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