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Subject: Re: Bitboards, pre-computing moves, and blocked squares?

Author: Robert Hyatt

Date: 12:07:29 11/30/04

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On November 30, 2004 at 12:51:38, Andrew N. Hunt wrote:

>Hi!
>
>I've recently implemented bitboards (standard and rotated) and have a question
>about pre-computing moves which contain blocked squares. Let's say I have the
>occupied rank:
>
>bQ, wN, _, wR, _, bP, bN, _
>
>and I want to find the valid moves for the white Rook. How do I handle modifying
>its bitboard rank: 11010110 to remove the blocked squares and only store the
>available squares: 01101100? (which I can then And with the white/black pieces
>to find valid Rook moves)
>
>Maybe I'm missing something obvious... :-?
>
>Many thanks!
>
>
>
>
>

First, generate all the moves (a single bitmap) which captures both pieces at
the end.  Now AND that with ~your_occupied_squares.  That will eliminate the
capture of your own piece, but not moving over empty squares or capturing the
opponent's pieces.



>ah.
>
>--------------------------------------------------------------------=
>Andy Hunt
>Manager, Electronic Documentation
>Wolfram Research, Inc.
>Voice: 217-398-0700  ext.260;  Fax:  217-398-0747
>Email: andy@wolfram.com; http://www.wolfram.com/
>--------------------------------------------------------------------=
>
>Power corrupts.  Absolute power is kind of neat.
> -- John Lehman, Secretary of the Navy, 1981-1987



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