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

[Ganesh Ajjanagadde]

On Fri, Oct 30, 2015 at 7:33 PM, Michael Niedermayer
<michael at niedermayer.cc> 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

I might be missing your exact usage of FFMIN/FFMAX, but note
FFMIN/FFMAX by themselves do not do any NaN handling. Maybe this
confusion will be clarified when you post v2. Ideas of achieving this
may be easily obtained in the commit I mentioned above:
4436a8f44dedc83767b3d9da9beb85d1fae2ca30.

>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Those who are best at talking, realize last or never when they are wrong.
>
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