177 lines
7.8 KiB
Haskell
177 lines
7.8 KiB
Haskell
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-- |
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-- Module : Data.Memory.Encoding.Base16
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-- License : BSD-style
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-- Maintainer : Vincent Hanquez <vincent@snarc.org>
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-- Stability : experimental
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-- Portability : unknown
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--
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-- Low-level Base16 encoding and decoding.
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--
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-- If you just want to encode or decode some bytes, you probably want to use
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-- the "Data.ByteArray.Encoding" module.
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--
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{-# LANGUAGE MagicHash #-}
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{-# LANGUAGE UnboxedTuples #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE BangPatterns #-}
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{-# LANGUAGE Rank2Types #-}
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module Data.Memory.Encoding.Base16
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( showHexadecimal
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, toHexadecimal
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, fromHexadecimal
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) where
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import Data.Memory.Internal.Compat
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import Data.Word
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import Basement.Bits
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import Basement.IntegralConv
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import GHC.Prim
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import GHC.Types
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import GHC.Word
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import GHC.Char (chr)
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import Control.Monad
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import Foreign.Storable
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import Foreign.Ptr (Ptr)
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-- | Transform a raw memory to an hexadecimal 'String'
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--
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-- user beware, no checks are made
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showHexadecimal :: (forall a . (Ptr Word8 -> IO a) -> IO a) -- ^ a 'with' type of function to hold reference to the object
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-> Int -- ^ length in bytes
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-> String
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showHexadecimal withPtr = doChunks 0
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where
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doChunks ofs len
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| len < 4 = doUnique ofs len
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| otherwise = do
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let !(a, b, c, d) = unsafeDoIO $ withPtr (read4 ofs)
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!(# w1, w2 #) = convertByte a
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!(# w3, w4 #) = convertByte b
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!(# w5, w6 #) = convertByte c
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!(# w7, w8 #) = convertByte d
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in wToChar w1 : wToChar w2 : wToChar w3 : wToChar w4
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: wToChar w5 : wToChar w6 : wToChar w7 : wToChar w8
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: doChunks (ofs + 4) (len - 4)
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doUnique ofs len
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| len == 0 = []
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| otherwise =
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let !b = unsafeDoIO $ withPtr (byteIndex ofs)
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!(# w1, w2 #) = convertByte b
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in wToChar w1 : wToChar w2 : doUnique (ofs + 1) (len - 1)
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read4 :: Int -> Ptr Word8 -> IO (Word8, Word8, Word8, Word8)
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read4 ofs p =
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liftM4 (,,,) (byteIndex ofs p) (byteIndex (ofs+1) p)
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(byteIndex (ofs+2) p) (byteIndex (ofs+3) p)
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wToChar :: Word8 -> Char
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wToChar w = chr (integralUpsize w)
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byteIndex :: Int -> Ptr Word8 -> IO Word8
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byteIndex i p = peekByteOff p i
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-- | Transform a number of bytes pointed by.@src in the hexadecimal binary representation in @dst
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--
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-- destination memory need to be of correct size, otherwise it will lead
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-- to really bad things.
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toHexadecimal :: Ptr Word8 -- ^ destination memory
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-> Ptr Word8 -- ^ source memory
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-> Int -- ^ number of bytes
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-> IO ()
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toHexadecimal bout bin n = loop 0
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where loop i
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| i == n = return ()
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| otherwise = do
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!w <- peekByteOff bin i
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let !(# !w1, !w2 #) = convertByte w
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pokeByteOff bout (i * 2) w1
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pokeByteOff bout (i * 2 + 1) w2
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loop (i+1)
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-- | Convert a value Word# to two Word#s containing
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-- the hexadecimal representation of the Word#
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convertByte :: Word8 -> (# Word8, Word8 #)
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convertByte bwrap = (# r tableHi b, r tableLo b #)
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where
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!(W# b) = integralUpsize bwrap
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r :: Addr# -> Word# -> Word8
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r table index = W8# (indexWord8OffAddr# table (word2Int# index))
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!tableLo =
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"0123456789abcdef0123456789abcdef\
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\0123456789abcdef0123456789abcdef\
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\0123456789abcdef0123456789abcdef\
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\0123456789abcdef0123456789abcdef\
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\0123456789abcdef0123456789abcdef\
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\0123456789abcdef0123456789abcdef\
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\0123456789abcdef0123456789abcdef\
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\0123456789abcdef0123456789abcdef"#
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!tableHi =
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"00000000000000001111111111111111\
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\22222222222222223333333333333333\
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\44444444444444445555555555555555\
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\66666666666666667777777777777777\
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\88888888888888889999999999999999\
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\aaaaaaaaaaaaaaaabbbbbbbbbbbbbbbb\
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\ccccccccccccccccdddddddddddddddd\
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\eeeeeeeeeeeeeeeeffffffffffffffff"#
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{-# INLINE convertByte #-}
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-- | convert a base16 @src in @dst.
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--
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-- n need to even
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fromHexadecimal :: Ptr Word8 -> Ptr Word8 -> Int -> IO (Maybe Int)
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fromHexadecimal dst src n
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| odd n = error "fromHexadecimal: invalid odd length."
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| otherwise = loop 0 0
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where loop di i
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| i == n = return Nothing
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| otherwise = do
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a <- rHi `fmap` peekByteOff src i
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b <- rLo `fmap` peekByteOff src (i+1)
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if a == 0xff || b == 0xff
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then return $ Just i
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else pokeByteOff dst di (a .|. b) >> loop (di+1) (i+2)
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rLo, rHi :: Word8 -> Word8
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rLo index = W8# (indexWord8OffAddr# tableLo (word2Int# widx))
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where !(W# widx) = integralUpsize index
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rHi index = W8# (indexWord8OffAddr# tableHi (word2Int# widx))
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where !(W# widx) = integralUpsize index
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!tableLo =
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"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\xff\xff\xff\xff\xff\xff\
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\\xff\x0a\x0b\x0c\x0d\x0e\x0f\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\x0a\x0b\x0c\x0d\x0e\x0f\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"#
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!tableHi =
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"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\x00\x10\x20\x30\x40\x50\x60\x70\x80\x90\xff\xff\xff\xff\xff\xff\
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\\xff\xa0\xb0\xc0\xd0\xe0\xf0\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xa0\xb0\xc0\xd0\xe0\xf0\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\
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\\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"#
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