SYNOPSIS

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

KEYWORDS

CATEGORY

COPYRIGHT

Copyright (c) 2010, Emiliano Gavilán