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Subject: Re: attacks_from[] and attacks_to[] info

Author: Russell Reagan

Date: 17:10:35 10/23/02

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On October 23, 2002 at 16:48:00, Peter Fendrich wrote:

>You, Steffen et al have posted some interesting ideas about this!
>I'm using rotated bitboards as described by Bob Hyatt (but a somewhat different
>implementation). I have to be very convinced before I rewrite all that stuff!

The one advantage that I see is that if you want to do something such as compute
mobility, you can do this faster with this method, since you can compute attacks
in parallel. I don't believe you can do this with rotated bitboards (but correct
me if I'm wrong). For basic move generation I think you still have to do them
one at a time, since the attack board for 'all rooks' will be different from the
attack board for 'rook on h1'.

I never implemented rotated bitboards, so I can't say how much faster or slower
the C-version of the algorithms will be on a 32-bit machine, but I don't think
anyone ever claimed that they would be faster "on a 32-bit machine." I've only
heard Gerd say that it would be faster on a 64-bit machine, specifically the
hammer.

If it's going to be that much work for you, I'd at least wait until 64-bit
machines are common, or until you can get your hands on a decent one.

Russell



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