merging changes from OPAE branch making this branch

old_rtl/VX_priority_encoder.v

@@ -0,0 +1,20 @@
+`include "VX_define.v"
+
+module VX_priority_encoder (
+    input  wire[`NW-1:0] valids,
+    output reg[`NW_M1:0] index,
+    output reg           found
+  );
+
+	integer i;
+	always @(*) begin
+		index = 0;
+		found = 0;
+		for (i = `NW-1; i >= 0; i = i - 1) begin
+			if (valids[i]) begin
+				index = i[`NW_M1:0];
+				found = 1;
+			end
+		end
+	end
+endmodule