module pcie_tlp_fifo_mux #
(
    // Input count
    parameter PORTS = 2,
    // TLP data width
    parameter TLP_DATA_WIDTH = 256,
    // TLP strobe width
    parameter TLP_STRB_WIDTH = TLP_DATA_WIDTH/32,
    // TLP header width
    parameter TLP_HDR_WIDTH = 128,
    // Sequence number width
    parameter SEQ_NUM_WIDTH = 6,
    // TLP segment count (input)
    parameter IN_TLP_SEG_COUNT = 1,
    // TLP segment count (output)
    parameter OUT_TLP_SEG_COUNT = IN_TLP_SEG_COUNT,
    // select round robin arbitration
    parameter ARB_TYPE_ROUND_ROBIN = 0,
    // LSB priority selection
    parameter ARB_LSB_HIGH_PRIORITY = 1,
    // FIFO depth
    parameter FIFO_DEPTH = 2048,
    // FIFO watermark level
    parameter FIFO_WATERMARK = FIFO_DEPTH/2
)
(
    input  wire                                              clk,
    input  wire                                              rst,

    /*
     * TLP input
     */
    input  wire [PORTS*TLP_DATA_WIDTH-1:0]                   in_tlp_data,
    input  wire [PORTS*TLP_STRB_WIDTH-1:0]                   in_tlp_strb,
    input  wire [PORTS*IN_TLP_SEG_COUNT*TLP_HDR_WIDTH-1:0]   in_tlp_hdr,
    input  wire [PORTS*IN_TLP_SEG_COUNT*SEQ_NUM_WIDTH-1:0]   in_tlp_seq,
    input  wire [PORTS*IN_TLP_SEG_COUNT*3-1:0]               in_tlp_bar_id,
    input  wire [PORTS*IN_TLP_SEG_COUNT*8-1:0]               in_tlp_func_num,
    input  wire [PORTS*IN_TLP_SEG_COUNT*4-1:0]               in_tlp_error,
    input  wire [PORTS*IN_TLP_SEG_COUNT-1:0]                 in_tlp_valid,
    input  wire [PORTS*IN_TLP_SEG_COUNT-1:0]                 in_tlp_sop,
    input  wire [PORTS*IN_TLP_SEG_COUNT-1:0]                 in_tlp_eop,
    output wire [PORTS-1:0]                                  in_tlp_ready,

    /*
     * TLP output
     */
    output wire [TLP_DATA_WIDTH-1:0]                         out_tlp_data,
    output wire [TLP_STRB_WIDTH-1:0]                         out_tlp_strb,
    output wire [OUT_TLP_SEG_COUNT*TLP_HDR_WIDTH-1:0]        out_tlp_hdr,
    output wire [OUT_TLP_SEG_COUNT*SEQ_NUM_WIDTH-1:0]        out_tlp_seq,
    output wire [OUT_TLP_SEG_COUNT*3-1:0]                    out_tlp_bar_id,
    output wire [OUT_TLP_SEG_COUNT*8-1:0]                    out_tlp_func_num,
    output wire [OUT_TLP_SEG_COUNT*4-1:0]                    out_tlp_error,
    output wire [OUT_TLP_SEG_COUNT-1:0]                      out_tlp_valid,
    output wire [OUT_TLP_SEG_COUNT-1:0]                      out_tlp_sop,
    output wire [OUT_TLP_SEG_COUNT-1:0]                      out_tlp_eop,
    input  wire                                              out_tlp_ready,

    /*
     * Flow control count output
     */
    output wire [3:0]                                        out_fc_ph,
    output wire [8:0]                                        out_fc_pd,
    output wire [3:0]                                        out_fc_nph,
    output wire [8:0]                                        out_fc_npd,
    output wire [3:0]                                        out_fc_cplh,
    output wire [8:0]                                        out_fc_cpld,

    /*
     * Control
     */
    input  wire [PORTS-1:0]                                  pause,

    /*
     * Status
     */
    output wire [PORTS*OUT_TLP_SEG_COUNT*SEQ_NUM_WIDTH-1:0]  sel_tlp_seq,
    output wire [PORTS*OUT_TLP_SEG_COUNT-1:0]                sel_tlp_seq_valid,
    output wire [PORTS-1:0]                                  fifo_half_full,
    output wire [PORTS-1:0]                                  fifo_watermark
);

parameter CL_PORTS = $clog2(PORTS);

parameter TLP_SEG_DATA_WIDTH = TLP_DATA_WIDTH / OUT_TLP_SEG_COUNT;
parameter TLP_SEG_STRB_WIDTH = TLP_STRB_WIDTH / OUT_TLP_SEG_COUNT;

parameter SEG_SEL_WIDTH = $clog2(OUT_TLP_SEG_COUNT);

parameter OUTPUT_FIFO_ADDR_WIDTH = 5;

// check configuration
initial begin
    if (TLP_HDR_WIDTH != 128) begin
        $error("Error: TLP segment header width must be 128 (instance %m)");
        $finish;
    end

    if (TLP_STRB_WIDTH*32 != TLP_DATA_WIDTH) begin
        $error("Error: PCIe interface requires dword (32-bit) granularity (instance %m)");
        $finish;
    end
end

reg frame_reg = 1'b0, frame_next, frame_cyc;
reg [CL_PORTS-1:0] port_reg = 0, port_next, port_cyc;
reg [SEG_SEL_WIDTH-1:0] seg_offset_cyc;
reg [SEG_SEL_WIDTH+1-1:0] seg_count_cyc;
reg valid, eop;
reg frame, abort;
reg [SEG_SEL_WIDTH-1:0] port_seg_offset_cyc[0:PORTS-1];
reg [SEG_SEL_WIDTH+1-1:0] port_seg_count_cyc[0:PORTS-1];

reg [OUT_TLP_SEG_COUNT-1:0] port_seg_valid[0:PORTS-1];
reg [OUT_TLP_SEG_COUNT-1:0] port_seg_eop[0:PORTS-1];

reg [OUT_TLP_SEG_COUNT-1:0] out_sel_reg = 0, out_sel_next, out_sel_cyc;
reg [CL_PORTS-1:0] out_sel_port_reg[0:OUT_TLP_SEG_COUNT-1], out_sel_port_next[0:OUT_TLP_SEG_COUNT-1];
reg [SEG_SEL_WIDTH+1-1:0] out_sel_seg_reg[0:OUT_TLP_SEG_COUNT-1], out_sel_seg_next[0:OUT_TLP_SEG_COUNT-1];

reg [PORTS*OUT_TLP_SEG_COUNT-1:0] sel_tlp_seq_valid_reg = 0, sel_tlp_seq_valid_next, sel_tlp_seq_valid_cyc;
reg [OUT_TLP_SEG_COUNT*SEQ_NUM_WIDTH-1:0] out_sel_tlp_seq_reg = 0, out_sel_tlp_seq_next;
reg [PORTS*OUT_TLP_SEG_COUNT-1:0] out_sel_tlp_seq_valid_reg = 0, out_sel_tlp_seq_valid_next;

// internal datapath
reg  [TLP_DATA_WIDTH-1:0]                   out_tlp_data_int;
reg  [TLP_STRB_WIDTH-1:0]                   out_tlp_strb_int;
reg  [OUT_TLP_SEG_COUNT*TLP_HDR_WIDTH-1:0]  out_tlp_hdr_int;
reg  [OUT_TLP_SEG_COUNT*SEQ_NUM_WIDTH-1:0]  out_tlp_seq_int;
reg  [OUT_TLP_SEG_COUNT*3-1:0]              out_tlp_bar_id_int;
reg  [OUT_TLP_SEG_COUNT*8-1:0]              out_tlp_func_num_int;
reg  [OUT_TLP_SEG_COUNT*4-1:0]              out_tlp_error_int;
reg  [OUT_TLP_SEG_COUNT-1:0]                out_tlp_valid_int;
reg  [OUT_TLP_SEG_COUNT-1:0]                out_tlp_sop_int;
reg  [OUT_TLP_SEG_COUNT-1:0]                out_tlp_eop_int;
wire                                        out_tlp_ready_int;

wire [TLP_DATA_WIDTH-1:0] fifo_tlp_data[0:PORTS-1];
wire [TLP_STRB_WIDTH-1:0] fifo_tlp_strb[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT*TLP_HDR_WIDTH-1:0] fifo_tlp_hdr[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT*SEQ_NUM_WIDTH-1:0] fifo_tlp_seq[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT*3-1:0] fifo_tlp_bar_id[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT*8-1:0] fifo_tlp_func_num[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT*4-1:0] fifo_tlp_error[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT-1:0] fifo_tlp_valid[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT-1:0] fifo_tlp_sop[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT-1:0] fifo_tlp_eop[0:PORTS-1];
wire [SEG_SEL_WIDTH-1:0] fifo_seg_offset[0:PORTS-1];
wire [SEG_SEL_WIDTH+1-1:0] fifo_seg_count[0:PORTS-1];
reg [PORTS-1:0] fifo_read_en_reg = 0, fifo_read_en_next;
reg [SEG_SEL_WIDTH+1-1:0] fifo_read_seg_count_reg[0:PORTS-1], fifo_read_seg_count_next[0:PORTS-1];

wire [OUT_TLP_SEG_COUNT-1:0] fifo_ctrl_tlp_valid[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT-1:0] fifo_ctrl_tlp_sop[0:PORTS-1];
wire [OUT_TLP_SEG_COUNT-1:0] fifo_ctrl_tlp_eop[0:PORTS-1];
wire [SEG_SEL_WIDTH-1:0] fifo_ctrl_seg_offset[0:PORTS-1];
wire [SEG_SEL_WIDTH+1-1:0] fifo_ctrl_seg_count[0:PORTS-1];
reg [PORTS-1:0] fifo_ctrl_read_en;
reg [SEG_SEL_WIDTH+1-1:0] fifo_ctrl_read_seg_count[0:PORTS-1];

generate

genvar n;

for (n = 0; n < PORTS; n = n + 1) begin

    pcie_tlp_fifo_raw #(
        .DEPTH(FIFO_DEPTH),
        .TLP_DATA_WIDTH(TLP_DATA_WIDTH),
        .TLP_STRB_WIDTH(TLP_STRB_WIDTH),
        .TLP_HDR_WIDTH(TLP_HDR_WIDTH),
        .SEQ_NUM_WIDTH(SEQ_NUM_WIDTH),
        .IN_TLP_SEG_COUNT(IN_TLP_SEG_COUNT),
        .OUT_TLP_SEG_COUNT(OUT_TLP_SEG_COUNT),
        .WATERMARK(FIFO_WATERMARK),
        .CTRL_OUT_EN(1)
    )
    pcie_tlp_fifo_inst (
        .clk(clk),
        .rst(rst),

        /*
         * TLP input
         */
        .in_tlp_data(in_tlp_data[TLP_DATA_WIDTH*n +: TLP_DATA_WIDTH]),
        .in_tlp_strb(in_tlp_strb[TLP_STRB_WIDTH*n +: TLP_STRB_WIDTH]),
        .in_tlp_hdr(in_tlp_hdr[IN_TLP_SEG_COUNT*TLP_HDR_WIDTH*n +: IN_TLP_SEG_COUNT*TLP_HDR_WIDTH]),
        .in_tlp_seq(in_tlp_seq[IN_TLP_SEG_COUNT*SEQ_NUM_WIDTH*n +: IN_TLP_SEG_COUNT*SEQ_NUM_WIDTH]),
        .in_tlp_bar_id(in_tlp_bar_id[IN_TLP_SEG_COUNT*3*n +: IN_TLP_SEG_COUNT*3]),
        .in_tlp_func_num(in_tlp_func_num[IN_TLP_SEG_COUNT*8*n +: IN_TLP_SEG_COUNT*8]),
        .in_tlp_error(in_tlp_error[IN_TLP_SEG_COUNT*4*n +: IN_TLP_SEG_COUNT*4]),
        .in_tlp_valid(in_tlp_valid[IN_TLP_SEG_COUNT*n +: IN_TLP_SEG_COUNT]),
        .in_tlp_sop(in_tlp_sop[IN_TLP_SEG_COUNT*n +: IN_TLP_SEG_COUNT]),
        .in_tlp_eop(in_tlp_eop[IN_TLP_SEG_COUNT*n +: IN_TLP_SEG_COUNT]),
        .in_tlp_ready(in_tlp_ready[n +: 1]),

        /*
         * TLP output
         */
        .out_tlp_data(fifo_tlp_data[n]),
        .out_tlp_strb(fifo_tlp_strb[n]),
        .out_tlp_hdr(fifo_tlp_hdr[n]),
        .out_tlp_seq(fifo_tlp_seq[n]),
        .out_tlp_bar_id(fifo_tlp_bar_id[n]),
        .out_tlp_func_num(fifo_tlp_func_num[n]),
        .out_tlp_error(fifo_tlp_error[n]),
        .out_tlp_valid(fifo_tlp_valid[n]),
        .out_tlp_sop(fifo_tlp_sop[n]),
        .out_tlp_eop(fifo_tlp_eop[n]),
        .out_seg_offset(fifo_seg_offset[n]),
        .out_seg_count(fifo_seg_count[n]),
        .out_read_en(fifo_read_en_reg[n]),
        .out_read_seg_count(fifo_read_seg_count_reg[n]),

        .out_ctrl_tlp_strb(),
        .out_ctrl_tlp_hdr(),
        .out_ctrl_tlp_valid(fifo_ctrl_tlp_valid[n]),
        .out_ctrl_tlp_sop(fifo_ctrl_tlp_sop[n]),
        .out_ctrl_tlp_eop(fifo_ctrl_tlp_eop[n]),
        .out_ctrl_seg_offset(fifo_ctrl_seg_offset[n]),
        .out_ctrl_seg_count(fifo_ctrl_seg_count[n]),
        .out_ctrl_read_en(fifo_ctrl_read_en[n]),
        .out_ctrl_read_seg_count(fifo_ctrl_read_seg_count[n]),

        /*
         * Status
         */
        .half_full(fifo_half_full[n +: 1]),
        .watermark(fifo_watermark[n +: 1])
    );

end

endgenerate

assign sel_tlp_seq = {PORTS{out_sel_tlp_seq_reg}};
assign sel_tlp_seq_valid = out_sel_tlp_seq_valid_reg;

pcie_tlp_fc_count #(
    .TLP_HDR_WIDTH(TLP_HDR_WIDTH),
    .TLP_SEG_COUNT(OUT_TLP_SEG_COUNT)
)
fc_count_inst (
    .clk(clk),
    .rst(rst),

    /*
     * TLP monitor
     */
    .tlp_hdr(out_tlp_hdr_int),
    .tlp_valid(out_tlp_valid_int),
    .tlp_sop(out_tlp_sop_int),
    .tlp_ready(1'b1),

    /*
     * Flow control count output
     */
    .out_fc_ph(out_fc_ph),
    .out_fc_pd(out_fc_pd),
    .out_fc_nph(out_fc_nph),
    .out_fc_npd(out_fc_npd),
    .out_fc_cplh(out_fc_cplh),
    .out_fc_cpld(out_fc_cpld)
);

integer port, cur_port, seg, cur_seg;

always @* begin
    frame_next = frame_reg;
    port_next = port_reg;

    out_tlp_data_int = 0;
    out_tlp_strb_int = 0;
    out_tlp_hdr_int = 0;
    out_tlp_seq_int = 0;
    out_tlp_bar_id_int = 0;
    out_tlp_func_num_int = 0;
    out_tlp_error_int = 0;
    out_tlp_valid_int = 0;
    out_tlp_sop_int = 0;
    out_tlp_eop_int = 0;

    fifo_read_en_next = 0;
    fifo_ctrl_read_en = 0;

    frame_cyc = frame_reg;
    port_cyc = port_reg;
    seg_offset_cyc = fifo_ctrl_seg_offset[port_reg];
    seg_count_cyc = 0;
    valid = 0;
    eop = 0;
    frame = frame_cyc;
    abort = 0;

    for (port = 0; port < PORTS; port = port + 1) begin
        port_seg_offset_cyc[port] = fifo_ctrl_seg_offset[port];
        port_seg_count_cyc[port] = 0;
        fifo_ctrl_read_seg_count[port] = 0;
        fifo_read_seg_count_next[port] = 0;
    end

    out_sel_next = 0;
    out_sel_cyc = 0;
    for (seg = 0; seg < OUT_TLP_SEG_COUNT; seg = seg + 1) begin
        out_sel_port_next[seg] = 0;
        out_sel_seg_next[seg] = 0;
    end

    sel_tlp_seq_valid_next = 0;
    sel_tlp_seq_valid_cyc = 0;
    out_sel_tlp_seq_next = 0;
    out_sel_tlp_seq_valid_next = 0;

    // compute mux settings
    for (port = 0; port < PORTS; port = port + 1) begin
        port_seg_valid[port] = {2{fifo_ctrl_tlp_valid[port]}} >> fifo_ctrl_seg_offset[port];
        port_seg_eop[port] = {2{fifo_ctrl_tlp_eop[port]}} >> fifo_ctrl_seg_offset[port];
    end

    for (seg = 0; seg < OUT_TLP_SEG_COUNT; seg = seg + 1) begin
        // select port
        if (!frame_cyc) begin
            if (ARB_TYPE_ROUND_ROBIN) begin
                // round robin arb - start checking after previously-selected port
                if (ARB_LSB_HIGH_PRIORITY) begin
                    if (port_cyc < PORTS-1) begin
                        cur_port = port_cyc + 1;
                    end else begin
                        cur_port = 0;
                    end
                end else begin
                    if (port_cyc > 0) begin
                        cur_port = port_cyc - 1;
                    end else begin
                        cur_port = PORTS-1;
                    end
                end
            end else begin
                // priority arb - start from high priority end
                if (ARB_LSB_HIGH_PRIORITY) begin
                    cur_port = 0;
                end else begin
                    cur_port = PORTS-1;
                end
            end
            for (port = 0; port < PORTS; port = port + 1) begin
                if (!frame_cyc) begin
                    // select port
                    port_cyc = cur_port;
                    seg_offset_cyc = port_seg_offset_cyc[cur_port];
                    seg_count_cyc = port_seg_count_cyc[cur_port];
                    if (!pause[cur_port] && port_seg_valid[cur_port][0]) begin
                        // set frame
                        frame_cyc = 1;
                        sel_tlp_seq_valid_cyc[OUT_TLP_SEG_COUNT*cur_port+seg] = 1'b1;
                    end
                end
                // next port
                if (ARB_LSB_HIGH_PRIORITY) begin
                    if (cur_port < PORTS-1) begin
                        cur_port = cur_port + 1;
                    end else begin
                        cur_port = 0;
                    end
                end else begin
                    if (cur_port > 0) begin
                        cur_port = cur_port - 1;
                    end else begin
                        cur_port = PORTS-1;
                    end
                end
            end
        end

        // route segment
        valid = port_seg_valid[port_cyc][0];
        eop = port_seg_eop[port_cyc][0];
        frame = frame_cyc;

        out_sel_cyc[seg] = 1'b1;
        out_sel_port_next[seg] = port_cyc;
        out_sel_seg_next[seg] = seg_offset_cyc;
        if (eop) begin
            // end of packet, clear frame
            frame_cyc = 0;
        end
        seg_offset_cyc = seg_offset_cyc + 1;
        seg_count_cyc = seg_count_cyc + 1;
        port_seg_offset_cyc[port_cyc] = seg_offset_cyc;
        port_seg_count_cyc[port_cyc] = seg_count_cyc;
        port_seg_valid[port_cyc] = port_seg_valid[port_cyc] >> 1;
        port_seg_eop[port_cyc] = port_seg_eop[port_cyc] >> 1;

        if (frame && !abort) begin
            if (valid) begin
                if (eop || seg == OUT_TLP_SEG_COUNT-1) begin
                    // end of packet or end of cycle, commit
                    fifo_read_seg_count_next[port_cyc] = seg_count_cyc;
                    fifo_ctrl_read_seg_count[port_cyc] = seg_count_cyc;
                    if (out_tlp_ready_int) begin
                        frame_next = frame_cyc;
                        port_next = port_cyc;
                        out_sel_next = out_sel_cyc;
                        fifo_read_en_next[port_cyc] = 1'b1;
                        fifo_ctrl_read_en[port_cyc] = 1'b1;
                        sel_tlp_seq_valid_next = sel_tlp_seq_valid_cyc;
                    end
                end
            end else begin
                // input has stalled, wait
                abort = 1;
            end
        end
    end

    // mux for output segments
    for (seg = 0; seg < OUT_TLP_SEG_COUNT; seg = seg + 1) begin
        out_tlp_data_int[seg*TLP_SEG_DATA_WIDTH +: TLP_SEG_DATA_WIDTH] = fifo_tlp_data[out_sel_port_reg[seg]][out_sel_seg_reg[seg]*TLP_SEG_DATA_WIDTH +: TLP_SEG_DATA_WIDTH];
        out_tlp_strb_int[seg*TLP_SEG_STRB_WIDTH +: TLP_SEG_STRB_WIDTH] = fifo_tlp_strb[out_sel_port_reg[seg]][out_sel_seg_reg[seg]*TLP_SEG_STRB_WIDTH +: TLP_SEG_STRB_WIDTH];
        out_tlp_hdr_int[seg*TLP_HDR_WIDTH +: TLP_HDR_WIDTH] = fifo_tlp_hdr[out_sel_port_reg[seg]][out_sel_seg_reg[seg]*TLP_HDR_WIDTH +: TLP_HDR_WIDTH];
        out_tlp_seq_int[seg*SEQ_NUM_WIDTH +: SEQ_NUM_WIDTH] = fifo_tlp_seq[out_sel_port_reg[seg]][out_sel_seg_reg[seg]*SEQ_NUM_WIDTH +: SEQ_NUM_WIDTH];
        out_tlp_bar_id_int[seg*3 +: 3] = fifo_tlp_bar_id[out_sel_port_reg[seg]][out_sel_seg_reg[seg]*3 +: 3];
        out_tlp_func_num_int[seg*8 +: 8] = fifo_tlp_func_num[out_sel_port_reg[seg]][out_sel_seg_reg[seg]*8 +: 8];
        out_tlp_error_int[seg*4 +: 4] = fifo_tlp_error[out_sel_port_reg[seg]][out_sel_seg_reg[seg]*4 +: 4];
        if (out_sel_reg[seg]) begin
            out_tlp_valid_int[seg +: 1] = fifo_tlp_valid[out_sel_port_reg[seg]][out_sel_seg_reg[seg] +: 1];
        end
        out_tlp_sop_int[seg +: 1] = fifo_tlp_sop[out_sel_port_reg[seg]][out_sel_seg_reg[seg] +: 1];
        out_tlp_eop_int[seg +: 1] = fifo_tlp_eop[out_sel_port_reg[seg]][out_sel_seg_reg[seg] +: 1];

        out_sel_tlp_seq_next[seg*SEQ_NUM_WIDTH +: SEQ_NUM_WIDTH] = fifo_tlp_seq[out_sel_port_reg[seg]][out_sel_seg_reg[seg]*SEQ_NUM_WIDTH +: SEQ_NUM_WIDTH];
    end
    out_sel_tlp_seq_valid_next = sel_tlp_seq_valid_reg;
end

integer i;

always @(posedge clk) begin
    frame_reg <= frame_next;
    port_reg <= port_next;

    out_sel_reg <= out_sel_next;
    for (i = 0; i < OUT_TLP_SEG_COUNT; i = i + 1) begin
        out_sel_port_reg[i] <= out_sel_port_next[i];
        out_sel_seg_reg[i] <= out_sel_seg_next[i];
    end

    fifo_read_en_reg <= fifo_read_en_next;
    for (i = 0; i < PORTS; i = i + 1) begin
        fifo_read_seg_count_reg[i] <= fifo_read_seg_count_next[i];
    end

    sel_tlp_seq_valid_reg <= sel_tlp_seq_valid_next;
    out_sel_tlp_seq_reg <= out_sel_tlp_seq_next;
    out_sel_tlp_seq_valid_reg <= out_sel_tlp_seq_valid_next;

    if (rst) begin
        frame_reg <= 1'b0;
        port_reg <= 0;

        out_sel_reg <= 0;

        fifo_read_en_reg <= 0;

        sel_tlp_seq_valid_reg <= 0;
        out_sel_tlp_seq_valid_reg <= 0;
    end
end

// output datapath logic
reg  [TLP_DATA_WIDTH-1:0]                   out_tlp_data_reg = 0;
reg  [TLP_STRB_WIDTH-1:0]                   out_tlp_strb_reg = 0;
reg  [OUT_TLP_SEG_COUNT*TLP_HDR_WIDTH-1:0]  out_tlp_hdr_reg = 0;
reg  [OUT_TLP_SEG_COUNT*SEQ_NUM_WIDTH-1:0]  out_tlp_seq_reg = 0;
reg  [OUT_TLP_SEG_COUNT*3-1:0]              out_tlp_bar_id_reg = 0;
reg  [OUT_TLP_SEG_COUNT*8-1:0]              out_tlp_func_num_reg = 0;
reg  [OUT_TLP_SEG_COUNT*4-1:0]              out_tlp_error_reg = 0;
reg  [OUT_TLP_SEG_COUNT-1:0]                out_tlp_valid_reg = 0;
reg  [OUT_TLP_SEG_COUNT-1:0]                out_tlp_sop_reg = 0;
reg  [OUT_TLP_SEG_COUNT-1:0]                out_tlp_eop_reg = 0;

reg [OUTPUT_FIFO_ADDR_WIDTH+1-1:0] out_fifo_wr_ptr_reg = 0;
reg [OUTPUT_FIFO_ADDR_WIDTH+1-1:0] out_fifo_rd_ptr_reg = 0;
reg out_fifo_half_full_reg = 1'b0;

wire out_fifo_full = out_fifo_wr_ptr_reg == (out_fifo_rd_ptr_reg ^ {1'b1, {OUTPUT_FIFO_ADDR_WIDTH{1'b0}}});
wire out_fifo_empty = out_fifo_wr_ptr_reg == out_fifo_rd_ptr_reg;

(* ramstyle = "no_rw_check, mlab" *)
reg  [TLP_DATA_WIDTH-1:0]                   out_fifo_out_tlp_data[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];
(* ramstyle = "no_rw_check, mlab" *)
reg  [TLP_STRB_WIDTH-1:0]                   out_fifo_out_tlp_strb[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];
(* ramstyle = "no_rw_check, mlab" *)
reg  [OUT_TLP_SEG_COUNT*TLP_HDR_WIDTH-1:0]  out_fifo_out_tlp_hdr[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];
(* ramstyle = "no_rw_check, mlab" *)
reg  [OUT_TLP_SEG_COUNT*SEQ_NUM_WIDTH-1:0]  out_fifo_out_tlp_seq[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];
(* ramstyle = "no_rw_check, mlab" *)
reg  [OUT_TLP_SEG_COUNT*3-1:0]              out_fifo_out_tlp_bar_id[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];
(* ramstyle = "no_rw_check, mlab" *)
reg  [OUT_TLP_SEG_COUNT*8-1:0]              out_fifo_out_tlp_func_num[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];
(* ramstyle = "no_rw_check, mlab" *)
reg  [OUT_TLP_SEG_COUNT*4-1:0]              out_fifo_out_tlp_error[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];
(* ramstyle = "no_rw_check, mlab" *)
reg  [OUT_TLP_SEG_COUNT-1:0]                out_fifo_out_tlp_valid[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];
(* ramstyle = "no_rw_check, mlab" *)
reg  [OUT_TLP_SEG_COUNT-1:0]                out_fifo_out_tlp_sop[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];
(* ramstyle = "no_rw_check, mlab" *)
reg  [OUT_TLP_SEG_COUNT-1:0]                out_fifo_out_tlp_eop[2**OUTPUT_FIFO_ADDR_WIDTH-1:0];

assign out_tlp_ready_int = !out_fifo_half_full_reg;

assign out_tlp_data = out_tlp_data_reg;
assign out_tlp_strb = out_tlp_strb_reg;
assign out_tlp_hdr = out_tlp_hdr_reg;
assign out_tlp_seq = out_tlp_seq_reg;
assign out_tlp_bar_id = out_tlp_bar_id_reg;
assign out_tlp_func_num = out_tlp_func_num_reg;
assign out_tlp_error = out_tlp_error_reg;
assign out_tlp_valid = out_tlp_valid_reg;
assign out_tlp_sop = out_tlp_sop_reg;
assign out_tlp_eop = out_tlp_eop_reg;

always @(posedge clk) begin
    out_tlp_valid_reg <= out_tlp_ready ? 0 : out_tlp_valid_reg;

    out_fifo_half_full_reg <= $unsigned(out_fifo_wr_ptr_reg - out_fifo_rd_ptr_reg) >= 2**(OUTPUT_FIFO_ADDR_WIDTH-1);

    if (!out_fifo_full && out_tlp_valid_int) begin
        out_fifo_out_tlp_data[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_data_int;
        out_fifo_out_tlp_strb[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_strb_int;
        out_fifo_out_tlp_hdr[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_hdr_int;
        out_fifo_out_tlp_seq[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_seq_int;
        out_fifo_out_tlp_bar_id[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_bar_id_int;
        out_fifo_out_tlp_func_num[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_func_num_int;
        out_fifo_out_tlp_error[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_error_int;
        out_fifo_out_tlp_valid[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_valid_int;
        out_fifo_out_tlp_sop[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_sop_int;
        out_fifo_out_tlp_eop[out_fifo_wr_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]] <= out_tlp_eop_int;
        out_fifo_wr_ptr_reg <= out_fifo_wr_ptr_reg + 1;
    end

    if (!out_fifo_empty && (!out_tlp_valid_reg || out_tlp_ready)) begin
        out_tlp_data_reg <= out_fifo_out_tlp_data[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        out_tlp_strb_reg <= out_fifo_out_tlp_strb[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        out_tlp_hdr_reg <= out_fifo_out_tlp_hdr[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        out_tlp_seq_reg <= out_fifo_out_tlp_seq[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        out_tlp_bar_id_reg <= out_fifo_out_tlp_bar_id[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        out_tlp_func_num_reg <= out_fifo_out_tlp_func_num[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        out_tlp_error_reg <= out_fifo_out_tlp_error[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        if (OUT_TLP_SEG_COUNT == 1) begin
            out_tlp_valid_reg <= 1'b1;
        end else begin
            out_tlp_valid_reg <= out_fifo_out_tlp_valid[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        end
        out_tlp_sop_reg <= out_fifo_out_tlp_sop[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        out_tlp_eop_reg <= out_fifo_out_tlp_eop[out_fifo_rd_ptr_reg[OUTPUT_FIFO_ADDR_WIDTH-1:0]];
        out_fifo_rd_ptr_reg <= out_fifo_rd_ptr_reg + 1;
    end

    if (rst) begin
        out_fifo_wr_ptr_reg <= 0;
        out_fifo_rd_ptr_reg <= 0;
        out_tlp_valid_reg <= 1'b0;
    end
end

endmodule