From: Spiro Trikaliotis (trik-news_at_gmx.de)
Date: 2003-09-22 08:33:53
Hello, On Sun, Sep 21, 2003 at 10:55:46PM +0200, Piotr Fusik wrote: > > > > Ah, OK. I thought there was an ISO standard for this? > > > > > > I've never heard of it. As far as I know there are several "good" polynomials > > > which are commonly used, but CRC-32 is definitely not an exact specification. > > The 90 KB document called "A PAINLESS GUIDE TO CRC ERROR DETECTION > ALGORITHMS" states that CRC-32 is actually standard (ZIP, Ethernet). In this generallity, this statement is not (totally) true. The CRC method itself is almost standard, and everyone (should) know what it means, at least, you can look it up. Anyway, for CRC to be a good method to recognize errors, the polynomial which is used has to be of very good quality. For this, there are some polynomials which are treated as standard and almost always used: CRC8, CRC16, CRC32. Actually, there are 2 different CRC16, one of the CCITT (almost always referenced to as CRC-CCITT or similar) and "the" CRC16. See, for example, http://ivs.cs.uni-magdeburg.de/EuK/Lehre/Sommersemester_2002/Codes.pdf, slides 25 to 27 (sorry, german only). Spiro. ---------------------------------------------------------------------- To unsubscribe from the list send mail to majordomo_at_musoftware.de with the string "unsubscribe cc65" in the body(!) of the mail.
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