Add inputs and an instruction to read from them.

cpu.sv

@@ -1,5 +1,6 @@
 module cpu 	(input logic clk, reset,
 			 input logic prog,
+			 input logic [15:0] inputs,
 			 input logic[31:0] pinst,
 			 input logic[7:0] paddr,
 			 output logic [31:0] disp);
@@ -12,7 +13,7 @@ module cpu 	(input logic clk, reset,
 	logic [15:0] const_val;
 	logic [31:0] const_extend;
 	logic [31:0] cpu_disp;
-	logic [31:0] reg_alu_out, const_alu_out;
+	logic [31:0] reg_alu_out, const_alu_out, val_out;
 	logic should_jump, should_write, use_const;
 	
 	assign op = inst[31:26];
@@ -63,6 +64,12 @@ module cpu 	(input logic clk, reset,
 		.left(reg_alu_out),
 		.right(const_alu_out),
 		.select(use_const),
+		.out(val_out));
+		
+	mux2 #(32) rd_mux(
+		.left(val_out),
+		.right({16'b0, inputs}),
+		.select(~inst[28] & inst[27] & inst[26]),
 		.out(rd_val));
 		
 	assign pc_compute = rt_val + const_val;