content: module UTF8 where
  
  -- From the Char module supplied with HBC.
  
  -- Take a Unicode string and encode it as a string
  -- with the UTF8 method.
  decodeUTF8 :: String -> String
  decodeUTF8 "" = ""
  decodeUTF8 (c:cs) | c < '\x80' = c : decodeUTF8 cs
  decodeUTF8 (c:c':cs) | '\xc0' <= c  && c  <= '\xdf' && 
  		      '\x80' <= c' && c' <= '\xbf' =
  	toEnum ((fromEnum c `mod` 0x20) * 0x40 + fromEnum c' `mod` 0x40) : decodeUTF8 cs
  decodeUTF8 (c:c':c'':cs) | '\xe0' <= c   && c   <= '\xef' && 
  		          '\x80' <= c'  && c'  <= '\xbf' &&
  		          '\x80' <= c'' && c'' <= '\xbf' =
  	toEnum ((fromEnum c `mod` 0x10 * 0x1000) + (fromEnum c' `mod` 0x40) * 0x40 + fromEnum c'' `mod` 0x40) : decodeUTF8 cs
  decodeUTF8 _ = error "UniChar.decodeUTF8: bad data"
  
  encodeUTF8 :: String -> String
  encodeUTF8 "" = ""
  encodeUTF8 (c:cs) =
  	if c > '\x0000' && c < '\x0080' then
  	    c : encodeUTF8 cs
  	else if c < toEnum 0x0800 then
  	    let i = fromEnum c
  	    in  toEnum (0xc0 + i `div` 0x40) : 
  	        toEnum (0x80 + i `mod` 0x40) : 
  		encodeUTF8 cs
  	else
  	    let i = fromEnum c
  	    in  toEnum (0xe0 + i `div` 0x1000) : 
  	        toEnum (0x80 + (i `mod` 0x1000) `div` 0x40) : 
  		toEnum (0x80 + i `mod` 0x40) : 
  		encodeUTF8 cs
  