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Subject: Re: Truly stupid bitboard question -- why rotate them?

Author: Greg Lazarou

Date: 17:44:59 03/22/99

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Do you really rotate them, or do you maintain the board in straight, 45 degree
(diagonals), 90 degree and 135 degree angles throughout?

Greg

On March 22, 1999 at 18:29:07, James Robertson wrote:

>On March 22, 1999 at 17:06:44, Dann Corbit wrote:
>
>>I understand that you can represent a chess board as a rotated bit sets.  But my
>>significantly stupid question is "Why rotate them -- what is the advantage?"
>
>To generate moves, you extract 8 adjacent bits from your 64-bit bitboard. This
>works great for rank moves since they are already perfectly lined up. But if you
>want to get file moves, you can't extract every 8th bit, and diagonal moves are
>even worse. If you rotate the bitboard, you can extract file and diagonal moves.
>
>James



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