Author: Rafael Andrist
Date: 10:43:00 10/22/00
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On October 22, 2000 at 11:26:58, Severi Salminen wrote: >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 I had this idea too. I haven't count exactly, but I think if you must do that 6 times (4 rooks + 2 queens) it would be slower. I generate the rotated bitboards with inline assembly.
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