[FFmpeg-devel] [PATCH] Make ff_inverse stay with libavutil, and optional copy it to libavcodec.

[Michael Niedermayer]

On Tue, Jul 20, 2010 at 06:16:51PM +0200, Diego Elio 'Flameeyes' Petten? wrote:
> The ff_inverse table is used by FASTDIV macro, defined in libavutil, but up
> to now the table was defined only in libavcodec.
> 
> After this change, the main copy of ff_inverse is part of libavutil (just
> like FASTDIV), but if CONFIG_SMALL is unset, then a different copy is made
> available to libavcodec, to avoid the performance penalty of using an
> external look up table.
> 
> Dynamic linking works, because the libraries are linked with -Bsymbolic, so
> the local copy of the symbol has priority over the external; static linking
> works because the table is on a standalone object file in both libraries,
> so the linker is able to discard one of the two.
> 
> Tested on Linux/x86-64 and Mac OS X/x86-64.
> ---
>  libavcodec/Makefile  |    2 +
>  libavcodec/dsputil.c |   38 -------------------------------
>  libavutil/Makefile   |    1 +
>  libavutil/inverse.c  |   60 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 63 insertions(+), 38 deletions(-)
>  create mode 100644 libavutil/inverse.c
> 
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 965948c..fab5211 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -609,6 +609,8 @@ OBJS-$(HAVE_W32THREADS)                += w32thread.o
>  
>  OBJS-$(CONFIG_MLIB)                    += mlib/dsputil_mlib.o           \
>  
> +OBJS-$(!CONFIG_SMALL)                  += ../libavutil/inverse.o

this needs a comment, in 2 years noone might rememeber why this was
done and in the meantime we would get patches from smart people
removing cruft

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
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