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Subject: Re: Bean counters Part2

Author: Peter Fendrich

Date: 07:58:28 08/20/98

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On August 19, 1998 at 22:58:12, Ernst A. Heinz wrote:

>On August 19, 1998 at 15:27:10, Peter Fendrich wrote:
>>
>>continuing from Part1...
>>
>>Method C (The Hacker trick without loops. Used by DarkThought)
>
>Peter,
>
>"DarkThought" is surely not the only one to use this famous HACKMEM trick.
>But my article about "How DarkThought plays chess" explicitly mentions your
>method A, too. The looping scheme is known to produce the best results
>for sparsely populated bitboards. Therefore, we use normal and sparse
>popcount functions/macros at different places in the code depending on the
>expected population density of 1-bits. In the static evaluation function
>the density is mostly low such that we use the sparse scheme there. During
>move generation, however, you often encounter biboards that benefit a lot
>from the HACKMEM scheme because they are heavily populated with 1-bits.
>
>=Ernst=

I've never seen the algorithm before I read about it in the DarkThought article
in ICCA Journal (or was it in you hompage? I don't remember).
It seems to be a good approach you have but I don't count bits at all in move
generation. What do you use it there for?
//Peter



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