using onehot multiplexer to reduce critical path

hw/rtl/libs/VX_onehot_mux.v

@@ -0,0 +1,20 @@
+`include "VX_platform.vh"
+
+module VX_onehot_mux #(
+    parameter DATAW = 1,
+    parameter COUNT = 1
+) (
+    input wire [COUNT-1:0][DATAW-1:0] data_in,    
+    input wire [COUNT-1:0]            sel_in,    
+    output wire [DATAW-1:0]           data_out
+); 
+    if (COUNT > 1) begin
+        for (genvar i = 0; i < COUNT; ++i) begin
+            assign data_out = sel_in[i] ? data_in[i] : 'z;
+        end
+    end else begin
+        `UNUSED_VAR (sel_in)
+        assign data_out = data_in;
+    end
+
+endmodule