module fpga_core
(
    /*
     * Clock: 125MHz
     * Synchronous reset
     */
    input  wire       clk,
    input  wire       rst,

    /*
     * GPIO
     */
    input  wire       btnu,
    input  wire       btnl,
    input  wire       btnd,
    input  wire       btnr,
    input  wire       btnc,
    input  wire [3:0] sw,
    output wire [7:0] led,

    /*
     * Ethernet: 1000BASE-T SGMII
     */
    input  wire       phy_gmii_clk,
    input  wire       phy_gmii_rst,
    input  wire       phy_gmii_clk_en,
    input  wire [7:0] phy_gmii_rxd,
    input  wire       phy_gmii_rx_dv,
    input  wire       phy_gmii_rx_er,
    output wire [7:0] phy_gmii_txd,
    output wire       phy_gmii_tx_en,
    output wire       phy_gmii_tx_er,
    output wire       phy_reset_n,
    input  wire       phy_int_n,

    /*
     * UART: 115200 bps, 8N1
     */
    input  wire       uart_rxd,
    output wire       uart_txd,
    output wire       uart_rts,
    input  wire       uart_cts
);

// 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 [7:0] rx_udp_payload_axis_tdata;
wire rx_udp_payload_axis_tvalid;
wire rx_udp_payload_axis_tready;
wire rx_udp_payload_axis_tlast;
wire rx_udp_payload_axis_tuser;

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] tx_udp_payload_axis_tdata;
wire tx_udp_payload_axis_tvalid;
wire tx_udp_payload_axis_tready;
wire tx_udp_payload_axis_tlast;
wire tx_udp_payload_axis_tuser;

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;

// Configuration
wire [47:0] local_mac   = 48'h02_00_00_00_00_00;
wire [31:0] local_ip    = {8'd192, 8'd168, 8'd1,   8'd128};
wire [31:0] gateway_ip  = {8'd192, 8'd168, 8'd1,   8'd1};
wire [31:0] subnet_mask = {8'd255, 8'd255, 8'd255, 8'd0};

// 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 = 0;
reg no_match_reg = 0;

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 tx_udp_payload_axis_tdata = tx_fifo_udp_payload_axis_tdata;
assign tx_udp_payload_axis_tvalid = tx_fifo_udp_payload_axis_tvalid;
assign tx_fifo_udp_payload_axis_tready = tx_udp_payload_axis_tready;
assign tx_udp_payload_axis_tlast = tx_fifo_udp_payload_axis_tlast;
assign tx_udp_payload_axis_tuser = tx_fifo_udp_payload_axis_tuser;

assign rx_fifo_udp_payload_axis_tdata = rx_udp_payload_axis_tdata;
assign rx_fifo_udp_payload_axis_tvalid = rx_udp_payload_axis_tvalid && match_cond_reg;
assign rx_udp_payload_axis_tready = (rx_fifo_udp_payload_axis_tready && match_cond_reg) || no_match_reg;
assign rx_fifo_udp_payload_axis_tlast = rx_udp_payload_axis_tlast;
assign rx_fifo_udp_payload_axis_tuser = rx_udp_payload_axis_tuser;

// Place first payload byte onto LEDs
reg valid_last = 0;
reg [7:0] led_reg = 0;

always @(posedge clk) begin
    if (rst) begin
        led_reg <= 0;
    end else begin
        if (tx_udp_payload_axis_tvalid) begin
            if (!valid_last) begin
                led_reg <= tx_udp_payload_axis_tdata;
                valid_last <= 1'b1;
            end
            if (tx_udp_payload_axis_tlast) begin
                valid_last <= 1'b0;
            end
        end
    end
end

//assign led = sw;
assign led = led_reg;
assign phy_reset_n = !rst;

assign uart_txd = 0;
assign uart_rts = 0;

eth_mac_1g_fifo #(
    .ENABLE_PADDING(1),
    .MIN_FRAME_LENGTH(64),
    .TX_FIFO_DEPTH(4096),
    .TX_FRAME_FIFO(1),
    .RX_FIFO_DEPTH(4096),
    .RX_FRAME_FIFO(1)
)
eth_mac_inst (
    .rx_clk(phy_gmii_clk),
    .rx_rst(phy_gmii_rst),
    .tx_clk(phy_gmii_clk),
    .tx_rst(phy_gmii_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),

    .gmii_rxd(phy_gmii_rxd),
    .gmii_rx_dv(phy_gmii_rx_dv),
    .gmii_rx_er(phy_gmii_rx_er),
    .gmii_txd(phy_gmii_txd),
    .gmii_tx_en(phy_gmii_tx_en),
    .gmii_tx_er(phy_gmii_tx_er),

    .rx_clk_enable(phy_gmii_clk_en),
    .tx_clk_enable(phy_gmii_clk_en),
    .rx_mii_select(1'b0),
    .tx_mii_select(1'b0),

    .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_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)
);

axis_fifo #(
    .DEPTH(8192),
    .DATA_WIDTH(8),
    .KEEP_ENABLE(0),
    .ID_ENABLE(0),
    .DEST_ENABLE(0),
    .USER_ENABLE(1),
    .USER_WIDTH(1),
    .FRAME_FIFO(0)
)
udp_payload_fifo (
    .clk(clk),
    .rst(rst),

    // AXI input
    .s_axis_tdata(rx_fifo_udp_payload_axis_tdata),
    .s_axis_tkeep(0),
    .s_axis_tvalid(rx_fifo_udp_payload_axis_tvalid),
    .s_axis_tready(rx_fifo_udp_payload_axis_tready),
    .s_axis_tlast(rx_fifo_udp_payload_axis_tlast),
    .s_axis_tid(0),
    .s_axis_tdest(0),
    .s_axis_tuser(rx_fifo_udp_payload_axis_tuser),

    // AXI output
    .m_axis_tdata(tx_fifo_udp_payload_axis_tdata),
    .m_axis_tkeep(),
    .m_axis_tvalid(tx_fifo_udp_payload_axis_tvalid),
    .m_axis_tready(tx_fifo_udp_payload_axis_tready),
    .m_axis_tlast(tx_fifo_udp_payload_axis_tlast),
    .m_axis_tid(),
    .m_axis_tdest(),
    .m_axis_tuser(tx_fifo_udp_payload_axis_tuser),

    // Status
    .status_overflow(),
    .status_bad_frame(),
    .status_good_frame()
);

endmodule