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64-bit CRC Transition To Bytewise Lookup-Table

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Old 06-30-2010
CPU & Memory 64-bit CRC Transition To Bytewise Lookup-Table
Good Evening,

I started working on the 17x17 4-colouring challenge, and I ran into a bit of an I/O snag.

It was an enormous headache to detect the differences in very similar 289-char strings.

Eventually, it made more sense to associate a CRC-Digest with each colouring.

After learning from a handful of incomplete web pages, and performing several calculations by hand, I decided to put together a comprehensive treatment of the CRC check process.

Please take a look at this single web page, and let me know if I left out anything important.

http://www.pathcom.com/~vadco/crc.html

My conclusion was that those people who are familiar with the CRC procedure, treat it as self-evident, while the rest need to figure it out by doing all kinds of research until they agree.


All the very best,

JohnPaul Adamovsky
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LEARN ABOUT MOJAVE

digest::crc5.18

Digest::CRC(3)						User Contributed Perl Documentation					    Digest::CRC(3)

NAME

       Digest::CRC - Generic CRC functions

SYNOPSIS

	 # Functional style

	 use Digest::CRC qw(crc64 crc32 crc16 crcccitt crc crc8 crcopenpgparmor);
	 $crc = crc64("123456789");
	 $crc = crc32("123456789");
	 $crc = crc16("123456789");
	 $crc = crcccitt("123456789");
	 $crc = crc8("123456789");
	 $crc = crcopenpgparmor("123456789");

	 $crc = crc($input,$width,$init,$xorout,$refout,$poly,$refin,$cont);

	 # add data to existing

	 $crc = crc32("ABCD", $crc);

	 # OO style
	 use Digest::CRC;

	 $ctx = Digest::CRC->new(type=>"crc16");
	 $ctx = Digest::CRC->new(width=>16, init=>0x2345, xorout=>0x0000,
				 refout=>1, poly=>0x8005, refin=>1, cont=>1);

	 $ctx->add($data);
	 $ctx->addfile(*FILE);

	 $digest = $ctx->digest;
	 $digest = $ctx->hexdigest;
	 $digest = $ctx->b64digest;

DESCRIPTION

       The Digest::CRC module calculates CRC sums of all sorts.  It contains wrapper functions with the correct parameters for CRC-CCITT, CRC-16,
       CRC-32 and CRC-64, as well as the CRC used in OpenPGP's ASCII-armored checksum.

SEE ALSO

       https://tools.ietf.org/html/rfc4880#section-6

AUTHOR

       Oliver Maul, oli@42.nu

COPYRIGHT

       CRC algorithm code taken from "A PAINLESS GUIDE TO CRC ERROR DETECTION
	ALGORITHMS".

       The author of this package disclaims all copyrights and releases it into the public domain.

perl v5.18.2							    2017-10-06							    Digest::CRC(3)