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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  tb_ethernet_with_cop.v                                      ////

////                                                              ////

////  This file is part of the Ethernet IP core project           ////

////  http://www.opencores.org/projects/ethmac/                   ////

////                                                              ////

////  Author(s):                                                  ////

////      - Igor Mohor (igorM@opencores.org)                      ////

////                                                              ////

////  All additional information is avaliable in the Readme.txt   ////

////  file.                                                       ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// Copyright (C) 2001, 2002 Authors                             ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// This source file is free software; you can redistribute it   ////

//// and/or modify it under the terms of the GNU Lesser General   ////

//// Public License as published by the Free Software Foundation; ////

//// either version 2.1 of the License, or (at your option) any   ////

//// later version.                                               ////

////                                                              ////

//// This source is distributed in the hope that it will be       ////

//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////

//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////

//// PURPOSE.  See the GNU Lesser General Public License for more ////

//// details.                                                     ////

////                                                              ////

//// You should have received a copy of the GNU Lesser General    ////

//// Public License along with this source; if not, download it   ////

//// from http://www.opencores.org/lgpl.shtml                     ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

// Revision 1.1  2002/09/18 16:40:40  mohor

// Simple testbench that includes eth_cop, eth_host and eth_memory modules.

// This testbench is used for testing the whole environment. Use tb_ethernet

// testbench for testing just the ethernet MAC core (many tests).

//

//

//

//

`include "tb_eth_defines.v"

`include "eth_defines.v"

`include "timescale.v"

module tb_ethernet_with_cop();

parameter Tp = 1;

reg           wb_clk_o;

reg           wb_rst_o;

reg           mtx_clk;

reg           mrx_clk;

wire   [3:0]  MTxD;

wire          MTxEn;

wire          MTxErr;

reg    [3:0]  MRxD;     // This goes to PHY

reg           MRxDV;    // This goes to PHY

reg           MRxErr;   // This goes to PHY

reg           MColl;    // This goes to PHY

reg           MCrs;     // This goes to PHY

wire          Mdi_I;

wire          Mdo_O;

wire          Mdo_OE;

wire          Mdc_O;

integer tx_log;

integer rx_log;

reg StartTB;

`ifdef ETH_XILINX_RAMB4

  reg gsr;

`endif

integer packet_ready_cnt, send_packet_cnt;

// Ethernet Slave Interface signals

wire [31:0] eth_sl_wb_adr_i, eth_sl_wb_dat_o, eth_sl_wb_dat_i;

wire  [3:0] eth_sl_wb_sel_i;

wire        eth_sl_wb_we_i, eth_sl_wb_cyc_i, eth_sl_wb_stb_i, eth_sl_wb_ack_o, eth_sl_wb_err_o;

// Memory Slave Interface signals

wire [31:0] mem_sl_wb_adr_i, mem_sl_wb_dat_o, mem_sl_wb_dat_i;

wire  [3:0] mem_sl_wb_sel_i;

wire        mem_sl_wb_we_i, mem_sl_wb_cyc_i, mem_sl_wb_stb_i, mem_sl_wb_ack_o, mem_sl_wb_err_o;

// Ethernet Master Interface signals

wire [31:0] eth_ma_wb_adr_o, eth_ma_wb_dat_i, eth_ma_wb_dat_o;

wire  [3:0] eth_ma_wb_sel_o;

wire        eth_ma_wb_we_o, eth_ma_wb_cyc_o, eth_ma_wb_stb_o, eth_ma_wb_ack_i, eth_ma_wb_err_i;

`ifdef ETH_WISHBONE_B3

wire  [2:0] eth_ma_wb_cti_o;

wire  [1:0] eth_ma_wb_bte_o;

`endif

// Host Master Interface signals

wire [31:0] host_ma_wb_adr_o, host_ma_wb_dat_i, host_ma_wb_dat_o;

wire  [3:0] host_ma_wb_sel_o;

wire        host_ma_wb_we_o, host_ma_wb_cyc_o, host_ma_wb_stb_o, host_ma_wb_ack_i, host_ma_wb_err_i;

eth_cop i_eth_cop

(

  // WISHBONE common

  .wb_clk_i(wb_clk_o), .wb_rst_i(wb_rst_o),

  // WISHBONE MASTER 1  Ethernet Master Interface is connected here

  .m1_wb_adr_i(eth_ma_wb_adr_o),  .m1_wb_sel_i(eth_ma_wb_sel_o),  .m1_wb_we_i (eth_ma_wb_we_o),

  .m1_wb_dat_o(eth_ma_wb_dat_i),  .m1_wb_dat_i(eth_ma_wb_dat_o),  .m1_wb_cyc_i(eth_ma_wb_cyc_o),

  .m1_wb_stb_i(eth_ma_wb_stb_o),  .m1_wb_ack_o(eth_ma_wb_ack_i),  .m1_wb_err_o(eth_ma_wb_err_i),

  // WISHBONE MASTER 2  Host Interface is connected here

  .m2_wb_adr_i(host_ma_wb_adr_o), .m2_wb_sel_i(host_ma_wb_sel_o), .m2_wb_we_i (host_ma_wb_we_o),

  .m2_wb_dat_o(host_ma_wb_dat_i), .m2_wb_dat_i(host_ma_wb_dat_o), .m2_wb_cyc_i(host_ma_wb_cyc_o),

  .m2_wb_stb_i(host_ma_wb_stb_o), .m2_wb_ack_o(host_ma_wb_ack_i), .m2_wb_err_o(host_ma_wb_err_i),

  // WISHBONE slave 1   Ethernet Slave Interface is connected here

        .s1_wb_adr_o(eth_sl_wb_adr_i),  .s1_wb_sel_o(eth_sl_wb_sel_i),  .s1_wb_we_o (eth_sl_wb_we_i),

        .s1_wb_cyc_o(eth_sl_wb_cyc_i),  .s1_wb_stb_o(eth_sl_wb_stb_i),  .s1_wb_ack_i(eth_sl_wb_ack_o),

        .s1_wb_err_i(eth_sl_wb_err_o),  .s1_wb_dat_i(eth_sl_wb_dat_o),  .s1_wb_dat_o(eth_sl_wb_dat_i),

  // WISHBONE slave 2   Memory Interface is connected here

        .s2_wb_adr_o(mem_sl_wb_adr_i),  .s2_wb_sel_o(mem_sl_wb_sel_i),  .s2_wb_we_o (mem_sl_wb_we_i),

        .s2_wb_cyc_o(mem_sl_wb_cyc_i),  .s2_wb_stb_o(mem_sl_wb_stb_i),  .s2_wb_ack_i(mem_sl_wb_ack_o),

        .s2_wb_err_i(mem_sl_wb_err_o),  .s2_wb_dat_i(mem_sl_wb_dat_o),  .s2_wb_dat_o(mem_sl_wb_dat_i)

);

// Connecting Ethernet top module

eth_top ethtop

(

  // WISHBONE common

  .wb_clk_i(wb_clk_o),              .wb_rst_i(wb_rst_o),

  // WISHBONE slave

        .wb_adr_i(eth_sl_wb_adr_i[11:2]), .wb_sel_i(eth_sl_wb_sel_i),   .wb_we_i(eth_sl_wb_we_i),

        .wb_cyc_i(eth_sl_wb_cyc_i),       .wb_stb_i(eth_sl_wb_stb_i),   .wb_ack_o(eth_sl_wb_ack_o),

        .wb_err_o(eth_sl_wb_err_o),       .wb_dat_i(eth_sl_wb_dat_i),   .wb_dat_o(eth_sl_wb_dat_o),

  // WISHBONE master

  .m_wb_adr_o(eth_ma_wb_adr_o),     .m_wb_sel_o(eth_ma_wb_sel_o), .m_wb_we_o(eth_ma_wb_we_o),

  .m_wb_dat_i(eth_ma_wb_dat_i),     .m_wb_dat_o(eth_ma_wb_dat_o), .m_wb_cyc_o(eth_ma_wb_cyc_o),

  .m_wb_stb_o(eth_ma_wb_stb_o),     .m_wb_ack_i(eth_ma_wb_ack_i), .m_wb_err_i(eth_ma_wb_err_i),

`ifdef ETH_WISHBONE_B3

  .m_wb_cti_o(eth_ma_wb_cti_o),     .m_wb_bte_o(eth_ma_wb_bte_o),

`endif

  //TX

  .mtx_clk_pad_i(mtx_clk), .mtxd_pad_o(MTxD), .mtxen_pad_o(MTxEn), .mtxerr_pad_o(MTxErr),

  //RX

  .mrx_clk_pad_i(mrx_clk), .mrxd_pad_i(MRxD), .mrxdv_pad_i(MRxDV), .mrxerr_pad_i(MRxErr),

  .mcoll_pad_i(MColl),    .mcrs_pad_i(MCrs),

  // MIIM

  .mdc_pad_o(Mdc_O), .md_pad_i(Mdi_I), .md_pad_o(Mdo_O), .md_padoe_o(Mdo_OE),

  .int_o()

  // Bist

`ifdef ETH_BIST

  , .trst(1'b0), .SO(), .SI(1'b0), .shift_DR(1'b0), .capture_DR(1'b0), .extest(1'b0), .tck(1'b0)

`endif

);

// Connecting Memory Interface Module

eth_memory i_eth_memory

(

  // WISHBONE common

        .wb_clk_i(wb_clk_o),         .wb_rst_i(wb_rst_o),

  // WISHBONE slave:   Memory Interface is connected here

        .wb_adr_i(mem_sl_wb_adr_i),  .wb_sel_i(mem_sl_wb_sel_i),  .wb_we_i (mem_sl_wb_we_i),

        .wb_cyc_i(mem_sl_wb_cyc_i),  .wb_stb_i(mem_sl_wb_stb_i),  .wb_ack_o(mem_sl_wb_ack_o),

        .wb_err_o(mem_sl_wb_err_o),  .wb_dat_o(mem_sl_wb_dat_o),  .wb_dat_i(mem_sl_wb_dat_i)

);

// Connecting Host Interface

eth_host eth_host

(

  // WISHBONE common

  .wb_clk_i(wb_clk_o),         .wb_rst_i(wb_rst_o),

  // WISHBONE master

  .wb_adr_o(host_ma_wb_adr_o), .wb_sel_o(host_ma_wb_sel_o), .wb_we_o (host_ma_wb_we_o),

  .wb_dat_i(host_ma_wb_dat_i), .wb_dat_o(host_ma_wb_dat_o), .wb_cyc_o(host_ma_wb_cyc_o),

  .wb_stb_o(host_ma_wb_stb_o), .wb_ack_i(host_ma_wb_ack_i), .wb_err_i(host_ma_wb_err_i)

);

// Reset pulse

initial

begin

  MCrs=0;                                     // This should come from PHY

  MColl=0;                                    // This should come from PHY

  MRxD=0;                                     // This should come from PHY

  MRxDV=0;                                    // This should come from PHY

  MRxErr=0;                                   // This should come from PHY

  packet_ready_cnt = 0;

  send_packet_cnt = 0;

  tx_log = $fopen("ethernet_tx.log");

  rx_log = $fopen("ethernet_rx.log");

  wb_rst_o =  1'b1;

`ifdef ETH_XILINX_RAMB4

  gsr           =  1'b0;

  #100 gsr      =  1'b1;

  #100 gsr      =  1'b0;

`endif

  #100 wb_rst_o =  1'b0;

  #100 StartTB  =  1'b1;

end

`ifdef ETH_XILINX_RAMB4

  assign glbl.GSR = gsr;

`endif

// Generating wb_clk_o clock

initial

begin

  wb_clk_o=0;

//  forever #20 wb_clk_o = ~wb_clk_o;  // 2*20 ns -> 25 MHz    

  forever #12.5 wb_clk_o = ~wb_clk_o;  // 2*12.5 ns -> 40 MHz    

end

// Generating mtx_clk clock

initial

begin

  mtx_clk=0;

  #3 forever #20 mtx_clk = ~mtx_clk;   // 2*20 ns -> 25 MHz

end

// Generating mrx_clk clock

initial

begin

  mrx_clk=0;

  #16 forever #20 mrx_clk = ~mrx_clk;   // 2*20 ns -> 25 MHz

end

reg [31:0] tmp;

initial

begin

  wait(StartTB);  // Start of testbench

  eth_host.wb_write(`ETH_MODER, 4'hf, 32'h0); // Reset OFF

  eth_host.wb_read(`ETH_MODER, 4'hf, tmp);

  eth_host.wb_write(`ETH_MAC_ADDR1, 4'hf, 32'h0002); // Set ETH_MAC_ADDR1 register

  eth_host.wb_write(`ETH_MAC_ADDR0, 4'hf, 32'h03040506); // Set ETH_MAC_ADDR0 register

  initialize_txbd(3);

  initialize_rxbd(4);

//  eth_host.wb_write(`ETH_MODER, 4'hf, `ETH_MODER_RXEN  | `ETH_MODER_TXEN | `ETH_MODER_PRO | 

//                                      `ETH_MODER_CRCEN | `ETH_MODER_PAD); // Set MODER register

//  eth_host.wb_write(`ETH_MODER, 4'hf, `ETH_MODER_RXEN  | `ETH_MODER_TXEN | 

//                                      `ETH_MODER_CRCEN | `ETH_MODER_PAD); // Set MODER register

//  eth_host.wb_write(`ETH_MODER, 4'hf, `ETH_MODER_RXEN  | `ETH_MODER_TXEN | `ETH_MODER_BRO | 

//                                      `ETH_MODER_CRCEN | `ETH_MODER_PAD); // Set MODER register

//  eth_host.wb_write(`ETH_MODER, 4'hf, `ETH_MODER_RXEN  | `ETH_MODER_TXEN | `ETH_MODER_PRO | 

//                                      `ETH_MODER_CRCEN | `ETH_MODER_PAD | `ETH_MODER_LOOPBCK); // Set MODER register

  eth_host.wb_write(`ETH_MODER, 4'hf, `ETH_MODER_RXEN  | `ETH_MODER_TXEN | `ETH_MODER_PRO |

                                      `ETH_MODER_CRCEN | `ETH_MODER_PAD | `ETH_MODER_LOOPBCK |

                                      `ETH_MODER_FULLD); // Set MODER register

  eth_host.wb_read(`ETH_MODER, 4'hf, tmp);

  set_packet(16'h364, 8'h1);

  set_packet(16'h234, 8'h11);

  send_packet;

  repeat (1000) @(posedge mrx_clk);   // Waiting for TxEthMac to finish transmit

//  repeat (10000) @(posedge wb_clk_o);   // Waiting for TxEthMac to finish transmit

  set_packet(16'h534, 8'h21);

//  set_packet(16'h34, 8'h31);

/*

  eth_host.wb_write(`ETH_CTRLMODER, 4'hf, 32'h4);   // Enable Tx Flow control

  eth_host.wb_write(`ETH_CTRLMODER, 4'hf, 32'h5);   // Enable Tx Flow control

  eth_host.wb_write(`ETH_TX_CTRL, 4'hf, 32'h10013); // Send Control frame with PAUSE_TV=0x0013

*/

  send_packet;

  repeat (1000) @(posedge mrx_clk);   // Waiting for TxEthMac to finish transmit

  send_packet;

  repeat (1000) @(posedge mrx_clk);   // Waiting for TxEthMac to finish transmit

/*

  send_packet;

*/

  repeat (10000) @(posedge wb_clk_o);   // Waiting for TxEthMac to finish transmit

/*

  GetDataOnMRxD(113, `UNICAST_XFR); // LengthRx bytes is comming on MRxD[3:0] signals

  repeat (10000) @(posedge wb_clk_o);   // Waiting for TxEthMac to finish transmit

  GetDataOnMRxD(500, `BROADCAST_XFR); // LengthRx bytes is comming on MRxD[3:0] signals

  repeat (1000) @(posedge mrx_clk);   // Waiting for TxEthMac to finish transmit

  GetDataOnMRxD(1200, `BROADCAST_XFR); // LengthRx bytes is comming on MRxD[3:0] signals

  GetDataOnMRxD(1000, `UNICAST_XFR); // LengthRx bytes is comming on MRxD[3:0] signals

  repeat (10000) @(posedge wb_clk_o);   // Waiting for TxEthMac to finish transmit

*/

  // Reading and printing interrupts

  eth_host.wb_read(`ETH_INT, 4'hf, tmp);

  $display("Print irq = 0x%0x", tmp);

  //Clearing all interrupts

  eth_host.wb_write(`ETH_INT, 4'hf, 32'h60);

  // Reading and printing interrupts

  eth_host.wb_read(`ETH_INT, 4'hf, tmp);

  $display("Print irq = 0x%0x", tmp);

  $display("\n\n End of simulation");

  $stop;

end

`ifdef ETH_WISHBONE_B3

integer single_cnt_tx, burst_cnt_tx, burst_cnt;

integer single_cnt_rx, burst_cnt_rx;

initial

begin

single_cnt_tx=0; burst_cnt_tx=0; burst_cnt=0;

single_cnt_rx=0; burst_cnt_rx=0;

end

// Single and burst cycle watcher

always @ (posedge wb_clk_o)

begin

  if(eth_ma_wb_ack_i) begin

    if(eth_ma_wb_cyc_o & eth_ma_wb_we_o & eth_ma_wb_cti_o==3'b000) begin

      if(burst_cnt!==0)

        $display("(%0t)(%m) ERROR !!!  burst_cnt should be 0 because this is a single access", $time);

      else

        single_cnt_rx=single_cnt_rx+1;

    end

    else if(eth_ma_wb_cyc_o & !eth_ma_wb_we_o & eth_ma_wb_cti_o==3'b000) begin

      if(burst_cnt!==0)

        $display("(%0t)(%m) ERROR !!!  burst_cnt should be 0 because this is a single access", $time);

      else

        single_cnt_tx=single_cnt_tx+1;

    end

    else if(eth_ma_wb_cyc_o & eth_ma_wb_cti_o==3'b010) begin // burst in progress

      burst_cnt=burst_cnt+1;

    end

    else if(eth_ma_wb_cyc_o & eth_ma_wb_we_o & eth_ma_wb_cti_o==3'b111 & burst_cnt==(`ETH_BURST_LENGTH-1)) begin

      burst_cnt_rx=burst_cnt_rx+1;

      burst_cnt=0;

    end

    else if(eth_ma_wb_cyc_o & !eth_ma_wb_we_o & eth_ma_wb_cti_o==3'b111 & burst_cnt==(`ETH_BURST_LENGTH-1)) begin

      burst_cnt_tx=burst_cnt_tx+1;

      burst_cnt=0;

    end

    else

      $display("(%0t)(%m) ERROR !!!  Unknown cycle type or sequence", $time);

  end

end

`endif  // ETH_WISHBONE_B3

task initialize_txbd;

  input [6:0] txbd_num;

  integer i;

  integer bd_status_addr, buf_addr, bd_ptr_addr;

  for(i=0; i<txbd_num; i=i+1) begin

    buf_addr = `TX_BUF_BASE + i * 32'h600;

    bd_status_addr = `TX_BD_BASE + i * 8;

    bd_ptr_addr = bd_status_addr + 4;

    // Initializing BD - status

    if(i==txbd_num-1)

      eth_host.wb_write(bd_status_addr, 4'hf, 32'h00007800);    // last BD: + WRAP

    else

      eth_host.wb_write(bd_status_addr, 4'hf, 32'h00005800);    // IRQ + PAD + CRC

    eth_host.wb_write(bd_ptr_addr, 4'hf, buf_addr);             // Initializing BD - pointer

  end

endtask // initialize_txbd

task initialize_rxbd;

  input [6:0] rxbd_num;

  integer i;

  integer bd_status_addr, buf_addr, bd_ptr_addr;

  for(i=0; i<rxbd_num; i=i+1) begin

    buf_addr = `RX_BUF_BASE + i * 32'h600;

    bd_status_addr = `RX_BD_BASE + i * 8;

    bd_ptr_addr = bd_status_addr + 4;

    // Initializing BD - status

    if(i==rxbd_num-1)

      eth_host.wb_write(bd_status_addr, 4'hf, 32'h0000e000);    // last BD: + WRAP

    else

      eth_host.wb_write(bd_status_addr, 4'hf, 32'h0000c000);    // IRQ + PAD + CRC

    eth_host.wb_write(bd_ptr_addr, 4'hf, buf_addr);             // Initializing BD - pointer

  end

endtask // initialize_rxbd

task set_packet;

  input  [15:0] len;

  input   [7:0] start_data;

  integer i, sd;

  integer bd_status_addr, bd_ptr_addr, buffer, bd;

  begin

    sd = start_data;

    bd_status_addr = `TX_BD_BASE + packet_ready_cnt * 8;

    bd_ptr_addr = bd_status_addr + 4;

    // Reading BD + buffer pointer

    eth_host.wb_read(bd_status_addr, 4'hf, bd);

    eth_host.wb_read(bd_ptr_addr, 4'hf, buffer);

    while(bd & `ETH_TX_BD_READY) begin  // Buffer is ready. Don't touch !!!

      repeat(100) @(posedge wb_clk_o);

      i=i+1;

      eth_host.wb_read(bd_status_addr, 4'hf, bd);

      if(i>1000)  begin

        $display("(%0t)(%m)Waiting for TxBD ready to clear timeout", $time);

        $stop;

      end

    end

    // First write might not be word allign.

    if(buffer[1:0]==1)  begin

      eth_host.wb_write(buffer-1, 4'h7, {8'h0, sd[7:0], sd[7:0]+3'h1, sd[7:0]+3'h2});

      sd=sd+3;

      i=3;

    end

    else if(buffer[1:0]==2)  begin

      eth_host.wb_write(buffer-2, 4'h3, {16'h0, sd[7:0], sd[7:0]+3'h1});

      sd=sd+2;

      i=2;

    end

    else if(buffer[1:0]==3)  begin

      eth_host.wb_write(buffer-3, 4'h1, {24'h0, sd[7:0]});

      sd=sd+1;

      i=1;

    end

    else

      i=0;

    for(i=i; i<len-4; i=i+4) begin   // Last 0-3 bytes are not written

      eth_host.wb_write(buffer+i, 4'hf, {sd[7:0], sd[7:0]+3'h1, sd[7:0]+3'h2, sd[7:0]+3'h3});

      sd=sd+4;

    end

    // Last word

    if(len-i==3)

      eth_host.wb_write(buffer+i, 4'he, {sd[7:0], sd[7:0]+3'h1, sd[7:0]+3'h2, 8'h0});

    else if(len-i==2)

      eth_host.wb_write(buffer+i, 4'hc, {sd[7:0], sd[7:0]+3'h1, 16'h0});

    else if(len-i==1)

      eth_host.wb_write(buffer+i, 4'h8, {sd[7:0], 24'h0});

    else if(len-i==4)

      eth_host.wb_write(buffer+i, 4'hf, {sd[7:0], sd[7:0]+3'h1, sd[7:0]+3'h2, sd[7:0]+3'h3});

    else

      $display("(%0t)(%m) ERROR", $time);

    // Checking WRAP bit

    if(bd & `ETH_TX_BD_WRAP)

      packet_ready_cnt = 0;

    else

      packet_ready_cnt = packet_ready_cnt+1;

    // Writing len to bd

    bd = bd | (len<<16);

    eth_host.wb_write(bd_status_addr, 4'hf, bd);

  end

endtask // set_packet

task send_packet;

  integer bd_status_addr, bd_ptr_addr, buffer, bd;

  begin

    bd_status_addr = `TX_BD_BASE + send_packet_cnt * 8;

    bd_ptr_addr = bd_status_addr + 4;

    // Reading BD + buffer pointer

    eth_host.wb_read(bd_status_addr, 4'hf, bd);

    eth_host.wb_read(bd_ptr_addr, 4'hf, buffer);

    if(bd & `ETH_TX_BD_WRAP)

      send_packet_cnt=0;

    else

      send_packet_cnt=send_packet_cnt+1;

    // Setting ETH_TX_BD_READY bit

    bd = bd | `ETH_TX_BD_READY;

    eth_host.wb_write(bd_status_addr, 4'hf, bd);

  end

endtask // send_packet

task GetDataOnMRxD;

  input [15:0] Len;

  input [31:0] TransferType;

  integer tt;

  begin

    @ (posedge mrx_clk);

    #1MRxDV=1'b1;

    for(tt=0; tt<15; tt=tt+1)

      begin

        MRxD=4'h5;              // preamble

        @ (posedge mrx_clk);

        #1;

      end

    MRxD=4'hd;                // SFD

    for(tt=1; tt<(Len+1); tt=tt+1)

      begin

        @ (posedge mrx_clk);

        #1;

            if(TransferType == `UNICAST_XFR && tt == 1)

                MRxD= 4'h0;   // Unicast transfer

              else if(TransferType == `BROADCAST_XFR && tt < 7)

                MRxD = 4'hf;

              else

          MRxD=tt[3:0]; // Multicast transfer

        @ (posedge mrx_clk);

              #1;

              if(TransferType == `BROADCAST_XFR && tt < 7)

                MRxD = 4'hf;

              else

          MRxD=tt[7:4];

      end

    @ (posedge mrx_clk);

    #1;

    MRxDV=1'b0;

  end

endtask // GetDataOnMRxD

endmodule