re: attacks_from[] and attacks_to[] info

Author: Gerd Isenberg

Date: 16:56:41 10/22/02

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On October 22, 2002 at 19:16:42, Gerd Isenberg wrote:

>On October 22, 2002 at 19:01:43, Peter Fendrich wrote:
>
>>On October 22, 2002 at 18:27:11, Gerd Isenberg wrote:
>>
>>Hi Gerd,
>>I'm not sure I understand this:
>>
>>- snip -
>>>Due to the
>>>simultanious feature this algorithms seem a favorably alternative to rotated
>>>bitboards, even without assembler.
>>- snip -
>>
>>Do you really mean that the c-code in the previous post in this thread is faster
>>than rotated bitboards?
>>
>>Peter
>
>Hi Peter,
>
>I believe yes on 64-bit processors in conjunktion with using this routines with
>sets of multiple pieces.
>
>I use it currently with mmx-registers in Leiden.
>
>http://www.talkchess.com/forums/1/message.html?259095
>
>See also the reply of Steffan using move target set for each direction!
>
>Regards,
>Gerd

Some more improvement is possible if you do several directions in parallel by
arranging the code sequences in an independent way. If enough registers are on
board that gains a lot. (Athlons seems to make four mmx-instructions in
parallel). For hammer i will try to use 128-bit xmm-registers with some
SSE2-assembler instructions, e.g. generating sets for both sides simultaniously.

This routines may also be helpfull in flood fill iterations, looking for pieces
reaching a target (set) in n or less moves.

Gerd



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