Author: Robert Hyatt
Date: 11:57:11 01/08/03
Go up one level in this thread
On January 08, 2003 at 04:43:12, scott farrell wrote:
>My chompster is bit board .... bit boards rule 4ever !!!
>
>I really like Ed's code for eval/SEE, call it what you like, by calculating all
>the attack and defend squares.
>
>MSCP does this to a lesser extent.
>
>Crafty doesnt seem to do it at all. Robert, am I correct here? do you eval each
>square in a 64 byte array at all? I couldnt see it.
No, no need to.
>
>Having used bitboards in chompster I have almost no loops anywhere in my
>program. 1 or 2 for move generation, and 1 for move ordering and 1 for searching
>each move, and only a very few in eval but all guarded by a simple bit board &
>so they dont fire too often.
>
>The only way I can think to implement the above, it to iterate over each
>attackBoard for each piece, which I have available during eval, but I dont
>really want to iterate over it, yuk ... too sssllloooowwwww.
That is what you have to do in SEE...
>
>It seems to me, without bit boards, you have to iterate everything, so it seems
>no problem to be iterating over attack vectors. But for us bit-boarders it seem
>ugly (too me anyway).
>
>All I could think of was to keep each attackVector for each piece. And when
>traversing each quare on the board, do something like this:
>
>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.
>
>Any help / ideas appreciated.
>
>Scott
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