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Fixes for newer Data.Bits #1

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Fixes for newer Data.Bits #1

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74c047a
Fixed use of a literal for a Bits value.
aninhumer Nov 2, 2012
772d3ed
Added zipPadWith to go with zipPad.
aninhumer Nov 2, 2012
ef2e513
Modifed (.|.) and xor to work with mismatched BitVector sizes.
aninhumer Nov 2, 2012
a282fe1
Added missing Bits methods for latest version.
aninhumer Nov 2, 2012
ffb6805
Exported zipPadWith.
aninhumer Nov 2, 2012
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20 changes: 16 additions & 4 deletions src/Data/Vector/Bit.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ module Data.Vector.Bit (
unpackInteger, packInteger, unpackInt, packInt,

-- * Utilities
pad, padMax, zipPad, trimLeading
pad, padMax, zipPad, zipPadWith, trimLeading
)

where
Expand Down Expand Up @@ -57,6 +57,11 @@ padMax xs ys = (padlen xs, padlen ys)
zipPad :: BitVector -> BitVector -> V.Vector (Bool, Bool)
zipPad xs ys = uncurry V.zip (padMax xs ys)

-- | Like 'V.zipWith', except pads the vectors to equal length
-- rather than discarding elements of the longer vector.
zipPadWith :: V.Unbox a => (Bool -> Bool -> a) -> BitVector -> BitVector -> V.Vector a
zipPadWith f xs ys = uncurry (V.zipWith f) (padMax xs ys)

-- | Discards any 'False' values at the most-significant end of the
-- given 'BitVector'.
trimLeading :: BitVector -> BitVector
Expand Down Expand Up @@ -85,8 +90,8 @@ instance Num BitVector where

instance Bits BitVector where
(.&.) = V.zipWith (&&)
(.|.) = V.zipWith (||)
xor = V.zipWith (/=)
(.|.) = zipPadWith (||)
xor = zipPadWith (/=)
complement = V.map not
shiftL v i = V.replicate i False V.++ v
shiftR = flip V.drop
Expand All @@ -96,6 +101,11 @@ instance Bits BitVector where
where (low, high) = V.splitAt (V.length v - i) v
bitSize = V.length
isSigned = const False
bit i = V.replicate i False `V.snoc` True
testBit v i = case (v V.!? i) of
Just x -> x
Nothing -> False
popCount v = V.length $ V.filter id v

-- | Converts an instance of 'Bits' to a 'BitVector'.
--
Expand All @@ -107,10 +117,12 @@ unpack w = trimLeading $ V.generate (bitSize w) (testBit w)

-- | Converts a 'BitVector' to an instance of 'Bits'.
pack :: (Bits a) => BitVector -> a
pack v = V.ifoldl' set 0 v
pack v = V.ifoldl' set zero v
where
set w i True = w `setBit` i
set w _ _ = w
-- Currently the best way to represent an empty Bits instance (Ugh)
zero = clearBit (bit 0) 0

unpackInteger :: Integer -> BitVector
unpackInteger = V.unfoldr f
Expand Down