[FFmpeg-devel] [PATCH] Add log2 check to configure and equivalent to internal.h

[Måns Rullgård]

Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:

> On Sat, Jul 11, 2009 at 12:18:03AM +0100, M?ns Rullg?rd wrote:
>> Alex Converse <alex.converse at gmail.com> writes:
>> 
>> > Hi,
>> >
>> > If someone on a system without log2 could test this, that would be great.
>> >
>> > Regards,
>> > Alex Converse
>> >
>> > diff --git a/configure b/configure
>> > index 7998273..48630f1 100755
>> > --- a/configure
>> > +++ b/configure
>> > @@ -911,6 +911,7 @@ HAVE_LIST="
>> >      libdc1394_1
>> >      libdc1394_2
>> >      llrint
>> > +    log2
>> >      loongson
>> >      lrint
>> >      lrintf
>> > @@ -2078,7 +2079,7 @@ check_lib math.h sin -lm
>> >  check_lib va/va.h vaInitialize -lva
>> >  
>> >  # test for C99 functions in math.h
>> > -for func in llrint lrint lrintf round roundf truncf; do
>> > +for func in log2 llrint lrint lrintf round roundf truncf; do
>> >      check_exec <<EOF && enable $func || disable $func
>> >  #include <math.h>
>> >  int main(void) { return ($func(3.999f) > 0)?0:1; }
>> 
>> What's with that weird runtime check anyway?  Looks pretty useless to
>> me.
>
> Not sure if I understand you right, but if the compiler optimizes away
> the function call it wouldn't be a good way to check if the function is
> available...

Why are these functions not checked with check_func, which seems to
work for everything else?

-- 
M?ns Rullg?rd
mans at mansr.com