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

[Muhammad Faiz]

On Tue, Nov 3, 2015 at 5:42 AM, Clément Bœsch <u at pkh.me> wrote:
> 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.
>
It seems good to do both
use fmax*/fmin* to support NaN handling
and add av_* (probably av_max*/av_min*)  to make it more consistent
with av_clip*/etc