[RC5] Re: RC5-72 Pentium 4 optimizations

Matt Andrews andrewsm at ufl.edu
Sun Sep 14 14:28:09 EDT 2003


I was looking at the "processor comparison" 
(http://n0cgi.distributed.net/faq/cache/264.html) in the FAQ today and I 
saw that there was a Pentium MMX core.  This core apprantly performed 
better than quite a few other processors.  I was wondering exactly how 
the writer of this core got extra performance out of MMX -- unless the 
older projects were different and did not require bit rotates, it seems 
that an MMX core's need to constantly transfer back to normal registers 
for rotates would outweigh the performance gain for the parallel 
computations.  If there's still a copy of this core around, I'd be 
interested in taking a look at it, and probably Slawek would too.   If 
there was a possibility of SSE2 (which would theoretically perform twice 
as well as an MMX core) actually increasing performance on the pentium 
4, I would join any effort to code the core.

-Matt Andrews




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