--- /dev/null
+! Copyright (C) 2013 John Benediktsson
+! See http://factorcode.org/license.txt for BSD license
+
+USING: io io.streams.string kernel locals make math math.bitwise
+math.order namespaces sequences ;
+
+IN: uu
+
+<PRIVATE
+
+ERROR: bad-length seq ;
+
+: check-length ( seq -- seq )
+ dup length 45 > [ bad-length ] when ; inline
+
+:: binary>ascii ( seq -- seq' )
+ 0 :> char!
+ 0 :> bits!
+ seq check-length [
+ dup length CHAR: \s + ,
+
+ [ dup empty? bits zero? and ] [
+
+ char 8 shift char!
+ bits 8 + bits!
+
+ dup empty? [
+ unclip-slice char bitor char!
+ ] unless
+
+ [ bits 6 >= ] [
+ bits 6 -
+ [ char swap neg shift 0x3f bitand CHAR: \s + , ]
+ [ bits! ] bi
+ ] while
+
+ ] until drop
+ ] "" make ;
+
+ERROR: illegal-character ch ;
+
+: check-illegal-character ( ch -- ch )
+ dup CHAR: \s dup 64 + between? [ illegal-character ] unless ;
+
+:: ascii>binary ( seq -- seq' )
+ 0 :> char!
+ 0 :> bits!
+
+ seq unclip-slice CHAR: \s - :> len!
+
+ [
+ [ dup empty? not len 0 > and ] [
+ dup empty? [ 0 ] [ unclip-slice ] if
+ dup "\r\n\0" member? [
+ drop 0
+ ] [
+ check-illegal-character
+ CHAR: \s -
+ ] if
+
+ char 6 shift bitor char!
+ bits 6 + bits!
+
+ bits 8 >= [
+ bits 8 -
+ [ char swap neg shift 0xff bitand , ]
+ [ on-bits char bitand char! ]
+ [ bits! ] tri
+ len 1 - len!
+ ] when
+ ] while drop
+
+ ] "" make ;
+
+PRIVATE>
+
+: uu-encode ( -- )
+ "begin" print
+ input-stream get [ binary>ascii print ] 45 (each-stream-block)
+ "end" print ;
+
+: string>uu ( seq -- seq' )
+ [ [ uu-encode ] with-string-writer ] with-string-reader ;
+
+: uu-decode ( -- )
+ [ [ "begin" head? ] [ not ] bi or ] [ readln ] do until
+ [
+ dup [ "end" head? ] [ not ] bi or
+ [ drop t ] [ ascii>binary write f ] if
+ ] [ readln ] do until ;
+
+: uu>string ( seq -- seq )
+ [ [ uu-decode ] with-string-writer ] with-string-reader ;