[FFmpeg-devel] r9017 breaks WMA decoding on Intel Macs

Michael Niedermayer michaelni
Thu May 31 20:21:13 CEST 2007


On Thu, May 31, 2007 at 04:44:33PM +0200, Guillaume Poirier wrote:
> Hi,
> Zuxy Meng wrote:
> > 2007/5/31, Guillaume POIRIER <poirierg at gmail.com>:
> >> On 5/31/07, Trent Piepho <xyzzy at speakeasy.org> wrote:
> >>> On Thu, 31 May 2007, Guillaume POIRIER wrote:
> >>>> On 5/30/07, Michael Niedermayer <michaelni at gmx.at> wrote:
> >>>>> On Wed, May 30, 2007 at 02:07:19PM +0200, Guillaume POIRIER wrote:
> >>>>>> Ok, fine with me. Michael, do you think that the patch I posted
> >>>>>> earlier (100% based on Trent's, only fixing minor issues) should be
> >>>>>> applied?
> >>>>> well, after actually reading the code ... the loops should be written
> >>>>> in asm not by using for() / while() this will make the code faster
> >>>>> and it will make the n+%m code naturally dissapear
> >>>> Well, after getting a hint from Apple guys, here's an updated patch
> >>>> that gets rid of all assembler warnings without touching the code as
> >>>> much as Trent had done.
> >>>>
> >>>> Now, maybe writing the loop in ASM ourselves will help, but at least,
> >>>> this patch doesn't harm and works on all supported platforms!
> >>> This won't assemble correctly if any of the memory operands already have a
> >>> displacement. Loren explained why:
> >>> http://article.gmane.org/gmane.comp.video.ffmpeg.devel/51453
> >> I agree. This patch's main purpose is to show how to write this
> >> routine with proper syntax (Bear in mind that all assemblers produce a
> >> warning here. To a certain extend, we may consider that the reason it
> >> works with FSF AS is just by pure luck.)
> >>
> >> When I have the time, I shall benchmark both yours and my patch to see
> >> what are the speed figures.... But IMHO, it's a bit pointless, because
> >> whatever the speed figures may look like, we are comparing 1 solution
> >> that appears to work by luck, and another that is more reliable. Speed
> >> isn't what your patch is after.
> > 
> > Hmm I really miss Intel syntax here, which I guess would be something
> > like "MOVLPS XMM6, [EAX+2*EBX+imm]" so using "+16" at the end doesn't
> > hurt in any case.
> So do I. I really hate AT&T's syntax.

i hate it too, but iam getting used to it ...
anyway it wouldnt help if we could get recent gas/gcc to handle intel syntax
as apples ancient as wont support it


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have often repented speaking, but never of holding my tongue.
-- Xenocrates
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