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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;
}
;;
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