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

Author: Peter Fendrich

Date: 13:48:00 10/23/02

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On October 23, 2002 at 10:29:27, Gerd Isenberg wrote:

>On October 23, 2002 at 03:36:58, Peter Fendrich wrote:
>
>>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
>>
>>Yes, I saw your mmx code but didn't think that c-code could match that. Maybe
>>64-bits processors would make a difference.
>
>Yes, with hammers sixteen general purpuse registers even c-code may be faster
>then.
>
>>BTW your link is outdated!
>>Peter
>
>oups, only valid for one week. If you like, i may send it by mail

Yes, please!

>- or hopefully it goes to the archives soon,

It will take some time IIRC.


>specially the replies of Steffan.
>His point was that i lose information, if i combine the directions to early into
>the final attack set register. His Idea is to hold eight disjoint direction sets
>for all sliding pieces, to gain really from generating attack sets for multiple
>pieces. These sets anded with ~ownPieces may be usefull as a kind of movelist
>entry with implicite bookholding.
>
>I stated that i use the mmx-stuff now in IsiChess instead of rotated bitboards,
>without changing function interfaces (so far).
>Due to valid move generation the winner is currently a mmx-routine, that gets
>all attacks by all pieces of one (opposite) side. So i get all tabu squares for
>the king to move. Instead of calling multiple getAttackedBy for possible king
>move (castle) target squares, i call getAllAttacks once.
>I made also dedicated mmx-routines for determing pinned pieces and covered
>checkers (remove checker?).
>
>Gerd

You, Steffen et al have posted some interesting ideas about this!
I'm using rotated bitboards as described by Bob Hyatt (but a somewhat different
implementation). I have to be very convinced before I rewrite all that stuff!

Peter



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