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Subject: Re: SSE2 bit[64] * byte[64] dot product

Author: Russell Reagan

Date: 00:05:47 07/20/04

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Hi Tony,

Did you get the email I sent you about a post you made here? My email is a
little unreliable sometimes, and my emails don't always reach their destination.
Anyway, I'll ask you here. This is your post, to refresh your memory. My
question is at the end.

On July 01, 2004 at 02:50:35, Tony Werten wrote:

>Hi all,
>
>although I like the principle of bitboards, it really bothers me that I can't
>seem to find a decent/fast way to evaluate weighted safe squares.
>
>Suppose I want to (simple) evaluate a rook, I generate a bitboard with all
>reachable squares and mask off the squares attacked by lower pieces (that's no
>problem).
>
>(This doesn't exacly generate safe squares, only the ones that aren't attacked
>at all by opponents pieces are, for the remaining squares one would need a SEE,
>but that's not the point )
>
>Now I can use this bitboard ( say rook on e4 ), mask the rank state, and look in
>a precomputed table how this rankstate scores on an e rank. No problem.
>
>But how to do the files ? If I use the rotated board, I need to have the
>opponents attackboard in this rotated board as well, wich would be very costly
>to compute (ie also for the bishops,queens ) and very complicated.
>
>Any ideas ? Am I missing something ?
>
>BTW, doing a popcount isn't a solution, since it violates the elegance of
>bitboards ( and is slow ?)
>
>Tony

So the main problem is that you can't *efficiently* generate attacks in a
rotated form, right? My question is, if I could generate attacks in a rotated
form at the same speed as normal attacks, would this be an acceptable solution
to the problem?



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