[FFmpeg-devel] [PATCH] lavu/libm: change macros to functions

[Ganesh Ajjanagadde]

On Thu, Dec 24, 2015 at 10:52 AM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
> Am 24.12.2015 19:34 schrieb "Ganesh Ajjanagadde" <gajjanagadde at gmail.com>:
>>
>> In the standard library, these are functions. We should match it; there
>> is no reason for these to be macros.
>>
>> While at it, add some trivial comments for readability and correct an
>> incorrect (at standard double precision) M_LN2 constant used in the exp2
>> fallback.
>>
>> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
>> ---
[...]
>>
>>  #if !HAVE_SINF
>> -#undef sinf
>> -#define sinf(x) ((float)sin(x))
>> -#endif
>> +static av_always_inline float sinf(float x)
>> +{
>> +    return sin(x);
>> +}
>> +#endif /* HAVE_SINF */
>>
>>  #if !HAVE_RINT
>>  static inline double rint(double x)
>> --
>> 2.6.4
>>
>
> Could this cause linkage issues if presence of such a function is
> mis-detected? Previously this worked fine. There was at least one such case
> where log2 IIRC was explicitly disabled in configure because its in the
> libc library but forgotten in the headers in one specific libc.

I believe it does, for instance if I force the fallback via e.g a
#define HAVE_RINT 0 on my machine, it fails to link.
However, this is really the job of configure: configure's task is to
ensure the lack of misdetection. Using a macro is an ad-hoc solution
to a more fundamental issue.
On this note, see the thread regarding exp10, exp10f: while sorting
them out, I want to do it as cleanly as possible.
If there are outstanding issues regarding misdetection, they need to
be fixed before this can go in.

>
> Not sure what the rules for static inline functions are in that regard.
>
> - Hendrik
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