NAME

       ascii85 - ascii85-encode/decode binary data

SYNOPSIS

       package require Tcl  8.4

       package require ascii85  ?1.0?

       ::ascii85::encode ?-maxlen maxlen? ?-wrapchar wrapchar? string

       ::ascii85::decode string

_________________________________________________________________________________________________

DESCRIPTION

       This package provides procedures to encode binary data into ascii85 and back.

       ::ascii85::encode ?-maxlen maxlen? ?-wrapchar wrapchar? string
              Ascii85 encodes the given binary string and returns the encoded result. Inserts the
              character wrapchar every maxlen characters of output. wrapchar defaults to newline.
              maxlen defaults to 76.

              Note  well:  If  your string is not simple ascii you should fix the string encoding
              before doing ascii85 encoding. See the examples.

              The command will throw an error for negative values of maxlen, or if maxlen is  not
              an integer number.

       ::ascii85::decode string
              Ascii85  decodes the given string and returns the binary data.  The decoder ignores
              whitespace in the string, as well as tabs and newlines.

EXAMPLES

              % ascii85::encode "Hello, world"
              87cURD_*#TDfTZ)

              % ascii85::encode [string repeat xyz 24]
              G^4U[H$X^\H?a^]G^4U[H$X^\H?a^]G^4U[H$X^\H?a^]G^4U[H$X^\H?a^]G^4U[H$X^\H?a^]G
              ^4U[H$X^\H?a^]
              % ascii85::encode -wrapchar "" [string repeat xyz 24]
              G^4U[H$X^\H?a^]G^4U[H$X^\H?a^]G^4U[H$X^\H?a^]G^4U[H$X^\H?a^]G^4U[H$X^\H?a^]G^4U[H$X^\H?a^]

              # NOTE: ascii85 encodes BINARY strings.
              % set chemical [encoding convertto utf-8 "C\u2088H\u2081\u2080N\u2084O\u2082"]
              % set encoded [ascii85::encode $chemical]
              6fN]R8E,5Pidu\UiduhZidua
              % set caffeine [encoding convertfrom utf-8 [ascii85::decode $encoded]]

REFERENCES

       [1]    http://en.wikipedia.org/wiki/Ascii85

       [2]    Postscript    Language    Reference    Manual,    3rd    Edition,     page     131.
              http://www.adobe.com/devnet/postscript/pdfs/PLRM.pdf

BUGS, IDEAS, FEEDBACK

       This  document,  and  the  package  it  describes, will undoubtedly contain bugs and other
       problems.   Please  report  such  in  the  category  base64   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.

KEYWORDS

       ascii85, encoding

CATEGORY

       Text processing

COPYRIGHT

       Copyright (c) 2010, Emiliano Gavilán