ASIC/FPGA Design and Verification Out Source Services

IP TTL filter digital design, implemented in VHDL.

1. This project implements an IP TTL filter in hardware. If an IPV4 packet is identified, the DUT checks its TTL field. Based on previous values of TTL in former packets, the machine decides if the packet is spoofed or not. The main page of this project.;



2. This page describes the simulation end procedure. First the simulation ends with an assert statement with error severity. I put ended okay in the message, so I easily see its successful end.
   assert false report "simulation ended okay from process p_2" severity error;
   As opposed to a real error report:
   assert tmp_ptr.next_rec /= null report "end of packet list too early 1" severity error;
   


3. When the simulation ends, I also need to print all the entries in the scoreboard of the reference model ( to be described soon). ...
   signal sim_end : boolean := false;
   ...
       --wait before end
       sim_end <= true;
       for j in 1 to 31 loop
         wait until rx_clk'event and rx_clk = '1';
       end loop;
       assert false report "simulation ended okay from process p_2" severity error;
   
     end process;--p_2
   ...
     begin
       if(rx_clk'event and rx_clk = '1') then
         v_spoofed_q <= '0';
         if(sim_end and scbd_print) then
           scbd_print := false;
           assert false report "scoreboard print" severity warning;
   
           --add an empty entry at the end
           new_sbd.ips := (others => '0');
           new_sbd.ttl := (others => '0');
           new_sbd.cnt := (others => '0');
           new_sbd.pkt_in_t := 0 ns;
           new_sbd.next_rec := null;
           tmp_ptr := scbd_ptr;
           while(tmp_ptr.next_rec /= null) loop
             tmp_ptr := tmp_ptr.next_rec;
           end loop;
           tmp_ptr.next_rec := new_sbd;
   
           tmp_ptr := scbd_ptr;
           while(tmp_ptr.next_rec /= null) loop
             write(my_line, sim_end'path_name);
             write(my_line, string'(" ips "));
             hwrite(my_line, tmp_ptr.ips);
             write(my_line, string'(" ttl "));
             hwrite(my_line, tmp_ptr.ttl);
             write(my_line, string'(" cnt "));
             hwrite(my_line, tmp_ptr.cnt);
             if(tmp_ptr.learning) then
               write(my_line, string'(" learning "));
             else
               write(my_line, string'(" checkSpf "));
             end if;
             write(my_line, string'(" packet in time "));
             write(my_line, tmp_ptr.pkt_in_t);
             writeline(output, my_line);
             tmp_ptr := tmp_ptr.next_rec;
           end loop;