| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Foundation.Bits
Synopsis
- (.<<.) :: Bits a => a -> Int -> a
- (.>>.) :: Bits a => a -> Int -> a
-
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
- zeroBits :: a
- bit :: Int -> a
- setBit :: a -> Int -> a
- clearBit :: a -> Int -> a
- complementBit :: a -> Int -> a
- testBit :: a -> Int -> Bool
- bitSizeMaybe :: a -> Maybe Int
- bitSize :: a -> Int
- isSigned :: a -> Bool
- shiftL :: a -> Int -> a
- unsafeShiftL :: a -> Int -> a
- shiftR :: a -> Int -> a
- unsafeShiftR :: a -> Int -> a
- rotateL :: a -> Int -> a
- rotateR :: a -> Int -> a
- popCount :: a -> Int
- alignRoundUp :: Int -> Int -> Int
- alignRoundDown :: Int -> Int -> Int
Documentation
class Eq a => Bits a where Source #
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 | shiftL , shiftR ), ( rotate | rotateL , rotateR ), bitSize , bitSizeMaybe , isSigned , testBit , bit , popCount
Methods
(.&.) :: a -> a -> a infixl 7 Source #
Bitwise "and"
(.|.) :: a -> a -> a infixl 5 Source #
Bitwise "or"
xor :: a -> a -> a infixl 6 Source #
Bitwise "xor"
complement :: a -> a Source #
Reverse all the bits in the argument
shift :: a -> Int -> a infixl 8 Source #
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.
rotate :: a -> Int -> a infixl 8 Source #
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.
zeroBits
is the value with all bits unset.
The following laws ought to hold (for all valid bit indices
n
):
-
clearBitzeroBitsn ==zeroBits -
setBitzeroBitsn ==bitn -
testBitzeroBitsn == False -
popCountzeroBits== 0
This method uses
as its default
implementation (which ought to be equivalent to
clearBit
(
bit
0) 0
zeroBits
for
types which possess a 0th bit).
Since: base-4.7.0.0
bit
i
is a value with the
i
th bit set and all other bits clear.
Can be implemented using
bitDefault
if
a
is also an
instance of
Num
.
See also
zeroBits
.
setBit :: a -> Int -> a Source #
x `setBit` i
is the same as
x .|. bit i
clearBit :: a -> Int -> a Source #
x `clearBit` i
is the same as
x .&. complement (bit i)
complementBit :: a -> Int -> a Source #
x `complementBit` i
is the same as
x `xor` bit i
testBit :: a -> Int -> Bool Source #
Return
True
if the
n
th bit of the argument is 1
Can be implemented using
testBitDefault
if
a
is also an
instance of
Num
.
bitSizeMaybe :: a -> Maybe Int Source #
Return the number of bits in the type of the argument. The actual
value of the argument is ignored. Returns Nothing
for types that do not have a fixed bitsize, like
Integer
.
Since: base-4.7.0.0
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
.
Default implementation based upon
bitSizeMaybe
provided since
4.12.0.0.
isSigned :: a -> Bool Source #
Return
True
if the argument is a signed type. The actual
value of the argument is ignored
shiftL :: a -> Int -> a infixl 8 Source #
Shift the argument left by the specified number of bits
(which must be non-negative). Some instances may throw an
Overflow
exception if given a negative input.
An instance can define either this and
shiftR
or the unified
shift
, depending on which is more convenient for the type in
question.
unsafeShiftL :: a -> Int -> a Source #
Shift the argument left by the specified number of bits. The
result is undefined for negative shift amounts and shift amounts
greater or equal to the
bitSize
.
Defaults to
shiftL
unless defined explicitly by an instance.
Since: base-4.5.0.0
shiftR :: a -> Int -> a infixl 8 Source #
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
. Some instances may throw an
Overflow
exception if given a negative input.
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.
unsafeShiftR :: a -> Int -> a Source #
Shift the first argument right by the specified number of bits, which must be non-negative and smaller than the number of bits in the type.
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.
Defaults to
shiftR
unless defined explicitly by an instance.
Since: base-4.5.0.0
rotateL :: a -> Int -> a infixl 8 Source #
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 infixl 8 Source #
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.
Return the number of set bits in the argument. This number is known as the population count or the Hamming weight.
Can be implemented using
popCountDefault
if
a
is also an
instance of
Num
.
Since: base-4.5.0.0
Instances
Round up (if needed) to a multiple of
alignment
closst to
m
alignment
needs to be a power of two
alignRoundUp 16 8 = 16 alignRoundUp 15 8 = 16