[FFmpeg-devel] [PATCH] Document av_gcd()

[Stefano Sabatini]

On date Sunday 2009-03-01 19:34:31 +0100, Stefano Sabatini encoded:
> On date Saturday 2009-02-28 18:49:27 +0100, Reimar D?ffinger encoded:
> > On Sat, Feb 28, 2009 at 06:23:37PM +0100, Michael Niedermayer wrote:
> > > On Sat, Feb 28, 2009 at 04:53:08PM +0100, Stefano Sabatini wrote:
> > > > Hi,
> > > > as in subject, regards.
> > > > -- 
> > > > FFmpeg = Funny and Forgiving Multimedia Pitiful Elected Ghost
> > > 
> > > > Index: libavutil/mathematics.h
> > > > ===================================================================
> > > > --- libavutil/mathematics.h	(revision 17629)
> > > > +++ libavutil/mathematics.h	(working copy)
> > > > @@ -50,6 +50,9 @@
> > > >      AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero.
> > > >  };
> > > >  
> > > > +/**
> > > > + * Returns the greatest common divisor of a and b.
> > > > + */
> > > >  int64_t av_const av_gcd(int64_t a, int64_t b);
> > > >  
> > > >  /**
> > > 
> > > ok,also please add
> > > "if either or both are <=0 then the behavior is undefined"
> > 
> > My r_frame_rate code in utils.c uses the = 0 case already, since I
> > considered that the common mathematical definition...
> 
> Trying to find a compromise, I think documenting the case gcd(a, 0) = a
> doesn't hurt.

Patches updated, implementing the case av_gcd(a, 0) = a rather than
av_gcd(0, b) = b we also have a theoretical speed advantage (one call
to function against two), but what's more important we don't need to
document/specify the behavior for the case:
av_gcd(0, b)

which may simplify optimizations.

Regards.
-- 
FFmpeg = Frenzy and Free Mysterious Prodigious Eccentric Geek
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