[FFmpeg-devel] [PATCH/DRAFT] MonkeyAudio Demuxer/Decoder
Michael Niedermayer
michaelni
Mon Jun 25 17:27:36 CEST 2007
Hi
On Mon, Jun 25, 2007 at 06:07:06PM +0300, Uoti Urpala wrote:
> On Mon, 2007-06-25 at 15:28 +0200, Michael Niedermayer wrote:
> > On Mon, Jun 25, 2007 at 02:59:31PM +0300, Kostya wrote:
> > [...]
> > > [...]
> > > > > > +
> > > > > > +static inline void vector_add (int16_t* v1, int16_t* v2, int order)
> > > > > > +{
> > > > > > + int or = 1;
> > > > > > + if (order > 32)
> > > > > > + or = (order >> 5);
> > > > > > +
> > > > > > + while (or--)
> > > > > > + {
> > > > > > + int i;
> > > > > > +
> > > > > > + for (i = 0; i < 16; i++)
> > > > > > + *v1++ += *v2++;
> > > > > > +
> > > > > > + if (order > 16)
> > > > > > + for (i = 0; i < 16; i++)
> > > > > > + *v1++ += *v2++;
> > > > > > + }
> > > > > > +}
> > > >
> > > > > and this whole function is just
> > > > > for (i = 0; i < order; i++)
> > > > > *v1++ += *v2++;
> > > >
> > > > I've tested it and it's not :-(
> > >
> > > it does this fixed number of times:
> > > order <= 16: 16 times;
> > > order <= 32: 32 times;
> > > order > 32: (order >> 5) * 32 times or order & ~31 times.
> >
> > this function isnt called with any order which is not a multiple of 16
> > or at least i thouhght so when i wrote my suggestion about simplifying
> > it
>
> Values greater than 32 are rounded down to the nearest multiple of 32,
> so (2n+1)*16 becomes (2n)*16.
all values larger than 32 with which the function is called are multiples
of 32 at least i cant see anyplace where its called with other values
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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