[FFmpeg-devel] [PATCH] fix compilation in cygwin

Michael Kostylev michael.kostylev
Wed Jan 13 12:59:31 CET 2010

On Wed Jan 13 01:32:20 2010
M?ns Rullg?rd wrote:

>>>>>>>>>>> +#if !HAVE_EXP2F
>>>>>>>>>>> +static av_always_inline av_const float exp2f(float x)
>>>>>>>>>>> +{
>>>>>>>>>>> +    return exp(x) * 0.693147180559945;
>>>>>>>>>>> +}
>>>>>>>>>>> +#endif /* HAVE_EXP2F */
>>>>>>>>>> Same again.  exp2() should be preferred.
>>>>>>>>> Let's hope that at least exp2() is supported...
>>>>>>>> exp2() is missing in NetBSD and DragonFly.
>>>>>>> We have a replacement for it, so it's OK.
>>>>>> We have a replacement for log2(), but not for exp2().
>>>>>> I'm slightly favorable of adding a replacement for exp2() (as
>>>>>> attached) as we do for log2(), since we can get some speed gain in
>>>>>> platforms where exp2() is supported and we'll eventually need exp2()
>>>>>> sooner or later.
>>>>>> [...]
>>>>> Well, this caused things to break in new and interesting ways:
>>>>> libavutil/internal.h:275: error: static declaration of 'exp2f'
>>>>> follows non-static declaration
>>>>> libavutil/internal.h:296: error: static declaration of 'log2f' follows non-static declaration
>>>>> uClibc apparently has declarations for those functions, but no actual
>>>>> implementations.  This is truly the week of idiots.
>>>> BTW, wouldn't compilation fail if log2f() is a macro?
>>> No.  The functions are required to be available as actual functions,
>>> even if a macro is also defined.
>> What about if we define them as macros? Should work on any case.
> Can someone test this on BSD and Windows?

No problem on *bsd and djgpp. 


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