Author: Anthony Cozzie
Date: 09:46:23 04/10/04
Go up one level in this thread
On April 09, 2004 at 23:48:36, Christophe Theron wrote: >On April 09, 2004 at 16:51:34, Anthony Cozzie wrote: > >>On April 09, 2004 at 15:26:34, Christophe Theron wrote: >> >>>On April 09, 2004 at 14:27:48, Sune Fischer wrote: >>> >>>> >>>>>Clearly, nothing beats the ugliness of bitboards. >>>> >>>>This may not be the best example to judge by. >>>> >>>>-S. >>>>> Christophe >>> >>> >>> >>>In the contrary, I think it's fairly typical of bitboard code. >>> >>>Elegance is supposed to be the strong point of bitboards. >>> >>>The only thing I find elegant is the pseudo-great starting idea "64 squares <-> >>>64 bits". >>> >>>Passed this point everything becomes unreadable and ugly. >>> >>>I also see it often used to pre-compute attack tables and such, which is in my >>>opinion contrary to one of the most important things I have learned in computer >>>chess: do not compute anything in advance if you are not certain that you will >>>use it. This is not an intrinsic problem of bitboards, it's just that use of >>>bitboards often go along with this misuse of computing resources, is it just by >>>chance? >>> >>>Bitboards are a great tool allowing you to compute very complex things in a >>>blink. The problem is that in a chess program you rarely need to do these >>>complex computations if you know what you are doing, and so you end up with ugly >>>and unreadable code and waste of resources (in particular of L1 and L2 caches). >>> >>>That being said, I do not want to be too harsh: it is probably possible to write >>>a top-level chess program using bitboards, a program that would be not very far >>>behind the programs using more portable approaches like 0x88 and derivatives. >>> >>>Somebody will write one some day. >>> >>> >>> >>> Christophe (setting up a shield for the upcoming flame) >> >>Correct me if I am wrong, but aren't attack tables the exact opposite of your >>"do not compute anything in advance" strategy? >> >>anthony > > > >Absolutely, and I think that computing attack tables at every node is >inefficient, and I do not do it. Some say bitboards can do that quickly, but I >have not use for it. > >Not sure if you have read my post correctly (or maybe I did a mistake?). > > > > Christophe Ah, I thought tiger used attack tables. I seem to remember some post by you where you claimed "Tiger is optimized for determining whether a piece attacks a square" or some such. anthony
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