Subversion Repositories udp_ip_stack

----------------------------------------------------------------------------------

-- Company: 

-- Engineer:            Peter Fall

-- 

-- Create Date:    16:20:42 06/01/2011 

-- Design Name: 

-- Module Name:    IPv4_RX - Behavioral 

-- Project Name: 

-- Target Devices: 

-- Tool versions: 

-- Description: 

--              handle simple IP RX

--              doesnt handle reassembly

--              checks and filters for IP protocol

--              checks and filters for IP addr

--              Handle IPv4 protocol

-- Dependencies: 

--

-- Revision: 

-- Revision 0.01 - File Created

-- Revision 0.02 - Improved error handling

-- Revision 0.03 - Added handling of broadcast address

-- Additional Comments: 

--

----------------------------------------------------------------------------------

library IEEE;

use IEEE.STD_LOGIC_1164.all;

use IEEE.NUMERIC_STD.all;

use work.axi.all;

use work.ipv4_types.all;

use work.arp_types.all;

entity IPv4_RX is

  port (

    -- IP Layer signals

    ip_rx             : out ipv4_rx_type;

    ip_rx_start       : out std_logic;  -- indicates receipt of ip frame.

    -- system signals

    clk               : in  std_logic;  -- same clock used to clock mac data and ip data

    reset             : in  std_logic;

    our_ip_address    : in  std_logic_vector (31 downto 0);

    rx_pkt_count      : out std_logic_vector(7 downto 0);   -- number of IP pkts received for us

    -- MAC layer RX signals

    mac_data_in       : in  std_logic_vector (7 downto 0);  -- ethernet frame (from dst mac addr through to last byte of frame)

    mac_data_in_valid : in  std_logic;  -- indicates data_in valid on clock

    mac_data_in_last  : in  std_logic   -- indicates last data in frame

    );

end IPv4_RX;

architecture Behavioral of IPv4_RX is

  type rx_state_type is (IDLE, ETH_HDR, IP_HDR, USER_DATA, WAIT_END, ERR);

  type rx_event_type is (NO_EVENT, DATA);

  type count_mode_type is (RST, INCR, HOLD);

  type settable_count_mode_type is (RST, INCR, SET_VAL, HOLD);

  type set_clr_type is (SET, CLR, HOLD);

  -- state variables

  signal rx_state         : rx_state_type;

  signal rx_count         : unsigned (15 downto 0);

  signal src_ip           : std_logic_vector (31 downto 0);  -- src IP captured from input

  signal dst_ip           : std_logic_vector (23 downto 0);  -- 1st 3 bytes of dst IP captured from input

  signal is_broadcast_reg : std_logic;

  signal protocol         : std_logic_vector (7 downto 0);   -- src protocol captured from input

  signal data_len         : std_logic_vector (15 downto 0);  -- src data length captured from input

  signal ip_rx_start_reg  : std_logic;  -- indicates start of user data

  signal hdr_valid_reg    : std_logic;  -- indicates that hdr data is valid

  signal frame_err_cnt    : unsigned (7 downto 0);  -- number of frame errors

  signal error_code_reg   : std_logic_vector (3 downto 0);

  signal rx_pkt_counter   : unsigned (7 downto 0);  -- number of rx frames received for us

  -- rx control signals

  signal next_rx_state     : rx_state_type;

  signal set_rx_state      : std_logic;

  signal rx_event          : rx_event_type;

  signal rx_count_mode     : settable_count_mode_type;

  signal set_dst_ip3       : std_logic;

  signal set_dst_ip2       : std_logic;

  signal set_dst_ip1       : std_logic;

  signal set_ip3           : std_logic;

  signal set_ip2           : std_logic;

  signal set_ip1           : std_logic;

  signal set_ip0           : std_logic;

  signal set_protocol      : std_logic;

  signal set_len_H         : std_logic;

  signal set_len_L         : std_logic;

  signal set_ip_rx_start   : set_clr_type;

  signal set_hdr_valid     : set_clr_type;

  signal set_frame_err_cnt : count_mode_type;

  signal dataval           : std_logic_vector (7 downto 0);

  signal rx_count_val      : unsigned (15 downto 0);

  signal set_error_code    : std_logic;

  signal error_code_val    : std_logic_vector (3 downto 0);

  signal set_pkt_cnt       : count_mode_type;

  signal set_data_last     : std_logic;

  signal dst_ip_rx         : std_logic_vector (31 downto 0);

  signal set_is_broadcast  : set_clr_type;

-- IP datagram header format

--

--      0          4          8                      16      19             24                    31

--      --------------------------------------------------------------------------------------------

--      | Version  | *Header  |    Service Type      |        Total Length including header        |

--      |   (4)    |  Length  |     (ignored)        |                 (in bytes)                  |

--      --------------------------------------------------------------------------------------------

--      |           Identification                   | Flags |       Fragment Offset               |

--      |                                            |       |      (in 32 bit words)              |

--      --------------------------------------------------------------------------------------------

--      |    Time To Live     |       Protocol       |             Header Checksum                 |

--      |     (ignored)       |                      |                                             |

--      --------------------------------------------------------------------------------------------

--      |                                   Source IP Address                                      |

--      |                                                                                          |

--      --------------------------------------------------------------------------------------------

--      |                                 Destination IP Address                                   |

--      |                                                                                          |

--      --------------------------------------------------------------------------------------------

--      |                          Options (if any - ignored)               |       Padding        |

--      |                                                                   |      (if needed)     |

--      --------------------------------------------------------------------------------------------

--      |                                          Data                                            |

--      |                                                                                          |

--      --------------------------------------------------------------------------------------------

--      |                                          ....                                            |

--      |                                                                                          |

--      --------------------------------------------------------------------------------------------

--

-- * - in 32 bit words 

begin

  -----------------------------------------------------------------------

  -- combinatorial process to implement FSM and determine control signals

  -----------------------------------------------------------------------

  rx_combinatorial : process (

    -- input signals

    mac_data_in, mac_data_in_valid, mac_data_in_last, our_ip_address,

    -- state variables

    rx_state, rx_count, src_ip, dst_ip, protocol, data_len, ip_rx_start_reg, hdr_valid_reg,

    frame_err_cnt, error_code_reg, rx_pkt_counter, is_broadcast_reg,

    -- control signals

    next_rx_state, set_rx_state, rx_event, rx_count_mode,

    set_ip3, set_ip2, set_ip1, set_ip0, set_protocol, set_len_H, set_len_L,

    set_dst_ip3, set_dst_ip2, set_dst_ip1,

    set_ip_rx_start, set_hdr_valid, set_frame_err_cnt, dataval, rx_count_val,

    set_error_code, error_code_val, set_pkt_cnt, set_data_last, dst_ip_rx, set_is_broadcast

    )

  begin

    -- set output followers

    ip_rx_start                <= ip_rx_start_reg;

    ip_rx.hdr.is_valid         <= hdr_valid_reg;

    ip_rx.hdr.protocol         <= protocol;

    ip_rx.hdr.data_length      <= data_len;

    ip_rx.hdr.src_ip_addr      <= src_ip;

    ip_rx.hdr.num_frame_errors <= std_logic_vector(frame_err_cnt);

    ip_rx.hdr.last_error_code  <= error_code_reg;

    ip_rx.hdr.is_broadcast     <= is_broadcast_reg;

    rx_pkt_count               <= std_logic_vector(rx_pkt_counter);

    -- transfer data upstream if in user data phase

    if rx_state = USER_DATA then

      ip_rx.data.data_in       <= mac_data_in;

      ip_rx.data.data_in_valid <= mac_data_in_valid;

      ip_rx.data.data_in_last  <= set_data_last;

    else

      ip_rx.data.data_in       <= (others => '0');

      ip_rx.data.data_in_valid <= '0';

      ip_rx.data.data_in_last  <= '0';

    end if;

    -- set signal defaults

    next_rx_state     <= IDLE;

    set_rx_state      <= '0';

    rx_event          <= NO_EVENT;

    rx_count_mode     <= HOLD;

    set_ip3           <= '0';

    set_ip2           <= '0';

    set_ip1           <= '0';

    set_ip0           <= '0';

    set_dst_ip3       <= '0';

    set_dst_ip2       <= '0';

    set_dst_ip1       <= '0';

    set_protocol      <= '0';

    set_len_H         <= '0';

    set_len_L         <= '0';

    set_ip_rx_start   <= HOLD;

    set_hdr_valid     <= HOLD;

    set_frame_err_cnt <= HOLD;

    rx_count_val      <= x"0000";

    set_error_code    <= '0';

    error_code_val    <= RX_EC_NONE;

    set_pkt_cnt       <= HOLD;

    dataval           <= (others => '0');

    set_data_last     <= '0';

    dst_ip_rx         <= (others => '0');

    set_is_broadcast  <= HOLD;

    -- determine event (if any)

    if mac_data_in_valid = '1' then

      rx_event <= DATA;

      dataval  <= mac_data_in;

    end if;

    -- RX FSM

    case rx_state is

      when IDLE =>

        rx_count_mode <= RST;

        case rx_event is

          when NO_EVENT =>              -- (nothing to do)

          when DATA =>

            rx_count_mode <= INCR;

            set_hdr_valid <= CLR;

            next_rx_state <= ETH_HDR;

            set_rx_state  <= '1';

        end case;

      when ETH_HDR =>

        case rx_event is

          when NO_EVENT =>                      -- (nothing to do)

          when DATA =>

            if rx_count = x"000d" then

              rx_count_mode <= RST;

              next_rx_state <= IP_HDR;

              set_rx_state  <= '1';

            else

              rx_count_mode <= INCR;

            end if;

                                                -- handle early frame termination

            if mac_data_in_last = '1' then

              error_code_val    <= RX_EC_ET_ETH;

              set_error_code    <= '1';

              set_frame_err_cnt <= INCR;

              set_ip_rx_start   <= CLR;

              set_data_last     <= '1';

              next_rx_state     <= IDLE;

              set_rx_state      <= '1';

            else

              case rx_count is

                when x"000c" =>

                  if mac_data_in /= x"08" then  -- ignore pkts that are not type=IP

                    next_rx_state <= WAIT_END;

                    set_rx_state  <= '1';

                  end if;

                when x"000d" =>

                  if mac_data_in /= x"00" then  -- ignore pkts that are not type=IP

                    next_rx_state <= WAIT_END;

                    set_rx_state  <= '1';

                  end if;

                when others =>          -- ignore other bytes in eth header

              end case;

            end if;

        end case;

      when IP_HDR =>

        case rx_event is

          when NO_EVENT =>              -- (nothing to do)

          when DATA =>

            if rx_count = x"0013" then

              rx_count_val  <= x"0001";         -- start counter at 1

              rx_count_mode <= SET_VAL;

            else

              rx_count_mode <= INCR;

            end if;

                                        -- handle early frame termination

            if mac_data_in_last = '1' then

              error_code_val    <= RX_EC_ET_IP;

              set_error_code    <= '1';

              set_frame_err_cnt <= INCR;

              set_ip_rx_start   <= CLR;

              set_data_last     <= '1';

              next_rx_state     <= IDLE;

              set_rx_state      <= '1';

            else

              case rx_count is

                when x"0000" =>

                  if mac_data_in /= x"45" then  -- ignore pkts that are not v4 with 5 header words

                    next_rx_state <= WAIT_END;

                    set_rx_state  <= '1';

                  end if;

                when x"0002" => set_len_H <= '1';

                when x"0003" => set_len_L <= '1';

                when x"0006" =>

                  if (mac_data_in(7) = '1') or (mac_data_in (4 downto 0) /= "00000") then

                                        -- ignore pkts that require reassembly (MF=1 or frag offst /= 0)

                    next_rx_state <= WAIT_END;

                    set_rx_state  <= '1';

                  end if;

                when x"0007" =>

                  if mac_data_in /= x"00" then  -- ignore pkts that require reassembly (frag offst /= 0)

                    next_rx_state <= WAIT_END;

                    set_rx_state  <= '1';

                  end if;

                when x"0009" => set_protocol <= '1';

                when x"000c" => set_ip3 <= '1';

                when x"000d" => set_ip2 <= '1';

                when x"000e" => set_ip1 <= '1';

                when x"000f" => set_ip0 <= '1';

                when x"0010" => set_dst_ip3 <= '1';

                  if ((mac_data_in /= our_ip_address(31 downto 24)) and

                      (mac_data_in /= IP_BC_ADDR(31 downto 24)))then  -- ignore pkts that are not addressed to us

                    next_rx_state <= WAIT_END;

                    set_rx_state  <= '1';

                  end if;

                when x"0011" => set_dst_ip2 <= '1';

                  if ((mac_data_in /= our_ip_address(23 downto 16)) and

                      (mac_data_in /= IP_BC_ADDR(23 downto 16)))then  -- ignore pkts that are not addressed to us

                    next_rx_state <= WAIT_END;

                    set_rx_state  <= '1';

                  end if;

                when x"0012" => set_dst_ip1 <= '1';

                  if ((mac_data_in /= our_ip_address(15 downto 8)) and

                      (mac_data_in /= IP_BC_ADDR(15 downto 8)))then  -- ignore pkts that are not addressed to us

                    next_rx_state <= WAIT_END;

                    set_rx_state  <= '1';

                  end if;

                when x"0013" =>

                  if ((mac_data_in /= our_ip_address(7 downto 0)) and

                      (mac_data_in /= IP_BC_ADDR(7 downto 0)))then  -- ignore pkts that are not addressed to us

                    next_rx_state <= WAIT_END;

                    set_rx_state  <= '1';

                  else

                    next_rx_state   <= USER_DATA;

                    set_pkt_cnt     <= INCR;                         -- count another pkt

                    set_rx_state    <= '1';

                    set_ip_rx_start <= SET;

                  end if;

                                        -- now have the dst IP addr

                  dst_ip_rx <= dst_ip & mac_data_in;

                  if dst_ip_rx = IP_BC_ADDR then

                    set_is_broadcast <= SET;

                  else

                    set_is_broadcast <= CLR;

                  end if;

                  set_hdr_valid <= SET;  -- header values are now valid, although the pkt may not be for us                                                                      

                  --if dst_ip_rx = our_ip_address or dst_ip_rx = IP_BC_ADDR then

                  --  next_rx_state   <= USER_DATA;

                  --  set_pkt_cnt     <= INCR;  -- count another pkt received

                  --  set_rx_state    <= '1';

                  --  set_ip_rx_start <= SET;

                  --else

                  --  next_rx_state <= WAIT_END;

                  --  set_rx_state  <= '1';

                  --end if;

                when others =>  -- ignore other bytes in ip header                                                                               

              end case;

            end if;

        end case;

      when USER_DATA =>

        case rx_event is

          when NO_EVENT =>              -- (nothing to do)

          when DATA =>

                                        -- note: data gets transfered upstream as part of "output followers" processing

            if rx_count = unsigned(data_len) then

              set_ip_rx_start <= CLR;

              rx_count_mode   <= RST;

              set_data_last   <= '1';

              if mac_data_in_last = '1' then

                next_rx_state   <= IDLE;

                set_ip_rx_start <= CLR;

              else

                next_rx_state <= WAIT_END;

              end if;

              set_rx_state <= '1';

            else

              rx_count_mode <= INCR;

                                        -- check for early frame termination

              if mac_data_in_last = '1' then

                error_code_val    <= RX_EC_ET_USER;

                set_error_code    <= '1';

                set_frame_err_cnt <= INCR;

                set_ip_rx_start   <= CLR;

                next_rx_state     <= IDLE;

                set_rx_state      <= '1';

              end if;

            end if;

        end case;

      when ERR =>

        set_frame_err_cnt <= INCR;

        set_ip_rx_start   <= CLR;

        if mac_data_in_last = '0' then

          set_data_last <= '1';

          next_rx_state <= WAIT_END;

          set_rx_state  <= '1';

        else

          next_rx_state <= IDLE;

          set_rx_state  <= '1';

        end if;

      when WAIT_END =>

        case rx_event is

          when NO_EVENT =>              -- (nothing to do)

          when DATA =>

            if mac_data_in_last = '1' then

              set_data_last   <= '1';

              next_rx_state   <= IDLE;

              set_rx_state    <= '1';

              set_ip_rx_start <= CLR;

            end if;

        end case;

    end case;

  end process;

  -----------------------------------------------------------------------------

  -- sequential process to action control signals and change states and outputs

  -----------------------------------------------------------------------------

  rx_sequential : process (clk)--, reset)

  begin

    if rising_edge(clk) then

      if reset = '1' then

        -- reset state variables

        rx_state         <= IDLE;

        rx_count         <= x"0000";

        src_ip           <= (others => '0');

        dst_ip           <= (others => '0');

        protocol         <= (others => '0');

        data_len         <= (others => '0');

        ip_rx_start_reg  <= '0';

        hdr_valid_reg    <= '0';

        is_broadcast_reg <= '0';

        frame_err_cnt    <= (others => '0');

        error_code_reg   <= RX_EC_NONE;

        rx_pkt_counter   <= x"00";

      else

        -- Next rx_state processing

        if set_rx_state = '1' then

          rx_state <= next_rx_state;

        else

          rx_state <= rx_state;

        end if;

        -- rx_count processing

        case rx_count_mode is

          when RST     => rx_count <= x"0000";

          when INCR    => rx_count <= rx_count + 1;

          when SET_VAL => rx_count <= rx_count_val;

          when HOLD    => rx_count <= rx_count;

        end case;

        -- frame error count processing

        case set_frame_err_cnt is

          when RST  => frame_err_cnt <= x"00";

          when INCR => frame_err_cnt <= frame_err_cnt + 1;

          when HOLD => frame_err_cnt <= frame_err_cnt;

        end case;

        -- ip pkt processing

        case set_pkt_cnt is

          when RST  => rx_pkt_counter <= x"00";

          when INCR => rx_pkt_counter <= rx_pkt_counter + 1;

          when HOLD => rx_pkt_counter <= rx_pkt_counter;

        end case;

        -- source ip capture

        if (set_ip3 = '1') then src_ip(31 downto 24) <= dataval; end if;

        if (set_ip2 = '1') then src_ip(23 downto 16) <= dataval; end if;

        if (set_ip1 = '1') then src_ip(15 downto 8)  <= dataval; end if;

        if (set_ip0 = '1') then src_ip(7 downto 0)   <= dataval; end if;

        -- dst ip capture

        if (set_dst_ip3 = '1') then dst_ip(23 downto 16) <= dataval; end if;

        if (set_dst_ip2 = '1') then dst_ip(15 downto 8)  <= dataval; end if;

        if (set_dst_ip1 = '1') then dst_ip(7 downto 0)   <= dataval; end if;

        if (set_protocol = '1') then

          protocol <= dataval;

        else

          protocol <= protocol;

        end if;

        if (set_len_H = '1') then

          data_len (15 downto 8) <= dataval;

          data_len (7 downto 0)  <= x"00";

        elsif (set_len_L = '1') then

                                        -- compute data length, taking into account that we need to subtract the header length

          data_len <= std_logic_vector(unsigned(data_len(15 downto 8) & dataval) - 20);

        else

          data_len <= data_len;

        end if;

        case set_ip_rx_start is

          when SET  => ip_rx_start_reg <= '1';

          when CLR  => ip_rx_start_reg <= '0';

          when HOLD => ip_rx_start_reg <= ip_rx_start_reg;

        end case;

        case set_is_broadcast is

          when SET  => is_broadcast_reg <= '1';

          when CLR  => is_broadcast_reg <= '0';

          when HOLD => is_broadcast_reg <= is_broadcast_reg;

        end case;

        case set_hdr_valid is

          when SET  => hdr_valid_reg <= '1';

          when CLR  => hdr_valid_reg <= '0';

          when HOLD => hdr_valid_reg <= hdr_valid_reg;

        end case;

        -- set error code

        if set_error_code = '1' then

          error_code_reg <= error_code_val;

        else

          error_code_reg <= error_code_reg;

        end if;

      end if;

    end if;

  end process;

end Behavioral;