Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Bitboard question

Author: Gian-Carlo Pascutto

Date: 10:36:46 05/25/02

Go up one level in this thread


On May 25, 2002 at 13:18:12, Russell Reagan wrote:

>I suppose it depends on how much "some shifting/anding" is, because you can
>calculate attacks and mobility using "some adding/testing" (a.k.a ray tracing).
>It seems to me like doing a little shifting and anding isn't clearly superior to
>doing some adding and if testing. So, am I missing something? Perhaps it is a
>slight bit faster and the couple of cpu cycles you save will eventually add up,
>but even with 64-bit computing, this doesn't seem like it would give you this
>giant boost that people talk about. Especially on a 32-bit machine, that
>shifting and anding that you talk about is twice as expensive since it has to do
>it twice for each 32-bit segment. So while it sounds nice when you hear someone
>describe bitboards, is it really that much better? I still don't get it.

1) shifting/anding is completely predictable, the if's are not (big difference!)
2) the 2 x 32 bits operations are fast on superscalar machines (all modern CPUs)
3) I do not believe bitboards are necessarily faster on 32 bit machines

--
GCP



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.