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[f-cpu] Omega Network

Hi y'all!

To clarify the `reversed omega network' issue: it's just an omega network
with inputs and outputs swapped (see picture 1).

You may ask, "what's the difference?"  It's not visible in the picture,
but there is a one important difference -- if the "forward" omega net is
used for bit shifting, the control logic for the last stage is minimal
while that for the first stage is huge.  So I reversed the net, and now
I have minimal logic in the first stage, and the more hairy decoders at
the end :)

Both versions can do the basic operations we need: rotate left/right
and/or bit reversal (see picture 2).  In contrast to other
implementations, the omega net also supports the SIMD versions of
these operations, with almost no overhead.

 Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
 "All I wanna do is have a little fun before I die"