Library Stdlib.Vectors.Bvector


N.B.: Using this encoding of bit vectors is discouraged. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v>.

Bit vectors. Contribution by Jean Duprat (ENS Lyon).

From Stdlib Require Export Bool Sumbool.
#[local] Set Warnings "-stdlib-vector".
From Stdlib Require Vector.
Export Vector.VectorNotations.

Local Open Scope nat_scope.

We build bit vectors in the spirit of List.v. The size of the vector is a parameter which is too important to be accessible only via function "length". The first idea is to build a record with both the list and the length. Unfortunately, this a posteriori verification leads to numerous lemmas for handling lengths. The second idea is to use a dependent type in which the length is a building parameter. This leads to structural induction that are slightly more complex and in some cases we will use a proof-term as definition, since the type inference mechanism for pattern-matching is sometimes weaker that the one implemented for elimination tactiques.

Section BOOLEAN_VECTORS.

A bit vector is a vector over booleans. Notice that the LEAST significant bit comes first (little-endian representation). We extract the least significant bit (head) and the rest of the vector (tail). We compute bitwise operation on vector: negation, and, or, xor. We compute size-preserving shifts: to the left (towards most significant bits, we hence use Vshiftout) and to the right (towards least significant bits, we use Vshiftin) by inserting a 'carry' bit (logical shift) or by repeating the most significant bit (arithmetical shift). NOTA BENE: all shift operations expect predecessor of size as parameter (they only work on non-empty vectors).

#[deprecated(since="8.20", note="Consider [list bool] instead. Please open an issue if you would like to keep using Bvector.")]
Definition Bvector := Vector.t bool.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition Bnil := @Vector.nil bool.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition Bcons := @Vector.cons bool.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition Bvect_true := Vector.const true.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition Bvect_false := Vector.const false.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition Blow := @Vector.hd bool.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition Bhigh := @Vector.tl bool.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition Bsign := @Vector.last bool.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition Bneg := @Vector.map _ _ negb.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition BVand := @Vector.map2 _ _ _ andb.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition BVor := @Vector.map2 _ _ _ orb.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition BVxor := @Vector.map2 _ _ _ xorb.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition BVeq m n := @Vector.eqb bool eqb m n.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition BshiftL (n:nat) (bv:Bvector (S n)) (carry:bool) :=
  Bcons carry n (Vector.shiftout bv).

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition BshiftRl (n:nat) (bv:Bvector (S n)) (carry:bool) :=
  Bhigh (S n) (Vector.shiftin carry bv).

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Definition BshiftRa (n:nat) (bv:Bvector (S n)) :=
  Bhigh (S n) (Vector.shiftrepeat bv).

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Fixpoint BshiftL_iter (n:nat) (bv:Bvector (S n)) (p:nat) : Bvector (S n) :=
  match p with
    | O => bv
    | S p' => BshiftL n (BshiftL_iter n bv p') false
  end.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Fixpoint BshiftRl_iter (n:nat) (bv:Bvector (S n)) (p:nat) : Bvector (S n) :=
  match p with
    | O => bv
    | S p' => BshiftRl n (BshiftRl_iter n bv p') false
  end.

#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Fixpoint BshiftRa_iter (n:nat) (bv:Bvector (S n)) (p:nat) : Bvector (S n) :=
  match p with
    | O => bv
    | S p' => BshiftRa n (BshiftRa_iter n bv p')
  end.

End BOOLEAN_VECTORS.

Module BvectorNotations.
Declare Scope Bvector_scope.
Delimit Scope Bvector_scope with Bvector.
#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Notation "^~ x" := (Bneg _ x) (at level 35, right associativity) : Bvector_scope.
#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Infix "^&" := (BVand _) (at level 40, left associativity) : Bvector_scope.
#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Infix "^⊕" := (BVxor _) (at level 45, left associativity) : Bvector_scope.
#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Infix "^|" := (BVor _) (at level 50, left associativity) : Bvector_scope.
#[deprecated(since="8.20", note="Consider [list bool] instead. See <https://github.com/coq/stdlib/blob/master/theories/Vectors/Vector.v> for details. Please open an issue if you would like to keep using Bvector.")]
Infix "=?" := (BVeq _ _) (at level 70, no associativity) : Bvector_scope.
Open Scope Bvector_scope.
End BvectorNotations.