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Subject: Re: question about when to use local varaibles

Author: Uri Blass

Date: 14:23:05 09/05/03

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On September 05, 2003 at 17:08:43, Robert Hyatt wrote:

>On September 05, 2003 at 16:17:48, Uri Blass wrote:
>
>>I want to have some rule when it is a good idea to use local varaibles.
>>
>>I believe that it is clear that when instead of changing the hash key zob[hply]
>>many times in my makemove it is better to start using local varaible and start
>>my makemove with
>>	__int64 zob=zobkey[hply];
>>and finish it with when hply was already increased by 1 with
>>zobkey[hply]=zob;
>>
>>My question is how many times using the same expression zobkey[hply]
>>justify using local varaible
>
>I don't see any benefit to doing what you are doing.  IE
>zobkey[hply+1]=zobkey[hply]; will make the copy.  The only thing you save
>is the indexing operation needed to access zobkey[hply+1] as you modify it.
>But a good compiler will probably be able to optimize that into a register
>anyway if you make sure that you copy and update it as quickly as possible
>before doing anything else...

I do not see how I do it without loss of speed because of other reasons.
part of the update that I do are only in case of capture or only in case of
castling and if I update it in the beginning without changing more information
then I may have the same if twice.

I will need to check if the move is a capture one time for updating the hash key
and one time for updating the board.

Uri



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