module eth_mac_mii_fifo #
(
    // target ("SIM", "GENERIC", "XILINX", "ALTERA")
    parameter TARGET = "GENERIC",
    // Clock input style ("BUFG", "BUFR", "BUFIO", "BUFIO2")
    // Use BUFR for Virtex-5, Virtex-6, 7-series
    // Use BUFG for Ultrascale
    // Use BUFIO2 for Spartan-6
    parameter CLOCK_INPUT_STYLE = "BUFIO2",
    parameter AXIS_DATA_WIDTH = 8,
    parameter AXIS_KEEP_ENABLE = (AXIS_DATA_WIDTH>8),
    parameter AXIS_KEEP_WIDTH = (AXIS_DATA_WIDTH/8),
    parameter ENABLE_PADDING = 1,
    parameter MIN_FRAME_LENGTH = 64,
    parameter TX_FIFO_DEPTH = 4096,
    parameter TX_FRAME_FIFO = 1,
    parameter TX_DROP_BAD_FRAME = TX_FRAME_FIFO,
    parameter TX_DROP_WHEN_FULL = 0,
    parameter RX_FIFO_DEPTH = 4096,
    parameter RX_FRAME_FIFO = 1,
    parameter RX_DROP_BAD_FRAME = RX_FRAME_FIFO,
    parameter RX_DROP_WHEN_FULL = RX_FRAME_FIFO
)
(
    input  wire                       rst,
    input  wire                       logic_clk,
    input  wire                       logic_rst,

    /*
     * AXI input
     */
    input  wire [AXIS_DATA_WIDTH-1:0] tx_axis_tdata,
    input  wire [AXIS_KEEP_WIDTH-1:0] tx_axis_tkeep,
    input  wire                       tx_axis_tvalid,
    output wire                       tx_axis_tready,
    input  wire                       tx_axis_tlast,
    input  wire                       tx_axis_tuser,

    /*
     * AXI output
     */
    output wire [AXIS_DATA_WIDTH-1:0] rx_axis_tdata,
    output wire [AXIS_KEEP_WIDTH-1:0] rx_axis_tkeep,
    output wire                       rx_axis_tvalid,
    input  wire                       rx_axis_tready,
    output wire                       rx_axis_tlast,
    output wire                       rx_axis_tuser,

    /*
     * MII interface
     */
    input  wire                       mii_rx_clk,
    input  wire [3:0]                 mii_rxd,
    input  wire                       mii_rx_dv,
    input  wire                       mii_rx_er,
    input  wire                       mii_tx_clk,
    output wire [3:0]                 mii_txd,
    output wire                       mii_tx_en,
    output wire                       mii_tx_er,

    /*
     * Status
     */
    output wire                       tx_error_underflow,
    output wire                       tx_fifo_overflow,
    output wire                       tx_fifo_bad_frame,
    output wire                       tx_fifo_good_frame,
    output wire                       rx_error_bad_frame,
    output wire                       rx_error_bad_fcs,
    output wire                       rx_fifo_overflow,
    output wire                       rx_fifo_bad_frame,
    output wire                       rx_fifo_good_frame,

    /*
     * Configuration
     */
    input  wire [7:0]                 ifg_delay
);

wire tx_clk;
wire rx_clk;
wire tx_rst;
wire rx_rst;

wire [7:0]  tx_fifo_axis_tdata;
wire        tx_fifo_axis_tvalid;
wire        tx_fifo_axis_tready;
wire        tx_fifo_axis_tlast;
wire        tx_fifo_axis_tuser;

wire [7:0]  rx_fifo_axis_tdata;
wire        rx_fifo_axis_tvalid;
wire        rx_fifo_axis_tlast;
wire        rx_fifo_axis_tuser;

// synchronize MAC status signals into logic clock domain
wire tx_error_underflow_int;

reg [0:0] tx_sync_reg_1 = 1'b0;
reg [0:0] tx_sync_reg_2 = 1'b0;
reg [0:0] tx_sync_reg_3 = 1'b0;
reg [0:0] tx_sync_reg_4 = 1'b0;

assign tx_error_underflow = tx_sync_reg_3[0] ^ tx_sync_reg_4[0];

always @(posedge tx_clk or posedge tx_rst) begin
    if (tx_rst) begin
        tx_sync_reg_1 <= 1'b0;
    end else begin
        tx_sync_reg_1 <= tx_sync_reg_1 ^ {tx_error_underflow_int};
    end
end

always @(posedge logic_clk or posedge logic_rst) begin
    if (logic_rst) begin
        tx_sync_reg_2 <= 1'b0;
        tx_sync_reg_3 <= 1'b0;
        tx_sync_reg_4 <= 1'b0;
    end else begin
        tx_sync_reg_2 <= tx_sync_reg_1;
        tx_sync_reg_3 <= tx_sync_reg_2;
        tx_sync_reg_4 <= tx_sync_reg_3;
    end
end

wire rx_error_bad_frame_int;
wire rx_error_bad_fcs_int;

reg [1:0] rx_sync_reg_1 = 2'd0;
reg [1:0] rx_sync_reg_2 = 2'd0;
reg [1:0] rx_sync_reg_3 = 2'd0;
reg [1:0] rx_sync_reg_4 = 2'd0;

assign rx_error_bad_frame = rx_sync_reg_3[0] ^ rx_sync_reg_4[0];
assign rx_error_bad_fcs = rx_sync_reg_3[1] ^ rx_sync_reg_4[1];

always @(posedge rx_clk or posedge rx_rst) begin
    if (rx_rst) begin
        rx_sync_reg_1 <= 2'd0;
    end else begin
        rx_sync_reg_1 <= rx_sync_reg_1 ^ {rx_error_bad_frame_int, rx_error_bad_frame_int};
    end
end

always @(posedge logic_clk or posedge logic_rst) begin
    if (logic_rst) begin
        rx_sync_reg_2 <= 2'd0;
        rx_sync_reg_3 <= 2'd0;
        rx_sync_reg_4 <= 2'd0;
    end else begin
        rx_sync_reg_2 <= rx_sync_reg_1;
        rx_sync_reg_3 <= rx_sync_reg_2;
        rx_sync_reg_4 <= rx_sync_reg_3;
    end
end

eth_mac_mii #(
    .TARGET(TARGET),
    .CLOCK_INPUT_STYLE(CLOCK_INPUT_STYLE),
    .ENABLE_PADDING(ENABLE_PADDING),
    .MIN_FRAME_LENGTH(MIN_FRAME_LENGTH)
)
eth_mac_1g_mii_inst (
    .rst(rst),
    .tx_clk(tx_clk),
    .tx_rst(tx_rst),
    .rx_clk(rx_clk),
    .rx_rst(rx_rst),
    .tx_axis_tdata(tx_fifo_axis_tdata),
    .tx_axis_tvalid(tx_fifo_axis_tvalid),
    .tx_axis_tready(tx_fifo_axis_tready),
    .tx_axis_tlast(tx_fifo_axis_tlast),
    .tx_axis_tuser(tx_fifo_axis_tuser),
    .rx_axis_tdata(rx_fifo_axis_tdata),
    .rx_axis_tvalid(rx_fifo_axis_tvalid),
    .rx_axis_tlast(rx_fifo_axis_tlast),
    .rx_axis_tuser(rx_fifo_axis_tuser),
    .mii_rx_clk(mii_rx_clk),
    .mii_rxd(mii_rxd),
    .mii_rx_dv(mii_rx_dv),
    .mii_rx_er(mii_rx_er),
    .mii_tx_clk(mii_tx_clk),
    .mii_txd(mii_txd),
    .mii_tx_en(mii_tx_en),
    .mii_tx_er(mii_tx_er),
    .tx_error_underflow(tx_error_underflow_int),
    .rx_error_bad_frame(rx_error_bad_frame_int),
    .rx_error_bad_fcs(rx_error_bad_fcs_int),
    .ifg_delay(ifg_delay)
);

axis_async_fifo_adapter #(
    .DEPTH(TX_FIFO_DEPTH),
    .S_DATA_WIDTH(AXIS_DATA_WIDTH),
    .S_KEEP_ENABLE(AXIS_KEEP_ENABLE),
    .S_KEEP_WIDTH(AXIS_KEEP_WIDTH),
    .M_DATA_WIDTH(8),
    .M_KEEP_ENABLE(0),
    .ID_ENABLE(0),
    .DEST_ENABLE(0),
    .USER_ENABLE(1),
    .USER_WIDTH(1),
    .FRAME_FIFO(TX_FRAME_FIFO),
    .USER_BAD_FRAME_VALUE(1'b1),
    .USER_BAD_FRAME_MASK(1'b1),
    .DROP_BAD_FRAME(TX_DROP_BAD_FRAME),
    .DROP_WHEN_FULL(TX_DROP_WHEN_FULL)
)
tx_fifo (
    // AXI input
    .s_clk(logic_clk),
    .s_rst(logic_rst),
    .s_axis_tdata(tx_axis_tdata),
    .s_axis_tkeep(tx_axis_tkeep),
    .s_axis_tvalid(tx_axis_tvalid),
    .s_axis_tready(tx_axis_tready),
    .s_axis_tlast(tx_axis_tlast),
    .s_axis_tid(0),
    .s_axis_tdest(0),
    .s_axis_tuser(tx_axis_tuser),
    // AXI output
    .m_clk(tx_clk),
    .m_rst(tx_rst),
    .m_axis_tdata(tx_fifo_axis_tdata),
    .m_axis_tkeep(),
    .m_axis_tvalid(tx_fifo_axis_tvalid),
    .m_axis_tready(tx_fifo_axis_tready),
    .m_axis_tlast(tx_fifo_axis_tlast),
    .m_axis_tid(),
    .m_axis_tdest(),
    .m_axis_tuser(tx_fifo_axis_tuser),
    // Status
    .s_status_overflow(tx_fifo_overflow),
    .s_status_bad_frame(tx_fifo_bad_frame),
    .s_status_good_frame(tx_fifo_good_frame),
    .m_status_overflow(),
    .m_status_bad_frame(),
    .m_status_good_frame()
);

axis_async_fifo_adapter #(
    .DEPTH(RX_FIFO_DEPTH),
    .S_DATA_WIDTH(8),
    .S_KEEP_ENABLE(0),
    .M_DATA_WIDTH(AXIS_DATA_WIDTH),
    .M_KEEP_ENABLE(AXIS_KEEP_ENABLE),
    .M_KEEP_WIDTH(AXIS_KEEP_WIDTH),
    .ID_ENABLE(0),
    .DEST_ENABLE(0),
    .USER_ENABLE(1),
    .USER_WIDTH(1),
    .FRAME_FIFO(TX_FRAME_FIFO),
    .USER_BAD_FRAME_VALUE(1'b1),
    .USER_BAD_FRAME_MASK(1'b1),
    .DROP_BAD_FRAME(TX_DROP_BAD_FRAME),
    .DROP_WHEN_FULL(TX_DROP_WHEN_FULL)
)
rx_fifo (
    // AXI input
    .s_clk(rx_clk),
    .s_rst(rx_rst),
    .s_axis_tdata(rx_fifo_axis_tdata),
    .s_axis_tkeep(0),
    .s_axis_tvalid(rx_fifo_axis_tvalid),
    .s_axis_tready(),
    .s_axis_tlast(rx_fifo_axis_tlast),
    .s_axis_tid(0),
    .s_axis_tdest(0),
    .s_axis_tuser(rx_fifo_axis_tuser),
    // AXI output
    .m_clk(logic_clk),
    .m_rst(logic_rst),
    .m_axis_tdata(rx_axis_tdata),
    .m_axis_tkeep(rx_axis_tkeep),
    .m_axis_tvalid(rx_axis_tvalid),
    .m_axis_tready(rx_axis_tready),
    .m_axis_tlast(rx_axis_tlast),
    .m_axis_tid(),
    .m_axis_tdest(),
    .m_axis_tuser(rx_axis_tuser),
    // Status
    .s_status_overflow(),
    .s_status_bad_frame(),
    .s_status_good_frame(),
    .m_status_overflow(rx_fifo_overflow),
    .m_status_bad_frame(rx_fifo_bad_frame),
    .m_status_good_frame(rx_fifo_good_frame)
);

endmodule