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sum(n) Cyclic Redundancy Checks sum(n) 





NAME


sum - Calculate a sum(1) compatible checksum






SYNOPSIS


package require Tcl 8.2


package require sum ?1.1.2?


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










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



  

  
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.

  

  
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.

  

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

  

  
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.

  

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

  

  
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 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(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>








  

    1.1.2
    tcllib