Author: Gerd Isenberg
Date: 14:07:53 05/06/04
Go up one level in this thread
On May 06, 2004 at 17:03:56, Robert Hyatt wrote: >On May 06, 2004 at 16:59:57, Sune Fischer wrote: > >>On May 06, 2004 at 16:07:16, Robert Hyatt wrote: >> >>>On May 06, 2004 at 13:00:06, Mathieu Pagé wrote: >>> >>>>Hi, >>>> >>>> Actualy my engine use pre-calculated bitboards to generate the moves. and I was >>>>asking myself if compressing them, in order to keep them in cache would make my >>>>move generator faster. I tought about two techniques to compress them. >>>> >>>>1. Use a 7 bits mask as a representation of the occupancy of the line as we >>>>always know that the position where the piece that we want to move is occupied. >>>>I already use this and it cut the space used by the index by a factor of two. >>>>I'm sure you were all aware of this trick. >>> >>>What about using a 5-bit mask then. You don't need the two endpoint bits anyway >>>as you attack those squares whether they are occupied or not. >> >>What if the square is on the edge and thus already removed? >>Seems you end up with some being 5 bit and some being 6 bit lines. > > >Doesn't matter. Remember that you already know whether you are on the edge or >not. The only thing that matters is the occupied squares between the two >extreme points. That is why I currently use 6 bits. But by removing the bit >for the piece being tested, that would/could drop to 5. > > >> >>>I use 6 bit myself as squeezing out the square the piece is on is not >>>convenient... >> >>-S.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.