Re: [linux-audio-dev] real-life 3dnow! results

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Subject: Re: [linux-audio-dev] real-life 3dnow! results
From: est_AT_hyperreal.org
Date: la elo    28 1999 - 02:18:16 EDT

est_AT_hyperreal.org discourseth:
>
> I looked at Intel's online mmx manual and found an instruction that
> cleans up my code a lot. It doesn't seem to speed things up much, but
> it *does* add clipping. It also makes other code optimizations easier.

Such as gaining a further 1.5- to 2-fold speedup by morphing the inner
loop into:

myloop:
        movq (%eax),%mm0
        pfmul %mm2,%mm0
        movq 8(%eax),%mm3
        pf2id %mm0,%mm1
        pfmul %mm2,%mm3
        packssdw %mm1,%mm1
        pf2id %mm3,%mm4
        movd %mm1,(%ebp)
        packssdw %mm4,%mm4
        addl $16,%eax
        movd %mm4,4(%ebp)
        addl $8,%ebp

        loop myloop

Further streamlining is possible..and scary. :)

Eric

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