Maintainer | Iago Abal <iago.abal@gmail.com> |
---|---|

Safe Haskell | None |

Implementation of bit-vectors as wrappers over `Integer`

.

- Bit-vectors are interpreted as unsigned integers (i.e. natural numbers) except for some very specific cases.
- Bit-vectors are
*size-polymorphic*insofar as most operations treat a bit-vector of size*n*as of size*m*for*m >= n*if required.

For documentation purposes we will write `[n]k`

to denote a bit-vector
of size `n`

representing the natural number `k`

.

- type BitVector = BV
- data BV
- size :: BV -> Int
- width :: BV -> Int
- nat :: BV -> Integer
- uint :: BV -> Integer
- int :: BV -> Integer
- bitVec :: Integral a => Int -> a -> BV
- ones :: Int -> BV
- zeros :: Int -> BV
- isNat :: BV -> Bool
- isPos :: BV -> Bool
- (==.) :: BV -> BV -> Bool
- (/=.) :: BV -> BV -> Bool
- (<.) :: BV -> BV -> Bool
- (<=.) :: BV -> BV -> Bool
- (>.) :: BV -> BV -> Bool
- (>=.) :: BV -> BV -> Bool
- slt :: BV -> BV -> Bool
- sle :: BV -> BV -> Bool
- sgt :: BV -> BV -> Bool
- sge :: BV -> BV -> Bool
- (@.) :: Integral ix => BV -> ix -> Bool
- index :: Integral ix => ix -> BV -> Bool
- (@@) :: Integral ix => BV -> (ix, ix) -> BV
- extract :: Integral ix => ix -> ix -> BV -> BV
- (!.) :: Integral ix => BV -> ix -> Bool
- least :: Integral ix => ix -> BV -> BV
- most :: Integral ix => ix -> BV -> BV
- msb :: BV -> Bool
- lsb :: BV -> Bool
- msb1 :: BV -> Int
- signumI :: Integral a => BV -> a
- sdiv :: BV -> BV -> BV
- srem :: BV -> BV -> BV
- smod :: BV -> BV -> BV
- lg2 :: BV -> BV
- (#) :: BV -> BV -> BV
- cat :: BV -> BV -> BV
- zeroExtend :: Integral size => size -> BV -> BV
- signExtend :: Integral size => size -> BV -> BV
- foldl_ :: (a -> Bool -> a) -> a -> BV -> a
- foldr_ :: (Bool -> a -> a) -> a -> BV -> a
- reverse_ :: BV -> BV
- replicate_ :: Integral size => size -> BV -> BV
- and_ :: [BV] -> BV
- or_ :: [BV] -> BV
- split :: Integral times => times -> BV -> [BV]
- group_ :: Integral size => size -> BV -> [BV]
- join :: [BV] -> BV
- module Data.Bits
- not_ :: BV -> BV
- nand :: BV -> BV -> BV
- nor :: BV -> BV -> BV
- xnor :: BV -> BV -> BV
- (<<.) :: BV -> BV -> BV
- shl :: BV -> BV -> BV
- (>>.) :: BV -> BV -> BV
- shr :: BV -> BV -> BV
- ashr :: BV -> BV -> BV
- (<<<.) :: BV -> BV -> BV
- rol :: BV -> BV -> BV
- (>>>.) :: BV -> BV -> BV
- ror :: BV -> BV -> BV
- fromBool :: Bool -> BV
- fromBits :: [Bool] -> BV
- toBits :: BV -> [Bool]
- showBin :: BV -> String
- showOct :: BV -> String
- showHex :: BV -> String
- maxNat :: (Integral a, Integral b) => a -> b
- integerWidth :: Integer -> Int

# Bit-vectors

Big-endian *pseudo size-polymorphic* bit-vectors.

# Creation

bitVec :: Integral a => Int -> a -> BVSource

Create a bit-vector given a size and an integer value.

`>>>`

[4]3`bitVec 4 3`

This function also handles negative values.

`>>>`

[4]15`bitVec 4 (-1)`

# Test

# Comparison

(==.) :: BV -> BV -> BoolSource

Fixed-size equality.

In contrast with `==`

, which is *size-polymorphic*, this equality
requires both bit-vectors to be of equal size.

`>>>`

False`[n]k ==. [m]k`

`>>>`

True`[n]k ==. [n]k`

# Indexing

(@.) :: Integral ix => BV -> ix -> BoolSource

Bit indexing.

`u @. i`

stands for the *i*-th bit of *u*.

`>>>`

False`[4]2 @. 0`

`>>>`

True`[4]2 @. 1`

(@@) :: Integral ix => BV -> (ix, ix) -> BVSource

Bit-string extraction.

u @@ (j,i) == fromBits (map (u @.) [j,j-1..i])

`>>>`

[3]3`[4]7 @@ (3,1)`

(!.) :: Integral ix => BV -> ix -> BoolSource

Reverse bit-indexing.

Index starting from the most significant bit.

u !. i == u @. (size u - i - 1)

`>>>`

False`[3]3 !. 0`

Most significant 1-bit.

*Pre*: input must be non-zero.

`>>>`

1`msb1 [4]2`

`>>>`

2`msb1 [4]4`

# Arithmetic

# List-like operations

zeroExtend :: Integral size => size -> BV -> BVSource

Logical extension.

`>>>`

[4]1`zeroExtend 3 [1]1`

signExtend :: Integral size => size -> BV -> BVSource

Arithmetic extension.

`>>>`

[4]1`signExtend 2 [2]1`

`>>>`

[4]15`signExtend 2 [2]3`

foldl_ :: (a -> Bool -> a) -> a -> BV -> aSource

foldl_ f z (fromBits [un, ..., u1, u0]) == ((((z `f` un) `f` ...) `f` u1) `f` u0)

foldl_ f e = fromBits . foldl f e . toBits

foldr_ :: (Bool -> a -> a) -> a -> BV -> aSource

foldr_ f z (fromBits [un, ..., u1, u0]) == un `f` (... `f` (u1 `f` (u0 `f` z)))

foldr_ f e = fromBits . foldr f e . toBits

replicate_ :: Integral size => size -> BV -> BVSource

*Pre*: if `replicate_ n u`

then `n > 0`

must hold.

replicate_ n == fromBits . concat . replicate n . toBits

split :: Integral times => times -> BV -> [BV]Source

Split a bit-vector *k* times.

`>>>`

[[2]0,[2]3,[2]3]`split 3 [4]15`

group_ :: Integral size => size -> BV -> [BV]Source

Split a bit-vector into *n*-wide pieces.

`>>>`

[[3]1,[3]7]`group_ 3 [4]15`

# Bitwise operations

module Data.Bits

An alias for `complement`

.

# Conversion

fromBits :: [Bool] -> BVSource

Create a bit-vector from a big-endian list of bits.

`>>>`

[3]1`fromBits [False, False, True]`

Create a big-endian list of bits from a bit-vector.

`>>>`

[True, False, True, True]`toBits [4]11`

# Pretty-printing

# Utilities

maxNat :: (Integral a, Integral b) => a -> bSource

Greatest natural number representable with *n* bits.

integerWidth :: Integer -> IntSource

Minimum width of a bit-vector to represent a given integer number.

`>>>`

3`integerWith 4`

`>>>`

4`integerWith (-4)`