1 files changed, 34 insertions, 8 deletions

diff --git a/src/Text/XXD.hs b/src/Text/XXD.hs
index d835b238..b73a1ea2 100644
--- a/src/Text/XXD.hs
+++ b/src/Text/XXD.hs
@@ -1,26 +1,52 @@
-module Text.XXD where
+{-# LANGUAGE RankNTypes          #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+module Text.XXD (xxd, xxd2) where
 
 import qualified Data.ByteString.Base16 as Base16
 import Data.ByteString (ByteString)
 import qualified Data.ByteString as B
+import Data.ByteArray (ByteArrayAccess,ByteArray)
+import qualified Data.ByteArray as BA
 import Data.Word
 import Data.Bits
 import Data.Char
+import Data.List
 import Text.Printf
 
 nibble :: Word8 -> Char
 nibble b = intToDigit (fromIntegral (b .&. 0x0F))
 
-xxd :: Int -> ByteString -> [String]
-xxd offset bs | B.null bs = []
-xxd offset bs             = printf "%03x: %s" offset ds : xxd (offset + B.length xs) bs'
+nibbles :: ByteArrayAccess ba => ba -> String
+nibbles xs = unwords $ map (\byte -> [nibble (byte `shiftR` 4), nibble byte])
+                     $ BA.unpack xs
+
+xxd0 :: (ByteArrayAccess ba) => (forall b. ByteArrayAccess b => b -> String) -> Int -> ba -> [String]
+xxd0 tr offset bs | BA.null bs = []
+xxd0 tr offset bs              = printf "%03x: %s%s" offset (nibbles xs) (tr xs)
+                                 : xxd0 tr (offset + BA.length xs) bs'
  where
-    ds = unwords $ map (\byte -> [nibble (byte `shiftR` 4), nibble byte])
-                 $ B.unpack xs
-    (xs,bs') = B.splitAt 16 bs
+    (xs,bs') = splitAtView 16 bs
+
+splitAtView :: (ByteArrayAccess ba) => Int -> ba -> (BA.View ba, BA.View ba)
+splitAtView n bs = (BA.takeView bs n, BA.dropView bs n)
+
+xxd :: ByteArrayAccess a => Int -> a -> [String]
+xxd = xxd0 (const "")
+
+-- | like xxd, but also shows ascii
+xxd2 :: ByteArrayAccess a => Int -> a -> [String]
+xxd2 = xxd0 withAscii
+
+withAscii :: ByteArrayAccess a => a -> [Char]
+withAscii row = replicate (50 - 3 * BA.length row) ' ' ++ myunpack row
+    where
+        myunpack s = map word8tochar (BA.unpack s)
+            where word8tochar w | (w .&. 0x80 /= 0) = '.'
+                  word8tochar w = let c = chr (fromIntegral w)
+                                      in if isPrint c then c else '.'
 
 {-
 main = do
     bs <- B.getContents
-    mapM_ putStrLn $ xxd 0 bs
+    mapM_ putStrLn $ xxd2 0 bs
     -}