@@ -1,145 +1,73 @@
11{-# LANGUAGE RankNTypes, MagicHash, BangPatterns, CPP #-}
22
3−-----------------------------------------------------------------------------
4−-- |
5−-- Module : Data.Binary.Bits.Get
6−-- Copyright : (c) Lennart Kolmodin 2010-2011
7−-- (c) Sylvain Henry 2015
8−-- License : BSD3-style (see LICENSE)
9−--
10−-- Maintainer : kolmodin@gmail.com
11−-- Stability : experimental
12−-- Portability : portable (should run where the package binary runs)
13−--
14−-- Parse bits easily. Parsing can be done either in a monadic style, or more
15−-- efficiently, using the 'Applicative' style.
16−--
17−-- For the monadic style, write your parser as a 'BitGet' monad using the
18−--
19−-- * 'getBool'
20−--
21−-- * 'getWord8'
22−--
23−-- * 'getWord16be'
24−--
25−-- * 'getWord32be'
26−--
27−-- * 'getWord64be'
28−--
29−-- * 'getByteString'
30−--
31−-- functions and run it with 'runBitGet'.
32−--
33−-- For the applicative style, compose the fuctions
34−--
35−-- * 'bool'
36−--
37−-- * 'word8'
38−--
39−-- * 'word16be'
40−--
41−-- * 'word32be'
42−--
43−-- * 'word64be'
44−--
45−-- * 'byteString'
46−--
47−-- to make a 'Block'.
48−-- Use 'block' to turn it into the 'BitGet' monad to be able to run it with
49−-- 'runBitGet'.
50−-----------------------------------------------------------------------------
51−
523module Data.Binary.Bits.Get
53− (
54− -- * BitGet monad
55−
56− -- $bitget
57−
58− BitGet
4+ ( BitGet
5+ , Block
596 , runBitGet
607
61− -- ** Get bytes
628 , getBool
63− , getBool#
649 , getWord8
65− , getWord16
66− , getWord32
67− , getWord64
6810 , getWord16be
6911 , getWord32be
7012 , getWord64be
7113
72− -- ** Skip bits
73− , skipBits
74− , alignByte
75−
76− -- * Blocks
77−
78− -- $blocks
79− , Block
80− , block
81−
82− -- ** Read in Blocks
8314 , bool
8415 , word8
85− , word16
86− , word32
87− , word64
8816 , word16be
8917 , word32be
9018 , word64be
9119 , byteString
92− , Data.Binary.Bits.Get.getByteString
93− , Data.Binary.Bits.Get.getLazyByteString
94− , Data.Binary.Bits.Get.isEmpty
9520
21+ , block
22+
23+ , Data.Binary.Bits.Get.getByteString
9624 ) where
9725
98−import Data.Binary.Get as B ( Get, getLazyByteString, isEmpty )
99−import 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
26+import Data.Binary.Get as B ( runGet, Get, getByteString )
10327
10428import Data.ByteString as B
105−import qualified Data.ByteString.Lazy as L
29+import Data.ByteString.Internal
10630import Data.ByteString.Unsafe
107−import Foreign.Marshal.Alloc (mallocBytes)
108−import Foreign.Ptr
109−import Foreign.Storable (poke)
110−import System.IO.Unsafe (unsafePerformIO)
31+
32+import qualified Data.ByteString.Lazy as L
11133
11234import Data.Bits
11335import Data.Word
36+import Data.List as List ( reverse )
37+
11438import Control.Applicative
115−import Control.Monad (when,foldM_)
11639
11740import Prelude as P
41+
42+#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
43+import GHC.Base
11844import GHC.Word
119−import GHC.Base (uncheckedShiftLWord8#, wordToWord8#, Int (..), andWord8#, Word8#, (-#), Int#, xorI#, eqWord8#, TYPE)
45+import GHC.Int
46+#endif
12047
121−-- $bitget
122−-- Parse bits using a monad.
123−--
124−-- @
125−--myBitParser :: 'Get' ('Word8', 'Word8')
126−--myBitParser = 'runGetBit' parse4by4
127−--
128−--parse4by4 :: 'BitGet' ('Word8', 'Word8')
129−--parse4by4 = do
130−-- bits <- 'getWord8' 4
131−-- more <- 'getWord8' 4
132−-- return (bits,more)
133−-- @
48+data S = S !ByteString -- Input
49+ !Int -- Bit offset (0-7)
50+ deriving (Show)
13451
135−-- $blocks
136−-- Parse more efficiently in blocks. Each block is read with only one boundry
137−-- check (checking that there is enough input) as the size of the block can be
138−-- calculated statically. This is somewhat limiting as you cannot make the
139−-- parsing depend on the input being parsed.
140−--
52+-- | A block that will be read with only one boundry check. Needs to know the
53+-- number of bits in advance.
54+data Block a = Block !Int (S -> a)
55+
56+instance Functor Block where
57+ fmap f (Block i p) = Block i (\s -> f (p s))
58+
59+instance Applicative Block where
60+ pure a = Block 0 (\_ -> a)
61+ (Block i p) <*> (Block j q) = Block (i+j) (\s -> p s $ q (incS i s))
62+ (Block i _) *> (Block j q) = Block (i+j) (q . incS i)
63+ (Block i p) <* (Block j _) = Block (i+j) p
64+
65+-- | Get a block. Guaranteed to be done with one single boundry check, and must
66+-- therefore require a statically known number of bits.
67+-- Build blocks using 'bool', 'word8', 'word16be', 'word32be', 'word64be' and 'Applicative'.
68+--
14169-- @
142−--data IPV6Header = IPV6Header {
70+-- data IPV6Header = IPV6Header {
14371-- ipv6Version :: 'Word8'
14472-- , ipv6TrafficClass :: 'Word8'
14573-- , ipv6FlowLabel :: 'Word32
@@ -150,8 +78,7 @@ import GHC.Base (uncheckedShiftLWord8#, wordToWord8#, Int (..), andWord8#, Word8
15078-- , ipv6DestinationAddress :: 'ByteString'
15179-- }
15280--
153−-- ipv6headerblock =
154−-- IPV6Header '<$>' 'word8' 4
81+-- parse = IPV6Header '<$>' 'word8' 4
15582-- '<*>' 'word8' 8
15683-- '<*>' 'word32be' 24
15784-- '<*>' 'word16be' 16
@@ -159,134 +86,174 @@ import GHC.Base (uncheckedShiftLWord8#, wordToWord8#, Int (..), andWord8#, Word8
15986-- '<*>' 'word8' 8
16087-- '<*>' 'byteString' 16
16188-- '<*>' 'byteString' 16
162−--
163−--ipv6Header :: 'Get' IPV6Header
164−--ipv6Header = 'runBitGet' ('block' ipv6headerblock)
16589-- @
90+block :: Block a -> BitGet a
91+block (Block i p) = do
92+ ensureBits i
93+ modifyState (\s -> (incS i s, p s))
94+
95+-- | make_mask 3 = 00000111
96+make_mask :: Bits a => Int -> a
97+make_mask n = (1 `shiftL` fromIntegral n) - 1
98+{-# SPECIALIZE make_mask :: Int -> Int #-}
99+{-# SPECIALIZE make_mask :: Int -> Word #-}
100+{-# SPECIALIZE make_mask :: Int -> Word8 #-}
101+{-# SPECIALIZE make_mask :: Int -> Word16 #-}
102+{-# SPECIALIZE make_mask :: Int -> Word32 #-}
103+{-# SPECIALIZE make_mask :: Int -> Word64 #-}
166104
167−data S = S {-# UNPACK #-} !ByteString -- Input
168− {-# UNPACK #-} !Int -- Bit offset (0-7)
169− !BitOrder -- Bit order
170− deriving (Show)
105+readBool :: S -> Bool
106+readBool (S bs n) = testBit (unsafeHead bs) (7-n)
171107
172−-- | Increment the current bit offset
173108incS :: Int -> S -> S
174−incS o (S bs n bo) = S (unsafeDrop d bs) n' bo
175− where
176− !o' = (n+o)
177− !d = byte_offset o'
178− !n' = bit_offset o'
109+incS o (S bs n) =
110+ let !o' = (n+o)
111+ !d = o' `shiftR` 3
112+ !n' = o' .&. make_mask 3
113+ in S (unsafeDrop d bs) n'
179114
180−-- | Read a single bit
181−readBool :: S -> Bool
182−readBool (S bs o bo) = case bo of
183− BB -> testBit (unsafeHead bs) (7-o)
184− BL -> testBit (unsafeHead bs) (7-o)
185− LL -> testBit (unsafeHead bs) o
186− LB -> testBit (unsafeHead bs) o
187−
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)
193− LL -> testBit# o
194− LB -> testBit# o
195− where
196− !(W8# w) = unsafeHead bs
197− testBit# n = I# (((w `andWord8#` (wordToWord8# 1## `uncheckedShiftLWord8#` n)) `eqWord8#` wordToWord8# 0##) `xorI#` 1#)
198−
199−
200−-- | Extract a range of bits from (ws :: ByteString)
201−--
202−-- Constraint: 8 * (length ws -1 ) < o+n <= 8 * length ws
203−extract :: (Num a, FastBits a) => BitOrder -> ByteString -> Int -> Int -> a
204−extract bo bs o n
205− | n == 0 = 0
206− | B.length bs == 0 = error "Empty ByteString"
207− | otherwise = rev . mask n . foldlWithIndex' f 0 $ bs
208− where
209− -- B.foldl' with index
210− foldlWithIndex' op b = fst . B.foldl' g (b,0)
211− where g (b',i) w = (op b' w i, (i+1))
212−
213− -- 'or' correctly shifted words
214− f b w i = b .|. (fromIntegral w `fastShift` off i)
215−
216− -- co-offset
217− r = B.length bs * 8 - (o + n)
218−
219− -- shift offset depending on the byte position (0..B.length-1)
220− off i = case bo of
221− LL -> 8*i - o
222− LB -> 8*i - o
223− BB -> (B.length bs -1 - i) * 8 - r
224− BL -> (B.length bs -1 - i) * 8 - r
225−
226− -- reverse bits if necessary
227− rev = case bo of
228− LB -> reverseBits n
229− BL -> reverseBits n
230− BB -> id
231− LL -> id
232−
233−
234−-- | Generic readWord
235−readWord :: (Num a, FastBits a) => Int -> S -> a
236−readWord n (S bs o bo)
237− | n == 0 = 0
238− | otherwise = extract bo (unsafeTake nbytes bs) o n
239− where nbytes = byte_offset (o+n+7)
240−
241−-- | Check that the number of bits to read is not greater than the first parameter
242−{-# INLINE readWordChecked #-}
243−readWordChecked :: (Num a, FastBits a) => Int -> Int -> S -> a
244−readWordChecked m n s
245− | n > m = error $ "Tried to read more than " ++ show m ++ " bits (" ++ show n ++")"
246− | otherwise = readWord n s
247−
248−-- | Read the given number of bytes and return them in Big-Endian order
249−--
250−-- Examples:
251−-- BB: xxxABCDE FGHIJKLM NOPxxxxx -> ABCDEFGH IJKLMNOP
252−-- LL: LMNOPxxx DEFGHIJK xxxxxABC -> ABCDEFGH IJKLMNOP
253−-- BL: xxxPONML KJIHGFED CBAxxxxx -> ABCDEFGH IJKLMNOP
254−-- LB: EDCBAxxx MLKJIHGF xxxxxPON -> ABCDEFGH IJKLMNOP
255115readByteString :: Int -> S -> ByteString
256−readByteString n (S bs o bo) =
257− let
258− bs' = unsafeTake (n+1) bs
259− bs'' = unsafeTake n bs
260− rev = B.map (reverseBits 8)
261− in case (o,bo) of
262− (0,BB) -> bs''
263− (0,LL) -> B.reverse bs''
264− (0,LB) -> rev bs''
265− (0,BL) -> rev . B.reverse $ bs''
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)
269− (_,BB) -> unsafePerformIO $ do
270− let len = n+1
271− ptr <- mallocBytes len
272− let f r i = do
273− let
274− w = unsafeIndex bs (len-i)
275− w' = (w `fastShiftL` o) .|. r
276− r' = w `fastShiftR` (8-o)
277− poke (ptr `plusPtr` (len-i)) w'
278− return r'
279− foldM_ f 0 [1..len]
280− unsafeInit <$> unsafePackMallocCStringLen (ptr,len)
116+readByteString n s@(S bs o)
117+ -- no offset, easy.
118+ | o == 0 = unsafeTake n bs
119+ -- offset. ugg. this is really naive and slow. but also pretty easy :)
120+ | otherwise = B.pack (P.map (readWord8 8) (P.take n (iterate (incS 8) s)))
121+
122+readWord8 :: Int -> S -> Word8
123+readWord8 n s@(S bs o)
124+ -- no bits at all, return 0
125+ | n == 0 = 0
126+
127+ -- all bits are in the same byte
128+ -- we just need to shift and mask them right
129+ | n <= 8 - o = let w = unsafeHead bs
130+ m = make_mask n
131+ w' = (w `shiftr_w8` (8 - o - n)) .&. m
132+ in w'
133+
134+ -- the bits are in two different bytes
135+ -- make a word16 using both bytes, and then shift and mask
136+ | n <= 8 = let w = (fromIntegral (unsafeHead bs) `shiftl_w16` 8) .|.
137+ (fromIntegral (unsafeIndex bs 1))
138+ m = make_mask n
139+ w' = (w `shiftr_w16` (16 - o - n)) .&. m
140+ in fromIntegral w'
141+
142+bit_offset :: Int -> Int
143+bit_offset n = make_mask 3 .&. n
144+
145+byte_offset :: Int -> Int
146+byte_offset n = n `shiftR` 3
147+
148+readWord16be :: Int -> S -> Word16
149+readWord16be n s@(S bs o)
150+
151+ -- 8 or fewer bits, use readWord8
152+ | n <= 8 = fromIntegral (readWord8 n s)
153+
154+ -- handle 9 or more bits, stored in two bytes
281155
156+ -- no offset, plain and simple 16 bytes
157+ | o == 0 && n == 16 = let msb = fromIntegral (unsafeHead bs)
158+ lsb = fromIntegral (unsafeIndex bs 1)
159+ w = (msb `shiftl_w16` 8) .|. lsb
160+ in w
161+
162+ -- no offset, but not full 16 bytes
163+ | o == 0 = let msb = fromIntegral (unsafeHead bs)
164+ lsb = fromIntegral (unsafeIndex bs 1)
165+ w = (msb `shiftl_w16` (n-8)) .|. (lsb `shiftr_w16` (16-n))
166+ in w
167+
168+ -- with offset, and n=9-16
169+ | n <= 16 = readWithOffset s shiftl_w16 shiftr_w16 n
170+
171+ | otherwise = error "readWord16be: tried to read more than 16 bits"
172+
173+readWithoutOffset :: (Bits a, Num a)
174+ => S -> (a -> Int -> a) -> (a -> Int -> a) -> Int -> a
175+readWithoutOffset s@(S bs o) shifterL shifterR n
176+ | o /= 0 = error "readWithoutOffset: there is an offset"
177+
178+ | bit_offset n == 0 && byte_offset n <= 4 =
179+ let segs = byte_offset n
180+ bn 0 = fromIntegral (unsafeHead bs)
181+ bn n = (bn (n-1) `shifterL` 8) .|. fromIntegral (unsafeIndex bs n)
182+
183+ in bn (segs-1)
184+
185+ | n <= 64 = let segs = byte_offset n
186+ o' = bit_offset (n - 8 + o)
187+
188+ bn 0 = fromIntegral (unsafeHead bs)
189+ bn n = (bn (n-1) `shifterL` 8) .|. fromIntegral (unsafeIndex bs n)
190+
191+ msegs = bn (segs-1) `shifterL` o'
192+
193+ last = (fromIntegral (unsafeIndex bs segs)) `shifterR` (8 - o')
194+
195+ w = msegs .|. last
196+ in w
197+
198+readWithOffset :: (Bits a, Num a)
199+ => S -> (a -> Int -> a) -> (a -> Int -> a) -> Int -> a
200+readWithOffset s@(S bs o) shifterL shifterR n
201+ | n <= 64 = let bits_in_msb = 8 - o
202+ (n',top) = (n - bits_in_msb
203+ , (fromIntegral (unsafeHead bs) .&. make_mask bits_in_msb) `shifterL` n')
204+
205+ segs = byte_offset n'
206+
207+ bn 0 = 0
208+ bn n = (bn (n-1) `shifterL` 8) .|. fromIntegral (unsafeIndex bs n)
209+
210+ o' = bit_offset n'
211+
212+ mseg = bn segs `shifterL` o'
213+
214+ last | o' > 0 = (fromIntegral (unsafeIndex bs (segs + 1))) `shifterR` (8 - o')
215+ | otherwise = 0
216+
217+ w = top .|. mseg .|. last
218+ in w
219+
220+
221+readWord32be :: Int -> S -> Word32
222+readWord32be n s@(S bs o)
223+ -- 8 or fewer bits, use readWord8
224+ | n <= 8 = fromIntegral (readWord8 n s)
225+
226+ -- 16 or fewer bits, use readWord16be
227+ | n <= 16 = fromIntegral (readWord16be n s)
228+
229+ | o == 0 = readWithoutOffset s shiftl_w32 shiftr_w32 n
230+
231+ | n <= 32 = readWithOffset s shiftl_w32 shiftr_w32 n
232+
233+ | otherwise = error "readWord32be: tried to read more than 32 bits"
234+
235+
236+readWord64be :: Int -> S -> Word64
237+readWord64be n s@(S bs o)
238+ -- 8 or fewer bits, use readWord8
239+ | n <= 8 = fromIntegral (readWord8 n s)
240+
241+ -- 16 or fewer bits, use readWord16be
242+ | n <= 16 = fromIntegral (readWord16be n s)
243+
244+ | o == 0 = readWithoutOffset s shiftl_w64 shiftr_w64 n
245+
246+ | n <= 64 = readWithOffset s shiftl_w64 shiftr_w64 n
247+
248+ | otherwise = error "readWord64be: tried to read more than 64 bits"
282249
283250------------------------------------------------------------------------
284−-- | 'BitGet' is a monad, applicative and a functor. See 'runBitGet'
285−-- for how to run it.
251+
286252newtype BitGet a = B { runState :: S -> Get (S,a) }
287253
288254instance Monad BitGet where
289255 return x = B $ \s -> return (s,x)
256+ fail str = B $ \_s -> fail str
290257 (B f) >>= g = B $ \s -> do (s',a) <- f s
291258 runState (g a) s'
292259
@@ -297,200 +264,109 @@ instance Applicative BitGet where
297264 pure x = return x
298265 fm <*> m = fm >>= \f -> m >>= \v -> return (f v)
299266
300−instance BitOrderable BitGet where
301− setBitOrder bo = do
302− (S bs o _) <- getState
303− putState (S bs o bo)
304−
305− getBitOrder = do
306− (S _ _ bo) <- getState
307− return bo
308−
309−instance Alignable BitGet where
310− -- | Skip the given number of bits
311− skipBits n = do
312− ensureBits n
313− withState (incS n)
314−
315− -- | Skip bits if necessary to align to the next byte
316− alignByte = do
317− (S _ o _) <- getState
318− when (o /= 0) $
319− skipBits (8-o)
320−
321−
322−
323−-- | Run a 'BitGet' within the Binary packages 'Get' monad. If a byte has
324−-- been partially consumed it will be discarded once 'runBitGet' is finished.
325267runBitGet :: BitGet a -> Get a
326268runBitGet bg = do
327− s <- mkInitState
328− (s',a) <- runState bg s
329− putBackState s'
269+ (_,a) <- runState bg (S B.empty 0)
330270 return a
331271
332−mkInitState :: Get S
333−mkInitState = do
334− bs <- get
335− put B.empty
336− return (S bs 0 BB)
337−
338−putBackState :: S -> Get ()
339−putBackState (S bs o _) = do
340− remaining <- get
341− let bs' = case o of
342− 0 -> bs
343− _ -> unsafeDrop 1 bs
344− put (bs' `B.append` remaining)
345−
346272getState :: BitGet S
347273getState = B $ \s -> return (s,s)
348274
349275putState :: S -> BitGet ()
350276putState s = B $ \_ -> return (s,())
351277
352−withState :: (S -> S) -> BitGet ()
353−withState f = do
354− s <- getState
355− putState $! f s
278+modifyState :: (S -> (S,a)) -> BitGet a
279+modifyState f = B $ \s -> return (f s)
356280
357281-- | Make sure there are at least @n@ bits.
358282ensureBits :: Int -> BitGet ()
359283ensureBits n = do
360− (S bs o bo) <- getState
284+ s@(S bs o) <- getState
361285 if n <= (B.length bs * 8 - o)
362286 then return ()
363287 else do let currentBits = B.length bs * 8 - o
364− let byteCount = byte_offset (n - currentBits + 7)
365− B $ \_ -> do B.ensureN byteCount
366− bs' <- B.get
367− put B.empty
368− return (S (bs`append`bs') o bo, ())
369−
370−-- | Test whether all input has been consumed, i.e. there are no remaining
371−-- undecoded bytes.
372−isEmpty :: BitGet Bool
373−isEmpty = B $ \ (S bs o bo) -> if B.null bs
374− then B.isEmpty >>= \e -> return (S bs o bo, e)
375− else return (S bs o bo, False)
376−
377−-- | Get 1 bit as a 'Bool'.
288+ let byteCount = (n - currentBits + 7) `div` 8
289+ B $ \s -> do bs' <- B.getByteString byteCount
290+ return (S (bs`append`bs') o, ())
291+
378292getBool :: BitGet Bool
379293getBool = block bool
380294
381−-- | Get 1 bit as a 'Bool'.
382−getBool# :: BitGet Int
383−getBool# = block bool#
384−
385−-- | Get @n@ bits as a 'Word8'. @n@ must be within @[0..8]@.
386295getWord8 :: Int -> BitGet Word8
387296getWord8 n = block (word8 n)
388297
389−-- | Get @n@ bits as a 'Word16'. @n@ must be within @[0..16]@.
390−getWord16 :: Int -> BitGet Word16
391−getWord16 n = block (word16 n)
392−
393298getWord16be :: Int -> BitGet Word16
394−getWord16be = getWord16
395−{-# DEPRECATED getWord16be "Use 'getWord16' instead" #-}
396−
397−-- | Get @n@ bits as a 'Word32'. @n@ must be within @[0..32]@.
398−getWord32 :: Int -> BitGet Word32
399−getWord32 n = block (word32 n)
299+getWord16be n = block (word16be n)
400300
401301getWord32be :: Int -> BitGet Word32
402−getWord32be = getWord32
403−{-# DEPRECATED getWord32be "Use 'getWord32' instead" #-}
404−
405−-- | Get @n@ bits as a 'Word64'. @n@ must be within @[0..64]@.
406−getWord64 :: Int -> BitGet Word64
407−getWord64 n = block (word64 n)
302+getWord32be n = block (word32be n)
408303
409304getWord64be :: Int -> BitGet Word64
410−getWord64be = getWord64
411−{-# DEPRECATED getWord64be "Use 'getWord64' instead" #-}
305+getWord64be n = block (word64be n)
412306
413−-- | Get @n@ bytes as a 'ByteString'.
414307getByteString :: Int -> BitGet ByteString
415308getByteString n = block (byteString n)
416309
417−-- | Get @n@ bytes as a lazy ByteString.
418−getLazyByteString :: Int -> BitGet L.ByteString
419−getLazyByteString n = do
420− (S _ o bo) <- getState
421− case o of
422− 0 -> B $ \s -> do
423− putBackState s
424− lbs <- B.getLazyByteString (fromIntegral n)
425− return (S B.empty 0 bo, lbs)
426− _ -> L.fromChunks . (:[]) <$> Data.Binary.Bits.Get.getByteString n
427−
428−
429−
430−
431−
432−-- | A block that will be read with only one boundary check. Needs to know the
433−-- number of bits in advance.
434−data Block a = Block Int (S -> a)
435−
436−instance Functor Block where
437− fmap f (Block i p) = Block i (\s -> f (p s))
438−
439−instance Applicative Block where
440− pure a = Block 0 (\_ -> a)
441− (Block i p) <*> (Block j q) = Block (i+j) (\s -> p s $ q (incS i s))
442− (Block i _) *> (Block j q) = Block (i+j) (q . incS i)
443− (Block i p) <* (Block j _) = Block (i+j) p
444−
445−-- | Get a block. Will be read with one single boundry check, and
446−-- therefore requires a statically known number of bits.
447−-- Build blocks using 'bool', 'word8', 'word16be', 'word32be', 'word64be',
448−-- 'byteString' and 'Applicative'.
449−block :: Block a -> BitGet a
450−block (Block i p) = do
451− ensureBits i
452− s <- getState
453− putState $! (incS i s)
454− return $! p s
455−
456−-- | Read a 1 bit 'Bool'.
457310bool :: Block Bool
458311bool = Block 1 readBool
459312
460−-- | Read a 1 bit 'Bool'.
461−bool# :: Block Int
462−bool# = Block 1 readBool#
463−
464−-- | Read @n@ bits as a 'Word8'. @n@ must be within @[0..8]@.
465313word8 :: Int -> Block Word8
466−word8 n = Block n (readWordChecked 8 n)
467−
468−-- | Read @n@ bits as a 'Word16'. @n@ must be within @[0..16]@.
469−word16 :: Int -> Block Word16
470−word16 n = Block n (readWordChecked 16 n)
314+word8 n = Block n (readWord8 n)
471315
472316word16be :: Int -> Block Word16
473−word16be = word16
474−{-# DEPRECATED word16be "Use 'word16' instead" #-}
475−
476−-- | Read @n@ bits as a 'Word32'. @n@ must be within @[0..32]@.
477−word32 :: Int -> Block Word32
478−word32 n = Block n (readWordChecked 32 n)
317+word16be n = Block n (readWord16be n)
479318
480319word32be :: Int -> Block Word32
481−word32be = word32
482−{-# DEPRECATED word32be "Use 'word32' instead" #-}
483−
484−-- | Read @n@ bits as a 'Word64'. @n@ must be within @[0..64]@.
485−word64 :: Int -> Block Word64
486−word64 n = Block n (readWordChecked 64 n)
320+word32be n = Block n (readWord32be n)
487321
488322word64be :: Int -> Block Word64
489−word64be = word64
490−{-# DEPRECATED word64be "Use 'word64' instead" #-}
323+word64be n = Block n (readWord64be n)
491324
492−-- | Read @n@ bytes as a 'ByteString'.
493325byteString :: Int -> Block ByteString
494−byteString n | n > 0 = Block (n*8) (readByteString n)
495− | otherwise = Block 0 (\_ -> B.empty)
326+byteString n = Block (n*8) (readByteString n)
496327
328+------------------------------------------------------------------------
329+-- Unchecked shifts, from the package binary
330+
331+shiftl_w16 :: Word16 -> Int -> Word16
332+shiftl_w32 :: Word32 -> Int -> Word32
333+shiftl_w64 :: Word64 -> Int -> Word64
334+
335+#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
336+shiftl_w8 (W8# w) (I# i) = W8# (w `uncheckedShiftL#` i)
337+shiftl_w16 (W16# w) (I# i) = W16# (w `uncheckedShiftL#` i)
338+shiftl_w32 (W32# w) (I# i) = W32# (w `uncheckedShiftL#` i)
339+
340+shiftr_w8 (W8# w) (I# i) = W8# (w `uncheckedShiftRL#` i)
341+shiftr_w16 (W16# w) (I# i) = W16# (w `uncheckedShiftRL#` i)
342+shiftr_w32 (W32# w) (I# i) = W32# (w `uncheckedShiftRL#` i)
343+
344+
345+#if WORD_SIZE_IN_BITS < 64
346+shiftl_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftL64#` i)
347+shiftr_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftRL64#` i)
348+
349+#if __GLASGOW_HASKELL__ <= 606
350+-- Exported by GHC.Word in GHC 6.8 and higher
351+foreign import ccall unsafe "stg_uncheckedShiftL64"
352+ uncheckedShiftL64# :: Word64# -> Int# -> Word64#
353+foreign import ccall unsafe "stg_uncheckedShiftRL64"
354+ uncheckedShiftRL64# :: Word64# -> Int# -> Word64#
355+#endif
356+
357+#else
358+shiftl_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftL#` i)
359+shiftr_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftRL#` i)
360+#endif
361+
362+#else
363+shiftl_w8 = shiftL
364+shiftl_w16 = shiftL
365+shiftl_w32 = shiftL
366+shiftl_w64 = shiftL
367+
368+shiftr_w8 = shiftR
369+shiftr_w16 = shiftR
370+shiftr_w32 = shiftR
371+shiftr_w64 = shiftR
372+#endif