Author: scott farrell
Date: 00:14:19 11/29/03
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On November 29, 2003 at 03:00:08, Gerd Isenberg wrote: >On November 28, 2003 at 21:27:52, scott farrell wrote: > >>Thanx Gerd, >> >>It gave a few percent speedup, funny thing is I didnt think of just fiddling >>with the current code, I was thinking more of ripping it out, or trying a >>non-table based approach. > >May be traversing your bitboards with finding lsb instead of msb is faster. >You should try the approaches of Walter Faxon or Matt Taylor (look in the >archives). I recently posted Matt Taylor's C-routines here: >http://www.talkchess.com/forums/1/message.html?331101 > mmm ... I'll read more when I get a chance, I like the 'read bit and clear' all in one go idea, which is what you do 90% of the time, read one just into order to clear it anyway. >About your incremental make/unmake move algorithm, i did similar in my former >dos-program - but don't like the runtime dependency on the number of changed >controls per move anymore. I used 32-attackTo bitboards only addressed by some >piece index from 0..31 (0..15 white pieces, 16..31 black pieces) and redundant >32-bit piecesets attackedBy[64] for each square. That saves the need of updating >some squares on the ray where sliders move. For instance if a rook (e.g. with >piece index 13) moves from h1 to h2, there is no need to update >controlledBy[h3..h8], because the piecesets don't change. Of course one needs >two arrays, to to map piece indices to squares and vice versa. > sounds interesting. I am early days with incremental attack boards. To start with I am striving for no bugs, so I reset probably more pieces than necessary, to make sure I capture the correct ones. I have a debugMovegen/debugAttack type mode, where it does it both incremently and non-incremently to compare, and halt if they are different. I'll move slowly forward on this front. I already liek the gains in knowing more about the pieces without all the trouble of working it out all the time. It should help heaps when I implement SEE. Thanks again. Scott >Gerd > ><snip>
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