[RC5] Re: RC5-72 Pentium 4 optimizations

Scott Dodson sdodson at sdodson.com
Sun Sep 14 18:05:40 EDT 2003

On Sun, 2003-09-14 at 13:28, Matt Andrews wrote:
> 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


The cores are available in the public source distribution, look in


sdodson at sdodson.com
sdodson at distributed.net

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