Define global variables for async state

compiler/obc/c/cgen.ml

@@ -504,6 +504,8 @@ let step_fun_call vr var_env sig_info objn out args async =
       | Some async -> args @ [Caddrof out; Caddrof async]
       | None -> args @ [Caddrof out]
 
+let async_global_var_name od = "g_async__" ^ (name od.o_ident)
+
 (** Generate the statement to call [objn].
     [outvl] is a list of lhs where to put the results.
     [args] is the list of expressions to use as arguments.
@@ -521,7 +523,7 @@ let generate_function_call vr var_env obj_env outvl objn args =
       cop_of_op_aux classln args
     else
       let async = match od.o_ack with
-        | Some _ -> Some (Cvar "GlobalValueToChange")
+        | Some _ -> Some (Cvar (async_global_var_name od))
         | None -> None
       in
       (* The step function takes scalar arguments and its own internal
@@ -924,6 +926,21 @@ let reset_fun_def_of_class_def cd =
     }
   }
 
+let filter_async_objs cd =
+  List.filter
+    (fun od ->
+       match od.o_ack with
+         | Some _ -> true
+         | None -> false)
+    cd.cd_objs
+
+let async_global_objs_defs cd =
+  List.map
+    (fun od ->
+       let name = async_global_var_name od in
+       let ty = Cty_id (qn_append od.o_class "_async") in
+       Cvardef (name, ty))
+    (filter_async_objs cd)
 
 (** [cdecl_and_cfun_of_class_def cd] translates the class definition [cd] to
     a C program. *)
@@ -937,7 +954,7 @@ let cdefs_and_cdecls_of_class_def cd =
   let in_struct_decl = in_decl_of_class_def cd in
   let out_struct_decl = out_decl_of_class_def cd in
   let async_struct_decl = async_decl_of_class_def cd in
-
+  let objs = async_global_objs_defs cd in
   let step = fun_def_of_step_fun cd.cd_name cd.cd_objs cd.cd_mems
     cd.cd_objs step_m in
   (* TODO(Arduino): let the user choose the backend they want *)
@@ -963,7 +980,7 @@ let cdefs_and_cdecls_of_class_def cd =
   let decls = List.map cdecl_of_cfundef defs in
 
   memory_struct_decl @ in_struct_decl @ out_struct_decl @ async_struct_decl
-    @ decls, defs
+    @ decls, objs @ defs
 
 (** {2 Type translation} *)