On Thu, Oct 15, 2015 at 8:31 AM, Clément Bœsch <u...@pkh.me> wrote: > On Thu, Oct 15, 2015 at 08:18:02AM -0400, Ganesh Ajjanagadde wrote: >> It has been demonstrated that using libc provided floating point >> functions is beneficial, in the context of fabs() vs FFABS. >> >> Unfortunately, MSVC 2012 (and earlier) lack the ISO C99 fmax, fmaxf, >> fmin, fminf functions. This patch adds them, thus making their usage in >> FFmpeg safe. >> > > Do we have any use of fmax/fmin? The functions don't exist to make > FFMAX-like faster, it actually is more complex: > > These functions return the maximum of x and y. > > If one argument is a NaN, the other argument is returned. > > If both arguments are NaN, a NaN is returned. > > Which means it's likely slower but will do more. Not that I mind, but in this > case, if we happen to use them, you will want to fix your local implementation > to match this behaviour.
2 comments: 1. There is a tradeoff: the gain from possible better optimization of >=, versus the nan handling. 2. NaN handling is not being done currently (by FFMAX and the like) - so I don't know and can't comment whether we want it. You are right that if we change to a fmax, we should make it consistent everywhere on all platforms . Anyone else has comments on this? > > [...] > > -- > Clément B. > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel