[RC5] AXP client slow on RC5

Greg Wooledge greg at wooledge.org
Sat Jun 2 09:36:33 EDT 2001


Dan Sugalski (dan at sidhe.org) wrote:
> On Fri, 1 Jun 2001 chicks at chicks.net wrote:
> > On Sat, 2 Jun 2001 bmeyer at cs.monash.edu.au wrote:

> > > P.S.: Can someone come up with a use of the rotate instruction outside
> > >       of cryptography?

> > - Dividing or multiplying integers by two.  :-)  Of course, most ALU's
> > optimize that sort of trickery into irrelevance these days.

> > - Getting at the return value of a system() in C.

> Neither of those are rotates. Shifts, yes, but not rotates.

I think rotates might be useful in some pseudo random number generation
algorithms.  But I don't know any PRNG algorithms (or parameters) that
are tied to the computer's word size like that -- most use a "strange"
number of bits, often much larger than the CPU word size.

-- 
Greg Wooledge                  |   "Truth belongs to everybody."
greg at wooledge.org              |    - The Red Hot Chili Peppers
http://wooledge.org/~greg/     |
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