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Subject: Re: Bitboards : why rotate ??

Author: Tim Foden

Date: 08:10:24 03/27/02

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On March 27, 2002 at 10:51:57, Matthias Gemuh wrote:

>
>Hi Experts,
>I generate moves at 10 million/sec on Athlon 1.4 GHz using unrotated bitboards
>(these include the illegal moves which would leave me in check). Are these 10
>million "pseudolegal"? Is this slow? How many would I generate with rotated
>bitboards?

Well, these simplest way for you to compare is to run Crafty's perf command on
example positions, as Crafty is a rotated bit-board program.

E.g.  After e4 e5 d4 d5 Nf3 Nf6 Nc3 Nc6 we get this position:

[D]r1bqkb1r/ppp2ppp/2n2n2/3pp3/3PP3/2N2N2/PPP2PPP/R1BQKB1R w KQkq - 4 5

On my machine (AXP1700, 1.47GHz) I get this (with an old version of Crafty):

EPD Kit revision date: 1996.04.21
unable to open book file [./book.bin].
book is disabled
unable to open book file [./books.bin].

Crafty v17.11

White(1): easy
pondering disabled.
White(1): setb r1bqkb1r/ppp2ppp/2n2n2/3pp3/3PP3/2N2N2/PPP2PPP/R1BQKB1R w KQkq -
4 5
White(1): perf
generated 37000000 moves, time=1.48 seconds
generated 24949426 moves per second
generated/made/unmade 37000000 moves, time=5.56 seconds
generated/made/unmade 6657070 moves per second
White(1):


So the rotated bitboards generate 24.9 million moves per second here.


However, this doesn't tell the whole story, as rotated bitboards are slower in
MakeMove, but can be faster in the static evaluation (depending on what you have
there).


Cheers, Tim.

>
>Regards,
>Matthias.



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