Computer Chess Club Archives




Subject: Re: Differences between 0x88 ,10x12 and Bitboards!?

Author: Uri Blass

Date: 12:57:27 11/19/02

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On November 19, 2002 at 15:12:15, Russell Reagan wrote:

>On November 19, 2002 at 13:57:02, Vincent Diepeveen wrote:
>>Yet a crucial aspect of evaluating is scanning and that's something
>>where bitboards are handicapped with 1 or 2 exceptions (you can
>>quickly scan a rank or file for presence of a piece X).
>In an 0x88 engine, you have to do potentially 8 tests to scan for the presence
>of a piece on a rank or file. Even if you are lucky enough to have zero branch
>mispredictions (doubtful), you still do 4 increments, and 4 tests on average.

I do not think that you have to do it.
You can remember in a special array the pieces that are in every rank and every
file and increment these arrays after every move that you make.

If you need to check often that quastion then the best thing is to remember the
information in special arrays and to update the arrays incrementally  every time
that you make a move.


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