/*

Copyright (c) 2014-2018 Alex Forencich

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

*/

// Language: Verilog 2001

`timescale 1ns / 1ps

/*
 * FPGA core logic
 */
module ethernet_core #
(
    parameter TARGET = "GENERIC",
    parameter LOCAL_MAC   = 48'h02_00_00_00_00_00,
    parameter LOCAL_IP    = {8'd192, 8'd168, 8'd1,   8'd128},
    parameter GATEWAY_IP  = {8'd192, 8'd168, 8'd1,   8'd1},
    parameter SUBNET_MASK = {8'd255, 8'd255, 8'd255, 8'd0}
)
(
    /*
     * Clock: 125MHz
     * Synchronous reset
     */
    input  wire       clk,
    input  wire       rst,

    /*
     * Ethernet: 100BASE-T MII
     */
    input  wire       phy_rx_clk,
    input  wire [3:0] phy_rxd,
    input  wire       phy_rx_dv,
    input  wire       phy_rx_er,
    input  wire       phy_tx_clk,
    output wire [3:0] phy_txd,
    output wire       phy_tx_en,
    output wire       phy_reset_n,
    
    /*
     * AXIS Interface
     */
         
    output wire [7:0] rx_udp_payload_axis_tdata,
    output wire rx_udp_payload_axis_tvalid,
    input  wire rx_udp_payload_axis_tready,
    output wire rx_udp_payload_axis_tlast,
    output wire rx_udp_payload_axis_tuser,

    input  wire [7:0] tx_udp_payload_axis_tdata,
    input  wire tx_udp_payload_axis_tvalid,
    output wire tx_udp_payload_axis_tready,
    input  wire tx_udp_payload_axis_tlast,
    input  wire tx_udp_payload_axis_tuser
);

// AXI between MAC and Ethernet modules
wire [7:0] rx_axis_tdata;
wire rx_axis_tvalid;
wire rx_axis_tready;
wire rx_axis_tlast;
wire rx_axis_tuser;

wire [7:0] tx_axis_tdata;
wire tx_axis_tvalid;
wire tx_axis_tready;
wire tx_axis_tlast;
wire tx_axis_tuser;

// Ethernet frame between Ethernet modules and UDP stack
wire rx_eth_hdr_ready;
wire rx_eth_hdr_valid;
wire [47:0] rx_eth_dest_mac;
wire [47:0] rx_eth_src_mac;
wire [15:0] rx_eth_type;
wire [7:0] rx_eth_payload_axis_tdata;
wire rx_eth_payload_axis_tvalid;
wire rx_eth_payload_axis_tready;
wire rx_eth_payload_axis_tlast;
wire rx_eth_payload_axis_tuser;

wire tx_eth_hdr_ready;
wire tx_eth_hdr_valid;
wire [47:0] tx_eth_dest_mac;
wire [47:0] tx_eth_src_mac;
wire [15:0] tx_eth_type;
wire [7:0] tx_eth_payload_axis_tdata;
wire tx_eth_payload_axis_tvalid;
wire tx_eth_payload_axis_tready;
wire tx_eth_payload_axis_tlast;
wire tx_eth_payload_axis_tuser;

// IP frame connections
wire rx_ip_hdr_valid;
wire rx_ip_hdr_ready;
wire [47:0] rx_ip_eth_dest_mac;
wire [47:0] rx_ip_eth_src_mac;
wire [15:0] rx_ip_eth_type;
wire [3:0] rx_ip_version;
wire [3:0] rx_ip_ihl;
wire [5:0] rx_ip_dscp;
wire [1:0] rx_ip_ecn;
wire [15:0] rx_ip_length;
wire [15:0] rx_ip_identification;
wire [2:0] rx_ip_flags;
wire [12:0] rx_ip_fragment_offset;
wire [7:0] rx_ip_ttl;
wire [7:0] rx_ip_protocol;
wire [15:0] rx_ip_header_checksum;
wire [31:0] rx_ip_source_ip;
wire [31:0] rx_ip_dest_ip;
wire [7:0] rx_ip_payload_axis_tdata;
wire rx_ip_payload_axis_tvalid;
wire rx_ip_payload_axis_tready;
wire rx_ip_payload_axis_tlast;
wire rx_ip_payload_axis_tuser;

wire tx_ip_hdr_valid;
wire tx_ip_hdr_ready;
wire [5:0] tx_ip_dscp;
wire [1:0] tx_ip_ecn;
wire [15:0] tx_ip_length;
wire [7:0] tx_ip_ttl;
wire [7:0] tx_ip_protocol;
wire [31:0] tx_ip_source_ip;
wire [31:0] tx_ip_dest_ip;
wire [7:0] tx_ip_payload_axis_tdata;
wire tx_ip_payload_axis_tvalid;
wire tx_ip_payload_axis_tready;
wire tx_ip_payload_axis_tlast;
wire tx_ip_payload_axis_tuser;

// UDP frame connections
wire rx_udp_hdr_valid;
wire rx_udp_hdr_ready;
wire [47:0] rx_udp_eth_dest_mac;
wire [47:0] rx_udp_eth_src_mac;
wire [15:0] rx_udp_eth_type;
wire [3:0] rx_udp_ip_version;
wire [3:0] rx_udp_ip_ihl;
wire [5:0] rx_udp_ip_dscp;
wire [1:0] rx_udp_ip_ecn;
wire [15:0] rx_udp_ip_length;
wire [15:0] rx_udp_ip_identification;
wire [2:0] rx_udp_ip_flags;
wire [12:0] rx_udp_ip_fragment_offset;
wire [7:0] rx_udp_ip_ttl;
wire [7:0] rx_udp_ip_protocol;
wire [15:0] rx_udp_ip_header_checksum;
wire [31:0] rx_udp_ip_source_ip;
wire [31:0] rx_udp_ip_dest_ip;
wire [15:0] rx_udp_source_port;
wire [15:0] rx_udp_dest_port;
wire [15:0] rx_udp_length;
wire [15:0] rx_udp_checksum;

wire tx_udp_hdr_valid;
wire tx_udp_hdr_ready;
wire [5:0] tx_udp_ip_dscp;
wire [1:0] tx_udp_ip_ecn;
wire [7:0] tx_udp_ip_ttl;
wire [31:0] tx_udp_ip_source_ip;
wire [31:0] tx_udp_ip_dest_ip;
wire [15:0] tx_udp_source_port;
wire [15:0] tx_udp_dest_port;
wire [15:0] tx_udp_length;
wire [15:0] tx_udp_checksum;

wire [7:0] rx_fifo_udp_payload_axis_tdata;
wire rx_fifo_udp_payload_axis_tvalid;
wire rx_fifo_udp_payload_axis_tready;
wire rx_fifo_udp_payload_axis_tlast;
wire rx_fifo_udp_payload_axis_tuser;

wire [7:0] tx_fifo_udp_payload_axis_tdata;
wire tx_fifo_udp_payload_axis_tvalid;
wire tx_fifo_udp_payload_axis_tready;
wire tx_fifo_udp_payload_axis_tlast;
wire tx_fifo_udp_payload_axis_tuser;

// IP ports not used
assign rx_ip_hdr_ready = 1;
assign rx_ip_payload_axis_tready = 1;

assign tx_ip_hdr_valid = 0;
assign tx_ip_dscp = 0;
assign tx_ip_ecn = 0;
assign tx_ip_length = 0;
assign tx_ip_ttl = 0;
assign tx_ip_protocol = 0;
assign tx_ip_source_ip = 0;
assign tx_ip_dest_ip = 0;
assign tx_ip_payload_axis_tdata = 0;
assign tx_ip_payload_axis_tvalid = 0;
assign tx_ip_payload_axis_tlast = 0;
assign tx_ip_payload_axis_tuser = 0;

// Loop back UDP
wire match_cond = rx_udp_dest_port == 1234;
wire no_match = !match_cond;

reg match_cond_reg;
reg no_match_reg;

always @(posedge clk) begin
    if (rst) begin
        match_cond_reg <= 0;
        no_match_reg <= 0;
    end else begin
        if (rx_udp_payload_axis_tvalid) begin
            if ((!match_cond_reg && !no_match_reg) ||
                (rx_udp_payload_axis_tvalid && rx_udp_payload_axis_tready && rx_udp_payload_axis_tlast)) begin
                match_cond_reg <= match_cond;
                no_match_reg <= no_match;
            end
        end else begin
            match_cond_reg <= 0;
            no_match_reg <= 0;
        end
    end
end

assign tx_udp_hdr_valid = rx_udp_hdr_valid && match_cond;
assign rx_udp_hdr_ready = (tx_eth_hdr_ready && match_cond) || no_match;
assign tx_udp_ip_dscp = 0;
assign tx_udp_ip_ecn = 0;
assign tx_udp_ip_ttl = 64;
assign tx_udp_ip_source_ip = LOCAL_IP;
assign tx_udp_ip_dest_ip = rx_udp_ip_source_ip;
assign tx_udp_source_port = rx_udp_dest_port;
assign tx_udp_dest_port = rx_udp_source_port;
assign tx_udp_length = rx_udp_length;
assign tx_udp_checksum = 0;

assign phy_reset_n = !rst;

eth_mac_mii_fifo #(
    .TARGET(TARGET),
    .CLOCK_INPUT_STYLE("BUFR"),
    .ENABLE_PADDING(1),
    .MIN_FRAME_LENGTH(64),
    .TX_FIFO_DEPTH(8),
    .TX_FRAME_FIFO(0),
    .RX_FIFO_DEPTH(8),
    .RX_FRAME_FIFO(0)
)
eth_mac_inst (
    .rst(rst),
    .logic_clk(clk),
    .logic_rst(rst),

    .tx_axis_tdata(tx_axis_tdata),
    .tx_axis_tvalid(tx_axis_tvalid),
    .tx_axis_tready(tx_axis_tready),
    .tx_axis_tlast(tx_axis_tlast),
    .tx_axis_tuser(tx_axis_tuser),

    .rx_axis_tdata(rx_axis_tdata),
    .rx_axis_tvalid(rx_axis_tvalid),
    .rx_axis_tready(rx_axis_tready),
    .rx_axis_tlast(rx_axis_tlast),
    .rx_axis_tuser(rx_axis_tuser),

    .mii_rx_clk(phy_rx_clk),
    .mii_rxd(phy_rxd),
    .mii_rx_dv(phy_rx_dv),
    .mii_rx_er(phy_rx_er),
    .mii_tx_clk(phy_tx_clk),
    .mii_txd(phy_txd),
    .mii_tx_en(phy_tx_en),
    .mii_tx_er(),

    .tx_fifo_overflow(),
    .tx_fifo_bad_frame(),
    .tx_fifo_good_frame(),
    .rx_error_bad_frame(),
    .rx_error_bad_fcs(),
    .rx_fifo_overflow(),
    .rx_fifo_bad_frame(),
    .rx_fifo_good_frame(),

    .ifg_delay(12)
);

eth_axis_rx
eth_axis_rx_inst (
    .clk(clk),
    .rst(rst),
    // AXI input
    .s_axis_tdata(rx_axis_tdata),
    .s_axis_tvalid(rx_axis_tvalid),
    .s_axis_tready(rx_axis_tready),
    .s_axis_tlast(rx_axis_tlast),
    .s_axis_tuser(rx_axis_tuser),
    // Ethernet frame output
    .m_eth_hdr_valid(rx_eth_hdr_valid),
    .m_eth_hdr_ready(rx_eth_hdr_ready),
    .m_eth_dest_mac(rx_eth_dest_mac),
    .m_eth_src_mac(rx_eth_src_mac),
    .m_eth_type(rx_eth_type),
    .m_eth_payload_axis_tdata(rx_eth_payload_axis_tdata),
    .m_eth_payload_axis_tvalid(rx_eth_payload_axis_tvalid),
    .m_eth_payload_axis_tready(rx_eth_payload_axis_tready),
    .m_eth_payload_axis_tlast(rx_eth_payload_axis_tlast),
    .m_eth_payload_axis_tuser(rx_eth_payload_axis_tuser),
    // Status signals
    .busy(),
    .error_header_early_termination()
);

eth_axis_tx
eth_axis_tx_inst (
    .clk(clk),
    .rst(rst),
    // Ethernet frame input
    .s_eth_hdr_valid(tx_eth_hdr_valid),
    .s_eth_hdr_ready(tx_eth_hdr_ready),
    .s_eth_dest_mac(tx_eth_dest_mac),
    .s_eth_src_mac(tx_eth_src_mac),
    .s_eth_type(tx_eth_type),
    .s_eth_payload_axis_tdata(tx_eth_payload_axis_tdata),
    .s_eth_payload_axis_tvalid(tx_eth_payload_axis_tvalid),
    .s_eth_payload_axis_tready(tx_eth_payload_axis_tready),
    .s_eth_payload_axis_tlast(tx_eth_payload_axis_tlast),
    .s_eth_payload_axis_tuser(tx_eth_payload_axis_tuser),
    // AXI output
    .m_axis_tdata(tx_axis_tdata),
    .m_axis_tvalid(tx_axis_tvalid),
    .m_axis_tready(tx_axis_tready),
    .m_axis_tlast(tx_axis_tlast),
    .m_axis_tuser(tx_axis_tuser),
    // Status signals
    .busy()
);

udp_complete #(
    .UDP_CHECKSUM_GEN_ENABLE(0),
    .ARP_CACHE_ADDR_WIDTH(4)
)
udp_complete_inst (
    .clk(clk),
    .rst(rst),
    // Ethernet frame input
    .s_eth_hdr_valid(rx_eth_hdr_valid),
    .s_eth_hdr_ready(rx_eth_hdr_ready),
    .s_eth_dest_mac(rx_eth_dest_mac),
    .s_eth_src_mac(rx_eth_src_mac),
    .s_eth_type(rx_eth_type),
    .s_eth_payload_axis_tdata(rx_eth_payload_axis_tdata),
    .s_eth_payload_axis_tvalid(rx_eth_payload_axis_tvalid),
    .s_eth_payload_axis_tready(rx_eth_payload_axis_tready),
    .s_eth_payload_axis_tlast(rx_eth_payload_axis_tlast),
    .s_eth_payload_axis_tuser(rx_eth_payload_axis_tuser),
    // Ethernet frame output
    .m_eth_hdr_valid(tx_eth_hdr_valid),
    .m_eth_hdr_ready(tx_eth_hdr_ready),
    .m_eth_dest_mac(tx_eth_dest_mac),
    .m_eth_src_mac(tx_eth_src_mac),
    .m_eth_type(tx_eth_type),
    .m_eth_payload_axis_tdata(tx_eth_payload_axis_tdata),
    .m_eth_payload_axis_tvalid(tx_eth_payload_axis_tvalid),
    .m_eth_payload_axis_tready(tx_eth_payload_axis_tready),
    .m_eth_payload_axis_tlast(tx_eth_payload_axis_tlast),
    .m_eth_payload_axis_tuser(tx_eth_payload_axis_tuser),
    // IP frame input
    .s_ip_hdr_valid(tx_ip_hdr_valid),
    .s_ip_hdr_ready(tx_ip_hdr_ready),
    .s_ip_dscp(tx_ip_dscp),
    .s_ip_ecn(tx_ip_ecn),
    .s_ip_length(tx_ip_length),
    .s_ip_ttl(tx_ip_ttl),
    .s_ip_protocol(tx_ip_protocol),
    .s_ip_source_ip(tx_ip_source_ip),
    .s_ip_dest_ip(tx_ip_dest_ip),
    .s_ip_payload_axis_tdata(tx_ip_payload_axis_tdata),
    .s_ip_payload_axis_tvalid(tx_ip_payload_axis_tvalid),
    .s_ip_payload_axis_tready(tx_ip_payload_axis_tready),
    .s_ip_payload_axis_tlast(tx_ip_payload_axis_tlast),
    .s_ip_payload_axis_tuser(tx_ip_payload_axis_tuser),
    // IP frame output
    .m_ip_hdr_valid(rx_ip_hdr_valid),
    .m_ip_hdr_ready(rx_ip_hdr_ready),
    .m_ip_eth_dest_mac(rx_ip_eth_dest_mac),
    .m_ip_eth_src_mac(rx_ip_eth_src_mac),
    .m_ip_eth_type(rx_ip_eth_type),
    .m_ip_version(rx_ip_version),
    .m_ip_ihl(rx_ip_ihl),
    .m_ip_dscp(rx_ip_dscp),
    .m_ip_ecn(rx_ip_ecn),
    .m_ip_length(rx_ip_length),
    .m_ip_identification(rx_ip_identification),
    .m_ip_flags(rx_ip_flags),
    .m_ip_fragment_offset(rx_ip_fragment_offset),
    .m_ip_ttl(rx_ip_ttl),
    .m_ip_protocol(rx_ip_protocol),
    .m_ip_header_checksum(rx_ip_header_checksum),
    .m_ip_source_ip(rx_ip_source_ip),
    .m_ip_dest_ip(rx_ip_dest_ip),
    .m_ip_payload_axis_tdata(rx_ip_payload_axis_tdata),
    .m_ip_payload_axis_tvalid(rx_ip_payload_axis_tvalid),
    .m_ip_payload_axis_tready(rx_ip_payload_axis_tready),
    .m_ip_payload_axis_tlast(rx_ip_payload_axis_tlast),
    .m_ip_payload_axis_tuser(rx_ip_payload_axis_tuser),
    // UDP frame input
    .s_udp_hdr_valid(tx_udp_hdr_valid),
    .s_udp_hdr_ready(tx_udp_hdr_ready),
    .s_udp_ip_dscp(tx_udp_ip_dscp),
    .s_udp_ip_ecn(tx_udp_ip_ecn),
    .s_udp_ip_ttl(tx_udp_ip_ttl),
    .s_udp_ip_source_ip(tx_udp_ip_source_ip),
    .s_udp_ip_dest_ip(tx_udp_ip_dest_ip),
    .s_udp_source_port(tx_udp_source_port),
    .s_udp_dest_port(tx_udp_dest_port),
    .s_udp_length(tx_udp_length),
    .s_udp_checksum(tx_udp_checksum),
    .s_udp_payload_axis_tdata(tx_udp_payload_axis_tdata),
    .s_udp_payload_axis_tvalid(tx_udp_payload_axis_tvalid),
    .s_udp_payload_axis_tready(tx_udp_payload_axis_tready),
    .s_udp_payload_axis_tlast(tx_udp_payload_axis_tlast),
    .s_udp_payload_axis_tuser(tx_udp_payload_axis_tuser),
    // UDP frame output
    .m_udp_hdr_valid(rx_udp_hdr_valid),
    .m_udp_hdr_ready(rx_udp_hdr_ready),
    .m_udp_eth_dest_mac(rx_udp_eth_dest_mac),
    .m_udp_eth_src_mac(rx_udp_eth_src_mac),
    .m_udp_eth_type(rx_udp_eth_type),
    .m_udp_ip_version(rx_udp_ip_version),
    .m_udp_ip_ihl(rx_udp_ip_ihl),
    .m_udp_ip_dscp(rx_udp_ip_dscp),
    .m_udp_ip_ecn(rx_udp_ip_ecn),
    .m_udp_ip_length(rx_udp_ip_length),
    .m_udp_ip_identification(rx_udp_ip_identification),
    .m_udp_ip_flags(rx_udp_ip_flags),
    .m_udp_ip_fragment_offset(rx_udp_ip_fragment_offset),
    .m_udp_ip_ttl(rx_udp_ip_ttl),
    .m_udp_ip_protocol(rx_udp_ip_protocol),
    .m_udp_ip_header_checksum(rx_udp_ip_header_checksum),
    .m_udp_ip_source_ip(rx_udp_ip_source_ip),
    .m_udp_ip_dest_ip(rx_udp_ip_dest_ip),
    .m_udp_source_port(rx_udp_source_port),
    .m_udp_dest_port(rx_udp_dest_port),
    .m_udp_length(rx_udp_length),
    .m_udp_checksum(rx_udp_checksum),
    .m_udp_payload_axis_tdata(rx_udp_payload_axis_tdata),
    .m_udp_payload_axis_tvalid(rx_udp_payload_axis_tvalid),
    .m_udp_payload_axis_tready(rx_udp_payload_axis_tready),
    .m_udp_payload_axis_tlast(rx_udp_payload_axis_tlast),
    .m_udp_payload_axis_tuser(rx_udp_payload_axis_tuser),
    // Status signals
    .ip_rx_busy(),
    .ip_tx_busy(),
    .udp_rx_busy(),
    .udp_tx_busy(),
    .ip_rx_error_header_early_termination(),
    .ip_rx_error_payload_early_termination(),
    .ip_rx_error_invalid_header(),
    .ip_rx_error_invalid_checksum(),
    .ip_tx_error_payload_early_termination(),
    .ip_tx_error_arp_failed(),
    .udp_rx_error_header_early_termination(),
    .udp_rx_error_payload_early_termination(),
    .udp_tx_error_payload_early_termination(),
    // Configuration
    .local_mac(LOCAL_MAC),
    .local_ip(LOCAL_IP),
    .gateway_ip(GATEWAY_IP),
    .subnet_mask(SUBNET_MASK),
    .clear_arp_cache(0)
);

endmodule