1 files changed, 52 insertions, 0 deletions
diff --git a/sched/scheduler.ml b/sched/scheduler.ml
new file mode 100644
index 0000000..130164b
--- /dev/null
+++ b/sched/scheduler.ml
@@ -0,0 +1,52 @@
+open Netlist_ast
+
+module Smap = Map.Make(String)
+
+exception Combinational_cycle
+
+let read_exp eq =
+	let add_arg x l = match x with
+		| Avar(f) -> f::l
+		| Aconst(_) -> l
+	in
+	let aux = function
+	| Earg(x) -> add_arg x []
+	| Ereg(i) -> []
+	| Enot(x) -> add_arg x []
+	| Ebinop(_, x, y) -> add_arg x (add_arg y [])
+	| Emux(a, b, c) -> add_arg a (add_arg b (add_arg c []))
+	| Erom(_, _, a) -> add_arg a []
+	| Eram(_, _, a, b, c, d) -> []
+	| Econcat(u, v) -> add_arg u (add_arg v [])
+	| Eslice(_, _, a) -> add_arg a []
+	| Eselect(_, a) -> add_arg a []
+	in
+		aux eq;;
+
+let schedule p =
+	let graph = Graph.mk_graph() in
+	let eq_map = List.fold_left (fun x (vn, eqn) -> Smap.add vn eqn x) Smap.empty p.p_eqs in
+	(* Add variables as graph nodes *)
+	List.iter (fun (k, _) -> Graph.add_node graph k) p.p_eqs;
+	(* Add dependencies as graph edges *)
+	List.iter 
+		(fun (n, e) -> List.iter
+			(fun m -> if Smap.mem m eq_map then Graph.add_edge graph m n else ())
+			(read_exp e))
+		p.p_eqs;
+	(* Verify there are no cycles *)
+	if Graph.has_cycle graph then raise Combinational_cycle;
+	(* Topological sort of graph nodes *)
+	let topo_vars = Graph.topological graph in
+	(* Construct new program with sorted expression list *)
+	{
+		p_eqs = List.fold_right
+			(fun n x -> if Smap.mem n eq_map then (n, Smap.find n eq_map)::x else x) topo_vars [];
+		p_inputs = p.p_inputs;
+		p_outputs = p.p_outputs;
+		p_vars = p.p_vars;
+	}
+	;;
+
+
+