Author: Severi Salminen
Date: 08:26:58 10/22/00
Hi!
I have started again from scratch to program a chess engine, now with C. I came
to this solution to generate rook moves without rotated bitboards:
I wont show you everything :) but here is some code from my mov_gen routine. E
holds all the pieces on board, j is the position of our Rook (0=H1 and 63=A8). F
is an empty bitboard and D holds the horizontal squares which we can move to
(calculated before this)
// Aligning the file info to right corner of bitboard and clearing all other
// bits:
E=(E>>(j&7))&0x0101010101010101;
for(k=0, F=0;k<8;k++)
{
F|=E;
E>>=7;
}
F&=0xff;
//After the loop F holds the file info and we can fetch the squares from
//a pre-compiled table and OR them with the horizontal destination squares
D|=FileMoves[j>>3][F]<<(j&7);
What I'd like to know if anyone has tried to compare this method with rotated
bitboards and I'd like to know if this is a lot slower (or faster;). I _must_ do
this loop (which can be optimized a little...) for every rook but I don't have
to update rotated bitboards at all after I make moves. Maybe the net speed is
quite equal and depends on move ordering and so on...Opinions?
Severi
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