15 Data.Bits
Date: 2010-07-20 13:11:00

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## Chapter 15
Data.Bits

module Data.Bits (
Bits((.&.),
(.|.),
xor,
complement,
shift,
rotate,
bit,
setBit,
clearBit,
complementBit,
testBit,
bitSize,
isSigned,
shiftL,
shiftR,
rotateL,
rotateR)
) where

This module defines bitwise operations for signed and unsigned integers.

class Num a => Bits a where

  The Bits class defines bitwise operations over integral types.
  - Bits are numbered from 0 with bit 0 being the least significant bit.

  Minimal complete definition: .&., .|., xor, complement, (shift or (shiftL and shiftR)), (rotate or (rotateL and rotateR)), bitSize and isSigned.

  Methods

  (.&.) :: a -> a -> a

    Bitwise ”and”

  (.|.) :: a -> a -> a

    Bitwise ”or”

  xor :: a -> a -> a

    Bitwise ”xor”

  complement :: a -> a

    Reverse all the bits in the argument

  shift :: a -> Int -> a

    shift x i shifts x left by i bits if i is positive, or right by -i bits otherwise. Right shifts perform sign extension on signed number types; i.e. they fill the top bits with 1 if the x is negative and with 0 otherwise.

    An instance can define either this unified shift or shiftL and shiftR, depending on which is more convenient for the type in question.

  rotate :: a -> Int -> a

    rotate x i rotates x left by i bits if i is positive, or right by -i bits otherwise.

    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.

  bit :: Int -> a

    bit i is a value with the ith bit set and all other bits clear

  setBit :: a -> Int -> a

    x ‘setBit‘ i is the same as x .|. bit i

  clearBit :: a -> Int -> a

    x ‘clearBit‘ i is the same as x .&. complement (bit i)

  complementBit :: a -> Int -> a

    x ‘complementBit‘ i is the same as x ‘xor‘ bit i

  testBit :: a -> Int -> Bool

    Return True if the nth bit of the argument is 1

  bitSize :: a -> Int

    Return the number of bits in the type of the argument. The actual value of the argument is ignored. The function bitSize is undefined for types that do not have a fixed bitsize, like Integer.

  isSigned :: a -> Bool

    Return True if the argument is a signed type. The actual value of the argument is ignored

  shiftL :: 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.

  shiftR :: a -> Int -> a

    Shift the first argument right by the specified number of bits (which must be non-negative). Right shifts perform sign extension on signed number types; i.e. they fill the top bits with 1 if the x is negative and with 0 otherwise.

    An instance can define either this and shiftL or the unified shift, depending on which is more convenient for the type in question.

  rotateL :: a -> Int -> a

    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.

  rotateR :: a -> Int -> a

    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.

instance Bits Int
instance Bits Int8
instance Bits Int16
instance Bits Int32
instance Bits Int64
instance Bits Integer
instance Bits Word
instance Bits Word8
instance Bits Word16
instance Bits Word32
instance Bits Word64
instance Bits WordPtr
instance Bits IntPtr
instance Bits CChar
instance Bits CSChar
instance Bits CUChar
instance Bits CShort
instance Bits CUShort
instance Bits CInt
instance Bits CUInt
instance Bits CLong
instance Bits CULong
instance Bits CLLong
instance Bits CULLong
instance Bits CPtrdiff
instance Bits CSize
instance Bits CWchar
instance Bits CSigAtomic
instance Bits CIntPtr
instance Bits CUIntPtr
instance Bits CIntMax
instance Bits CUIntMax

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