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Subject: Re: Acknowledgement MMX-Flood Filler

Author: Gerd Isenberg

Date: 13:43:36 09/13/02

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On September 13, 2002 at 15:57:51, Sune Fischer wrote:

>On September 13, 2002 at 14:36:21, Gerd Isenberg wrote:
>
>>On September 13, 2002 at 04:07:55, Sune Fischer wrote:
>>
>>>On September 12, 2002 at 21:19:08, Gerd Isenberg wrote:
>>>
>>>>Hi all,
>>>>
>>>>My first MMX-Routine (MSC inline asm) that gains considerable performance!
>>>
>>>Wow, that's great. How much faster do think it is?
>>>
>>
>>A loop of 100,000,000 * 2 calls with the two sample pathes take (XP2.1):
>>
>>C-Version with inlined shift    80 seconds
>>shlightly improved mmx version  56 seconds
>>10fold unrolled boolean mmx     35 seconds
>>
>>I find with paddb a nice replacement for left shift one (board right) with no
>>need to mask for byte-wraps.
>
>I notice you do a lookup into the table scBBOfBit.
>I found that doing the shift on the fly was a tiny bit faster, I imagine with
>MMX that the gain would be even larger, have you tried it?
>
>-S.

Ahh, not yet. But can you tell me an easy way to get a 0x00...0001 inside a mmx
register? You have to do a read a bitboard via memory. Therefore the lookup
saves the shift, but otherwise it's more cache friendly.

Gerd




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