X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FBits.hs;h=d33f7ee2a73bb9dc99bf33374168e151f530e28c;hb=e9e2a5412bb7cda8d13a063ac403d9f18ac97380;hp=d4e417783d1bb5681ebc6ccb471e9ed87684ef36;hpb=d95dbc7bb80eb696da3c449229d9c223ba2ed2e6;p=ghc-base.git diff --git a/Data/Bits.hs b/Data/Bits.hs index d4e4177..d33f7ee 100644 --- a/Data/Bits.hs +++ b/Data/Bits.hs @@ -1,4 +1,4 @@ -{-# OPTIONS -fno-implicit-prelude #-} +{-# OPTIONS_GHC -fno-implicit-prelude #-} ----------------------------------------------------------------------------- -- | -- Module : Data.Bits @@ -13,12 +13,11 @@ -- integers. Instances of the class 'Bits' for the 'Int' and -- 'Integer' types are available from this module, and instances for -- explicitly sized integral types are available from the --- "Int" and "Word" modules. +-- "Data.Int" and "Data.Word" modules. -- ----------------------------------------------------------------------------- module Data.Bits ( - -- * The 'Bits' class Bits( (.&.), (.|.), xor, -- :: a -> a -> a complement, -- :: a -> a @@ -31,11 +30,8 @@ module Data.Bits ( testBit, -- :: a -> Int -> Bool bitSize, -- :: a -> Int isSigned, -- :: a -> Bool - - -- * Shifts and rotates - -- $shifts - shiftL, shiftR, -- :: Bits a => a -> Int -> a - rotateL, rotateR -- :: Bits a => a -> Int -> a + shiftL, shiftR, -- :: a -> Int -> a + rotateL, rotateR -- :: a -> Int -> a ) -- instance Bits Int @@ -46,13 +42,20 @@ module Data.Bits ( -- See library document for details on the semantics of the -- individual operations. -#ifdef __GLASGOW_HASKELL__ +#if defined(__GLASGOW_HASKELL__) || defined(__HUGS__) #include "MachDeps.h" +#endif + +#ifdef __GLASGOW_HASKELL__ import GHC.Num import GHC.Real import GHC.Base #endif +#ifdef __HUGS__ +import Hugs.Bits +#endif + infixl 8 `shift`, `rotate`, `shiftL`, `shiftR`, `rotateL`, `rotateR` infixl 7 .&. infixl 6 `xor` @@ -77,24 +80,32 @@ class Num a => Bits a where {-| Reverse all the bits in the argument -} complement :: a -> a - {-| Signed shift the argument left by the specified number of bits. - Right shifts are specified by giving a negative value. -} + {-| Shift the argument left by the specified number of bits. + Right shifts (signed) are specified by giving a negative value. + + An instance can define either this unified 'shift' or 'shiftL' and + 'shiftR', depending on which is more convenient for the type in + question. -} shift :: a -> Int -> a - -- An instance can define either this unified shift or shiftL+shiftR, - -- depending on which is more convenient for the type in question. x `shift` i | i<0 = x `shiftR` (-i) | i==0 = x | i>0 = x `shiftL` i - {-| Signed rotate the argument left by the specified number of bits. + {-| Rotate the argument left by the specified number of bits. Right rotates are specified by giving a negative value. - 'rotate' is well defined only if 'bitSize' is also well defined - ('bitSize' is undefined for 'Integer', for example). - -} + For unbounded types like 'Integer', 'rotate' is equivalent to 'shift'. + + An instance can define either this unified 'rotate' or 'rotateL' and + 'rotateR', depending on which is more convenient for the type in + question. -} rotate :: a -> Int -> a + x `rotate` i | i<0 = x `rotateR` (-i) + | i==0 = x + | i>0 = x `rotateL` i + {- -- Rotation can be implemented in terms of two shifts, but care is -- needed for negative values. This suggested implementation assumes @@ -125,7 +136,9 @@ class Num a => Bits a where testBit :: a -> Int -> Bool {-| Return the number of bits in the type of the argument. The actual - value of the argument is ignored -} + value of the argument is ignored. The function 'bitSize' is + undefined for types that do not have a fixed bitsize, like 'Integer'. + -} bitSize :: a -> Int {-| Return 'True' if the argument is a signed type. The actual @@ -138,26 +151,51 @@ class Num a => Bits a where x `complementBit` i = x `xor` bit i x `testBit` i = (x .&. bit i) /= 0 - -- $shifts - -- These functions might sometimes be more convenient than the unified - -- versions 'shift' and 'rotate'. - - shiftL, shiftR :: a -> Int -> a - rotateL, rotateR :: a -> Int -> a + {-| Shift the argument left by the specified number of bits + (which must be non-negative). + + An instance can define either this and 'shiftR' or the unified + 'shift', depending on which is more convenient for the type in + question. -} + shiftL :: a -> Int -> a x `shiftL` i = x `shift` i + + {-| Shift the argument right (signed) by the specified number of bits + (which must be non-negative). + + An instance can define either this and 'shiftL' or the unified + 'shift', depending on which is more convenient for the type in + question. -} + shiftR :: a -> Int -> a x `shiftR` i = x `shift` (-i) + + {-| Rotate the argument left by the specified number of bits + (which must be non-negative). + + An instance can define either this and 'rotateR' or the unified + 'rotate', depending on which is more convenient for the type in + question. -} + rotateL :: a -> Int -> a x `rotateL` i = x `rotate` i + + {-| Rotate the argument right by the specified number of bits + (which must be non-negative). + + An instance can define either this and 'rotateL' or the unified + 'rotate', depending on which is more convenient for the type in + question. -} + rotateR :: a -> Int -> a x `rotateR` i = x `rotate` (-i) -#ifdef __GLASGOW_HASKELL__ instance Bits Int where +#ifdef __GLASGOW_HASKELL__ (I# x#) .&. (I# y#) = I# (word2Int# (int2Word# x# `and#` int2Word# y#)) (I# x#) .|. (I# y#) = I# (word2Int# (int2Word# x# `or#` int2Word# y#)) (I# x#) `xor` (I# y#) = I# (word2Int# (int2Word# x# `xor#` int2Word# y#)) complement (I# x#) = I# (word2Int# (int2Word# x# `xor#` int2Word# (-1#))) (I# x#) `shift` (I# i#) - | i# >=# 0# = I# (x# `iShiftL#` i#) - | otherwise = I# (x# `iShiftRA#` negateInt# i#) + | i# >=# 0# = I# (x# `iShiftL#` i#) + | otherwise = I# (x# `iShiftRA#` negateInt# i#) (I# x#) `rotate` (I# i#) = I# (word2Int# ((x'# `shiftL#` i'#) `or#` (x'# `shiftRL#` (wsib -# i'#)))) @@ -165,10 +203,51 @@ instance Bits Int where x'# = int2Word# x# i'# = word2Int# (int2Word# i# `and#` int2Word# (wsib -# 1#)) wsib = WORD_SIZE_IN_BITS# {- work around preprocessor problem (??) -} - bitSize _ = WORD_SIZE_IN_BITS - isSigned _ = True + bitSize _ = WORD_SIZE_IN_BITS +#else /* !__GLASGOW_HASKELL__ */ + +#ifdef __HUGS__ + (.&.) = primAndInt + (.|.) = primOrInt + xor = primXorInt + complement = primComplementInt + shift = primShiftInt + bit = primBitInt + testBit = primTestInt + bitSize _ = SIZEOF_HSINT*8 +#elif defined(__NHC__) + (.&.) = nhc_primIntAnd + (.|.) = nhc_primIntOr + xor = nhc_primIntXor + complement = nhc_primIntCompl + shiftL = nhc_primIntLsh + shiftR = nhc_primIntRsh + bitSize _ = 32 +#endif /* __NHC__ */ + + x `rotate` i + | i<0 && x<0 = let left = i+bitSize x in + ((x `shift` i) .&. complement ((-1) `shift` left)) + .|. (x `shift` left) + | i<0 = (x `shift` i) .|. (x `shift` (i+bitSize x)) + | i==0 = x + | i>0 = (x `shift` i) .|. (x `shift` (i-bitSize x)) + +#endif /* !__GLASGOW_HASKELL__ */ + + isSigned _ = True + +#ifdef __NHC__ +foreign import ccall nhc_primIntAnd :: Int -> Int -> Int +foreign import ccall nhc_primIntOr :: Int -> Int -> Int +foreign import ccall nhc_primIntXor :: Int -> Int -> Int +foreign import ccall nhc_primIntLsh :: Int -> Int -> Int +foreign import ccall nhc_primIntRsh :: Int -> Int -> Int +foreign import ccall nhc_primIntCompl :: Int -> Int +#endif /* __NHC__ */ instance Bits Integer where +#ifdef __GLASGOW_HASKELL__ (S# x) .&. (S# y) = S# (word2Int# (int2Word# x `and#` int2Word# y)) x@(S# _) .&. y = toBig x .&. y x .&. y@(S# _) = x .&. toBig y @@ -192,45 +271,60 @@ instance Bits Integer where complement (S# x) = S# (word2Int# (int2Word# x `xor#` int2Word# (0# -# 1#))) complement (J# s d) = case complementInteger# s d of (# s, d #) -> J# s d +#else + -- reduce bitwise binary operations to special cases we can handle + + x .&. y | x<0 && y<0 = complement (complement x `posOr` complement y) + | otherwise = x `posAnd` y + + x .|. y | x<0 || y<0 = complement (complement x `posAnd` complement y) + | otherwise = x `posOr` y + + x `xor` y | x<0 && y<0 = complement x `posXOr` complement y + | x<0 = complement (complement x `posXOr` y) + | y<0 = complement (x `posXOr` complement y) + | otherwise = x `posXOr` y + + -- assuming infinite 2's-complement arithmetic + complement a = -1 - a +#endif shift x i | i >= 0 = x * 2^i | otherwise = x `div` 2^(-i) rotate x i = shift x i -- since an Integer never wraps around - bitSize _ = error "Bits.bitSize(Integer)" + bitSize _ = error "Data.Bits.bitSize(Integer)" isSigned _ = True -#endif - -#ifdef __NHC__ -instance Bits Int where - (.&.) = nhc_primIntAnd - (.|.) = nhc_primIntOr - xor = nhc_primIntXor - complement = nhc_primIntCompl - shiftL = nhc_primIntLsh - shiftR = nhc_primIntRsh - bitSize _ = 32 - isSigned _ = True - -foreign import ccall nhc_primIntAnd :: Int -> Int -> Int -foreign import ccall nhc_primIntOr :: Int -> Int -> Int -foreign import ccall nhc_primIntXor :: Int -> Int -> Int -foreign import ccall nhc_primIntLsh :: Int -> Int -> Int -foreign import ccall nhc_primIntRsh :: Int -> Int -> Int -foreign import ccall nhc_primIntCompl :: Int -> Int - -instance Bits Integer where - -- (.&.) a b = undefined - -- (.|.) a b = undefined - -- xor a b = undefined - complement a = (-a) - x `shift` i | i<0 = x `div` (2^(-i)) - | i==0 = x - | i>0 = x * (2^i) - x `rotate` i = x `shift` i -- an Integer never wraps - bitSize _ = error "Data.Bits: bitSize :: Integer -> Int" - isSigned _ = True - -#endif +#ifndef __GLASGOW_HASKELL__ +-- Crude implementation of bitwise operations on Integers: convert them +-- to finite lists of Ints (least significant first), zip and convert +-- back again. + +-- posAnd requires at least one argument non-negative +-- posOr and posXOr require both arguments non-negative + +posAnd, posOr, posXOr :: Integer -> Integer -> Integer +posAnd x y = fromInts $ zipWith (.&.) (toInts x) (toInts y) +posOr x y = fromInts $ longZipWith (.|.) (toInts x) (toInts y) +posXOr x y = fromInts $ longZipWith xor (toInts x) (toInts y) + +longZipWith :: (a -> a -> a) -> [a] -> [a] -> [a] +longZipWith f xs [] = xs +longZipWith f [] ys = ys +longZipWith f (x:xs) (y:ys) = f x y:longZipWith f xs ys + +toInts :: Integer -> [Int] +toInts n + | n == 0 = [] + | otherwise = mkInt (n `mod` numInts):toInts (n `div` numInts) + where mkInt n | n > toInteger(maxBound::Int) = fromInteger (n-numInts) + | otherwise = fromInteger n + +fromInts :: [Int] -> Integer +fromInts = foldr catInt 0 + where catInt d n = (if d<0 then n+1 else n)*numInts + toInteger d + +numInts = toInteger (maxBound::Int) - toInteger (minBound::Int) + 1 +#endif /* !__GLASGOW_HASKELL__ */