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--
-- Copyright 2019 Ettus Research, A National Instruments brand
--
-- SPDX-License-Identifier: LGPL-3.0
--
-- Module: arp_responder
-- Description: Processing IP to send replies for ARP frames (for IPv4)
-- arp_responder checks the incoming ARP frame against the input port ip_addr,
-- and if the frame is a request for this module's ip_addr, the module will
-- format an ARP reply and send it on the outgoing AXI-S interface.
--
-- mac_addr and ip_addr must be kept stable for this module to function. They
-- are not registered within the IP.
--
-- s_axis_tuser indicates there is an error in the packet, and it should be discarded
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity arp_responder is
port (
aclk : in std_logic;
aresetn : in std_logic;
mac_addr : in std_logic_vector(47 downto 0);
ip_addr : in std_logic_vector(31 downto 0);
s_axis_tdata : in std_logic_vector(63 downto 0);
s_axis_tvalid : in std_logic;
s_axis_tready : out std_logic;
s_axis_tkeep : in std_logic_vector(7 downto 0);
s_axis_tlast : in std_logic;
s_axis_tuser : in std_logic;
m_axis_tdata : out std_logic_vector(63 downto 0);
m_axis_tvalid : out std_logic;
m_axis_tready : in std_logic;
m_axis_tkeep : out std_logic_vector(7 downto 0);
m_axis_tlast : out std_logic;
m_axis_tuser : out std_logic
);
end arp_responder;
architecture arch of arp_responder is
type pkt_state_t is (PKT_IDLE, PKT_RECV, PKT_SEND, PKT_DROP);
signal pkt_state : pkt_state_t;
signal pkt_recv_count : unsigned(3 downto 0);
signal pkt_send_count : unsigned(3 downto 0);
--All of these are LSB-0 for bits, but first byte transmitted is byte 0
-- In ChipScope, bytes will appear swapped versus typical diagrams
signal src_mac_be : std_logic_vector(47 downto 0);
signal sender_hw_addr_be : std_logic_vector(47 downto 0);
signal sender_protocol_addr_be : std_logic_vector(31 downto 0);
signal target_protocol_addr_be : std_logic_vector(31 downto 0);
signal ip_addr_be : std_logic_vector(31 downto 0);
begin
m_axis_tuser <= '0';
m_axis_tvalid <= '1' when (pkt_state = PKT_SEND) else '0';
ip_addr_be <= ip_addr(7 downto 0) & ip_addr(15 downto 8) &
ip_addr(23 downto 16) & ip_addr(31 downto 24);
s_axis_tready <= '1' when (pkt_state = PKT_IDLE) or (pkt_state = PKT_RECV) or (pkt_state = PKT_DROP)
else '0';
tx_reply : process (src_mac_be, mac_addr, ip_addr, sender_hw_addr_be,
sender_protocol_addr_be, pkt_send_count)
begin
m_axis_tdata <= (others => 'X');
m_axis_tkeep <= (others => '1');
m_axis_tlast <= '0';
case (to_integer(pkt_send_count)) is
when 0 =>
m_axis_tdata(47 downto 0) <= src_mac_be;
m_axis_tdata(63 downto 48) <= mac_addr(39 downto 32) & mac_addr(47 downto 40);
m_axis_tkeep <= X"FF";
m_axis_tlast <= '0';
when 1 =>
m_axis_tdata(31 downto 0) <= mac_addr(7 downto 0) & mac_addr(15 downto 8) &
mac_addr(23 downto 16) & mac_addr(31 downto 24);
m_axis_tdata(47 downto 32) <= X"0608";
m_axis_tdata(63 downto 48) <= X"0100";
m_axis_tkeep <= X"FF";
m_axis_tlast <= '0';
when 2 =>
m_axis_tdata(15 downto 0) <= X"0008"; --PTYPE
m_axis_tdata(23 downto 16) <= X"06"; --HLEN
m_axis_tdata(31 downto 24) <= X"04"; --PLEN
m_axis_tdata(47 downto 32) <= X"0200"; --OPER
m_axis_tdata(63 downto 48) <= mac_addr(39 downto 32) & mac_addr(47 downto 40); --SHA
m_axis_tkeep <= X"FF";
m_axis_tlast <= '0';
when 3 =>
m_axis_tdata(31 downto 0) <= mac_addr(7 downto 0) & mac_addr(15 downto 8) &
mac_addr(23 downto 16) & mac_addr(31 downto 24); --SHA
m_axis_tdata(63 downto 32) <= ip_addr(7 downto 0) & ip_addr(15 downto 8) &
ip_addr(23 downto 16) & ip_addr(31 downto 24); --SPA
m_axis_tkeep <= X"FF";
m_axis_tlast <= '0';
when 4 =>
m_axis_tdata(47 downto 0) <= sender_hw_addr_be; --THA
m_axis_tdata(63 downto 48) <= sender_protocol_addr_be(15 downto 0); --TPA
m_axis_tkeep <= X"FF";
m_axis_tlast <= '0';
when 5 =>
m_axis_tdata(15 downto 0) <= sender_protocol_addr_be(31 downto 16); --TPA
m_axis_tdata(63 downto 16) <= (others => '0');
m_axis_tkeep <= X"03";
m_axis_tlast <= '1';
when others =>
null;
end case;
end process;
process (aclk)
variable pkt_nonmatch : boolean := false;
begin
if rising_edge(aclk) then
case (pkt_state) is
when PKT_IDLE =>
if (s_axis_tvalid = '1') and (s_axis_tlast = '0') and (s_axis_tuser = '0') then
pkt_state <= PKT_RECV;
pkt_recv_count <= to_unsigned(1, pkt_recv_count'length);
src_mac_be(15 downto 0) <= s_axis_tdata(63 downto 48);
end if;
when PKT_RECV =>
pkt_nonmatch := false;
pkt_send_count <= to_unsigned(0, pkt_send_count'length);
if (s_axis_tvalid = '1') and (s_axis_tuser = '1') then
pkt_nonmatch := true;
elsif (s_axis_tvalid = '1') and (s_axis_tuser = '0') then
if (to_integer(pkt_recv_count) < 7) then
pkt_recv_count <= pkt_recv_count + 1;
end if;
case (to_integer(pkt_recv_count)) is
when 1 =>
src_mac_be(47 downto 16) <= s_axis_tdata(31 downto 0);
if (s_axis_tdata(47 downto 32) /= X"0608") or --eth_type
(s_axis_tdata(63 downto 48) /= X"0100") or --HTYPE
(s_axis_tlast = '1') then
pkt_nonmatch := true;
end if;
when 2 =>
sender_hw_addr_be(15 downto 0) <= s_axis_tdata(63 downto 48);
if (s_axis_tdata(15 downto 0) /= X"0008") or --PTYPE
(s_axis_tdata(23 downto 16) /= X"06") or --HLEN
(s_axis_tdata(31 downto 24) /= X"04") or --PLEN
(s_axis_tdata(47 downto 32) /= X"0100") or --OPER
(s_axis_tlast = '1') then
pkt_nonmatch := true;
end if;
when 3 =>
sender_hw_addr_be(47 downto 16) <= s_axis_tdata(31 downto 0);
sender_protocol_addr_be <= s_axis_tdata(63 downto 32);
if (s_axis_tlast = '1') then
pkt_nonmatch := true;
end if;
when 4 =>
--THA = s_axis_tdata(47 downto 0)
target_protocol_addr_be(15 downto 0) <= s_axis_tdata(63 downto 48);
if (s_axis_tdata(63 downto 48) /= ip_addr_be(15 downto 0)) or
(s_axis_tlast = '1') then
pkt_nonmatch := true;
end if;
when 5 =>
target_protocol_addr_be(31 downto 16) <= s_axis_tdata(15 downto 0);
if (s_axis_tdata(15 downto 0) /= ip_addr_be(31 downto 16)) then
pkt_nonmatch := true;
end if;
when others =>
null;
end case;
end if;
if (pkt_nonmatch) then
if (s_axis_tlast = '1') then
pkt_state <= PKT_IDLE;
else
pkt_state <= PKT_DROP;
end if;
elsif (s_axis_tlast = '1') then
pkt_state <= PKT_SEND;
end if;
when PKT_SEND =>
if (m_axis_tready = '1') then
pkt_send_count <= pkt_send_count + 1;
if (pkt_send_count = 5) then
pkt_state <= PKT_IDLE;
end if;
end if;
when PKT_DROP =>
if (s_axis_tvalid = '1') and (s_axis_tlast = '1') then
pkt_state <= PKT_IDLE;
end if;
end case;
if aresetn = '0' then
pkt_state <= PKT_IDLE;
end if;
end if;
end process;
end arch;
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