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Subject: Re: bitboards and MMX registers

Author: Rafael Andrist

Date: 09:32:21 08/21/01

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On August 21, 2001 at 06:28:00, Dominic C. Marcello wrote:

>Has anyone out there written (or thought of writing) a chess program using
>bitboards that utilizes the 64 bit MMX registers on the P6 and later chips? I've
>begun work on one, with the parts requiring the MMX registers in assembly
>(NASM), and would appreciate anyone who can give me pointers on how best to go
>about it.

I use 64-Bit-MMX registers. You can speed up this parts of the program around
50-100 percent. But don't forget to inline this code because all this gain can
be lost be function call overhead. I wrote only some small parts of the code
this way, because it's very difficult to change optimized asm code.

My program doesn't use special MMX instructions and therefor it runs also on a
P1 with MMX. The P3 offers some nice instructions like psadbw (useful for
population count), but I don't see why to use special P6 specific instructions
in the near future.

Rafael B. Andrist



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