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Subject: Re: Puzzling Assembler Question

Author: Gerd Isenberg

Date: 00:28:16 02/21/04

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On February 20, 2004 at 13:42:25, Russell Reagan wrote:

>On February 20, 2004 at 07:42:58, Roberto Nerici wrote:
>
>>This was an interesting test that you did. However, my results are a bit
>>different. On a P3-733 and using MSVC6, I found the "Gerd" test the fastest by a
>>fair bit, followed by "table16" and "eugene2", with "eugene" (the one you're
>>using) slower still.


Sorry, the routine called "Gerd" was definitely invented by Matt Taylor!

Gerd

>>
>>I had to make some very minor changes to get it to compile under VC6, but
>>nothing that should make a difference. However, I did then make one further
>>change: I declared the scan routines as __inline and this speeded them all up
>>compared to letting the compiler inline what it wanted.
>
>It probably varies depending upon the CPU you use. I don't trust the test
>results of the bitscans that use 16-bit tables however, because in this test the
>16-bit lookup table will usually get stuffed into the cache. When the chess
>program is running, the entire 16-bit table will rarely be in the cache, so I
>like the ones that use smaller lookup tables better for an actual chess program.



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