Provided by: tcllib_2.0+dfsg-4_all 
NAME
crc16 - Perform a 16bit Cyclic Redundancy Check
SYNOPSIS
package require Tcl 8.5 9
package require crc16 ?1.1.5?
::crc::crc16 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc16 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::crc-ccitt ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc-ccitt ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::xmodem ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::xmodem ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::kermit ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::kermit ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::modbus ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::modbus ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::mcrf4xx ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::mcrf4xx ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::genibus ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::genibus ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::crc-x25 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc-x25 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::crc-sdlc ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc-sdlc ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::crc-usb ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc-usb ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::buypass ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::buypass ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::umts ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::umts ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::gsm ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::gsm ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::unknown2 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::unknown2 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::maxim ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::maxim ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::unknown3 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::unknown3 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::unknown4 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::unknown4 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::cms ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::cms ?-format format? ?-seed value? ?-implementation procname? -filename file
________________________________________________________________________________________________________________
DESCRIPTION
This package provides a Tcl-only implementation of the CRC algorithms based upon information provided at
http://www.microconsultants.com/tips/crc/crc.txt There are a number of permutations available for
calculating CRC checksums and this package can handle all of them. Defaults are set up for the most
common cases.
COMMANDS
::crc::crc16 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc16 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::crc-ccitt ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc-ccitt ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::xmodem ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::xmodem ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::kermit ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::kermit ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::modbus ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::modbus ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::mcrf4xx ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::mcrf4xx ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::genibus ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::genibus ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::crc-x25 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc-x25 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::crc-sdlc ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc-sdlc ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::crc-usb ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::crc-usb ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::buypass ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::buypass ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::umts ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::umts ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::gsm ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::gsm ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::unknown2 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::unknown2 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::maxim ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::maxim ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::unknown3 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::unknown3 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::unknown4 ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::unknown4 ?-format format? ?-seed value? ?-implementation procname? -filename file
::crc::cms ?-format format? ?-seed value? ?-implementation procname? -- message
::crc::cms ?-format format? ?-seed value? ?-implementation procname? -filename file
The command takes either string data or a file name and returns a checksum value calculated using
the CRC algorithm. The command used sets up the CRC polynomial, initial value and bit ordering for
the desired standard checksum calculation. The result is formatted using the format(3tcl)
specifier provided or as an unsigned integer (%u) by default.
A number of common polynomials are in use with the CRC algorithm and the most commonly used of
these are included in this package. For convenience each of these has a command alias in the crc
namespace.
It is possible to implement the CRC-32 checksum using this crc16 package as the implementation is
sufficiently generic to extend to 32 bit checksums. As an example this has been done already -
however this is not the fastest method to implement this algorithm in Tcl and a separate crc32
package is available.
OPTIONS
-filename name
Return a checksum for the file contents instead of for parameter data.
-format string
Return the checksum using an alternative format template.
-seed value
Select an alternative seed value for the CRC calculation. The default is 0 for the CRC16
calculation and 0xFFFF for the CCITT version. This can be useful for calculating the CRC for data
structures without first converting the whole structure into a string. The CRC of the previous
member can be used as the seed for calculating the CRC of the next member. It is also used for
accumulating a checksum from fragments of a large message (or file)
-implementation procname
This hook is provided to allow users to provide their own implementation (perhaps a C compiled
extension). The procedure specfied is called with two parameters. The first is the data to be
checksummed and the second is the seed value. An integer is expected as the result.
The package provides some implementations of standard CRC polynomials for the XMODEM, CCITT and
the usual CRC-16 checksum. For convenience, additional commands have been provided that make use
of these implementations.
-- Terminate option processing. Please note that using the option termination flag is important when
processing data from parameters. If the binary data looks like one of the options given above then
the data will be read as an option if this marker is not included. Always use the -- option
termination flag before giving the data argument.
EXAMPLES
% crc::crc16 -- "Hello, World!"
64077
% crc::crc-ccitt -- "Hello, World!"
26586
% crc::crc16 -format 0x%X -- "Hello, World!"
0xFA4D
% crc::crc16 -file crc16.tcl
51675
AUTHORS
Pat Thoyts
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please
report such in the category crc of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist]. Please
also report any ideas for enhancements you may have for either package and/or documentation.
When proposing code changes, please provide unified diffs, i.e the output of diff -u.
Note further that attachments are strongly preferred over inlined patches. Attachments can be made by
going to the Edit form of the ticket immediately after its creation, and then using the left-most button
in the secondary navigation bar.
SEE ALSO
cksum(3tcl), crc32(3tcl), sum(3tcl)
KEYWORDS
checksum, cksum, crc, crc16, crc32, cyclic redundancy check, data integrity, security
CATEGORY
Hashes, checksums, and encryption
COPYRIGHT
Copyright (c) 2002, 2017, Pat Thoyts
tcllib 1.1.5 crc16(3tcl)