cksum(n) 1.1.0 crc "Cyclic Redundancy Checks"
cksum - Calculate a cksum(1) compatible checksum
TABLE OF CONTENTS
SYNOPSIS
DESCRIPTION
COMMANDS
OPTIONS
PROGRAMMING INTERFACE
EXAMPLES
AUTHORS
SEE ALSO
KEYWORDS
COPYRIGHT
package require Tcl 8.2
package require cksum ?1.1.0?
This package provides a Tcl implementation of the cksum(1) algorithm
based upon information provided at in the GNU implementation of this
program as part of the GNU Textutils 2.0 package.
- ::crc::cksum ?-format format? ?-chunksize size? [ -channel chan | -filename file | string ]
-
The command takes string data or a channel or file name and returns a
checksum value calculated using the cksum(1) algorithm. The
result is formatted using the format(n) specifier provided or as
an unsigned integer (%u) by default.
- -channel name
-
Return a checksum for the data read from a channel. The command will
read data from the channel until the eof is true. If you need
to be able to process events during this calculation see the
PROGRAMMING INTERFACE section
- -filename name
-
This is a convenience option that opens the specified file, sets the
encoding to binary and then acts as if the -channel option had
been used. The file is closed on completion.
- -format string
-
Return the checksum using an alternative format template.
The cksum package implements the checksum using a context variable to
which additional data can be added at any time. This is expecially
useful in an event based environment such as a Tk application or a web
server package. Data to be checksummed may be handled incrementally
during a fileevent handler in discrete chunks. This can improve
the interactive nature of a GUI application and can help to avoid
excessive memory consumption.
- ::crc::CksumInit
-
Begins a new cksum context. Returns a token ID that must be used for the
remaining functions. An optional seed may be specified if required.
- ::crc::CksumUpdate token data
-
Add data to the checksum identified by token. Calling
CksumUpdate $token "abcd" is equivalent to calling
CksumUpdate $token "ab" followed by
CksumUpdate $token "cb". See EXAMPLES.
- ::crc::CksumFinal token
-
Returns the checksum value and releases any resources held by this
token. Once this command completes the token will be invalid. The
result is a 32 bit integer value.
|
% crc::cksum "Hello, World!"
2609532967
|
|
% crc::cksum -format 0x%X "Hello, World!"
0x9B8A5027
|
|
% crc::cksum -file cksum.tcl
1828321145
|
|
% set tok [crc::CksumInit]
% crc::CksumUpdate $tok "Hello, "
% crc::CksumUpdate $tok "World!"
% crc::CksumFinal $tok
2609532967
|
Pat Thoyts
crc32(n), sum(n)
checksum, cksum, crc, crc32, cyclic redundancy check, data integrity, security
Copyright © 2002, Pat Thoyts