Date: Thu, 23 Jan 1997 16:16:19 +0200 (IST) From: Nadav Eiron <nadav@cs.technion.ac.il> To: "Ron G. Minnich" <rminnich@Sarnoff.COM> Cc: Michael Smith <msmith@atrad.adelaide.edu.au>, hackers@freebsd.org Subject: Re: CRC-16 algorithms? Message-ID: <Pine.GSO.3.95-heb-2.07.970123161155.27398A-100000@csd> In-Reply-To: <Pine.SUN.3.91.970123081644.28093E-100000@terra>
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On Thu, 23 Jan 1997, Ron G. Minnich wrote: > If anyone out there can get me the coefficients, I can deliver a program > that will do the crc-16. But working out the polynomial minus the > coefficients, well, I'll go with Barbie on this one: "Math is hard, let's > go shopping" > > Not impossible: assuming this crc is accumulated 16 bits at a time, there > are only 2^16 possible polynomials, after all ... at least it's not some > crc-32! > > michael let me know if you don't get anywhere. I think you should check out the CRC used on HDLC. Look in the Tanenbaum book. There are actually not nearly that much useful CRC generating polynomials, because all useful polynomials should: 1. Be a multiple of (x+1). 2. Have a LSB of 1. However, most CRC codes complement some of the bits, either in the message or in the generated reminder to make the all zeros string, as well as the all ones string illegal. > > ron > > Ron Minnich |"Failure is not an option" -- Gene Kranz > rminnich@sarnoff.com | -- except, of course, on Microsoft products > (609)-734-3120 | > ftp://ftp.sarnoff.com/pub/mnfs/www/docs/cluster.html > > > Nadav
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