@@ -4,6 +4,7 @@
5-- Module : Data.Binary.Bits.Get
5-- Module : Data.Binary.Bits.Get
6-- Copyright : (c) Lennart Kolmodin 2010-2011
6-- Copyright : (c) Lennart Kolmodin 2010-2011
7+-- (c) Sylvain Henry 2015
7-- License : BSD3-style (see LICENSE)
8-- License : BSD3-style (see LICENSE)
9-- Maintainer : kolmodin@gmail.com
10-- Maintainer : kolmodin@gmail.com
@@ -55,13 +56,11 @@ module Data.Binary.Bits.Get
55 -- $bitget
56 -- $bitget
59 , runBitGet
59 , runBitGet
63 -- ** Get bytes
61 -- ** Get bytes
65 , getWord8
64 , getWord8
66 , getWord16
65 , getWord16
67 , getWord32
66 , getWord32
@@ -98,6 +97,9 @@ module Data.Binary.Bits.Get
99import Data.Binary.Get as B ( Get, getLazyByteString, isEmpty )
98import Data.Binary.Get as B ( Get, getLazyByteString, isEmpty )
100import Data.Binary.Get.Internal as B ( get, put, ensureN )
99import Data.Binary.Get.Internal as B ( get, put, ensureN )
100+import Data.Binary.Bits.BitOrder
101+import Data.Binary.Bits.Internal
102+import Data.Binary.Bits.Alignment
102import Data.ByteString as B
104import Data.ByteString as B
103import qualified Data.ByteString.Lazy as L
105import qualified Data.ByteString.Lazy as L
@@ -113,12 +115,8 @@ import Control.Applicative
113import Control.Monad (when,foldM_)
115import Control.Monad (when,foldM_)
115import Prelude as P
117import Prelude as P
117−#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
119import GHC.Word
118import GHC.Word
120−#endif
119+import GHC.Base (uncheckedShiftLWord8#, wordToWord8#, Int (..), andWord8#, Word8#, (-#), Int#, xorI#, eqWord8#, TYPE)
123-- $bitget
121-- $bitget
124-- Parse bits using a monad.
122-- Parse bits using a monad.
@@ -171,16 +169,6 @@ data S = S {-# UNPACK #-} !ByteString -- Input
171 !BitOrder -- Bit order
169 !BitOrder -- Bit order
172 deriving (Show)
170 deriving (Show)
174−-- | Compute bit offset (equivalent to x `mod` 8 but faster)
175−bit_offset :: Int -> Int
176−bit_offset n = make_mask 3 .&. n
177−{-# INLINE bit_offset #-}
179−-- | Compute byte offset (equivalent to x `div` 8 but faster)
180−byte_offset :: Int -> Int
181−byte_offset n = n `shiftR` 3
182−{-# INLINE byte_offset #-}
184-- | Increment the current bit offset
172-- | Increment the current bit offset
185incS :: Int -> S -> S
173incS :: Int -> S -> S
186incS o (S bs n bo) = S (unsafeDrop d bs) n' bo
174incS o (S bs n bo) = S (unsafeDrop d bs) n' bo
@@ -189,83 +177,70 @@ incS o (S bs n bo) = S (unsafeDrop d bs) n' bo
189 !d = byte_offset o'
177 !d = byte_offset o'
190 !n' = bit_offset o'
178 !n' = bit_offset o'
192−-- | Select the bit ordering
193−selectBitOrderS :: BitOrder -> S -> S
194−selectBitOrderS bo (S bs o _) = S bs o bo
196−-- | make_mask 3 = 00000111
197−make_mask :: (Bits a, Num a) => Int -> a
198−make_mask n = (1 `shiftL` fromIntegral n) - 1
199−{-# SPECIALIZE make_mask :: Int -> Int #-}
200−{-# SPECIALIZE make_mask :: Int -> Word #-}
201−{-# SPECIALIZE make_mask :: Int -> Word8 #-}
202−{-# SPECIALIZE make_mask :: Int -> Word16 #-}
203−{-# SPECIALIZE make_mask :: Int -> Word32 #-}
204−{-# SPECIALIZE make_mask :: Int -> Word64 #-}
206−-- | Keep only the n least-significant bits of the given value
207−mask :: (Bits a, Num a) => Int -> a -> a
208−mask n v = v .&. make_mask n
213−-- E.g. two words of 5 bits: ABCDE, VWXYZ
214−-- - BB: ABCDEVWX YZxxxxxx
215−-- - LB: XYZABCDE xxxxxxVW
216−-- - BL: EDCBAZYX WVxxxxxx -- not implemented
217−-- - LL: XWVEDCBA xxxxxxZY -- not implemented
218−data BitOrder = BB | LB deriving (Show)
221-- | Read a single bit
180-- | Read a single bit
222readBool :: S -> Bool
181readBool :: S -> Bool
223readBool (S bs o bo) = case bo of
182readBool (S bs o bo) = case bo of
224 BB -> testBit (unsafeHead bs) (7-o)
183 BB -> testBit (unsafeHead bs) (7-o)
184+ BL -> testBit (unsafeHead bs) (7-o)
185+ LL -> testBit (unsafeHead bs) o
225 LB -> testBit (unsafeHead bs) o
186 LB -> testBit (unsafeHead bs) o
188+-- | Read a single bit
189+readBool# :: S -> Int
190+readBool# (S bs (I# o) bo) = case bo of
191+ BB -> testBit# (7# -# o)
192+ BL -> testBit# (7# -# o)
196+ !(W8# w) = unsafeHead bs
197+ testBit# n = I# (((w `andWord8#` (wordToWord8# 1## `uncheckedShiftLWord8#` n)) `eqWord8#` wordToWord8# 0##) `xorI#` 1#)
227-- | Extract a range of bits from (ws :: ByteString)
200-- | Extract a range of bits from (ws :: ByteString)
229-- Constraint: 8 * (length ws -1 ) < o+n <= 8 * length ws
202-- Constraint: 8 * (length ws -1 ) < o+n <= 8 * length ws
230−extract :: (Num a, Bits a, FastBits a) => BitOrder -> ByteString -> Int -> Int -> a
203+extract :: (Num a, FastBits a) => BitOrder -> ByteString -> Int -> Int -> a
231extract bo bs o n
204extract bo bs o n
232 | n == 0 = 0
205 | n == 0 = 0
233 | B.length bs == 0 = error "Empty ByteString"
206 | B.length bs == 0 = error "Empty ByteString"
234− | otherwise = mask n (foldlWithIndex' f 0 bs)
207+ | otherwise = rev . mask n . foldlWithIndex' f 0 $ bs
236 -- B.foldl' with index
209 -- B.foldl' with index
237 foldlWithIndex' op b = fst . B.foldl' g (b,0)
210 foldlWithIndex' op b = fst . B.foldl' g (b,0)
238 where g (b',i) w = (op b' w i, (i+1))
211 where g (b',i) w = (op b' w i, (i+1))
240 -- 'or' correctly shifted words
213 -- 'or' correctly shifted words
241− f b w i = b .|. (fromIntegral w `fastShift` off i)
214+ f b w i = b .|. (fromIntegral w `fastShift` off i)
243 -- co-offset
216 -- co-offset
244− r = B.length bs * 8 - (o + n)
217+ r = B.length bs * 8 - (o + n)
246 -- shift offset depending on the byte position (0..B.length-1)
219 -- shift offset depending on the byte position (0..B.length-1)
247− off i = case bo of
220+ off i = case bo of
248 LB -> 8*i - o
222 LB -> 8*i - o
249 BB -> (B.length bs -1 - i) * 8 - r
223 BB -> (B.length bs -1 - i) * 8 - r
224+ BL -> (B.length bs -1 - i) * 8 - r
226+ -- reverse bits if necessary
252-- | Generic readWord
234-- | Generic readWord
253−readWord :: (Num a, Bits a, FastBits a) => Int -> S -> a
235+readWord :: (Num a, FastBits a) => Int -> S -> a
254readWord n (S bs o bo)
236readWord n (S bs o bo)
255 | n == 0 = 0
237 | n == 0 = 0
256− | o+n <= 8 = extract bo (unsafeTake 1 bs) o n
257− | o+n <= 16 = extract bo (unsafeTake 2 bs) o n
258− | o+n <= 24 = extract bo (unsafeTake 3 bs) o n
259− | o+n <= 32 = extract bo (unsafeTake 4 bs) o n
260− | o+n <= 40 = extract bo (unsafeTake 5 bs) o n
261− | o+n <= 48 = extract bo (unsafeTake 6 bs) o n
262− | o+n <= 56 = extract bo (unsafeTake 7 bs) o n
263− | o+n <= 64 = extract bo (unsafeTake 8 bs) o n
264− | otherwise = extract bo (unsafeTake ((o+n+7) `div` 8) bs) o n
238+ | otherwise = extract bo (unsafeTake nbytes bs) o n
239+ where nbytes = byte_offset (o+n+7)
266-- | Check that the number of bits to read is not greater than the first parameter
241-- | Check that the number of bits to read is not greater than the first parameter
267{-# INLINE readWordChecked #-}
242{-# INLINE readWordChecked #-}
268−readWordChecked :: (Num a, Bits a, FastBits a) => Int -> Int -> S -> a
243+readWordChecked :: (Num a, FastBits a) => Int -> Int -> S -> a
269readWordChecked m n s
244readWordChecked m n s
270 | n > m = error $ "Tried to read more than " ++ show m ++ " bits (" ++ show n ++")"
245 | n > m = error $ "Tried to read more than " ++ show m ++ " bits (" ++ show n ++")"
271 | otherwise = readWord n s
246 | otherwise = readWord n s
@@ -273,39 +248,37 @@ readWordChecked m n s
273-- | Read the given number of bytes and return them in Big-Endian order
248-- | Read the given number of bytes and return them in Big-Endian order
275-- Examples:
250-- Examples:
276−-- BB: xxxABCDE FGHIJKLM NOPQRxxx -> ABCDEFGH IJKLMNOP QRxxxxxx
251+-- BB: xxxABCDE FGHIJKLM NOPxxxxx -> ABCDEFGH IJKLMNOP
277−-- LB: NOPQRxxx FGHIJKLM xxxABCDE -> ABCDEFGH IJKLMNOP QRxxxxxx
252+-- LL: LMNOPxxx DEFGHIJK xxxxxABC -> ABCDEFGH IJKLMNOP
253+-- BL: xxxPONML KJIHGFED CBAxxxxx -> ABCDEFGH IJKLMNOP
254+-- LB: EDCBAxxx MLKJIHGF xxxxxPON -> ABCDEFGH IJKLMNOP
278readByteString :: Int -> S -> ByteString
255readByteString :: Int -> S -> ByteString
279−readByteString n (S bs o bo)
256+readByteString n (S bs o bo) =
258+ bs' = unsafeTake (n+1) bs
259+ bs'' = unsafeTake n bs
260+ rev = B.map (reverseBits 8)
280− | o == 0 = case bo of
261+ in case (o,bo) of
281− BB -> unsafeTake n bs
262+ (0,BB) -> bs''
263+ (0,LL) -> B.reverse bs''
282− LB -> B.reverse (unsafeTake n bs)
265+ (0,BL) -> rev . B.reverse $ bs''
283−
266+ (_,LL) -> readByteString n (S (B.reverse bs') (8-o) BB)
267+ (_,BL) -> rev . B.reverse $ readByteString n (S bs' o BB)
268+ (_,LB) -> rev . B.reverse $ readByteString n (S bs' o LL)
284− | otherwise = unsafePerformIO $ do
269+ (_,BB) -> unsafePerformIO $ do
285− let len = n+1
270+ let len = n+1
286− ptr <- mallocBytes len
271+ ptr <- mallocBytes len
289− let f r i = do
272+ let f r i = do
291− w = unsafeIndex bs (len-i)
274+ w = unsafeIndex bs (len-i)
292− w' = (w `fastShiftL` o) .|. r
275+ w' = (w `fastShiftL` o) .|. r
293− r' = w `fastShiftR` (8-o)
276+ r' = w `fastShiftR` (8-o)
294− poke (ptr `plusPtr` (len-i)) w'
277+ poke (ptr `plusPtr` (len-i)) w'
295− return r'
278+ return r'
296− foldM_ f 0 [1..len]
279+ foldM_ f 0 [1..len]
297− unsafeInit <$> unsafePackMallocCStringLen (ptr,len)
280+ unsafeInit <$> unsafePackMallocCStringLen (ptr,len)
302− w = unsafeIndex bs (i-1)
303− w' = (w `fastShiftL` (8-o)) .|. r
304− r' = w `fastShiftR` o
305− poke (ptr `plusPtr` (len-i)) w'
308− unsafeTail <$> unsafePackMallocCStringLen (ptr,len)
310------------------------------------------------------------------------
283------------------------------------------------------------------------
311-- | 'BitGet' is a monad, applicative and a functor. See 'runBitGet'
284-- | 'BitGet' is a monad, applicative and a functor. See 'runBitGet'
@@ -314,7 +287,6 @@ newtype BitGet a = B { runState :: S -> Get (S,a) }
315instance Monad BitGet where
288instance Monad BitGet where
316 return x = B $ \s -> return (s,x)
289 return x = B $ \s -> return (s,x)
317− fail str = B $ \s -> putBackState s >> fail str
318 (B f) >>= g = B $ \s -> do (s',a) <- f s
290 (B f) >>= g = B $ \s -> do (s',a) <- f s
319 runState (g a) s'
291 runState (g a) s'
@@ -325,6 +297,29 @@ instance Applicative BitGet where
325 pure x = return x
297 pure x = return x
326 fm <*> m = fm >>= \f -> m >>= \v -> return (f v)
298 fm <*> m = fm >>= \f -> m >>= \v -> return (f v)
300+instance BitOrderable BitGet where
302+ (S bs o _) <- getState
303+ putState (S bs o bo)
306+ (S _ _ bo) <- getState
309+instance Alignable BitGet where
310+ -- | Skip the given number of bits
315+ -- | Skip bits if necessary to align to the next byte
317+ (S _ o _) <- getState
328-- | Run a 'BitGet' within the Binary packages 'Get' monad. If a byte has
323-- | Run a 'BitGet' within the Binary packages 'Get' monad. If a byte has
329-- been partially consumed it will be discarded once 'runBitGet' is finished.
324-- been partially consumed it will be discarded once 'runBitGet' is finished.
330runBitGet :: BitGet a -> Get a
325runBitGet :: BitGet a -> Get a
@@ -359,13 +354,6 @@ withState f = do
359 s <- getState
354 s <- getState
360 putState $! f s
355 putState $! f s
362−-- | Get the bit ordering
363−getBitOrder :: BitGet BitOrder
365− (S _ _ bo) <- getState
369-- | Make sure there are at least @n@ bits.
357-- | Make sure there are at least @n@ bits.
370ensureBits :: Int -> BitGet ()
358ensureBits :: Int -> BitGet ()
371ensureBits n = do
359ensureBits n = do
@@ -379,33 +367,6 @@ ensureBits n = do
379 put B.empty
367 put B.empty
380 return (S (bs`append`bs') o bo, ())
368 return (S (bs`append`bs') o bo, ())
382−-- | Skip the given number of bits
383−skipBits :: Int -> BitGet ()
388−-- | Skip bits if necessary to align to the next byte
389−alignByte :: BitGet ()
391− (S _ o _) <- getState
395−-- | Select the bit ordering
396−selectBitOrder :: BitOrder -> BitGet ()
397−selectBitOrder = withState . selectBitOrderS
399−withBitOrder :: BitOrder -> BitGet a -> BitGet a
400−withBitOrder bo f = do
409-- | Test whether all input has been consumed, i.e. there are no remaining
370-- | Test whether all input has been consumed, i.e. there are no remaining
410-- undecoded bytes.
371-- undecoded bytes.
411isEmpty :: BitGet Bool
372isEmpty :: BitGet Bool
@@ -417,6 +378,10 @@ isEmpty = B $ \ (S bs o bo) -> if B.null bs
417getBool :: BitGet Bool
378getBool :: BitGet Bool
418getBool = block bool
379getBool = block bool
381+-- | Get 1 bit as a 'Bool'.
382+getBool# :: BitGet Int
383+getBool# = block bool#
420-- | Get @n@ bits as a 'Word8'. @n@ must be within @[0..8]@.
385-- | Get @n@ bits as a 'Word8'. @n@ must be within @[0..8]@.
421getWord8 :: Int -> BitGet Word8
386getWord8 :: Int -> BitGet Word8
422getWord8 n = block (word8 n)
387getWord8 n = block (word8 n)
@@ -492,6 +457,10 @@ block (Block i p) = do
492bool :: Block Bool
457bool :: Block Bool
493bool = Block 1 readBool
458bool = Block 1 readBool
460+-- | Read a 1 bit 'Bool'.
462+bool# = Block 1 readBool#
495-- | Read @n@ bits as a 'Word8'. @n@ must be within @[0..8]@.
464-- | Read @n@ bits as a 'Word8'. @n@ must be within @[0..8]@.
496word8 :: Int -> Block Word8
465word8 :: Int -> Block Word8
497word8 n = Block n (readWordChecked 8 n)
466word8 n = Block n (readWordChecked 8 n)
@@ -525,84 +494,3 @@ byteString :: Int -> Block ByteString
525byteString n | n > 0 = Block (n*8) (readByteString n)
494byteString n | n > 0 = Block (n*8) (readByteString n)
526 | otherwise = Block 0 (\_ -> B.empty)
495 | otherwise = Block 0 (\_ -> B.empty)
529−---------------------------------------------------------------------
530−-- Unchecked shifts, from the "binary" package
532−-- | Class for types supporting fast bit shifting
533−class FastBits a where
534− fastShiftR :: a -> Int -> a
535− fastShiftL :: a -> Int -> a
537− {-# INLINE fastShift #-}
538− fastShift :: a -> Int -> a
540− | n > 0 = fastShiftL x n
541− | n < 0 = fastShiftR x (negate n)
544−instance FastBits Word8 where
545− fastShiftR = shiftr_w8
546− fastShiftL = shiftl_w8
548−instance FastBits Word16 where
549− fastShiftR = shiftr_w16
550− fastShiftL = shiftl_w16
552−instance FastBits Word32 where
553− fastShiftR = shiftr_w32
554− fastShiftL = shiftl_w32
556−instance FastBits Word64 where
557− fastShiftR = shiftr_w64
558− fastShiftL = shiftl_w64
561−shiftl_w8 :: Word8 -> Int -> Word8
562−shiftl_w16 :: Word16 -> Int -> Word16
563−shiftl_w32 :: Word32 -> Int -> Word32
564−shiftl_w64 :: Word64 -> Int -> Word64
566−shiftr_w8 :: Word8 -> Int -> Word8
567−shiftr_w16 :: Word16 -> Int -> Word16
568−shiftr_w32 :: Word32 -> Int -> Word32
569−shiftr_w64 :: Word64 -> Int -> Word64
571−#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
572−shiftl_w8 (W8# w) (I# i) = W8# (w `uncheckedShiftL#` i)
573−shiftl_w16 (W16# w) (I# i) = W16# (w `uncheckedShiftL#` i)
574−shiftl_w32 (W32# w) (I# i) = W32# (w `uncheckedShiftL#` i)
576−shiftr_w8 (W8# w) (I# i) = W8# (w `uncheckedShiftRL#` i)
577−shiftr_w16 (W16# w) (I# i) = W16# (w `uncheckedShiftRL#` i)
578−shiftr_w32 (W32# w) (I# i) = W32# (w `uncheckedShiftRL#` i)
581−#if WORD_SIZE_IN_BITS < 64
582−shiftl_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftL64#` i)
583−shiftr_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftRL64#` i)
585−#if __GLASGOW_HASKELL__ <= 606
586−-- Exported by GHC.Word in GHC 6.8 and higher
587−foreign import ccall unsafe "stg_uncheckedShiftL64"
588− uncheckedShiftL64# :: Word64# -> Int# -> Word64#
589−foreign import ccall unsafe "stg_uncheckedShiftRL64"
590− uncheckedShiftRL64# :: Word64# -> Int# -> Word64#
594−shiftl_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftL#` i)
595−shiftr_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftRL#` i)