NAME

       tcl::transform::crc32 - Crc32 transformation

SYNOPSIS

       package require Tcl  8.6

       package require tcl::transform::core  ?1?

       package require tcl::transform::crc32  ?1?

       ::tcl::transform::crc32 chan -option value...

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DESCRIPTION

       The  tcl::transform::crc32  package  provides  a command creating a channel transformation
       which passes the read and written bytes through unchanged (like tcl::transform::identity),
       but  additionally  continuously  computes  the crc32 checksums of the data it has seen for
       each direction and stores them in  Tcl  variables  specified  at  construction  time.  The
       checksum in question is zlib's crc32.

       Related     transformations     in     this     module     are    tcl::transform::adler32,
       tcl::transform::counter, tcl::transform::identity, and tcl::transform::observe.

       The internal TclOO class  implementing  the  transform  handler  is  a  sub-class  of  the
       tcl::transform::core framework.

API

       ::tcl::transform::crc32 chan -option value...
              This command creates a crc32 checksumming transformation on top of the channel chan
              and returns its handle. The accepted options are

              -read-variable varname
                     The value of the option is the name of a global or namespaced variable,  the
                     location  where  the  transformation  has to store the crc32 checksum of the
                     data read from the channel.

                     If not specified, or the empty string, the checksum of the read direction is
                     not saved.

              -write-variable varname
                     The  value of the option is the name of a global or namespaced variable, the
                     location where the transformation has to store the  crc32  checksum  of  the
                     data written to the channel.

                     If  not  specified, or the empty string, the checksum of the write direction
                     is not saved.

BUGS, IDEAS, FEEDBACK

       This document, and the package it describes,  will  undoubtedly  contain  bugs  and  other
       problems.   Please  report  such  in  the  category  virtchannel 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.

KEYWORDS

       channel  transformation,  checksum,  crc32,  reflected  channel,  tip 230, transformation,
       virtual channel

CATEGORY

       Channels

COPYRIGHT

       Copyright (c) 2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>