Author: pavel
Date: 14:16:07 05/11/02
Go up one level in this thread
On May 11, 2002 at 15:57:38, Daniel Clausen wrote:
>On May 11, 2002 at 15:04:14, pavel wrote:
>
>>On May 11, 2002 at 09:46:49, Vincent Diepeveen wrote:
>>
>>>On May 11, 2002 at 05:48:17, Matthias Gemuh wrote:
>>>
>>>for attacktables, bitboards isn't the fastest thing.
>>>
>>>Bitboards is a tradeoff. You put less information into
>>>a single 64 bits word. So you can use instructions like AND and OR
>>>more easily.
>>>
>>>However to get attacktables you might want to look at gnuchess 4.0 (not
>>>5.0 which was raped and rewritten to bitboards for some unknown reason).
>>>
>>>Gnuchess is putting more information into a single word for each
>>>square. The advantage is you can faster work with complex knowledge.
>>>
>>>The disadvantage is obviously a slowdown in speed because you use
>>>more knowledge.
>>
>>So in short it means, bitboard helps put more information (==more knowledge)in a
>>single square (64 bits?), if that is what I understand.
>>
>
>[snip]
>
>
>Not quite. In a bitboard approach, each bit represents one square of the
>chessboard, and you can store exactly 1 bit of information about each square.
>(ie square is occupued by a white piece or not, square is attacked by an enemy
>knight or not, you get the idea) Storing more information requires more
>bitboards. (1 bitboard for each bit of information :)
>
>Let's compare this to an alternative board representation, say 'int square[64]'.
>In this approach we have an integer (is >= 32 bit, if your compiler is ANSI-C)
>and therefore can store much more information about a particular square.
>
>This doesn't mean that bitboard-programs necessarily are dumber though. (ok,
>mine is :p) Just use more bitboards if you want to use more information :) For
>example Crafty is a bitboard-engine and is quite intelligent, IMHO. (YMMV)
>
>HTH
>
>Sargon
Hey sargon,
thanks for the explanation.
Few questions.
1) Is there any limitation as to how many bitboards I can use per square?
2) Whats an alternative to bitboard approach?
3) How is it better (if it is)?
thanks
pavs
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