code refactoring for Vivado compatibility

hw/rtl/cache/VX_flush_ctrl.sv

@@ -0,0 +1,36 @@
+`include "VX_cache_define.vh"
+
+module VX_flush_ctrl #(
+    // Size of cache in bytes
+    parameter CACHE_SIZE        = 16384, 
+    // Size of line inside a bank in bytes
+    parameter CACHE_LINE_SIZE   = 1, 
+    // Number of banks
+    parameter NUM_BANKS         = 1
+) (
+    input wire  clk,
+    input wire  reset,    
+    output wire [`LINE_SELECT_BITS-1:0] addr_out,
+    output wire valid_out
+);
+    reg flush_enable;
+    reg [`LINE_SELECT_BITS-1:0] flush_ctr;
+
+    always @(posedge clk) begin
+        if (reset) begin
+            flush_enable <= 1;
+            flush_ctr    <= 0;
+        end else begin
+            if (flush_enable) begin
+                if (flush_ctr == ((2 ** `LINE_SELECT_BITS)-1)) begin
+                    flush_enable <= 0;
+                end
+                flush_ctr <= flush_ctr + 1;            
+            end
+        end
+    end
+
+    assign addr_out  = flush_ctr;
+    assign valid_out = flush_enable;
+
+endmodule