[FFmpeg-devel] [PATCH] configure+libm.h: add fmin/fmax/fminf/fmaxf emulation

Clément Bœsch u at pkh.me
Tue Nov 3 14:42:55 CET 2015


On Sat, Oct 31, 2015 at 12:33:54AM +0100, Michael Niedermayer wrote:
> On Sat, Oct 31, 2015 at 12:14:44AM +0100, Hendrik Leppkes wrote:
> > On Fri, Oct 30, 2015 at 11:35 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > > From: Michael Niedermayer <michael at niedermayer.cc>
> > >
> > > This should fix the build failure of avf_showcqt.c
> > >
> > > An alternative solution would be to add a check for fmin/fmax to fate-source and
> > > then to replace them by FFMIN/FFMAX, i can do that if preferred?
> > >
> > > Untested due to lack of a affected platform
> > >
> > > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > > ---
> > >  configure        |    8 ++++++++
> > >  libavutil/libm.h |   28 ++++++++++++++++++++++++++++
> > >  2 files changed, 36 insertions(+)
> > >
> > > diff --git a/configure b/configure
> > > index 95790f4..e6f5d2c 100755
> > > --- a/configure
> > > +++ b/configure
> > > @@ -1770,6 +1770,10 @@ MATH_FUNCS="
> > >      exp2
> > >      exp2f
> > >      expf
> > > +    fmax
> > > +    fmaxf
> > > +    fmin
> > > +    fminf
> > >      isinf
> > >      isnan
> > >      ldexpf
> > > @@ -5304,6 +5308,10 @@ check_lib math.h sin -lm && LIBM="-lm"
> > >  disabled crystalhd || check_lib libcrystalhd/libcrystalhd_if.h DtsCrystalHDVersion -lcrystalhd || disable crystalhd
> > >
> > >  atan2f_args=2
> > > +fmax_args=2
> > > +fmaxf_args=2
> > > +fmin_args=2
> > > +fminf_args=2
> > >  copysign_args=2
> > >  ldexpf_args=2
> > >  powf_args=2
> > > diff --git a/libavutil/libm.h b/libavutil/libm.h
> > > index 6c17b28..ba837a2 100644
> > > --- a/libavutil/libm.h
> > > +++ b/libavutil/libm.h
> > > @@ -43,6 +43,34 @@
> > >  #define atan2f(y, x) ((float)atan2(y, x))
> > >  #endif
> > >
> > > +#if !HAVE_FMAX
> > > +#undef fmax
> > > +static av_always_inline double fmax(double x, double y)
> > > +{
> > > +    if (x < y) return y;
> > > +    else       return x;
> > > +}
> > > +#endif
> > > +
> > > +#if !HAVE_FMIN
> > > +#undef fmin
> > > +static av_always_inline double fmin(double x, double y)
> > > +{
> > > +    if (x < y) return x;
> > > +    else       return y;
> > > +}
> > > +#endif
> > 
> > Wasn't there a concern that these emulations don't behave identical to
> > the C library versions in regards to NaN handling?
> > I faintly remember something in the previous discussion.
> 
> yes, i forgot about that :(
> i replaced them by FFMIN / FFMAX
> 

Sorry to raise this again but i htink it must handle NaN, or we need to
use a av_ prefix to define our own semantic.

-- 
Clément B.
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