Functions listed by SuSv3 but not (yet) included in uClibc

Aurelien Jacobs aurel at
Fri Jan 15 18:50:25 UTC 2010

On Tue, Jan 12, 2010 at 10:32:23AM -0500, A. Craig West wrote:
> I recently ran into a problem building ffmpeg on a uclibc system,
> where ffmpeg appears to depend on the log2f function. A bit of
> investigation led me to a section of code in libm/float_wrappers.c,
> with #undef L_log2f, and the comment:
>  /* For the time being, do _NOT_ implement these functions
>  * that are defined by SuSv3 */
> What is missing is any explanation of WHY these functions are left
> unimplemented.

Attached patch enable those function to allow ffmpeg/x264/... to build.

> There is the secondary issue of why ffmpeg requires
> this function, but that isn't really pertinent to this list...

Significant overall speed difference compared to the double version
(on libc which actually implement a float version).

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