proposition: Lemma sext_neg_natToWord_nat_cast: forall sz2 sz1 sz n (e: sz1 + sz2 = sz), 2 * n < pow2 sz1 -> nat_cast word e (sext (wneg (natToWord sz1 n)) sz2) = wneg (natToWord sz n).
proof: Proof. intros. rewrite nat_cast_eq_rect. apply sext_wneg_natToWord. assumption. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Morphisms_Prop Coq.Classes.Equivalence Coq.Arith.PeanoNat Coq.ZArith.BinInt  Coq.Arith.Arith Coq.NArith.NArith Coq.Bool.Bool Coq.ZArith.ZArith Coq.Logic.Eqdep_dec Coq.Logic.EqdepFacts Coq.Program.Tactics Coq.Program.Equality Coq.setoid_ring.Ring Coq.setoid_ring.Ring_polynom bbv.Nomega bbv.ZLib bbv.NatLib bbv.NLib bbv.N_Z_nat_conversions bbv.DepEq bbv.DepEqNat bbv.ReservedNotations Coq.micromega.Lia