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Subject: Re: Reversed vs. Rotated Bitboards

Author: Marcus Heidkamp

Date: 23:51:53 01/28/02

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On January 28, 2002 at 10:48:59, Sune Fischer wrote:

>On January 28, 2002 at 10:28:32, Marcus Heidkamp wrote:
>

[snipped]

>>Conclusion: My advice would be to live with as few as possible memory based
>>variables, and reversed bitboards are just too many.
>>
>>Marcus
>
>I agree, but I don't follow. The idea of reversed bitboard is _not_ to use
>lookup tables but instead do some extra operations.
>
>-S.

As far as I understand the reversed bitboard approach, you need additional
bitboards for the different directions of occupied squares to store the game
position - at least four more bitboards. This will make the move generator
slower, at least, that is what I think. I already try to avoid the lookup tables
like the plague... :-)

But we should remember that move generation by itself is only a small part of
the total computation time required by a chess engine. I just do the assembler
stuff for fun, it really won't help a lot for the whole engine.

Marcus



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