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Subject: Re: Bitboards verses Offsets ?

Author: Stuart Cracraft

Date: 07:18:52 10/17/04

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On October 16, 2004 at 22:31:45, TEERAPONG TOVIRAT wrote:

>On October 16, 2004 at 10:58:17, Ron Peterson wrote:
>
>>     I have seen some messeages about the use of bitboards for move generation.
>>I use a offset approch for my move generator and I am pleased with the speed.  I
>>have enclosed a copy of my "gen_white_knight" code.
>>     My question is what type of speed increase wuold you expect to get in a
>>move generator using bitboard?  50%?  100%?
>
>Hi,
>
>I think bitboards generate move faster especially capture moves. But it's slower
>in makemove() and unmakemove() because it has to update a lot of data.
>However, you can do a lot of tricks with bitboards in eval().  So,if you want to
>compare the two methods, you 've to compare the performance not only speed of
>movegen().
>
>Regards,
>Teerapong

Movegen is not the issue with bitboards.
In fact, it is a drawback. Much harder to implement
movegen with bitboards than with 0x88 or mailbox.

The joy is in bitboard eval-ing.

You should make a hybrid program at first using
mailbox or 0x88 movegen, regular incheck/attack
routines, and bitboards for movegen.

Later, when you have more time or want bigger
challenges, convert to bitboarding using examples
like GNU Chess and Crafty.

I think the next challenge above that is to do
what Slate and Atkin did and that is to maintain
incremental attack tables that are updated after
each makemove and unmakemove.

Stuart




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