Subversion Repositories udp_ip_stack

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-- Company: 

-- Engineer:            Peter Fall

-- 

-- Create Date:    5 June 2011 

-- Design Name: 

-- Module Name:    UDP_RX - Behavioral 

-- Project Name: 

-- Target Devices: 

-- Tool versions: 

-- Description: 

--              handle simple UDP RX

--              doesnt check the checsum

-- Dependencies: 

--

-- Revision: 

-- Revision 0.01 - File Created

-- Revision 0.02 - Improved error handling

-- Additional Comments: 

--

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

library IEEE;

use IEEE.STD_LOGIC_1164.all;

use IEEE.NUMERIC_STD.all;

use work.axi.all;

use work.ipv4_types.all;

entity UDP_RX is

  port (

    -- UDP Layer signals

    udp_rx_start : out std_logic;       -- indicates receipt of udp header

    udp_rxo      : out udp_rx_type;

    -- system signals

    clk          : in  std_logic;

    reset        : in  std_logic;

    -- IP layer RX signals

    ip_rx_start  : in  std_logic;       -- indicates receipt of ip header

    ip_rx        : in  ipv4_rx_type

    );

end UDP_RX;

architecture Behavioral of UDP_RX is

  type rx_state_type is (IDLE, UDP_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_port         : std_logic_vector (15 downto 0);  -- src port captured from input

  signal dst_port         : std_logic_vector (15 downto 0);  -- dst port captured from input

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

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

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

  signal src_ip_addr      : std_logic_vector (31 downto 0);  -- captured from IP hdr

  -- 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 rx_count_val     : unsigned (15 downto 0);

  signal set_sph          : std_logic;

  signal set_spl          : std_logic;

  signal set_dph          : std_logic;

  signal set_dpl          : std_logic;

  signal set_len_H        : std_logic;

  signal set_len_L        : std_logic;

  signal set_udp_rx_start : set_clr_type;

  signal set_hdr_valid    : set_clr_type;

  signal dataval          : std_logic_vector (7 downto 0);

  signal set_pkt_cnt      : count_mode_type;

  signal set_src_ip       : std_logic;

  signal set_data_last    : std_logic;

-- IP datagram header format

--

--      0          4          8                      16      19             24                    31

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

--      |              source port number            |              dest port number               |

--      |                                            |                                             |

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

--      |                length (bytes)              |                checksum                     |

--      |          (header and data combined)        |                                             |

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

--      |                                          Data                                            |

--      |                                                                                          |

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

--      |                                          ....                                            |

--      |                                                                                          |

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

begin

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

  -- combinatorial process to implement FSM and determine control signals

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

  rx_combinatorial : process (

    -- input signals

    ip_rx, ip_rx_start,

    -- state variables

    rx_state, rx_count, src_port, dst_port, data_len, udp_rx_start_reg, hdr_valid_reg, src_ip_addr,

    -- control signals

    next_rx_state, set_rx_state, rx_event, rx_count_mode, rx_count_val,

    set_sph, set_spl, set_dph, set_dpl, set_len_H, set_len_L, set_data_last,

    set_udp_rx_start, set_hdr_valid, dataval, set_pkt_cnt, set_src_ip

    )

  begin

    -- set output followers

    udp_rx_start            <= udp_rx_start_reg;

    udp_rxo.hdr.is_valid    <= hdr_valid_reg;

    udp_rxo.hdr.data_length <= data_len;

    udp_rxo.hdr.src_port    <= src_port;

    udp_rxo.hdr.dst_port    <= dst_port;

    udp_rxo.hdr.src_ip_addr <= src_ip_addr;

    -- transfer data upstream if in user data phase

    if rx_state = USER_DATA then

      udp_rxo.data.data_in       <= ip_rx.data.data_in;

      udp_rxo.data.data_in_valid <= ip_rx.data.data_in_valid;

      udp_rxo.data.data_in_last  <= set_data_last;

    else

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

      udp_rxo.data.data_in_valid <= '0';

      udp_rxo.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_sph          <= '0';

    set_spl          <= '0';

    set_dph          <= '0';

    set_dpl          <= '0';

    set_len_H        <= '0';

    set_len_L        <= '0';

    set_udp_rx_start <= HOLD;

    set_hdr_valid    <= HOLD;

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

    set_src_ip       <= '0';

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

    set_data_last    <= '0';

    -- determine event (if any)

    if ip_rx.data.data_in_valid = '1' then

      rx_event <= DATA;

      dataval  <= ip_rx.data.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 =>

            if ip_rx.hdr.protocol = x"11" then

                                        -- UDP protocol

              rx_count_mode <= INCR;

              set_hdr_valid <= CLR;

              set_src_ip    <= '1';

              set_sph       <= '1';

              next_rx_state <= UDP_HDR;

              set_rx_state  <= '1';

            else

                                        -- non-UDP protocol - ignore this pkt

              set_hdr_valid <= CLR;

              next_rx_state <= WAIT_END;

              set_rx_state  <= '1';

            end if;

        end case;

      when UDP_HDR =>

        case rx_event is

          when NO_EVENT =>              -- (nothing to do)

          when DATA =>

            if rx_count = x"0007" then

              rx_count_mode <= SET_VAL;

              rx_count_val  <= x"0001";

              next_rx_state <= USER_DATA;

              set_rx_state  <= '1';

            else

              rx_count_mode <= INCR;

            end if;

                                        -- handle early frame termination

            if ip_rx.data.data_in_last = '1' then

              next_rx_state <= IDLE;

              set_rx_state  <= '1';

            else

              case rx_count is

                when x"0000" => set_sph <= '1';

                when x"0001" => set_spl <= '1';

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

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

                when x"0004" => set_len_H <= '1';

                when x"0005" => set_len_L <= '1'; set_hdr_valid <= SET;  -- header values are now valid, although the pkt may not be for us

                when x"0006" =>                           -- ignore checksum values

                when x"0007" => set_udp_rx_start <= SET;  -- indicate frame received

                when others =>  -- ignore other bytes in udp 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_udp_rx_start <= CLR;

              rx_count_mode    <= RST;

              set_data_last    <= '1';

              if ip_rx.data.data_in_last = '1' then

                next_rx_state    <= IDLE;

                set_udp_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

                                        -- TODO need to mark frame as errored

              if ip_rx.data.data_in_last = '1' then

                next_rx_state <= IDLE;

                set_rx_state  <= '1';

                set_data_last <= '1';

              end if;

            end if;

        end case;

      when ERR =>

        if ip_rx.data.data_in_last = '0' then

          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 ip_rx.data.data_in_last = '1' then

              next_rx_state <= IDLE;

              set_rx_state  <= '1';

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

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

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

        udp_rx_start_reg <= '0';

        hdr_valid_reg    <= '0';

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

      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;

        -- port number capture

        if (set_sph = '1') then src_port(15 downto 8) <= dataval; end if;

        if (set_spl = '1') then src_port(7 downto 0)  <= dataval; end if;

        if (set_dph = '1') then dst_port(15 downto 8) <= dataval; end if;

        if (set_dpl = '1') then dst_port(7 downto 0)  <= dataval; 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) - 8);

        else

          data_len <= data_len;

        end if;

        case set_udp_rx_start is

          when SET  => udp_rx_start_reg <= '1';

          when CLR  => udp_rx_start_reg <= '0';

          when HOLD => udp_rx_start_reg <= udp_rx_start_reg;

        end case;

        -- capture src IP address

        if set_src_ip = '1' then

          src_ip_addr <= ip_rx.hdr.src_ip_addr;

        else

          src_ip_addr <= src_ip_addr;

        end if;

        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;

      end if;

    end if;

  end process;

end Behavioral;