[manpage_begin yencode n 1.1.2]
[copyright {2002, Pat Thoyts}]
[moddesc   {Text encoding & decoding binary data}]
[titledesc {Y-encode/decode binary data}]
[category  {Text processing}]
[require Tcl 8.2]
[require yencode [opt 1.1.2]]
[description]
[para]

This package provides a Tcl-only implementation of the yEnc file
encoding. This is a recently introduced method of encoding binary
files for transmission through Usenet. This encoding packs binary data
into a format that requires an 8-bit clean transmission layer but that
escapes characters special to the [term NNTP] posting protocols. See 
[uri http://www.yenc.org/] for details concerning the algorithm.

[list_begin definitions]

[call [cmd ::yencode::encode] [arg string]]

returns the yEnc encoded data.

[call [cmd ::yencode::decode] [arg "string"]]

Decodes the given yEnc encoded data.

[call [cmd ::yencode::yencode] \
  [opt "[option -name] [arg string]"] \
  [opt "[option -line] [arg integer]"] \
  [opt "[option -crc32] [arg boolean]"] \
  "([option -file] [arg filename] | [opt [option --]] [arg string])"]

Encode a file or block of data.

[call [cmd ::yencode::ydecode] \
  "([option -file] [arg filename] | [opt [option --]] [arg string])"]

Decode a file or block of data. A file may contain more than one
embedded file so the result is a list where each element is a three
element list of filename, file size and data.

[list_end]

[section OPTIONS]

[list_begin definitions]

[def "-filename name"]

Cause the yencode or ydecode commands to read their data from the
named file rather that taking a string parameter.

[def "-name string"]

The encoded data header line contains the suggested file name to be
used when unpacking the data. Use this option to change this from the
default of "data.dat".

[def "-line integer"]

The yencoded data header line contains records the line length used
during the encoding. Use this option to select a line length other
that the default of 128. Note that NNTP imposes a 1000 character line
length limit and some gateways may have trouble with more than 255
characters per line.

[def "-crc32 boolean"]

The yEnc specification recommends the inclusion of a cyclic redundancy
check value in the footer. Use this option to change the default from
[arg true] to [arg false].

[list_end]

[para]
[example {
% set d [yencode::yencode -file testfile.txt]
=ybegin line=128 size=584 name=testfile.txt
 -o- data not shown -o-
=yend size=584 crc32=ded29f4f
}]

[section References]

[list_begin enum]
[enum] [uri http://www.yenc.org/yenc-draft.1.3.txt]
[list_end]

[section {BUGS, IDEAS, FEEDBACK}]

This document, and the package it describes, will undoubtedly contain
bugs and other problems.

Please report such in the category [emph base64] of the
[uri {http://sourceforge.net/tracker/?group_id=12883} {Tcllib SF Trackers}].

Please also report any ideas for enhancements you may have for either
package and/or documentation.


[keywords encoding yEnc yencode ydecode]
[manpage_end]