@@ -1,292 +1,239 @@
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+ ( T(..)
595 , runBitGet
6+ , BitGet
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
91− , byteString
19+
20+ , block
21+
9222 , Data.Binary.Bits.Get.getByteString
93− , Data.Binary.Bits.Get.getLazyByteString
94− , Data.Binary.Bits.Get.isEmpty
23+
24+ , readBool
25+ , readWord8
26+ , readWord16be
9527
9628 ) where
9729
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
30+import Data.Binary.Get as B ( runGet, Get, getByteString )
10331
10432import Data.ByteString as B
105−import qualified Data.ByteString.Lazy as L
33+import Data.ByteString.Internal
10634import Data.ByteString.Unsafe
107−import Foreign.Marshal.Alloc (mallocBytes)
108−import Foreign.Ptr
109−import Foreign.Storable (poke)
110−import System.IO.Unsafe (unsafePerformIO)
35+
36+import qualified Data.ByteString.Lazy as L
11137
11238import Data.Bits
11339import Data.Word
40+import Data.List as List ( reverse )
41+
11442import Control.Applicative
115−import Control.Monad (when,foldM_)
11643
11744import Prelude as P
45+
46+#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
47+import GHC.Base
11848import GHC.Word
119−import GHC.Base (uncheckedShiftLWord8#, wordToWord8#, Int (..), andWord8#, Word8#, (-#), Int#, xorI#, eqWord8#, TYPE)
120−
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−-- @
134−
135−-- $blocks
136−-- Parse more efficiently in blocks. Each block is read with only one boundry
137−-- check (checking that there is enough input) as the size of the block can be
138−-- calculated statically. This is somewhat limiting as you cannot make the
139−-- parsing depend on the input being parsed.
140−--
141−-- @
142−--data IPV6Header = IPV6Header {
143−-- ipv6Version :: 'Word8'
144−-- , ipv6TrafficClass :: 'Word8'
145−-- , ipv6FlowLabel :: 'Word32
146−-- , ipv6PayloadLength :: 'Word16'
147−-- , ipv6NextHeader :: 'Word8'
148−-- , ipv6HopLimit :: 'Word8'
149−-- , ipv6SourceAddress :: 'ByteString'
150−-- , ipv6DestinationAddress :: 'ByteString'
151−-- }
152−--
153−-- ipv6headerblock =
154−-- IPV6Header '<$>' 'word8' 4
155−-- '<*>' 'word8' 8
156−-- '<*>' 'word32be' 24
157−-- '<*>' 'word16be' 16
158−-- '<*>' 'word8' 8
159−-- '<*>' 'word8' 8
160−-- '<*>' 'byteString' 16
161−-- '<*>' 'byteString' 16
162−--
163−--ipv6Header :: 'Get' IPV6Header
164−--ipv6Header = 'runBitGet' ('block' ipv6headerblock)
165−-- @
166−
167−data S = S {-# UNPACK #-} !ByteString -- Input
168− {-# UNPACK #-} !Int -- Bit offset (0-7)
169− !BitOrder -- Bit order
49+import GHC.Int
50+#endif
51+
52+data T a b = !a :*: !b deriving (Show)
53+
54+data S = S !ByteString -- ^ Input
55+ !Int -- ^ Bit offset (0-7)
17056 deriving (Show)
17157
172−-- | Increment the current bit offset
173−incS :: 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'
58+-- | A block that will be read with only one boundry check.
59+data Block a = Block Int (S -> a)
60+
61+instance Functor Block where
62+ fmap f (Block i p) = Block i (\s -> f (p s))
63+
64+instance Applicative Block where
65+ pure a = Block 0 (\_ -> a)
66+ (Block i p) <*> (Block j q) = Block (i+j) (\s -> p s $ q (incS i s))
67+ (Block i _) *> (Block j q) = Block (i+j) (q . incS i)
68+ (Block i p) <* (Block j _) = Block (i+j) p
69+
70+block :: Block a -> BitGet a
71+block (Block i p) = do
72+ ensureBits i
73+ modifyState (\s -> (incS i s, p s))
74+
75+-- | make_mask 3 = 00000111
76+make_mask :: Bits a => Int -> a
77+make_mask n = (1 `shiftL` fromIntegral n) - 1
78+{-# SPECIALIZE make_mask :: Int -> Int #-}
79+{-# SPECIALIZE make_mask :: Int -> Word #-}
80+{-# SPECIALIZE make_mask :: Int -> Word8 #-}
81+{-# SPECIALIZE make_mask :: Int -> Word16 #-}
82+{-# SPECIALIZE make_mask :: Int -> Word32 #-}
83+{-# SPECIALIZE make_mask :: Int -> Word64 #-}
17984
180−-- | Read a single bit
18185readBool :: 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
86+readBool (S bs n) = testBit (unsafeHead bs) (7-n)
87+
88+incS :: Int -> S -> S
89+incS o (S bs n) =
90+ let !o' = (n+o)
91+ !d = o' `shiftR` 3
92+ !n' = o' .&. make_mask 3
93+ in S (unsafeDrop d bs) n'
94+
25595readByteString :: 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)
96+readByteString n s@(S bs o)
97+ -- no offset, easy.
98+ | o == 0 = unsafeTake n bs
99+ -- offset. ugg. this is really naive and slow. but also pretty easy :)
100+ | otherwise = B.pack (P.map (readWord8 8) (P.take n (iterate (incS 8) s)))
101+
102+readWord8 :: Int -> S -> Word8
103+readWord8 n s@(S bs o)
104+ -- no bits at all, return 0
105+ | n == 0 = 0
106+
107+ -- all bits are in the same byte
108+ -- we just need to shift and mask them right
109+ | n <= 8 - o = let w = unsafeHead bs
110+ m = make_mask n
111+ w' = (w `shiftr_w8` (8 - o - n)) .&. m
112+ in w'
113+
114+ -- the bits are in two different bytes
115+ -- make a word16 using both bytes, and then shift and mask
116+ | n <= 8 = let w = (fromIntegral (unsafeHead bs) `shiftl_w16` 8) .|.
117+ (fromIntegral (unsafeIndex bs 1))
118+ m = make_mask n
119+ w' = (w `shiftr_w16` (16 - o - n)) .&. m
120+ in fromIntegral w'
121+
122+bit_offset :: Int -> Int
123+bit_offset n = make_mask 3 .&. n
124+
125+byte_offset :: Int -> Int
126+byte_offset n = n `shiftR` 3
127+
128+readWord16be :: Int -> S -> Word16
129+readWord16be n s@(S bs o)
130+
131+ -- 8 or fewer bits, use readWord8
132+ | n <= 8 = fromIntegral (readWord8 n s)
133+
134+ -- handle 9 or more bits, stored in two bytes
135+
136+ -- no offset, plain and simple 16 bytes
137+ | o == 0 && n == 16 = let msb = fromIntegral (unsafeHead bs)
138+ lsb = fromIntegral (unsafeIndex bs 1)
139+ w = (msb `shiftl_w16` 8) .|. lsb
140+ in w
141+
142+ -- no offset, but not full 16 bytes
143+ | o == 0 = let msb = fromIntegral (unsafeHead bs)
144+ lsb = fromIntegral (unsafeIndex bs 1)
145+ w = (msb `shiftl_w16` (n-8)) .|. (lsb `shiftr_w16` (16-n))
146+ in w
147+
148+ -- with offset, and n=9-16
149+ | n <= 16 = readWithOffset s shiftl_w16 shiftr_w16 n
150+
151+ | otherwise = error "readWord16be: tried to read more than 16 bits"
152+
153+readWithoutOffset :: (Bits a, Num a)
154+ => S -> (a -> Int -> a) -> (a -> Int -> a) -> Int -> a
155+readWithoutOffset s@(S bs o) shifterL shifterR n
156+ | o /= 0 = error "readWithoutOffset: there is an offset"
157+
158+ | bit_offset n == 0 && byte_offset n <= 4 =
159+ let segs = byte_offset n
160+ bn 0 = fromIntegral (unsafeHead bs)
161+ bn n = (bn (n-1) `shifterL` 8) .|. fromIntegral (unsafeIndex bs n)
162+
163+ in bn (segs-1)
164+
165+ | n <= 64 = let segs = byte_offset n
166+ o' = bit_offset (n - 8 + o)
167+
168+ bn 0 = fromIntegral (unsafeHead bs)
169+ bn n = (bn (n-1) `shifterL` 8) .|. fromIntegral (unsafeIndex bs n)
170+
171+ msegs = bn (segs-1) `shifterL` o'
172+
173+ last = (fromIntegral (unsafeIndex bs segs)) `shifterR` (8 - o')
174+
175+ w = msegs .|. last
176+ in w
177+
178+readWithOffset :: (Bits a, Num a)
179+ => S -> (a -> Int -> a) -> (a -> Int -> a) -> Int -> a
180+readWithOffset s@(S bs o) shifterL shifterR n
181+ | n <= 64 = let bits_in_msb = 8 - o
182+ (n',top) = (n - bits_in_msb
183+ , (fromIntegral (unsafeHead bs) .&. make_mask bits_in_msb) `shifterL` n')
184+
185+ segs = byte_offset n'
186+
187+ bn 0 = 0
188+ bn n = (bn (n-1) `shifterL` 8) .|. fromIntegral (unsafeIndex bs n)
281189
190+ o' = bit_offset n'
191+
192+ mseg = bn segs `shifterL` o'
193+
194+ last | o' > 0 = (fromIntegral (unsafeIndex bs (segs + 1))) `shifterR` (8 - o')
195+ | otherwise = 0
196+
197+ w = top .|. mseg .|. last
198+ in w
199+
200+
201+readWord32be :: Int -> S -> Word32
202+readWord32be n s@(S bs o)
203+ -- 8 or fewer bits, use readWord8
204+ | n <= 8 = fromIntegral (readWord8 n s)
205+
206+ -- 16 or fewer bits, use readWord16be
207+ | n <= 16 = fromIntegral (readWord16be n s)
208+
209+ | o == 0 = readWithoutOffset s shiftl_w32 shiftr_w32 n
210+
211+ | n <= 32 = readWithOffset s shiftl_w32 shiftr_w32 n
212+
213+ | otherwise = error "readWord32be: tried to read more than 32 bits"
214+
215+
216+readWord64be :: Int -> S -> Word64
217+readWord64be n s@(S bs o)
218+ -- 8 or fewer bits, use readWord8
219+ | n <= 8 = fromIntegral (readWord8 n s)
220+
221+ -- 16 or fewer bits, use readWord16be
222+ | n <= 16 = fromIntegral (readWord16be n s)
223+
224+ | o == 0 = readWithoutOffset s shiftl_w64 shiftr_w64 n
225+
226+ | n <= 64 = readWithOffset s shiftl_w64 shiftr_w64 n
227+
228+ | otherwise = error "readWord64be: tried to read more than 64 bits"
282229
283230------------------------------------------------------------------------
284−-- | 'BitGet' is a monad, applicative and a functor. See 'runBitGet'
285−-- for how to run it.
231+-- unrolled codensity/state monad
286232newtype BitGet a = B { runState :: S -> Get (S,a) }
287233
288234instance Monad BitGet where
289235 return x = B $ \s -> return (s,x)
236+ fail str = B $ \_s -> fail str
290237 (B f) >>= g = B $ \s -> do (s',a) <- f s
291238 runState (g a) s'
292239
@@ -297,200 +244,192 @@ instance Applicative BitGet where
297244 pure x = return x
298245 fm <*> m = fm >>= \f -> m >>= \v -> return (f v)
299246
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.
325247runBitGet :: BitGet a -> Get a
326248runBitGet bg = do
327− s <- mkInitState
328− (s',a) <- runState bg s
329− putBackState s'
249+ (_,a) <- runState bg (S B.empty 0)
330250 return a
331251
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−
346252getState :: BitGet S
347253getState = B $ \s -> return (s,s)
348254
349255putState :: S -> BitGet ()
350256putState s = B $ \_ -> return (s,())
351257
352−withState :: (S -> S) -> BitGet ()
353−withState f = do
354− s <- getState
355− putState $! f s
258+modifyState :: (S -> (S,a)) -> BitGet a
259+modifyState f = B $ \s -> return (f s)
356260
357261-- | Make sure there are at least @n@ bits.
358262ensureBits :: Int -> BitGet ()
359263ensureBits n = do
360− (S bs o bo) <- getState
264+ s@(S bs o) <- getState
361265 if n <= (B.length bs * 8 - o)
362266 then return ()
363267 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'.
268+ let byteCount = (n - currentBits + 7) `div` 8
269+ B $ \s -> do bs' <- B.getByteString byteCount
270+ return (S (bs`append`bs') o, ())
271+
378272getBool :: BitGet Bool
379273getBool = block bool
380274
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]@.
386275getWord8 :: Int -> BitGet Word8
387276getWord8 n = block (word8 n)
388277
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−
393278getWord16be :: 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)
279+getWord16be n = block (word16be n)
400280
401281getWord32be :: 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)
282+getWord32be n = block (word32be n)
408283
409284getWord64be :: Int -> BitGet Word64
410−getWord64be = getWord64
411−{-# DEPRECATED getWord64be "Use 'getWord64' instead" #-}
285+getWord64be n = block (word64be n)
412286
413−-- | Get @n@ bytes as a 'ByteString'.
414287getByteString :: Int -> BitGet ByteString
415288getByteString n = block (byteString n)
416289
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'.
457290bool :: Block Bool
458291bool = Block 1 readBool
459292
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]@.
465293word8 :: 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)
294+word8 n = Block n (readWord8 n)
471295
472296word16be :: 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)
297+word16be n = Block n (readWord16be n)
479298
480299word32be :: 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)
300+word32be n = Block n (readWord32be n)
487301
488302word64be :: Int -> Block Word64
489−word64be = word64
490−{-# DEPRECATED word64be "Use 'word64' instead" #-}
303+word64be n = Block n (readWord64be n)
491304
492−-- | Read @n@ bytes as a 'ByteString'.
493305byteString :: Int -> Block ByteString
494−byteString n | n > 0 = Block (n*8) (readByteString n)
495− | otherwise = Block 0 (\_ -> B.empty)
306+byteString n = Block (n*8) (readByteString n)
307+
308+------------------------------------------------------------------------
309+-- Unchecked shifts, from the package binary
310+
311+shiftl_w16 :: Word16 -> Int -> Word16
312+shiftl_w32 :: Word32 -> Int -> Word32
313+shiftl_w64 :: Word64 -> Int -> Word64
314+
315+#if defined(__GLASGOW_HASKELL__) && !defined(__HADDOCK__)
316+shiftl_w8 (W8# w) (I# i) = W8# (w `uncheckedShiftL#` i)
317+shiftl_w16 (W16# w) (I# i) = W16# (w `uncheckedShiftL#` i)
318+shiftl_w32 (W32# w) (I# i) = W32# (w `uncheckedShiftL#` i)
319+
320+shiftr_w8 (W8# w) (I# i) = W8# (w `uncheckedShiftRL#` i)
321+shiftr_w16 (W16# w) (I# i) = W16# (w `uncheckedShiftRL#` i)
322+shiftr_w32 (W32# w) (I# i) = W32# (w `uncheckedShiftRL#` i)
323+
324+
325+#if WORD_SIZE_IN_BITS < 64
326+shiftl_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftL64#` i)
327+shiftr_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftRL64#` i)
328+
329+#if __GLASGOW_HASKELL__ <= 606
330+-- Exported by GHC.Word in GHC 6.8 and higher
331+foreign import ccall unsafe "stg_uncheckedShiftL64"
332+ uncheckedShiftL64# :: Word64# -> Int# -> Word64#
333+foreign import ccall unsafe "stg_uncheckedShiftRL64"
334+ uncheckedShiftRL64# :: Word64# -> Int# -> Word64#
335+#endif
336+
337+#else
338+shiftl_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftL#` i)
339+shiftr_w64 (W64# w) (I# i) = W64# (w `uncheckedShiftRL#` i)
340+#endif
341+
342+#else
343+shiftl_w8 = shiftL
344+shiftl_w16 = shiftL
345+shiftl_w32 = shiftL
346+shiftl_w64 = shiftL
347+
348+shiftr_w8 = shiftR
349+shiftr_w16 = shiftR
350+shiftr_w32 = shiftR
351+shiftr_w64 = shiftR
352+#endif
353+
354+{-
355+data R a where
356+ RBool :: R Bool
357+ RWord8 :: Int -> R Word8
358+ RWord16be :: Int -> R Word16
359+ RWord32be :: Int -> R Word32
360+ RByteString :: Int -> R ByteString
361+ RThis :: a -> R a
362+ RNextTo :: R a -> R b -> R (T a b)
363+ RMap :: R b -> (b -> R a) -> R a
364+ RMapPure :: R a -> (a -> b) -> R b
365+ RList :: Int -> R a -> R [a]
366+ RCheck :: R a -> (a -> Bool) -> String -> R a
367+
368+instance Functor R where
369+ fmap f m = RMapPure m f
370+
371+instance Show (R a) where
372+ show r = case r of
373+ RBool -> "Bool"
374+
375+size_in_bits :: forall a. R a -- ^ The record
376+ -> Int -- ^ Number of bits
377+size_in_bits r = case r of
378+ RBool -> 1
379+ RWord8 n -> min n 8
380+ RWord16be n -> min n 16
381+ RWord32be n -> min n 16
382+ RByteString n -> 8 * n
383+ RThis _ -> 0
384+ RList n r -> n * size_in_bits r
385+ RMap r _ -> size_in_bits r
386+ RMapPure r _ -> size_in_bits r
387+ RCheck r _ _ -> size_in_bits r
388+ RNextTo a b -> size_in_bits a + size_in_bits b
389+
390+size_in_bytes :: forall a. R a
391+ -> Int
392+size_in_bytes r = byte_offset (size_in_bits r + 7)
393+
394+get :: R a -> Get a
395+get r = do
396+ bs <- getByteString (size_in_bytes r)
397+ a :*: s <- getR (S bs 0) r
398+ return a
399+
400+getR :: S -> R a -> Get (T a S)
401+getR s0 r = do
402+ case r of
403+ RBool -> return (readBool s0)
404+ RWord8 n -> return (readWord8 s0 n)
405+ RWord16be n -> return (readWord16be s0 n)
406+ RWord32be n -> return (readWord32be s0 n)
407+ RByteString n -> return (readByteString s0 n)
408+ RThis x -> return (x :*: s0)
409+ RNextTo a b -> do
410+ t :*: s <- getR s0 a
411+ u :*: s' <- getR s b
412+ return (t:*:u:*:s')
413+ RMap r p -> do
414+ a :*: s@(S bs o) <- getR s0 r
415+ let codepath = p a
416+ required_bytes = byte_offset (size_in_bits r - o)
417+ bs' <- getByteString required_bytes
418+ getR (S (bs `append` bs') o) codepath
419+ RMapPure r f -> do
420+ a :*: s <- getR s0 r
421+ return (f a :*: s)
422+ RList n r ->
423+ let loop 0 s acc = return (List.reverse acc :*: s)
424+ loop m s acc = do
425+ a :*: s' <- getR s r
426+ loop (m-1) s' (a:acc)
427+ in loop n s0 []
428+ RCheck r c m -> do
429+ a :*: s <- getR s0 r
430+ if c a
431+ then return (a :*: s)
432+ else fail m
433+-}
434+
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