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 calculated using the sum(1) algorithm.
              The result is formatted using the format(n) specifier provided
              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 completion.

       -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://sourceforge.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

CATEGORY
       Hashes, checksums, and encryption

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




crc                                  1.1.0                              sum(n)
