Definition MAX_FDS := Int.repr (Z_of_nat 1024).Definition mount_fs (fstore: forall (name: int), option file) :=
  mkfs MAX_FDS (mkfsdata (fun _:int => None) (fun _:int => None) (fun _:int => None)) fstore.Inductive xT: Type := mkxT: forall (z: Z) (c: cT) (fs: fs), xT.Inductive xT: Type := mkxT: forall (z: Z) (c: cT) (fs: fs), xT.Definition get_ext := match s with mkxT z _ _ => z end.Definition get_core := match s with mkxT _ c _ => c end.Definition get_fs := match s with mkxT _ _ fs => fs end.Definition proj_core (i: nat) (s: xT) := if eq_nat_dec i 0 then Some (get_core s) else None.Definition active := fun _: xT => 0.Definition runnable := fun (s: xT) =>
  match at_external csem (get_core s), halted csem (get_core s) with
  | None, None => true
  | _, _ => false
  end.Definition proj_zint (s: xT) := get_fs s.Definition proj_zext (z: fs*Z) := snd z.Definition zmult := @pair fs Z.(*SYS_READ/WRITE_SIG: fd, buf, count*)
Notation SYS_READ_SIG := (mksignature (AST.Tint::AST.Tint::AST.Tint::nil) (Some AST.Tint)).Notation SYS_WRITE_SIG := (mksignature (AST.Tint::AST.Tint::AST.Tint::nil) (Some AST.Tint)).(*SYS_OPEN_SIG: name*)
Notation SYS_OPEN_SIG := (mksignature (AST.Tint::AST.Tint::nil) (Some AST.Tint)).Notation SYS_READ := (EF_external 3%positive SYS_READ_SIG).Notation SYS_WRITE :=  (EF_external 4%positive SYS_WRITE_SIG).Notation SYS_OPEN := (EF_external 8%positive SYS_OPEN_SIG).Definition int2fmode (i: int): option fmode :=
  if Int.eq i Int.zero then Some RDONLY
  else if Int.eq i Int.one then Some WRONLY
       else if Int.eq i (Int.repr 3%Z) then Some RDWR
            else None.Definition val2oint (v: val): option int :=
  match v with
  | Vundef => None
  | Vint i => Some i
  | Vfloat _ => None
  | Vptr _ _ => None
  | Vlong _ => None (*LENB: is this ok, Gordon?*)
  end.Definition address := (block * int)%type.Definition val2oadr (v: val): option address :=
  match v with
  | Vundef => None
  | Vint i => None
  | Vlong i => None
  | Vfloat _ => None
  | Vptr b ofs => Some (b, ofs)
  end.Definition val2omode (mode: val): option fmode :=
  match val2oint mode with Some i => int2fmode i | None => None end.Fixpoint read_file_aux (nbytes sz cur: nat): list memval :=
  match nbytes with
  | O => nil
  | S nbytes' => if eq_nat_dec sz cur then nil
                 else contents cur :: read_file_aux nbytes' sz (S cur)
  end.

Lemma read_file_aux_length nbytes sz cur: length (read_file_aux nbytes sz cur) <= nbytes.