[FFmpeg-devel] [PATCH] Fix warning in av_rescale_rnd (in libavutil/mathematics.c)

[Michael Niedermayer]

On Sat, Jul 03, 2010 at 08:22:39AM -0700, Eli Friedman wrote:
> On Sat, Jul 3, 2010 at 7:23 AM, M?ns Rullg?rd <mans at mansr.com> wrote:
> > Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
> >
> >> On Sat, Jul 03, 2010 at 12:17:25PM +0200, Michael Niedermayer wrote:
> >>> On Sat, Jul 03, 2010 at 12:42:08AM -0700, Eli Friedman wrote:
> >>> > Patch attached. ?Fixes warning "comparison of unsigned expression >= 0
> >>> > is always true".
> >>>
> >>> god damn, its a assert(), what is wrong with asserting that a variable
> >>> is unsigned or if signed is positive. Why is gcc so retarded
> >>
> >> Umm, gcc just can't know your intention. I have seen this kind of
> >> thing quite a few times where it was an actual bug because someone
> >> forgot to make a variable signed.
> >> That said, casting the value to int before the comparison should
> >> avoid the warning...
> >
> > Or cast it to unsigned and check only the upper limit.
> 
> Version like this attached.
> 
> -Eli

> Index: libavutil/mathematics.c
> ===================================================================
> --- libavutil/mathematics.c	(revision 24018)
> +++ libavutil/mathematics.c	(working copy)
> @@ -78,7 +78,7 @@
>      int64_t r=0;
>      assert(c > 0);
>      assert(b >=0);
> -    assert(rnd >=0 && rnd<=5 && rnd!=4);
> +    assert((unsigned)rnd<=5 && rnd!=4);

ok

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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