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-------------------------------------------------------------------------------
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-- arpsnd.vhd
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--
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-- Author(s): Jussi Nieminen after Ashley Partis and Jorgen Peddersen
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-- Created: Feb 2001
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-- Last Modified: Feb 2001
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--
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-- Sits transparently between the internet send and ethernet send layers.
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-- All frame send requests from the internet layer are passed through after
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-- the destination MAC is either looked up from the ARP table, or an ARP
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-- request is sent out and an ARP reply is receiver. ARP replies are created
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-- and then sent to the ethernet later after being requested by the ARP layer.
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-- After each frame is passed on to the ethernet layer and then sent, it informs
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-- the layer above that the frame has been sent.
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--
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-- Licenced under LGPL.
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-------------------------------------------------------------------------------
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_unsigned.all;
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use work.udp_ip_pkg.all;
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entity ARPSnd is
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port (
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clk : in std_logic; -- clock
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rstn : in std_logic; -- aysnchronous active low reset
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request_MAC_in : in std_logic; -- IP layer want's to know a MAC addr
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targer_IP_in : in std_logic_vector (31 downto 0); -- destination IP from the internet layer
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ARP_entry_valid_in : in std_logic; -- input from ARP indicating that it contains the requested IP
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gen_ARP_reply_in : in std_logic; -- input from ARP requesting an ARP reply
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gen_ARP_IP_in : in std_logic_vector (31 downto 0); -- input from ARP saying which IP to send a reply to
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lookup_MAC_in : in std_logic_vector (47 downto 0); -- input from ARP giving a requested MAC
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lookup_IP_out : out std_logic_vector (31 downto 0); -- output to ARP requesting an IP to be looked up in the table
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sending_reply_out : out std_logic; -- output to ARP to tell it's sending the ARP reply
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target_MAC_out : out std_logic_vector (47 downto 0); -- destination MAC for the physical layer
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requested_MAC_out : out std_logic_vector( 47 downto 0 ); -- requested MAC to UDP/IP
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req_MAC_valid_out : out std_logic;
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gen_frame_out : out std_logic; -- tell the ethernet layer (PHY) to send a frame
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frame_type_out : out std_logic_vector( frame_type_w_c-1 downto 0 );
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frame_size_out : out std_logic_vector (10 downto 0); -- tell the PHY what size the frame size is
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tx_ready_out : out std_logic; -- idle signal
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wr_data_valid_out : out std_logic;
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wr_data_out : out std_logic_vector (15 downto 0);
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wr_re_in : in std_logic
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);
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end ARPSnd;
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architecture ARPSnd_arch of ARPSnd is
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-- FSM state definitions
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type STATETYPE is (stIdle, stGenARPReply, stGetReplyMAC, stStoreARPReply, stCheckARPEntry, stCheckARPEntry2,
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stGenARPRequest, stStoreARPRequest, stWaitForValidEntry, stGiveMAC);
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signal presState : STATETYPE;
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signal nextState : STATETYPE;
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-- signals to synchronously increment and reset the counter
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signal cnt : std_logic_vector (4 downto 0);
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signal incCnt : std_logic;
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signal rstCnt : std_logic;
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-- next write data value
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signal nextWrData : std_logic_vector (15 downto 0);
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-- signals and buffers to latch input data
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signal latchTargetIP : std_logic;
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signal latchInternetIP : std_logic;
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signal IP_r : std_logic_vector (31 downto 0);
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signal latchTargetMAC : std_logic;
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signal MAC_r : std_logic_vector (47 downto 0);
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-- 20 second ARP reply timeout counter at 50MHz
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signal ARP_timeout_cnt_r : std_logic_vector (29 downto 0);
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signal rstARPCnt : std_logic;
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signal ARP_cnt_overflow_r : std_logic;
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signal wr_data_r : std_logic_vector( 15 downto 0 );
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signal wr_data_valid : std_logic;
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signal start_tx : std_logic;
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signal MAC_to_output : std_logic;
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signal req_MAC_valid_r : std_logic;
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constant ARP_frame_size_c : std_logic_vector( 10 downto 0 ) := "00000011100";
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-------------------------------------------------------------------------------
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begin
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-------------------------------------------------------------------------------
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-- connect output to register
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wr_data_out <= wr_data_r;
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req_MAC_valid_out <= req_MAC_valid_r;
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process (rstn, clk)
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begin
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-- set up the asynchronous active low reset
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if rstn = '0' then
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presState <= stIdle;
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cnt <= (others => '0');
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wr_data_valid_out <= '0';
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wr_data_r <= (others => '0');
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ARP_timeout_cnt_r <= (others => '0');
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ARP_cnt_overflow_r <= '0';
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IP_r <= (others => '0');
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MAC_r <= (others => '0');
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gen_frame_out <= '0';
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target_MAC_out <= (others => '0');
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frame_size_out <= (others => '0');
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frame_type_out <= (others => '0');
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req_MAC_valid_r <= '0';
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requested_MAC_out <= (others => '0');
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elsif clk'event and clk = '1' then
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presState <= nextState;
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-- set the write data bus to it's next value
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wr_data_r <= nextWrData;
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-- register valid signal
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if wr_data_valid = '1' then
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wr_data_valid_out <= '1';
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end if;
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-- start a tx
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if start_tx = '1' then
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if latchTargetMAC = '1' then
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target_MAC_out <= lookup_MAC_in;
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else
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target_MAC_out <= x"FFFFFFFFFFFF";
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end if;
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gen_frame_out <= '1'; -- goes to 'new tx' and 'snd_req' (udp)
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frame_size_out <= ARP_frame_size_c;
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frame_type_out <= ARP_frame_type_c;
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end if;
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if wr_re_in = '1' then
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-- clear gen_frame_out when eth cntrl starts to read
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gen_frame_out <= '0';
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-- also clear the valid signal
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wr_data_valid_out <= '0';
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end if;
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-- increment and reset the counter synchronously to avoid race conditions
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if incCnt = '1' then
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cnt <= cnt + 1;
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elsif rstCnt = '1' then
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cnt <= (others => '0');
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end if;
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-- set the ARP counter to 1
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if rstARPCnt = '1' then
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ARP_timeout_cnt_r <= "00" & x"0000001";
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ARP_cnt_overflow_r <= '0';
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-- if the ARP counter isn't 0, keep incrementing it
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elsif ARP_timeout_cnt_r /= "00" & x"0000000" then
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ARP_timeout_cnt_r <= ARP_timeout_cnt_r + 1;
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ARP_cnt_overflow_r <= '0';
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-- if the counter is 0, set the overflow signal
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else
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ARP_cnt_overflow_r <= '1';
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end if;
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-- latch the IP to send the ARP request to, send the ARP reply to or to lookup
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-- from either the ARP layer or internet send layer
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if latchTargetIP = '1' then
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IP_r <= gen_ARP_IP_in;
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elsif latchInternetIP = '1' then
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IP_r <= targer_IP_in;
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end if;
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-- latch the MAC from the ARP table that has been looked up
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if latchTargetMAC = '1' then
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MAC_r <= lookup_MAC_in;
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end if;
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if MAC_to_output = '1' then
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-- put out the MAC when we have it
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requested_MAC_out <= MAC_r;
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req_MAC_valid_r <= '1';
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elsif request_MAC_in = '0' then
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-- clear the valid signal when IP layer stops requesting
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req_MAC_valid_r <= '0';
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end if;
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end if;
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end process;
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-- ARP header format
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--
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-- 0 8 16 31
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-- --------------------------------------------------------------------------------------------
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-- | Hardware Type | Protocol Type |
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-- | | |
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-- --------------------------------------------------------------------------------------------
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-- | Hardware Address | Protocol Address | Operation |
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-- | Length | Length | |
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-- --------------------------------------------------------------------------------------------
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-- | Sender Hardware Address (MAC) (bytes 0 - 3) |
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-- | |
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-- --------------------------------------------------------------------------------------------
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-- | Sender MAC (bytes 4 - 5) | Sender IP Address (bytes 0 - 1) |
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-- | | |
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-- --------------------------------------------------------------------------------------------
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-- | Sender IP (bytes 2 - 3) | Target Hardware Address (bytes 0 - 1) |
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-- | | |
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-- --------------------------------------------------------------------------------------------
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-- | Target MAC (bytes 2 - 5) |
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-- | |
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-- --------------------------------------------------------------------------------------------
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-- | Target IP Address (bytes 0 - 3) |
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-- | |
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-- --------------------------------------------------------------------------------------------
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--
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-- main FSM process
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process (presState, gen_ARP_reply_in, cnt, IP_r, MAC_r, wr_data_r, req_MAC_valid_r,
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ARP_entry_valid_in, ARP_cnt_overflow_r, request_MAC_in, wr_re_in)
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begin
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-- remember the value of the RAM write data bus by default
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nextWrData <= wr_data_r;
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-- lookup the latched IP by default
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lookup_IP_out <= IP_r;
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rstCnt <= '0';
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incCnt <= '0';
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sending_reply_out <= '0';
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tx_ready_out <= '0';
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latchInternetIP <= '0';
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latchTargetIP <= '0';
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latchTargetMAC <= '0';
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rstARPCnt <= '0';
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wr_data_valid <= '0';
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MAC_to_output <= '0';
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start_tx <= '0';
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case presState is
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when stIdle =>
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-- wait for a frame to arrive
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-- if req_MAC_valid_r = '1', we have just arrived from state stGiveMAC
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-- and we don't want to get again to stCheckARPEntry.
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if (req_MAC_valid_r = '1' or request_MAC_in = '0')
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and gen_ARP_reply_in = '0'
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then
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nextState <= stIdle;
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tx_ready_out <= '1';
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rstCnt <= '1';
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-- create an ARP reply when asked, giving ARP message priority
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elsif gen_ARP_reply_in = '1' then
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nextState <= stGetReplyMAC;
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-- latch the target IP from the ARP layer
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latchTargetIP <= '1';
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-- IP layer wants to have a MAC address
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else
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nextState <= stCheckARPEntry;
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-- latch input from the IP layer
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latchInternetIP <= '1';
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end if;
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-- create the ARP reply, getting the target MAC from the ARP table
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when stGetReplyMAC =>
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nextState <= stGenARPReply;
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lookup_IP_out <= IP_r;
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latchTargetMAC <= '1';
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-- tell the ARP table that we're sending the reply
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sending_reply_out <= '1';
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start_tx <= '1';
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-- generate each byte of the ARP reply according to count
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when stGenARPReply =>
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wr_data_valid <= '1';
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nextState <= stStoreARPReply;
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case cnt is
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-- Hardware type
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when "00000" =>
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nextWrData <= x"0100"; -- remember, it's x"LSByte MSByte"
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-- Protocol type
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when "00001" =>
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nextWrData <= x"0008";
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-- Hardware and protocol Address lengths in bytes (x"PAL HAL")
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when "00010" =>
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nextWrData <= x"0406";
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-- Operation
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when "00011" =>
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nextWrData <= x"0200";
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-- Sender Hardware Address bytes 1 and 0
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when "00100" =>
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nextWrData <= MAC_addr_c( 39 downto 32 ) & MAC_addr_c (47 downto 40);
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-- Sender Hardware Address bytes 3 and 2
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when "00101" =>
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nextWrData <= MAC_addr_c( 23 downto 16 ) & MAC_addr_c (31 downto 24);
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-- Sender Hardware Address bytes 5 and 4
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when "00110" =>
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nextWrData <= MAC_addr_c( 7 downto 0 ) & MAC_addr_c (15 downto 8);
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-- Sender IP Address bytes 1 and 0
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when "00111" =>
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nextWrData <= own_IP_c( 23 downto 16 ) & own_IP_c (31 downto 24);
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-- Sender IP Address bytes 3 and 2
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when "01000" =>
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nextWrData <= own_IP_c( 7 downto 0 ) & own_IP_c (15 downto 8);
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-- Target Hardware Address bytes 1 and 0
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when "01001" =>
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nextWrData <= MAC_r( 39 downto 32 ) & MAC_r( 47 downto 40 );
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-- Target Hardware Address bytes 3 and 2
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when "01010" =>
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nextWrData <= MAC_r( 23 downto 16 ) & MAC_r( 31 downto 24 );
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-- Target Hardware Address bytes 5 and 4
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when "01011" =>
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nextWrData <= MAC_r( 7 downto 0 ) & MAC_r( 15 downto 8 );
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-- Target IP Address bytes 1 and 0
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when "01100" =>
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nextWrData <= IP_r( 23 downto 16 ) & IP_r (31 downto 24);
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-- Target IP Address bytes 3 and 2
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when "01101" =>
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nextWrData <= IP_r( 7 downto 0 ) & IP_r (15 downto 8);
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when others => null;
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end case;
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-- store the ARP reply for the Ethernet sender
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344 |
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when stStoreARPReply =>
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if wr_re_in = '1' then
|
347 |
|
|
if cnt = "01101" then
|
348 |
|
|
nextState <= stIdle;
|
349 |
|
|
else
|
350 |
|
|
nextState <= stGenARPReply;
|
351 |
|
|
incCnt <= '1';
|
352 |
|
|
end if;
|
353 |
|
|
|
354 |
|
|
else
|
355 |
|
|
nextState <= stStoreARPReply;
|
356 |
|
|
end if;
|
357 |
|
|
|
358 |
|
|
|
359 |
|
|
-----------------------------------------------------------------------------------
|
360 |
|
|
-- handle frames passed on to us from the Internet layer
|
361 |
|
|
-- check to the see if the desired IP is in the ARP table
|
362 |
|
|
when stCheckARPEntry =>
|
363 |
|
|
nextState <= stCheckARPEntry2;
|
364 |
|
|
lookup_IP_out <= IP_r;
|
365 |
|
|
|
366 |
|
|
-- check to see if the ARP entry is valid
|
367 |
|
|
when stCheckARPEntry2 =>
|
368 |
|
|
lookup_IP_out <= IP_r;
|
369 |
|
|
-- if it's not a valid ARP entry, then generate an ARP request to find the
|
370 |
|
|
-- desired MAC address
|
371 |
|
|
if ARP_entry_valid_in = '0' then
|
372 |
|
|
nextState <= stGenArpRequest;
|
373 |
|
|
start_tx <= '1';
|
374 |
|
|
-- otherwise pass the MAC to the UDP/IP block
|
375 |
|
|
else
|
376 |
|
|
nextState <= stGiveMAC;
|
377 |
|
|
latchTargetMAC <= '1';
|
378 |
|
|
end if;
|
379 |
|
|
|
380 |
|
|
-- create each byte of the ARP request according to cnt
|
381 |
|
|
when stGenARPRequest =>
|
382 |
|
|
|
383 |
|
|
wr_data_valid <= '1';
|
384 |
|
|
nextState <= stStoreARPRequest;
|
385 |
|
|
case cnt is
|
386 |
|
|
|
387 |
|
|
|
388 |
|
|
-- Hardware type
|
389 |
|
|
when "00000" =>
|
390 |
|
|
nextWrData <= x"0100"; -- remember, it's x"LSByte MSByte"
|
391 |
|
|
|
392 |
|
|
-- Protocol type
|
393 |
|
|
when "00001" =>
|
394 |
|
|
nextWrData <= x"0008";
|
395 |
|
|
|
396 |
|
|
-- Hardware and protocol Address lengths in bytes (x"PAL HAL")
|
397 |
|
|
when "00010" =>
|
398 |
|
|
nextWrData <= x"0406";
|
399 |
|
|
|
400 |
|
|
-- Operation
|
401 |
|
|
when "00011" =>
|
402 |
|
|
nextWrData <= x"0100";
|
403 |
|
|
|
404 |
|
|
-- Sender Hardware Address bytes 1 and 0
|
405 |
|
|
when "00100" =>
|
406 |
|
|
nextWrData <= MAC_addr_c( 39 downto 32 ) & MAC_addr_c (47 downto 40);
|
407 |
|
|
|
408 |
|
|
-- Sender Hardware Address bytes 3 and 2
|
409 |
|
|
when "00101" =>
|
410 |
|
|
nextWrData <= MAC_addr_c( 23 downto 16 ) & MAC_addr_c (31 downto 24);
|
411 |
|
|
|
412 |
|
|
-- Sender Hardware Address bytes 5 and 4
|
413 |
|
|
when "00110" =>
|
414 |
|
|
nextWrData <= MAC_addr_c( 7 downto 0 ) & MAC_addr_c (15 downto 8);
|
415 |
|
|
|
416 |
|
|
-- Sender IP Address bytes 1 and 0
|
417 |
|
|
when "00111" =>
|
418 |
|
|
nextWrData <= own_IP_c( 23 downto 16 ) & own_IP_c (31 downto 24);
|
419 |
|
|
|
420 |
|
|
-- Sender IP Address bytes 3 and 2
|
421 |
|
|
when "01000" =>
|
422 |
|
|
nextWrData <= own_IP_c( 7 downto 0 ) & own_IP_c (15 downto 8);
|
423 |
|
|
|
424 |
|
|
-- Target Hardware Address bytes 1 and 0
|
425 |
|
|
when "01001" =>
|
426 |
|
|
nextWrData <= (others => '0');
|
427 |
|
|
|
428 |
|
|
-- Target Hardware Address bytes 3 and 2
|
429 |
|
|
when "01010" =>
|
430 |
|
|
nextWrData <= (others => '0');
|
431 |
|
|
|
432 |
|
|
-- Target Hardware Address bytes 5 and 4
|
433 |
|
|
when "01011" =>
|
434 |
|
|
nextWrData <= (others => '0');
|
435 |
|
|
|
436 |
|
|
-- Target IP Address bytes 1 and 0
|
437 |
|
|
when "01100" =>
|
438 |
|
|
nextWrData <= IP_r( 23 downto 16 ) & IP_r (31 downto 24);
|
439 |
|
|
|
440 |
|
|
-- Target IP Address bytes 3 and 2
|
441 |
|
|
when "01101" =>
|
442 |
|
|
nextWrData <= IP_r( 7 downto 0 ) & IP_r (15 downto 8);
|
443 |
|
|
|
444 |
|
|
when others => null;
|
445 |
|
|
end case;
|
446 |
|
|
|
447 |
|
|
-- store the ARP reply for the Ethernet sender
|
448 |
|
|
when stStoreARPRequest =>
|
449 |
|
|
|
450 |
|
|
if wr_re_in = '1' then
|
451 |
|
|
if cnt = "01101" then
|
452 |
|
|
nextState <= stWaitForValidEntry;
|
453 |
|
|
rstARPCnt <= '1';
|
454 |
|
|
else
|
455 |
|
|
nextState <= stGenARPRequest;
|
456 |
|
|
incCnt <= '1';
|
457 |
|
|
end if;
|
458 |
|
|
|
459 |
|
|
else
|
460 |
|
|
nextState <= stStoreARPRequest;
|
461 |
|
|
end if;
|
462 |
|
|
|
463 |
|
|
|
464 |
|
|
-- wait for the ARP entry to become valid
|
465 |
|
|
when stWaitForValidEntry =>
|
466 |
|
|
-- if the ARP entry becomes valid then we fire off the reply
|
467 |
|
|
if ARP_entry_valid_in = '1' then
|
468 |
|
|
tx_ready_out <= '1';
|
469 |
|
|
nextState <= stGiveMAC;
|
470 |
|
|
latchTargetMAC <= '1';
|
471 |
|
|
|
472 |
|
|
-- otherwise give a certain amount of time for the ARP reply to come
|
473 |
|
|
-- back in (21.5 secs on a 50MHz clock)
|
474 |
|
|
else
|
475 |
|
|
-- if the reply doesn't come back, then inform the above layer that the
|
476 |
|
|
-- frame was sent. Assume the higher level protocol can account for this
|
477 |
|
|
-- problem, or possibly an error signal could be created once a higher level
|
478 |
|
|
-- protocol has been written that can accomodate this
|
479 |
|
|
if ARP_cnt_overflow_r = '1' then
|
480 |
|
|
nextState <= stIdle;
|
481 |
|
|
else
|
482 |
|
|
nextState <= stWaitForValidEntry;
|
483 |
|
|
end if;
|
484 |
|
|
end if;
|
485 |
|
|
lookup_IP_out <= IP_r;
|
486 |
|
|
|
487 |
|
|
|
488 |
|
|
when stGiveMAC =>
|
489 |
|
|
|
490 |
|
|
MAC_to_output <= '1';
|
491 |
|
|
nextState <= stIdle;
|
492 |
|
|
|
493 |
|
|
when others => nextState <= stIdle;
|
494 |
|
|
end case;
|
495 |
|
|
end process;
|
496 |
|
|
|
497 |
|
|
end ARPSnd_arch;
|