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Subject: Re: Use of square eval using Bit Boards aka Ed's Rebel Evaluation,but for bb

Author: Russell Reagan

Date: 02:03:08 01/08/03

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On January 08, 2003 at 04:43:12, scott farrell wrote:

>for (sq=0; sq<64;sq++){
>  if(  (mask[sq] & whiteQueenAttacks) !=0)
>    attackers++;
>  if(  (mask[sq] & blackQueenAttacks) !=0)
>    defenders++;
>  ......
>}
>if (attackers>defenders)
>    ATTACK_NOW_!!!!!
>
>atleast this method I dont have ot itereate the actuall attack vectors, and
>avoid slow msb/pop type routines.

If are only interested in the number of attackers, instead of doing a
64-iteration loop, just do a popcount. It shouldn't be any slower than what you
are doing above, and it will only take N iterations when there are N attacks on
the board, so it should always be faster.

As for using Ed's idea with bitboards, I am interested in this too, but it's
late and my brain isn't all here, so maybe I'll have some other ideas after I
get some sleep :)

Russell



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