proposition: Lemma dropmsb_iter_shlB n count c (p: BITS n) : dropmsb (iter count shlB (joinmsb (c, p))) = iter count shlB p.
proof: Proof. induction count => //. + apply toNat_inj. rewrite /iter. by rewrite dropmsb_joinmsb. + rewrite !iterS. rewrite -IHcount. by rewrite shlB_dropmsb. Qed.
imports: HB(structures) mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq fintype tuple zmodp div) ssrextra.tuple ssrextra.nat spec spec.properties operations mathcomp(ssralg)