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crc32(n) 1.0.1 "Cyclic Redundancy Check (crc32)"
crc32 - Perform a 32bit Cyclic Redundancy Check
package require Tcl 8.2
package require crc32 ?1.0.1?
This package provides a Tcl-only implementation of the CRC-32
algorithm based upon information provided at
http://www.naaccr.org/standard/crc32/document.html
If the Trf package is available then the crc-zlib
command is used to perform the calculation.
- ::crc::crc32 ?-format format? ?-seed value? ?-implementation procname? message
-
- ::crc::crc32 ?-format format? ?-seed value? ?-implementation procname? -filename file
-
The command takes string data or a file name and returns a checksum
value calculated using the CRC-32 algorithm. The result is formatted
using the format(n) specifier provided or as an unsigned integer
(%u) by default.
- -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 0xffffffff. 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.
Note that as the Trf command crc-zlib cannot accept a
seed value, use of this option will force the use of the Tcl only
implementation.
- -implementation procname
-
This hook is provided to allow users to provide their own
implementation (perhaps a C compiled extension) or to explicitly
request use of the Tcl only implementation when Trf is
installed (by setting -implementation crc::Crc32_tcl. The
procedure specfied is called with two parameters. The first is the
data to be checksummed and the second is the seed value. A 32bit
integer is expected as the result.
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% crc::crc32 "Hello, World!"
3964322768
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% crc::crc32 -format 0x%X "Hello, World!"
0xEC4AC3D0
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% crc::crc32 -file crc32.tcl
483919716
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Pat Thoyts
cksum(n) , crc16(n) , sum(n)
checksum , cksum , crc , crc32 , cyclic redundancy check , data integrity , security
Copyright © 2002, Pat Thoyts