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Subject: Re: question about move generation.

Author: Frank Schneider

Date: 12:46:00 11/16/99

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On November 16, 1999 at 13:01:40, Peter Kappler wrote:

>On November 16, 1999 at 11:32:45, Antonio Dieguez wrote:
>
>>about "high perfomance move generation", anybody have tried to generate moves
>>incrementally? I mean in the same way you update bitboards or any other aspect
>>of the board?, for example after 1.a2-a3 a7-a6, you would never generate queen
>>moves, as you already now that the available moves of her will not change if the
>>from and to squares of that moves are not connected with her, and so on, trying
>>to generate only the neccesary moves of each pieces, its more complicated but it
>>works and am sure it has been tried, but is better?
>
>Hi Antonio,
>
>I've thought about trying it, but it's definitely complicated.  I think Bob
>started this way on Crafty and then switched back.  I'm pretty sure a few others
>have tried this, hopefully someone will post some performance comparisons.
>
>--Peter

Hi,

Gromit 2.20 uses incremental movegeneration. About 50-80% of the moves
can be reused.
Every piece has its movelist. When a move is made attacktables are updated
and an 'affected' bitmask (2x16 Bit) is computed. Only moves of affected
pieces have to be generated later.

Works quite well if you have to update attacktables anyway.


However, the overall gain in performance is small.

Frank



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