[mythtv-users] VIA C3 Deinterlacing and 3dnow

[Nathan Poznick]

Thus spake Robert Kulagowski:
>  
> > In the documentation though it said that if I check out
> > /proc/cpuinfo that I have mmx and 3dnow, does the C3 just  have a
> > trimmed down version of 3dnow?
> 
> Well, from the docs and a PDF I downloaded from the AMD website,
> 3dnow is supposed to have most of the SSE instructions.  However, I'm
> not a microcode guy, so if someone knows for a fact that either the
> C3 doesn't have all the instructions, or I'm misreading the AMD docs
> and you actually need 3dnow+ or whatever they call it I'll go ahead
> and update.

I know that the C3 lacks the CMOV instruction... that's an optional part
of the Pentium Pro spec... compilers and whatnot are supposed to check
to see if it exists before using it, but there've been some issues with
that I think.  I think it boiled down to the fact that it's not always
safe to compile something as i686 if it's to run on a C3 chip.

Now, if there's some hand-tuned asm in there that uses the CMOV
instruction, that would definately break it on a C3.

-- 
Nathan Poznick <poznick at conwaycorp.net>

I live in that solitude which is painful in youth, but delicious in the
years of maturity. - Albert Einstein

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