Require Export VST.msl.iter_sepcon.
Require Export VST.concurrency.semax_conc_pred.
Require Export VST.concurrency.semax_conc.
Require Export VST.floyd.proofauto.
Require Export VST.floyd.sublist.
(* general list lemmas *)
Notation vint z := (Vint (Int.repr z)).
Notation vptrofs z := (Vptrofs (Ptrofs.repr z)).
Hint Resolve repable_0.
Definition complete MAX l := l ++ repeat (vptrofs 0) (Z.to_nat MAX - length l).
Definition remove_at {A} i (l : list A) := firstn i l ++ skipn (S i) l.
Open Scope logic.
Definition rotate {A} (l : list A) n m := sublist (m - n) (Zlength l) l ++
sublist 0 (m - n) l.

Lemma Znth_head : forall reqs head m, Zlength reqs <= m -> 0 <= head < m ->
Zlength reqs > 0 ->
Znth head (rotate (complete m reqs) head m) = Znth 0 reqs.