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Subject: Re: Design choices in Crafty

Author: Dieter Buerssner

Date: 13:00:16 06/24/04

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On June 24, 2004 at 11:56:54, Dezhi Zhao wrote:

>On June 24, 2004 at 11:17:50, Robert Hyatt wrote:
>
>>On June 24, 2004 at 09:03:57, Gian-Carlo Pascutto wrote:

>>>2) You need to handle the branch too. The cost of that is going to be way
>>>higher than the cost of setting up/restoring a register.
>>
>>
>>That branch is probably predicted perfectly.  it is "yes" "no" "yes" "no".
>>something the PIV handles well although others do not.

I don't think, that it really matters (speed wise), but I would assume, that it
is not a simple yes no yes no sequence. You can hit qsearch, and no capture
moves are possible. You retract one move, and hit qsearch again, with the same
color to move. Both time eval is called with the same wtm. In other cases, your
yes no sequence will happen. But to me, it doesn't look very predictable at all.
Neither would I think, that it influences speed much (branch predicted correctly
or not). I think, like Gerd, the main issue is easiness of changing the code and
the chance to code some bugs. With basically duplicated code, the probability
for errors will be higher.

I did some speed test for my incheck function. Coding it seperately for white
and black produces somewhat better code. In practice, I found no speed
difference.

Regards,
Dieter




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