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Subject: Re: Mixing 0x88 and bitboards

Author: Gian-Carlo Pascutto

Date: 22:43:45 06/25/02

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On June 25, 2002 at 20:07:42, Robert Hyatt wrote:

>>No, this is 1 pawnhashtable lookup. Don't care how you got the information you
>>put in the hashtable, because of the hitrate that's not important.
>
>OK... "is the king in the square of the pawn?"  You can't hash that with
>pawn hashing because the king can be on 64 different squares.

classical (in my program)

5 loads
1 compare

bitboards

3 64-bit loads
1 64-bit AND

Slower on 32-bit, faster on 64.

>"are my rooks connected?"  two loads, an AND,
>and a branch to see if one rook is attacking the other.

I don't see, how this can work :)

You need one load for the Rook bitboard, and how are you going
to check whether the path between them is onobstructed with the
remaining 1 load and 1 AND?

>>Bitboards are best for pawns (imo) but because of the hashtable, it's not that
>>important. (Altough "is this rook behind and not in front of a passed pawn"
>>would save me some time with bitboards instead of what I'm doing now.
>
>that is another example.  No hashing helps there either.  Ditto for questions
>like "does white have an outside passed pawn?" and so forth...

Why wouldn't you be able to hash 'outside passed pawn' ?

--
GCP



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