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{-# LANGUAGE UnboxedTuples #-}
module Feistel where
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as L
import Data.Word
import Data.Bits
import Data.Binary
import System.Endian
toW32Pair :: B.ByteString -> ( Word32, Word32 )
toW32Pair b = let (x1, x2) = B.splitAt 4 b
w1 = decode32be x1
w2 = decode32be x2
in ( w1,w2 )
fromW32Pair :: (Word32, Word32) -> B.ByteString
fromW32Pair (w1,w2)
= let w1' = fromIntegral w1
w2' = fromIntegral w2
w = (w1' `shiftL` 32) .|. w2'
in encode64be w
decode32be :: B.ByteString -> Word32
decode32be s = id $!
(fromIntegral (s `B.index` 0) `shiftL` 24) .|.
(fromIntegral (s `B.index` 1) `shiftL` 16) .|.
(fromIntegral (s `B.index` 2) `shiftL` 8) .|.
(fromIntegral (s `B.index` 3) )
encode64be :: Word64 -> B.ByteString
encode64be w = B.pack . map fromIntegral $
[ (w `shiftR` 56) .&. 0xff
, (w `shiftR` 48) .&. 0xff
, (w `shiftR` 40) .&. 0xff
, (w `shiftR` 32) .&. 0xff
, (w `shiftR` 24) .&. 0xff
, (w `shiftR` 16) .&. 0xff
, (w `shiftR` 8) .&. 0xff
, w .&. 0xff
]
splitWord32 :: Word32 -> (# Word8, Word8, Word8, Word8 #)
splitWord32 w = (# a,b,c,d #)
where
a = fromIntegral $ w `shiftR` 24
b = fromIntegral $ w `shiftR` 16
c = fromIntegral $ w `shiftR` 8
d = fromIntegral $ w
|
