code refactoring for Vivado compatibility

hw/rtl/libs/VX_lzc.sv

@@ -0,0 +1,31 @@
+`include "VX_platform.vh"
+
+`TRACING_OFF
+module VX_lzc #(
+    parameter N    = 2,
+    parameter MODE = 0, // 0 -> trailing zero, 1 -> leading zero
+    parameter LOGN = $clog2(N)
+) (
+    input  wire [N-1:0]    in_i,
+    output wire [LOGN-1:0] cnt_o,
+    output wire            valid_o
+);
+    wire [N-1:0][LOGN-1:0] indices;
+
+    for (genvar i = 0; i < N; ++i) begin
+        assign indices[i] = MODE ? LOGN'(N-1-i) : LOGN'(i);
+    end
+
+    VX_find_first #(
+        .N       (N),
+        .DATAW   (LOGN),
+        .REVERSE (MODE)
+    ) find_first (        
+        .data_i  (indices),
+        .valid_i (in_i),
+        .data_o  (cnt_o),
+        .valid_o (valid_o)
+    );
+  
+endmodule
+`TRACING_ON