code refactoring for Vivado compatibility

hw/rtl/libs/VX_bits_insert.sv

@@ -0,0 +1,20 @@
+`include "VX_platform.vh"
+
+module VX_bits_insert #(
+    parameter N   = 1,
+    parameter S   = 1,
+    parameter POS = 0
+) (
+    input wire [N-1:0] data_in,    
+    input wire [S-1:0] sel_in,    
+    output wire [N+S-1:0] data_out
+); 
+    if (POS == 0) begin
+        assign data_out = {data_in, sel_in};
+    end else if (POS == N) begin
+        assign data_out = {sel_in, data_in};
+    end else begin
+        assign data_out = {data_in[N-1:POS], sel_in, data_in[POS-1:0]};
+    end    
+
+endmodule