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Subject: Re: significant math

Author: Gerd Isenberg

Date: 23:32:50 11/20/02

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On November 20, 2002 at 18:15:49, Steffan Westcott wrote:

>On November 20, 2002 at 15:17:57, Gerd Isenberg wrote:
>
>>Hi Steffan,
>>
>>I guess your serialized move structure containes at least one bitboard, with
>>"ored" singular source and destination boards, easy to separate (source = bb &
>>ownpieces), nice for immediate updating the complete board representation, but
>>some more memory traffic for the move list.
>>
>>I'm also thinking about this issue, inspirated by your recent posts.
>>Doing bit scans and rebuilding a singular bitboard later by 1<<sq all the
>>time...
>
>Avoid anything to do with bit indexing as much as possible! See my reply to
>Alessandro for some detail on my 'movelist' representation.
>

Yes, but my current program does.

>>With a smart finite state move generator, i think it is best looking for
>>validity of killers and may be capture last moved or enprised pieces without
>>further generating and the need of complex bookholding.
>
>I generate all pseudo legal moves in one go (even before looking in the
>transposition table) and initialise my movelist. This avoids repeated work when
>validating moves suggested by the various standard heuristics (history, killer,
>etc).

Aha, i see.

>
>>Don't like the idea of too many recursive bitboards in my node class, happy
>>about throwing some rotated bitboards out. I like your mentioned unique
>>direction target moveboards on the stack.
>
>I don't understand what you mean by 'recursive bitboards'. Could you expand on
>this?

Recursive variables, local variables in recursive functions.
I ment statefull (bookholding) bitboards, which are used during finite state
machine move generation, and therefore needed in every node of a path from root
to leaf.

If i understand it right, that is exactly what you do, as a form of this fixed
unsorted pseudo movelists. I guess eight bitboards for queens and knights each,
four for bishop, rooks and three for pawns and for the king one is enough.

>
>>Btw. is your from/to-hashkey function fast enough to outperform two 64bit scans?
>
>Yes, thanks :-b

Aha, what magic function could that be? Mod sucks...
But you don't need to tell too many implementation details of course :-)

Cheers,
Gerd

>
>Cheers,
>Steffan



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