[FFmpeg-devel] [PATCH v1] Bug #8027 - Wrong result for FFSIGN(0)

[Song, Ruiling]

> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of Ulf Zibis
> Sent: Wednesday, July 17, 2019 2:34 PM
> To: ffmpeg-devel at ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH v1] Bug #8027 - Wrong result for
> FFSIGN(0)
> 
> Again with the patch attached ...
> 
> Am 17.07.19 um 08:30 schrieb Ulf Zibis:
> > Hi,
> >
> > I have a patch for bug #8027 <https://trac.ffmpeg.org/ticket/8027> (see
> > attachment).
Why do you think FFSIGN(0.0) should return +1? What issue do you meet?
I think the value of FFSIGN(0) depends on how we define the behavior of FFSIGN().

Thanks!
Ruiling
> >
> > But there is still a problem with -0.0, but FFABS(-0.0) works fine.
> >
> > Testcode:
> >    av_log(NULL, AV_LOG_ERROR, "FFSIGN(0): %d\n", FFSIGN(0));
> >     av_log(NULL, AV_LOG_ERROR, "FFSIGN(-0): %d\n", FFSIGN(-0));
> >     av_log(NULL, AV_LOG_ERROR, "FFSIGN(0.0D): %d\n", FFSIGN(0.0D));
> >     av_log(NULL, AV_LOG_ERROR, "FFSIGN(-0.0D): %d\n", FFSIGN(-0.0D));
> >     av_log(NULL, AV_LOG_ERROR, "FFSIGN(-0.0F): %d\n", FFSIGN(-0.0F));
> >     av_log(NULL, AV_LOG_ERROR, "FFSIGN(-0.0): %d\n", FFSIGN(-0.0));
> >
> >     av_log(NULL, AV_LOG_ERROR, "FFABS(0): %d\n", FFABS(0));
> >     av_log(NULL, AV_LOG_ERROR, "FFABS(-0): %d\n", FFABS(-0));
> >     av_log(NULL, AV_LOG_ERROR, "FFABS(0.0D): %f\n", FFABS(0.0D));
> >     av_log(NULL, AV_LOG_ERROR, "FFABS(-0.0D): %f\n", FFABS(-0.0D));
> >     av_log(NULL, AV_LOG_ERROR, "FFABS(-0.0F): %f\n", FFABS(-0.0F));
> >     av_log(NULL, AV_LOG_ERROR, "FFABS(-0.0): %f\n", FFABS(-0.0));
> >
> > Results:
> > FFSIGN(0): 1
> > FFSIGN(-0): 1
> > FFSIGN(0.0D): 1
> > FFSIGN(-0.0D): 1
> > FFSIGN(-0.0F): 1
> > FFSIGN(-0.0): 1
> > FFABS(0): 0
> > FFABS(-0): 0
> > FFABS(0.0D): 0.000000
> > FFABS(-0.0D): -0.000000
> > FFABS(-0.0F): -0.000000
> > FFABS(-0.0): -0.000000
> >
> > -Ulf
> >
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