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sum(n)                                    Cyclic Redundancy Checks                                    sum(n)



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NAME
       sum - Calculate a sum(1) compatible checksum

SYNOPSIS
       package require Tcl  8.2

       package require sum  ?1.1.0?

       ::crc::sum ?-bsd | -sysv? ?-format fmt? ?-chunksize size? [ -filename file | -channel chan | string ]

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DESCRIPTION
       This package provides a Tcl-only implementation of the sum(1)  command  which  calculates  a  16  bit
       checksum  value from the input data.  The BSD sum algorithm is used by default but the SysV algorithm
       is also available.

COMMANDS
       ::crc::sum ?-bsd | -sysv? ?-format fmt? ?-chunksize size? [ -filename file | -channel chan | string ]
              The command takes string data or a file name or a channel and returns a checksum value  calcu-lated calculated
              lated  using  the sum(1) algorithm. The result is formatted using the format(n) specifier pro-vided provided
              vided or as an unsigned integer (%u) by default.


OPTIONS
       -sysv  The SysV algorithm is fairly naive. The byte values are summed and any overflow is  discarded.
              The  lowest  16  bits are returned as the checksum.  Input with the same content but different
              ordering will give the same result.

       -bsd   This algorithm is similar to the SysV version but includes a bit rotation step which  provides
              a dependency on the order of the data values.

       -filename name
              Return a checksum for the file contents instead of for parameter data.

       -channel chan
              Return  a  checksum  for  the  contents of the specified channel. The channel must be open for
              reading and should be configured for binary translation. The channel will no be closed on com-pletion. completion.
              pletion.

       -chunksize size
              Set  the  block size used when reading data from either files or channels. This value defaults
              to 4096.

       -format string
              Return the checksum using an alternative format template.


EXAMPLES
       % crc::sum "Hello, World!"
       37287



       % crc::sum -format 0x%X "Hello, World!"
       0x91A7



       % crc::sum -file sum.tcl
       13392


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  SF  Trackers  [http://source-
       forge.net/tracker/?group_id=12883].  Please also report any ideas for enhancements you may  have  for
       either package and/or documentation.

SEE ALSO
       cksum(n), crc32(n), sum(1)

KEYWORDS
       checksum, cksum, crc, crc32, cyclic redundancy check, data integrity, security, sum

COPYRIGHT
       Copyright (c) 2002, Pat Thoyts <patthoyts@users.sourceforge.net>




crc                                                 1.1.0                                             sum(n)