Safe Haskell | Safe |
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This module defines bitwise operations for signed and unsigned integers.

- class Eq a => Bits a where
- (.&.) :: a -> a -> a
- (.|.) :: a -> a -> a
- xor :: a -> a -> a
- complement :: a -> a
- shift :: a -> Int -> a
- rotate :: a -> Int -> a
- bit :: Int -> a
- setBit :: a -> Int -> a
- clearBit :: a -> Int -> a
- complementBit :: a -> Int -> a
- testBit :: a -> Int -> Bool
- bitSize :: a -> Int
- isSigned :: a -> Bool
- shiftL :: a -> Int -> a
- shiftR :: a -> Int -> a
- rotateL :: a -> Int -> a
- rotateR :: a -> Int -> a

# Documentation

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`

, `isSigned`

, `testBit`

, `bit`

, and `popCount`

. The latter three can
be implemented using `testBitDefault`

, 'bitDefault, and `popCountDefault`

, if
`a`

is also an instance of `Num`

.

(.&.) :: 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

shifts `shift`

x i`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.

rotates `rotate`

x i`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 i`

is a value with the `i`

th bit set and all other bits clear

`x `setBit` i`

is the same as `x .|. bit i`

`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`

Return `True`

if the `n`

th bit of the argument is 1

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`

.

Return `True`

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

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.

Shift the first argument right by the specified number of bits. The
result is undefined for negative shift amounts and shift amounts
greater or equal to the `bitSize`

.

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.