Author: Jean Efpraxiadis
Date: 07:32:55 06/02/03
Go up one level in this thread
On June 02, 2003 at 02:04:23, Russell Reagan wrote:
>On June 01, 2003 at 23:41:58, Jean Efpraxiadis wrote:
>
>>If the location of each piece of the board was stored in a array and updated in
>>make and unmake move, so that the move generator could use these locations
>>instead of taking the board square by square, that would be fine. I am not
>>looking for a bitboard implementation of TSCP. I doubt someone took the trouble
>>to modify TSCP that way. Anyway, a version of TSCP with hash tables would do
>>still do it for me. The rest I am willing to do myself if I have to.
>
>I didn't mean to redo the entire thing in bitboards. I think it would be much
>simpler and easier to use two bitboards as "piece lists" and work with those, as
>opposed to working with an array and updating that (which gets tricky if you're
>not careful.
>
>Since I was bored and tired of working on my own program for today, I made a few
>changes to TSCP to support piece lists in this way, using bitboards. The basic
>idea is that I replaced the loop over the whole board:
>
>for (i = 0; i < 64; i++) {
> // code goes here...
>}
>
>With this (hope you understand how bitboards work):
>
>/* Bitboard occupied[2]; */
>
>Bitboard pieces = occupied[side];
>while (pieces) {
> i = SomeBit(pieces); // Get the index of some bit (doesn't matter which)
> pieces ^= MASK(i); // Clear the bit
> // code goes here...
>}
>
>You can find the code that I made changes to at
>http://home.attbi.com/~rreagan/tscp_bb.zip
>
>Any changes I made are commented in one of the following ways:
>
>/* BEGIN BITBOARD STUFF */
>// ...
>/* END BITBOARD STUFF */
>
>/* BITBOARD STUFF ADDED */
>/* STUFF REMOVED */
>
>I changed every loop over the entire board in board.c and eval.c and it runs 13%
>faster now (according to nps and time, using the 'bench' command). Maybe an
>array based piece list would be faster, but this seems easier, at least to me.
>
>I also got different node counts when I ran the 'bench' command with the new
>version, so there might be a bug somewhere, but as far as testing the speed gain
>I think it's fairly accurate.
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