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Subject: Re: Bitboard by any simple engine?

Author: Sune Fischer

Date: 13:09:22 05/29/04

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On May 29, 2004 at 14:41:28, Anthony Cozzie wrote:

>On May 29, 2004 at 14:26:55, Russell Reagan wrote:
>
>>On May 29, 2004 at 04:24:18, Tony Werten wrote:
>>
>>>Yes, you would have to hop to nextsquare to see how it would go from there. Now
>>>you only have to look what square we are talking about, and if !nil, you will
>>>always know that the nextsquare will be given at *sq++
>>>
>>>So you basicly made "nextsq" and "location of nextsq" independant of each other,
>>>thereby making it independant of board representation and making it more
>>>efficient since you will be traveling through the array in a row, rather than
>>>randomly accesed.
>>
>>Would this be any faster than a traditional array based move generator? As far
>>as I can tell, the array based movegen will iterate over an array, while the
>>move table approach loops over a linked list (effectively). Looping over an
>>array will almost always be at least as fast as looping through a linked list,
>>right? Plus the move table approach uses more memory to accomplish the same
>>thing. You may get some other advantages from a move table approach, but with
>>regard to speed, the move table approach doesn't seem like it would be the
>>fastest.
>
>The magic of Vincent's generator is that there are almost no branches and
>relatively little memory.  The two biggest wastes of time in a modern deeply
>pipelined superscalar processor are branch mispredictions and cache misses.
>
>anthony

I really don't understand all the hype about a generator.
I just had a look at a profile, mine spends something like 5% generating moves.
That's hardly worth even looking at to optimize.

It might be due to its incremental design that it's so fast though ;)

Sorting the moves however, now that takes time.

-S.



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