Thread View: comp.std.unix
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Started by James W. Williams
Mon, 06 Aug 1990 15:30
need POSIX cksum tables
Author: James W. Williams
Date: Mon, 06 Aug 1990 15:30
Date: Mon, 06 Aug 1990 15:30
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From: James W. Williams <williams@nssdcs.gsfc.nasa.gov> I am implementing, for BSD 4.4, the POSIX cksum program as described in P1003.2/D10. This program uses table look-up to calculate a CRC "checksum" for each of its file arguments. This table consists of 256 hexadecimal constants and it would be extremely tedious and error-prone for me to type this in. If someone out there on the committee has this table on line and could mail it to me, I would be most grateful. So as not to waste net bandwidth, and clog my mailbox with multiple copies of the table, I suggest you just let me know that you have it, and I'll pick a random person to actually send it to me. While I have your attention, the section on this program, 4.9, is titled "cksum - Display file checksums and block counts". Given that this program, unlike the sum programs of BSD and system V, prints byte counts, not block counts, shouldn't the section title be "cksum - Display file checksums and byte counts"? Also, it is noted that this program is not backward compatible with either the BSD or system V versions of sum, thus it was given a new name. It is further noted that the term "checksum" is used for historical reasons, even though the algorithm given is not, technically, a checksum. This seems oddly inconsistent. Given that the name is changing, why not call it crcsum, or just crc? Thanks for your help and attention, Spoken: Jim Williams Domain: williams@nssdcs.gsfc.nasa.gov Phone: +1-301-555-1212 UUCP: uunet!mimsy!williams USPS: NASA/GSFC, Code 633, Greenbelt, MD 20771 Motto: There is no 'd' in "kluge"! It rhymes with "deluge", not "sludge". Volume-Number: Volume 21, Number 14
Re: need POSIX cksum tables
Author: Andrew Hume
Date: Tue, 07 Aug 1990 05:46
Date: Tue, 07 Aug 1990 05:46
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From: andrew@alice.uucp (Andrew Hume) i would hate to cause trouble but can anyone justify why cksum uses anything other than CRC-32 for its polynomial? (i am not 1000% sure it isn't but am fairly sure.) it really frosts my shorts when CCITT and other folks bust their chops developing and testing 32 bit CRCs, find a really good one and then posix picks some hokey thing whose only apparent recommendation is that pathalias uses it (not strictly the highest form of praise). Volume-Number: Volume 21, Number 23
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