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Subject: Re: Yet another bitboard question (YABQ)

Author: Sune Fischer

Date: 02:27:05 08/04/02

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On August 04, 2002 at 04:35:02, Russell Reagan wrote:
>
>I actually was thinking about all of what you were just saying earlier today. I
>am looking over the source code of all of the bitboard engines that I have, and
>figuring out how they all do stuff, and what operations are needed, which
>bitboards are needed, and so on. I'd probably just go nuts with bitboards, have
>bitboards for "pawns and king" or something, just in case I ever wanted to use
>it :)
>
>So basically what I'm doing now is trying to determine which ones I need and
>which ones are overkill. Maybe you can tell me how I'm doing. For example, I
>don't think you need an "all pieces" bitboard, since you can compute it via
>(whitePieces | blackPieces) which is a single OR operation (well, more on
>32-bit, but...). That is cheap compared to the cost of keeping up with an "all
>pieces" bitboard and incrementally updating that one at every node just to avoid
>the single OR operation. So that makes me think "all pieces" is overkill. Is
>that right or not? Then again, there is the need to use "all pieces" to compute
>the rank/file/diagonal states. Hmm...help?

I decided to keep the all occupied board, it's cheap to generate like you said,
just one OR at the end of makemove.
I haven't test if doing the OR on the fly is faster, of course it also depends
on how often you need it.

-S.
>Russell



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