Author: Robert Hyatt
Date: 15:36:08 10/19/99
Go up one level in this thread
On October 19, 1999 at 18:19:41, Daniel Clausen wrote: >Hi > >On October 19, 1999 at 11:23:30, Robert Hyatt wrote: > >>On October 19, 1999 at 07:45:33, Antonio Dieguez wrote: >> >>>I have read somewhere "atacking bitboards" >>>What are exactly them? it has for example the data about all squares atacked by >>>white and black? but how are they updated? it looks very complicated. >>> >>> >>>me. >> >> >>It is somewhat complicated, but doesn't have to be computationally expensive. >>IE for non-sliding pieces, you can simply look up in a table to find which >>squares a piece on "SQ" attacks. For sliding pieces it is more complicated, >>but rotated bitmaps turns this into a series of table lookups as well.. > >I'm using bitboards in my chess engine and I'm concentrating on the eval >for once. [:)] I noticed that as long as I can't answer questions like >"is square XY attacked by the opponent" and things like dat, then my eval >tends to be too static, ie it plays the same moves in all games. (more or >less :) > >Ideally I would have a bitboard attacks[64], which shows has all the pieces >attacking a certain square. If I don't have that, I basically have to >make a testCheckForSquare(XY). > >So I'd like to implement these attacks[64] bitboard, but they prolly should >be updates incrementally after each move. :) Do you think this is possible >in a reasonable amount of time? I thought about that for some time, but every >time I do this my head hurts after 10 mins because it seems rather complex. >So, the question to all bitboard hackers is: do you think this is a good >idea? :) > >Kind regards, > -sargon Yes, you can compute them. Early versions of crafty (prior to rotated bitmaps) did this. I found that the cost was more than the benefit however, and don't keep them any longer... but I do use that same sort of information, in (say) Swap(), but I just compute it as needed... You should try it both ways, as programs are different...
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.