add simple control unit

1 files changed, 36 insertions, 0 deletions

diff --git a/control_unit.v b/control_unit.v
new file mode 100644
index 0000000..00ebd4f
--- /dev/null
+++ b/control_unit.v
@@ -0,0 +1,36 @@
+module control_unit (
+	input clk,
+	
+	input fetch_ready,
+	
+	output fetch_en,
+	output decode_en,
+	output alu_en,
+	
+	output incr_pc,
+	
+	output [9:0] dbg_state
+);
+
+	reg [9:0] current_state;
+	
+	initial begin
+		current_state = 10'b1;
+	end
+	
+	assign fetch_en = current_state[0];
+	assign decode_en = current_state[1];
+	assign alu_en = current_state[2];
+	
+	assign incr_pc = current_state[1];
+	
+	always @(posedge clk) begin
+		case(current_state)
+			10'b1: if(fetch_ready) current_state <= 10'b10;
+			10'b10: current_state <= 10'b100;
+			10'b100: current_state <= 10'b1;
+		endcase
+	end
+	
+	assign dbg_state = current_state;
+endmodule