code refactoring for Vivado compatibility

hw/rtl/libs/VX_find_first.sv

@@ -0,0 +1,44 @@
+`include "VX_platform.vh"
+
+`TRACING_OFF
+module VX_find_first #(
+    parameter N       = 1,
+    parameter DATAW   = 1,
+    parameter REVERSE = 0,
+    parameter LOGN    = $clog2(N)
+) (
+    input  wire [N-1:0][DATAW-1:0] data_i,
+    input  wire [N-1:0]            valid_i,    
+    output wire [DATAW-1:0]        data_o,
+    output wire                    valid_o
+);
+    localparam TL = (1 << LOGN) - 1;
+    localparam TN = (1 << (LOGN+1)) - 1;
+
+`IGNORE_WARNINGS_BEGIN
+    wire [TN-1:0] s_n;
+    wire [TN-1:0][DATAW-1:0] d_n;
+`IGNORE_WARNINGS_END
+
+    for (genvar i = 0; i < N; ++i) begin
+        assign s_n[TL+i] = REVERSE ? valid_i[N-1-i] : valid_i[i];
+        assign d_n[TL+i] = REVERSE ? data_i[N-1-i] : data_i[i];
+    end
+    
+    for (genvar i = TL+N; i < TN; ++i) begin
+        assign s_n[i] = 0;
+        assign d_n[i] = 'x;
+    end
+
+    for (genvar j = 0; j < LOGN; ++j) begin
+        for (genvar i = 0; i < (2**j); ++i) begin
+            assign s_n[2**j-1+i] = s_n[2**(j+1)-1+i*2] | s_n[2**(j+1)-1+i*2+1];
+            assign d_n[2**j-1+i] = s_n[2**(j+1)-1+i*2] ? d_n[2**(j+1)-1+i*2] : d_n[2**(j+1)-1+i*2+1];
+        end
+    end     
+        
+    assign valid_o = s_n[0];
+    assign data_o  = d_n[0];
+  
+endmodule
+`TRACING_ON