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Subject: Re: Bitboards : why rotate ??

Author: Matthias Gemuh

Date: 12:25:12 03/27/02

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On March 27, 2002 at 13:29:46, Alvaro Jose Povoa Cardoso wrote:

>Could you please explain your scheme?
>How do you compute the rooks and bishops attacks?
>Do you use the Alessandro Damiani algorithms?
>If not, could you explain what you do in some detail?
>
>All I have done so far was a checkers engine.
>I'm in the process of determine a reasonable aproach of speed but without the
>complexity of rotated bitboards (particularly the 45ยบ ones for bishops)
>
>Best regards,
>Alvaro Cardoso


I use an idea from famous Dr. Hyatt.
Precompute squares which could obstruct a sliding piece from moving from "nFrom"
to "nTo" and store results in 64x64 matrix of bitboards (in chess).
An "AND" operation of matrix element (nFrom,nTo) and bitboard "all occupied
squares" yielding 0 means the road is free. Attack !

Regards,
Matthias.



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