[Ffmpeg-devel] [PATCH] (somewhat) optimized C aes 128 bit

Reimar Döffinger Reimar.Doeffinger
Sun Jan 14 15:24:46 CET 2007

On Sun, Jan 14, 2007 at 02:57:46PM +0100, Michael Niedermayer wrote:
> > Main bottleneck seems to be SUBSTSHIFTROWS, for which I have no idea how
> > to optimize it further right now in C.
> > SSE shuffle instruction could probably be very useful to optimize the
> > shifting, but the invsubst table lookup still seems not nice - except
> > maybe by using a 64k size table and thus always looking up two at once...
> cant the substitution stuff be merged into the multbl? i think it should
> be possible ...

I currently don't see a way unless combining it also with the XORBLOCK
which would mean a different tbl for each round, too, and would mean
rebuilding the tables when changing the key which I would prefer to avoid,
I think it would be nice for the key changing operation being a not too
slow operation.

Reimar D?ffinger

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