From: | ncm(at)zembu(dot)com (Nathan Myers) |
---|---|
To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | CRC-64 |
Date: | 2000-12-14 21:08:10 |
Message-ID: | 20001214130810.A11704@store.zembu.com |
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Lists: | pgsql-hackers |
I have obtained the CRC-64 code used in the SWISS-PROT genetic
database:
ftp://ftp.ebi.ac.uk/pub/software/swissprot/Swissknife/SPcrc.tar.gz
(Thanks go to Henning Hermjakob <hhe(at)ebi(dot)ac(dot)uk> of the European
Bioinformatics Institute.) From the README:
The code in this package has been derived from the BTLib package
obtained from Christian Iseli <chris(at)ludwig-alpha(dot)unil(dot)ch>.
From his mail:
The reference is: W. H. Press, S. A. Teukolsky, W. T. Vetterling, and
B. P. Flannery, "Numerical recipes in C", 2nd ed., Cambridge University
Press. Pages 896ff.
The generator polynomial is x64 + x4 + x3 + x1 + 1.
Choosing a good polynomial is considered a black art. A good tutorial
on CRC practice is at
http://www.repairfaq.org/filipg/LINK/F_crc_v3.html
and there's a clear exposition of the theory in Tanenbaum's
"Computer Networks". Note that initialization is important, and
often neglected: one quality to check is, does a block of all zeroes,
and a zero CRC, come out as an error?
Nathan Myers
ncm(at)zembu(dot)com
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