Re: New CRC algorithm: Slicing by 8

On Mon, 2006-10-23 at 05:22 -0400, Gregory Stark wrote:
> "Simon Riggs" <simon@2ndquadrant.com> writes:
> 
> > Slice-By-8 was first mentioned here:
> 
> Are you sure? 
> 
> US patent 7,047,479 filed in 2002 sounds like it may be relevant: 
> 
>
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=7047479.PN.

Yes, I'm sure.

That patent is titled "Parallel CRC formulation" and the abstract
describes the use of two threads to calculate different parts of the
CRC. It's designed for parallel circuit designs in hardware.

That doesn't resemble SB8 at all - there's still only one thread. The
cleverness of SB8 is to calculate more bytes simultaneously *without*
requiring a corresponding increase in the size of the lookup table. 

We have the original author's word that no patent has been filed. Even
if we disbelieve that, which I have no reason to do, that alone would be
sufficient to make a counter-claim for any damages claimed by any
hypothetical patent holder in the future.


What is the difference between this case and other patches?


--  Simon Riggs              EnterpriseDB   http://www.enterprisedb.com