CLaSH.Prelude.BitIndex

Documentation

>>> :set -XDataKinds
>>> import CLaSH.Prelude

(!) :: (BitPack a, KnownNat (BitSize a), Integral i) => a -> i -> Bit

Get the bit at the specified bit index.

NB: Bit indices are DESCENDING.

>>> pack (7 :: Unsigned 6)
000111
>>> (7 :: Unsigned 6) ! 1
1
>>> (7 :: Unsigned 6) ! 5
0
>>> (7 :: Unsigned 6) ! 6
*** Exception: (!): 6 is out of range [5..0]

slice :: (BitPack a, BitSize a ~ ((m + 1) + i)) => a -> SNat m -> SNat n -> BitVector ((m + 1) - n)

Get a slice between bit index m and and bit index n.

NB: Bit indices are DESCENDING.

>>> pack (7 :: Unsigned 6)
000111
>>> slice (7 :: Unsigned 6) d4 d2
001
>>> slice (7 :: Unsigned 6) d6 d4

<interactive>:...
    Couldn't match type ‘7 + i0’ with ‘6’
    The type variable ‘i0’ is ambiguous
    Expected type: (6 + 1) + i0
      Actual type: BitSize (Unsigned 6)
    In the expression: slice (7 :: Unsigned 6) d6 d4
    In an equation for ‘it’: it = slice (7 :: Unsigned 6) d6 d4

split :: (BitPack a, BitSize a ~ (m + n), KnownNat n) => a -> (BitVector m, BitVector n)

Split a value of a bit size m + n into a tuple of values with size m and size n.

>>> pack (7 :: Unsigned 6)
000111
>>> split (7 :: Unsigned 6) :: (BitVector 2, BitVector 4)
(00,0111)

replaceBit :: (BitPack a, KnownNat (BitSize a), Integral i) => a -> i -> Bit -> a

Set the bit at the specified index

NB: Bit indices are DESCENDING.

>>> pack (-5 :: Signed 6)
111011
>>> replaceBit (-5 :: Signed 6) 4 0
-21
>>> pack (-21 :: Signed 6)
101011
>>> replaceBit (-5 :: Signed 6) 5 0
27
>>> pack (27 :: Signed 6)
011011
>>> replaceBit (-5 :: Signed 6) 6 0
*** Exception: replaceBit: 6 is out of range [5..0]

setSlice :: (BitPack a, BitSize a ~ ((m + 1) + i)) => a -> SNat m -> SNat n -> BitVector ((m + 1) - n) -> a

Set the bits between bit index m and bit index n.

NB: Bit indices are DESCENDING.

>>> pack (-5 :: Signed 6)
111011
>>> setSlice (-5 :: Signed 6) d4 d3 0
-29
>>> pack (-29 :: Signed 6)
100011
>>> setSlice (-5 :: Signed 6) d6 d5 0

<interactive>:...
    Couldn't match type ‘7 + i0’ with ‘6’
    The type variable ‘i0’ is ambiguous
    Expected type: (6 + 1) + i0
      Actual type: BitSize (Signed 6)
    In the expression: setSlice (- 5 :: Signed 6) d6 d5 0
    In an equation for ‘it’: it = setSlice (- 5 :: Signed 6) d6 d5 0

msb :: (BitPack a, KnownNat (BitSize a)) => a -> Bit

Get the most significant bit.

>>> pack (-4 :: Signed 6)
111100
>>> msb (-4 :: Signed 6)
1
>>> pack (4 :: Signed 6)
000100
>>> msb (4 :: Signed 6)
0

lsb :: BitPack a => a -> Bit

Get the least significant bit.

>>> pack (-9 :: Signed 6)
110111
>>> lsb (-9 :: Signed 6)
1
>>> pack (-8 :: Signed 6)
111000
>>> lsb (-8 :: Signed 6)
0