`include "common.svh"

module router_tb;

logic clk, rstx;

typedef struct packed {
	logic [7:0] node;
	logic [7:0] dev;
} ds_t;

typedef struct packed {
	ds_t src;
	ds_t dst;
} addr_t;

typedef struct packed {
	int unsigned i;
} data_t;

localparam N = 1;
localparam M = 2;

logic [N+2-1:0] valid_o[M], ready_i[M];
logic [N+2-1:0] valid_i[M], ready_o[M];
addr_t[N+2-1:0] addr_o[M],  addr_i[M];
data_t[N+2-1:0] data_o[M],  data_i[M];

for (genvar i = 0; i < M; ++i) begin :gen_router
	router #(
		.N(N),
		.I(i),

		.data_t(data_t),
		.addr_t(addr_t)
	) router (
		.clk_i(clk),
		.rstx_i(rstx),


		.valid_i(valid_i[i]),
		.ready_o(ready_o[i]),
		.addr_i (addr_i [i]),
		.data_i (data_i [i]),

		.valid_o(valid_o[i]),
		.ready_i(ready_i[i]),
		.addr_o (addr_o [i]),
		.data_o (data_o [i])
	);
end

/* easy to get confused, but here's what we're testing:
 *
 *     dev0               dev1
 *      |                  ^
 *      v                  |
 *      P2                 P2
 *    +-------+          +-------+
 * P1 | node0 | P0 -> P1 | node1 | P0
 *    +-------+          +-------+
 *
 * dev0  sends a   packet to node0, 1 -> valid_i[0][2]
 * node0 sends the packet to node1, valid_o[0][0] -> valid_i[1][1]
 * node1 sends the packet to dev1 , valid_o[1][2]
 */

/* node0 -> node1 */
assign valid_i[1][1] = valid_o[0][0];
assign data_i [1][1] = data_o [0][0];
assign addr_i [1][1] = addr_o [0][0];
assign ready_i[1][1] = ready_o[0][0];

/* node1 -> node0 */
assign valid_i[0][0] = valid_o[1][1];
assign data_i [0][0] = data_o [1][1];
assign addr_i [0][0] = addr_o [1][1];
assign ready_i[0][0] = ready_o[1][1];


initial begin :test
	logic found = 0;

	$dumpfile("router_tb.vcd");
	$dumpvars();

	for (int i = 0; i < M; ++i)
	for (int j = 0; j < N + 2; ++j) begin :init
		valid_i[i][j] = '0;
		ready_i[i][j] = '0;

		addr_i [i][j] = '{
			src: '{
				node: 0,
				dev:  0
			},

			dst: '{
				node: 0,
				dev:  0
			}
		};
		data_i [i][j] = '{i: 0};
	end

	clk = 0;
	rstx = 0;

	#1

	rstx = 1;

	/* send value 3 from first dev to second */
	valid_i[0][2] = 1'b1;
	data_i [0][2] = '{i: 3};
	addr_i [0][2] = '{
		src: '{
			node: 0,
			dev:  0
		},

		dst: '{
			node: 1,
			dev:  0
		}
	};

	/* mark receiver as ready */
	ready_i[1][2] = 1'b1;

	#1 clk = 1;
	#1 clk = 0;

	valid_i[0][2] = 1'b0;

	for (int i = 0; i < 10; ++i) begin
		if (valid_o[1][2]) begin
			found = 1;
			break;
		end

		#1 clk = ~clk;
	end

	assert (found)
	else $error("took too long to produce output");

	assert (data_o[1][2] == 3)
	else $error("got wrong result");

	#10 $finish;
end
endmodule