Author: Sune Fischer
Date: 01:10:46 09/14/02
Go up one level in this thread
On September 13, 2002 at 20:28:01, Steffan Westcott wrote:
>
>Here is some more material for people interested in flood-fill based algorithms,
>of the ilk I first mentioned in this article :
>http://www.talkchess.com/forums/1/message.html?251180
>
>The following routine determines if a path of set bits in 'path' 8-way connect
>(ie. king move) any set bit in sq1 with any set bit in sq2 (this is the same as
>SquaresAreConnected). Also, it will return an array of bitboards showing all
>possible shortest paths - This is probably best explained by showing an example
>:
Got it :)
I just thought of another application on the passed pawns.
This way one doesn't need a 8x64 byte table or calls to firstone().
I can't say if it's faster than the lookup though, I'll probably
use it anyway.
//===================================================================
// find the passed and semi-passed pawns:
BITBOARD WhitePassedPawns(BITBOARD w_pawns,BITBOARD b_pawns) {
BITBOARD passed=0,tempA,tempB;
int i=0;
tempA=(w_pawns<<8)&~b_pawns;
while (tempA) {
tempB=tempA&rank8;
i+=8;
if (tempB) // a pawn has reached the 8th rank
passed|=tempB>>i; // shift it back to where it originally came from
tempA=(tempA<<8)&~b_pawns;
}
return passed;
}
//===================================================================
(disclamer: I didn't test it, but you get the idea)
-S.
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