(** Size of integers, in bits. *)

Definition Zsize (x: Z) : Z :=
  match x with
  | Zpos p => Zpos (Pos.size p)
  | _ => 0
  end.Definition size (x: int) : Z := Zsize (unsigned x).Remark Zsize_pos: forall x, 0 <= Zsize x.Remark Zsize_pos': forall x, 0 < x -> 0 < Zsize x.

Lemma Ztestbit_size_1: forall x, 0 < x -> Z.testbit x (Z.pred (Zsize x)) = true.