--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/netserver/Codec/Binary/Base64.hs	Sun Jan 25 13:48:41 2009 +0000
@@ -0,0 +1,113 @@
+-- |
+-- Module    : Codec.Binary.Base64
+-- Copyright : (c) 2007 Magnus Therning
+-- License   : BSD3
+--
+-- Implemented as specified in RFC 4648
+-- (<http://tools.ietf.org/html/rfc4648>).
+--
+-- Further documentation and information can be found at
+-- <http://www.haskell.org/haskellwiki/Library/Data_encoding>.
+module Codec.Binary.Base64
+    ( encode
+    , decode
+    , decode'
+    , chop
+    , unchop
+    ) where
+
+import Control.Monad
+import Data.Array
+import Data.Bits
+import Data.Maybe
+import Data.Word
+import qualified Data.Map as M
+
+-- {{{1 enc/dec map
+_encMap =
+    [ (0, 'A'), (1, 'B'), (2, 'C'), (3, 'D'), (4, 'E')
+    , (5, 'F') , (6, 'G'), (7, 'H'), (8, 'I'), (9, 'J')
+    , (10, 'K'), (11, 'L'), (12, 'M'), (13, 'N'), (14, 'O')
+    , (15, 'P'), (16, 'Q'), (17, 'R'), (18, 'S'), (19, 'T')
+    , (20, 'U'), (21, 'V'), (22, 'W'), (23, 'X'), (24, 'Y')
+    , (25, 'Z'), (26, 'a'), (27, 'b'), (28, 'c'), (29, 'd')
+    , (30, 'e'), (31, 'f'), (32, 'g'), (33, 'h'), (34, 'i')
+    , (35, 'j'), (36, 'k'), (37, 'l'), (38, 'm'), (39, 'n')
+    , (40, 'o'), (41, 'p'), (42, 'q'), (43, 'r'), (44, 's')
+    , (45, 't'), (46, 'u'), (47, 'v'), (48, 'w'), (49, 'x')
+    , (50, 'y'), (51, 'z'), (52, '0'), (53, '1'), (54, '2')
+    , (55, '3'), (56, '4'), (57, '5'), (58, '6'), (59, '7')
+    , (60, '8'), (61, '9'), (62, '+'), (63, '/') ]
+
+-- {{{1 encodeArray
+encodeArray :: Array Word8 Char
+encodeArray = array (0, 64) _encMap
+
+-- {{{1 decodeMap
+decodeMap :: M.Map Char Word8
+decodeMap  = M.fromList [(snd i, fst i) | i <- _encMap]
+
+-- {{{1 encode
+-- | Encode data.
+encode :: [Word8]
+    -> String
+encode = let
+        pad n = take n $ repeat 0
+        enc [] = ""
+        enc l@[o] = (++ "==") . take 2 .enc $ l ++ pad 2
+        enc l@[o1, o2] = (++ "=") . take 3 . enc $ l ++ pad 1
+        enc (o1:o2:o3:os) = let
+                i1 = o1 `shiftR` 2
+                i2 = (o1 `shiftL` 4 .|. o2 `shiftR` 4) .&. 0x3f
+                i3 = (o2 `shiftL` 2 .|. o3 `shiftR` 6) .&. 0x3f
+                i4 = o3 .&. 0x3f
+            in (foldr (\ i s -> (encodeArray ! i) : s) "" [i1, i2, i3, i4]) ++ enc os
+    in enc
+
+-- {{{1 decode
+-- | Decode data (lazy).
+decode' :: String
+    -> [Maybe Word8]
+decode' = let
+        pad n = take n $ repeat $ Just 0
+        dec [] = []
+        dec l@[Just eo1, Just eo2] = take 1 . dec $ l ++ pad 2
+        dec l@[Just eo1, Just eo2, Just eo3] = take 2 . dec $ l ++ pad 1
+        dec (Just eo1:Just eo2:Just eo3:Just eo4:eos) = let
+                o1 = eo1 `shiftL` 2 .|. eo2 `shiftR` 4
+                o2 = eo2 `shiftL` 4 .|. eo3 `shiftR` 2
+                o3 = eo3 `shiftL` 6 .|. eo4
+            in Just o1:Just o2:Just o3:(dec eos)
+        dec _ = [Nothing]
+    in
+        dec . map (flip M.lookup decodeMap) . takeWhile (/= '=')
+
+-- | Decode data (strict).
+decode :: String
+    -> Maybe [Word8]
+decode = sequence . decode'
+
+-- {{{1 chop
+-- | Chop up a string in parts.
+--
+--   The length given is rounded down to the nearest multiple of 4.
+--
+--   /Notes:/
+--
+--   * PEM requires lines that are 64 characters long.
+--
+--   * MIME requires lines that are at most 76 characters long.
+chop :: Int     -- ^ length of individual lines
+    -> String
+    -> [String]
+chop n "" = []
+chop n s = let
+        enc_len | n < 4 = 4
+                | otherwise = n `div` 4 * 4
+    in (take enc_len s) : chop n (drop enc_len s)
+
+-- {{{1 unchop
+-- | Concatenate the strings into one long string.
+unchop :: [String]
+    -> String
+unchop = foldr (++) ""