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Subject: Re: 64 bit 90 degree rotations -- a summary from USENET

Author: Rafael Andrist

Date: 04:17:16 06/11/02

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On June 10, 2002 at 18:49:17, Dann Corbit wrote:

>On June 10, 2002 at 17:21:32, Peter Fendrich wrote:
>
>>On June 10, 2002 at 15:47:14, Dann Corbit wrote:
>>
>>Dann,
>>why do you collect these rotating functions?
>>When it comes to me I don't make any rotating during search just during the
>>initial phase when the program starts.
>>During search it is lookups in order to get the rotated file or diagonal.
>
>Suppose that you wanted to switch from 0x88 to bitboard, and all that you
>maintained was a single, non-rotated bitboard when in 0x88 mode?

You need to generate the rotated bitboards only once (after each new entered
position). Then you can simply update them wihtout re-generating them all the
time - so I don't see why it is so important for you to get such a fast code for
that. BTW the bitboards rotated 45°, 90° and 135° may be implemented
differently.

regards
Rafael B. Andrist



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