[XviD-devel] recent mmx patch (xvid_bench results)

[jmtest at voila.fr]

So the conclusion is: send my mem_transfer to trash, it's the best place for it.
Sorry for this one.

The H263 rewrite should be better (and speed improvement visible in the bench).
But I missed that  cmov is only available since pentium pro... I will rewrite this part.
Since RC4 we have an exhaustive loop in test_quant(). This goes through all the quant, 
all the input values and compare the C output with the asm output. 
I hope this will avoid the case of bad functions that pass the bench...

Regards,

Jean-Marc



> Message du 13/04/04 à 23h05
> De : Edouard Gomez <ed.gomez at free.fr>
> A : xvid-devel at xvid.org
> Copie à : 
> Objet : Re: [XviD-devel] recent mmx patch (xvid_bench results)
> 
> suxen_drol (suxen_drol at hotmail.com) wrote:
> > err.. i havent had time to weed through the transfer code.
> 
> The error was that the new code was doing the sub operations on bytes,
> to save cycles, but that isn't possible because of overflows, and signed
> 8 to 16 conversions using a simple unpack operation.
>  
> > however the the crash was casused by some conditional moves. the cmov
> > instructions is generally supported by cpus with MMXEXT. my cpu which
> > only has MMX.
> > 
> > * quant_h263_intra_mmx has cmovs. this should be renamed to _xmm and  
> > version developed without the cmovs called '_mmx'.
> > 
> > * dequant_h263_intra_mmx has cmovs. we already have an _xmm version, and
> > i assume it is faster than the _mmx (somebody may want to check).
> > therefore, the cmovs should be replaced.
> 
> Ok doki, we'll just place a test somewhere to avoid that sigill problem.
> 
> -- 
> Edouard Gomez
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