proposition: Lemma shrB_shlBaux n (p: BITS n) : shrB (shlBaux p) = joinmsb (false, p).
proof: Proof. apply toNat_inj. rewrite toNat_shrB toNat_shlBaux toNat_joinmsb. by rewrite mul0n add0n doubleK. 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)