[manpage_begin ascii85 n 1.0]
[keywords ascii85]
[keywords encoding]
[copyright "2010, Emiliano Gavil\u00e1n"]
[moddesc   {Text encoding & decoding binary data}]
[titledesc {ascii85-encode/decode binary data}]
[category  {Text processing}]
[require Tcl 8.4]
[require ascii85 [opt 1.0]]
[description]
[para]

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

[list_begin definitions]

[call [cmd ::ascii85::encode] [opt "[option -maxlen] [arg maxlen]"] [opt "[option -wrapchar] [arg wrapchar]"] [arg string]]

Ascii85 encodes the given binary [arg string] and returns the encoded
result. Inserts the character [arg wrapchar] every [arg maxlen]
characters of output. [arg wrapchar] defaults to newline. [arg maxlen]
defaults to [const 76].

[para]

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

[para]

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

[call [cmd ::ascii85::decode] [arg "string"]]

Ascii85 decodes the given [arg "string"] and returns the binary data.
The decoder ignores whitespace in the string, as well as tabs and
newlines.

[list_end]

[section {EXAMPLES}]

[example {
% ascii85::encode "Hello, world"
87cURD_*#TDfTZ)
}]

[example {
% 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^]
}]

[example {
# 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]]
}]

[section References]

[list_begin enum]
[enum] [uri http://en.wikipedia.org/wiki/Ascii85]
[enum] Postscript Language Reference Manual, 3rd Edition, page 131.
       [uri http://www.adobe.com/devnet/postscript/pdfs/PLRM.pdf]
[list_end]

[vset CATEGORY base64]
[include ../doctools2base/include/feedback.inc]
[manpage_end]
