[Mplayer-dev-eng] [PATCH] libac3 SSE support

[Nick Kurshev]

Hi, Felix Bьnemann!

On 2001-07-10 23:36:28 you wrote:

>>>NK> In attach SSE support for libac3.
>>>NK> Please test it and apply if it works, otherwise - simply forget about.
>>>
>>>Great, it works (I've tested with 2.0 and 5.1 48kHz AC3) and it gives
>>>speedup of approx 10-15% on PIII coppermine.
>>>
>>>Btw. grabbed pcm dump of output and it differs, but think it's due to
>>>different srfft algorithm I think, I think it's no prob cause it
>>>sounds ok (did diff of audiodump.wav of mplayer with --disable-sse and
>>>--enable-sse).
>>>
>NK> The same problem was with old mp3 stuff, IMHO. It's normal since P3 has
>NK> minor different precision for FPU and SSE units (I still don't study this question
>NK> in detail). But problem is not in algorithms since there is used same algorithm
>NK> for all types of decoders (SSE, 3DNOW).
>
>NK> Maybe you'll want port dct64_3dnow.s (dct64_k7.s even better) to SSE as
>NK> dct64_sse.s? At least phases 1-5? They can be simply converted from
>NK> 3dnow to sse, but phases 6-10 could be interleaved with 1-5 to get better
>NK> performance. (I think that per 1 SSE opcodes need 2 FPU opcodes to load
>NK> cpu optimally).
>of course I'd like to, question is if I manage, think I'll get the
>basic stuff, but some of the complex instructions sometimes confuse
>me.
>But I'll take a look at it.
>
>Btw. how are instructions with 3 parameters converted from intel to
>at&t syntax?
>
In reverse order ;)
If you mean shufps or pshuw then:
Intel syntax:
shufps mm0, mm2, 5
at&t:
shufps $5, %mm2, %mm0

Best regards! Nick (2001-07-11 10:25:56)


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