io.vhdl

   39 io_sync: process(clk, rst)                                                                                              
   40 begin                                                                                                                   
   41     if (rst = '1') then                                                                                                 
   42         io_pipe <= (others => '0');                                                                                     
   43     elsif (rising_edge(clk)) then                                                                                       
   44         io_pipe(0) <= dri; -- Add new value to start of queue                                                           
   45         io_pipe <= io_pipe(io_pipe_len - 1 downto 0) & '0' ; --Left shift whole queue                                   
   46         if (io_pipe(io_pipe_len) = '1') then                                                                            
   47             if (filter_counter < io_delay) then                                                                                     
   48                 filter_counter <= filter_counter + 1;                                                                               
   49             else                                                                                                                    
   50                 filter_counter <= io_delay;                                                                                         
   51                 dfo <= '1';                                                                                                         
   52             end if;                                                                                                                 
   53         else                                                                                                                        
   54             if (filter_counter > 0) then                                                                                            
   55                 filter_counter <= filter_counter - 1;                                                                               
   56             else                                                                                                                    
   57                 filter_counter <= 0;                                                                                                
   58                 dfo <= '0';                                                                                                         
   59             end if;                                                                                                                 
   60         end if;                                                                                                                     
   61     end if;                                                                                                                         
   62                                                                                                                                     
   63 end process;