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//////////////////////////////////////////////////////////////////////
////                                                              ////
////  Ethernet MAC Stimulus                                       ////
////                                                              ////
////  Description                                                 ////
////  Ethernet MAC stimulus tasks. Taken from the project         ////
////  testbench in the ethmac core.                               ////
////                                                              ////
////  To Do:                                                      ////
////                                                              ////
////                                                              ////
////  Author(s):                                                  ////
////      - Tadej Markovic, tadej@opencores.org                   ////
////      - Igor Mohor,     igorM@opencores.org                   ////
////      - Julius Baxter   julius.baxter@orsoc.se                ////
////                                                              ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
////                                                              ////
//// Copyright (C) 2009 Authors and OPENCORES.ORG                 ////
////                                                              ////
//// 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                     ////
////                                                              ////
//////////////////////////////////////////////////////////////////////
`define TIME $display("Time: %0t", $time)
 
// Defines for ethernet test to trigger sending/receiving
// Is straight forward when using RTL design, but if using netlist then paths to
// the RX/TX enabled bits depend on synthesis tool, etc, but ones here appear to
// work with design put through Synplify, with hierarchy maintained.
`define ETH_TOP dut.ethmac0
`define ETH_BD_RAM_PATH `ETH_TOP.wishbone.bd_ram
`define ETH_MODER_PATH `ETH_TOP.ethreg1.MODER_0
 
`ifdef RTL_SIM
 `ifdef ethmac_IS_GATELEVEL
  `define ETH_MODER_TXEN_BIT `ETH_MODER_PATH.r_TxEn;
  `define ETH_MODER_RXEN_BIT `ETH_MODER_PATH.r_RxEn;
 `else
  `define ETH_MODER_TXEN_BIT `ETH_MODER_PATH.DataOut[1];
  `define ETH_MODER_RXEN_BIT `ETH_MODER_PATH.DataOut[0];
 `endif
`endif
 
`ifdef GATE_SIM
 `define ETH_MODER_TXEN_BIT `ETH_MODER_PATH.r_TxEn;
 `define ETH_MODER_RXEN_BIT `ETH_MODER_PATH.r_RxEn;
`endif
 
reg [15:0] eth_stim_rx_packet_length;
reg [7:0] st_data;
reg [31:0] lfsr;
integer lfsr_last_byte;
 
// Is number of ethernet packets to send if doing the eth-rx test.
parameter eth_stim_num_rx_only_num_packets = 12; // Set to 0 for continuous RX
parameter eth_stim_num_rx_only_packet_size = 60;
parameter eth_stim_num_rx_only_packet_size_change = 2'b01;  // 2'b01: Increment
parameter eth_stim_num_rx_only_packet_size_change_amount = 127;
parameter eth_stim_num_rx_only_IPG = 800_000; // ps
 
// Do call/response test
reg eth_stim_do_rx_reponse_to_tx;
reg eth_stim_do_overflow_test;
 
parameter num_tx_bds = 16;
parameter num_tx_bds_mask = 4'hf;
parameter num_rx_bds = 16;
parameter num_rx_bds_mask = 4'hf;
parameter max_eth_packet_size = 16'h0600;
 
// If running eth-rxtxbig test (sending and receiving maximum packets), then
// set this parameter to the max packet size, otherwise min packet size
//parameter rx_while_tx_min_packet_size = max_eth_packet_size;
parameter rx_while_tx_min_packet_size = 32;
 
// Use the smallest possible IPG
parameter eth_stim_use_min_IPG = 0;
parameter eth_stim_IPG_delay_max = 100_000_000; // Maximum 100 us
//parameter eth_stim_IPG_delay_max = 100_000_000; // Maximum 100mS between packets
parameter eth_stim_IPG_min_10mb = 9600_000; // 9.6 uS
parameter eth_stim_IPG_min_100mb = 800_000; // 860+~100 = 960 nS 100MBit min IPG
parameter eth_stim_check_rx_packet_contents = 1;
parameter eth_stim_check_tx_packet_contents = 1;
 
parameter eth_inject_errors = 0;
 
// When running simulations where you don't want to feed packets to the design
// like this...
parameter eth_stim_disable_rx_stim = 0;
 
// Delay between seeing that the buffer descriptor for an RX packet says it's
// been received and ending up in the memory.
// For 25MHz sdram controller, use following:
//parameter  Td_rx_packet_check = (`BOARD_CLOCK_PERIOD * 2000);
// For 64MHz sdram controller, use following:
parameter  Td_rx_packet_check = (`BOARD_CLOCK_PERIOD * 500);
 
integer expected_rxbd;// init to 0
integer expected_txbd;
 
wire ethmac_rxen;
wire ethmac_txen;
assign ethmac_rxen = eth_stim_disable_rx_stim ? 0 : `ETH_MODER_RXEN_BIT;
assign ethmac_txen = `ETH_MODER_TXEN_BIT;
 
integer eth_rx_num_packets_sent = 0;
integer eth_rx_num_packets_checked = 0;
integer num_tx_packets = 1;
 
integer rx_packet_lengths [0:1023]; // Array of packet lengths
 
 
integer speed_loop;
 
// When txen is (re)enabled, the tx bd pointer goes back to 0
always @(posedge ethmac_txen)
  expected_txbd = 0;
 
   reg  eth_stim_waiting;
 
initial
  begin
     #1;
     //lfsr = 32'h84218421; // Init pseudo lfsr
     lfsr = 32'h00700001; // Init pseudo lfsr
     lfsr_last_byte = 0;
 
     eth_stim_waiting = 1;
     expected_rxbd = num_tx_bds; // init this here
 
     eth_stim_do_rx_reponse_to_tx = 0;
     eth_stim_do_overflow_test = 0;
 
     while (eth_stim_waiting) // Loop, waiting for enabling of MAC by software
       begin
          #100;
          // If RX enable and not TX enable...
          if(ethmac_rxen === 1'b1 & !(ethmac_txen===1'b1))
            begin
               if (eth_inject_errors)
                 begin
                    do_rx_only_stim(16, 64, 0, 0);
                    do_rx_only_stim(128, 64, 1'b1, 8);
                    do_rx_only_stim(256, 64, 1'b1, 4);
                    eth_stim_waiting = 0;
                 end
               else
                 begin
                    //do_rx_only_stim(eth_stim_num_rx_only_num_packets, 
                    //eth_stim_num_rx_only_packet_size, 0, 0);
 
                    // Call packet send loop directly. No error injection.
                    send_packet_loop(eth_stim_num_rx_only_num_packets,
                                     eth_stim_num_rx_only_packet_size,
                                     eth_stim_num_rx_only_packet_size_change,
                                     eth_stim_num_rx_only_packet_size_change_amount,
                                     eth_phy0.eth_speed,     // Speed
                                     eth_stim_num_rx_only_IPG, // IPG
                               48'h0012_3456_789a, 48'h0708_090A_0B0C, 1,
                               0, 0, 0);
 
                    eth_stim_waiting = 0;
                 end
            end // if (ethmac_rxen === 1'b1 & !(ethmac_txen===1'b1))
          // If both RX and TX enabled
          else if (ethmac_rxen === 1'b1 & ethmac_txen===1'b1)
            begin
               // Both enabled - let's wait for the first packet transmitted
               // to see what stimulus we should provide
               while (num_tx_packets==1)
                 #1000;
 
               $display("* ethmac RX/TX test request: %x", eth_phy0.tx_mem[0]);
 
               // Check the first received byte's value
                 case (eth_phy0.tx_mem[0])
                   0:
                     begin
                        // kickoff call/response here
                        eth_stim_do_rx_reponse_to_tx = 1;
                     end
                   1:
                     begin
                        // kickoff overflow test here
                        eth_stim_do_overflow_test = 1;
                     end
                   default:
                     begin
                        do_rx_while_tx_stim(1400);
                     end
                 endcase // case (eth_phy0.tx_mem[0])
 
               eth_stim_waiting = 0;
            end
       end // while (eth_stim_waiting)     
 
  end // initial begin
 
   // Main Ethernet RX testing stimulus task.
   // Sends a set of packets at both speeds
   task do_rx_only_stim;
      input [31:0] num_packets;
      input [31:0] start_packet_size;
      input        inject_errors;
      input [31:0] inject_errors_mod;
 
      begin
 
         for(speed_loop=1;speed_loop<3;speed_loop=speed_loop+1)
           begin
 
              send_packet_loop(num_packets, start_packet_size, 2'b01, 1,
                               speed_loop[0], 10000,
                               48'h0012_3456_789a, 48'h0708_090A_0B0C, 1,
                               inject_errors, inject_errors_mod, 0);
 
           end
 
      end
   endtask // do_rx_stim
 
   // Generate RX packets while there's TX going on
   // Sends a set of packets at both speeds
   task do_rx_while_tx_stim;
      input [31:0] num_packets;
      reg [31:0] IPG; // Inter-packet gap
      reg [31:0] packet_size;
 
      integer    j;
      begin
 
         for(j=0;j<num_packets;j=j+1)
           begin
              // Determine delay between RX packets:
 
              if (eth_stim_use_min_IPG)
                begin
                   // Assign based on whether we're in 100mbit or 10mbit mode
                   IPG = eth_phy0.eth_speed ? eth_stim_IPG_min_100mb :
                         eth_stim_IPG_min_10mb;
                   // Add a little bit of variability
                   // Add up to 15
                   IPG = IPG + ($random & 32'h000000f);
                end
              else
                begin
                   IPG = $random;
 
                   while (IPG > eth_stim_IPG_delay_max)
                     IPG = IPG / 2;
 
 
                end
              $display("do_rx_while_tx IPG = %0d", IPG);
              // Determine size of next packet:
              if (rx_while_tx_min_packet_size == max_eth_packet_size)
                // We want to transmit biggest packets possible, easy case
                packet_size = max_eth_packet_size - 4;
              else
                begin
                   // Constrained random sized packets
                   packet_size = $random;
 
                   while (packet_size > (max_eth_packet_size-4))
                     packet_size = packet_size / 2;
 
                   // Now divide by least significant bits of j
                   packet_size = packet_size / {29'd0,j[1:0],1'b1};
                   if (packet_size < 60)
                     packet_size = packet_size + 60;
                end
 
              $display("do_rx_while_tx packet_size = %0d", packet_size);
              send_packet_loop(1, packet_size, 2'b01, 1, eth_phy0.eth_speed,
                               IPG, 48'h0012_3456_789a,
                               48'h0708_090A_0B0C, 1, 1'b0, 0, 0);
 
              // If RX enable went low, wait for it go high again
              if (ethmac_rxen===1'b0)
                begin
 
                   while (ethmac_rxen===1'b0)
                     begin
                        @(posedge ethmac_rxen);
                        #10000;
                     end
 
                   // RX disabled and when re-enabled we reset the buffer descriptor number
                   expected_rxbd = num_tx_bds;
 
                end
 
           end // for (j=0;j<num_packets;j=j+1)
      end
   endtask // do_rx_stim
 
   // Registers used in detecting transmitted packets
   reg eth_stim_tx_loop_keep_polling;
   reg [31:0] ethmac_txbd_lenstat, ethmac_last_txbd_lenstat;
   reg        eth_stim_detected_packet_tx;
 
   // If in call-response mode, whenever we receive a TX packet, we generate
   // one and send it back
   always @(negedge eth_stim_detected_packet_tx)
     begin
        if (eth_stim_do_rx_reponse_to_tx & ethmac_rxen)
          // Continue if we are enabled
          do_rx_response_to_tx();
     end
 
 
   // If in call-response mode, whenever we receive a TX packet, we generate
   // one and send it back
   always @(posedge eth_stim_do_overflow_test)
     begin
          // Continue if we are enabled
          do_overflow_stimulus();
     end
 
   // Generate RX packet in rsponse to TX packet
   task do_rx_response_to_tx;
      //input unused;
 
     reg [31:0] IPG; // Inter-packet gap
      reg [31:0] packet_size;
 
      integer    j;
      begin
 
         // Get packet size test wants us to send
         packet_size = {eth_phy0.tx_mem[0],eth_phy0.tx_mem[1],
                        eth_phy0.tx_mem[2],eth_phy0.tx_mem[3]};
 
 
         IPG = {eth_phy0.tx_mem[4],eth_phy0.tx_mem[5],
                eth_phy0.tx_mem[6],eth_phy0.tx_mem[7]};
 
 
         $display("do_rx_response_to_tx IPG = %0d", IPG);
         if (packet_size == 0)
           begin
              // Constrained random sized packets
              packet_size = $random;
 
              while (packet_size > (max_eth_packet_size-4))
                packet_size = packet_size / 2;
 
              if (packet_size < 60)
                packet_size = packet_size + 60;
           end
 
         $display("do_rx_response_to_tx packet_size = %0d", packet_size);
         send_packet_loop(1, packet_size, 2'b01, 1, eth_phy0.eth_speed,
                          IPG, 48'h0012_3456_789a,
                          48'h0708_090A_0B0C, 1, 1'b0, 0, 0);
 
         // If RX enable went low, wait for it go high again
         if (ethmac_rxen===1'b0)
           begin
 
              while (ethmac_rxen===1'b0)
                begin
                   @(posedge ethmac_rxen);
                   #10000;
                end
 
              // RX disabled and when re-enabled we reset the buffer 
              // descriptor number
              expected_rxbd = num_tx_bds;
 
           end
 
      end
   endtask // do_rx_response_to_tx
 
   // Generate RX packet in rsponse to TX packet
   task do_overflow_stimulus;
      //input unused;
      reg [31:0] IPG; // Inter-packet gap
      reg [31:0] packet_size;
 
      integer    j;
 
      begin
 
         // Maximum packet size
         packet_size = 1500;
 
         // Minimum IPG
         IPG = eth_stim_IPG_min_100mb;
 
         $display("do_overflow_stimulus IPG = %0d", IPG);
 
 
         $display("do_overflow_stimulus packetsize = %0d", packet_size);
 
         send_packet_loop(num_rx_bds, packet_size, 2'b01, 1,
                          eth_phy0.eth_speed,
                          IPG, 48'h0012_3456_789a,
                          48'h0708_090A_0B0C, 1, 1'b0, 0, 0);
 
         // This one should cause overflow, don't check it gets there OK
         send_packet_loop(1, packet_size, 2'b01, 1,
                          eth_phy0.eth_speed,
                          IPG, 48'h0012_3456_789a,
                          48'h0708_090A_0B0C, 1, 1'b0, 0, 1);
 
         // Wind back expected RXBD number
         if (expected_rxbd == num_tx_bds)
           expected_rxbd = num_tx_bds + num_rx_bds - 1;
         else
           expected_rxbd = expected_rxbd - 1;
 
         // This one should cause overflow, don't check it gets there OK
         send_packet_loop(1, packet_size, 2'b01, 1,
                          eth_phy0.eth_speed,
                          IPG, 48'h0012_3456_789a,
                          48'h0708_090A_0B0C, 1, 1'b0, 0, 1);
 
         // Wind back expected RXBD number
         if (expected_rxbd == num_tx_bds)
           expected_rxbd = num_tx_bds + num_rx_bds - 1;
         else
           expected_rxbd = expected_rxbd - 1;
 
 
         // This one should cause overflow, don't check it gets there OK
         send_packet_loop(1, packet_size, 2'b01, 1,
                          eth_phy0.eth_speed,
                          IPG, 48'h0012_3456_789a,
                          48'h0708_090A_0B0C, 1, 1'b0, 0, 1);
 
         // Wind back expected RXBD number
         if (expected_rxbd == num_tx_bds)
           expected_rxbd = num_tx_bds + num_rx_bds - 1;
         else
           expected_rxbd = expected_rxbd - 1;
 
 
         // This one should cause overflow, don't check it gets there OK
         send_packet_loop(1, packet_size, 2'b01, 1,
                          eth_phy0.eth_speed,
                          IPG, 48'h0012_3456_789a,
                          48'h0708_090A_0B0C, 1, 1'b0, 0, 1);
 
         // Wind back expected RXBD number
         if (expected_rxbd == num_tx_bds)
           expected_rxbd = num_tx_bds + num_rx_bds - 1;
         else
           expected_rxbd = expected_rxbd - 1;
 
 
         // Wait until a buffer descriptor becomes available
         while(`ETH_TOP.wishbone.RxBDRead==1'b1)
           #1000;
 
         $display("%t: RxBDRead gone low",$time);
         #10000;
 
 
 
         send_packet_loop(1, packet_size, 2'b01, 1, eth_phy0.eth_speed,
                          IPG, 48'h0012_3456_789a,
                          48'h0708_090A_0B0C, 1, 1'b0, 0, 0);
 
 
         // If RX enable went low, wait for it go high again
         if (ethmac_rxen===1'b0)
           begin
 
              while (ethmac_rxen===1'b0)
                begin
                   @(posedge ethmac_rxen);
                   #10000;
                end
 
              // RX disabled and when re-enabled we reset the buffer 
              // descriptor number
              expected_rxbd = num_tx_bds;
 
           end
 
      end
   endtask // do_overflow_stimulus
 
 
   //
   // always@() to check the TX buffer descriptors
   //
   always @(posedge ethmac_txen)
     begin
         ethmac_last_txbd_lenstat = 0;
         eth_stim_tx_loop_keep_polling=1;
         // Wait on the TxBD Ready bit
         while(eth_stim_tx_loop_keep_polling)
           begin
              #10;
              get_bd_lenstat(expected_txbd, ethmac_txbd_lenstat);
              // Check if we've finished transmitting this BD
              if (!ethmac_txbd_lenstat[15] & ethmac_last_txbd_lenstat[15])
                // Falling edge of TX BD Ready
                eth_stim_detected_packet_tx = 1;
 
              ethmac_last_txbd_lenstat = ethmac_txbd_lenstat;
 
              // If TX en goes low then exit
              if (!ethmac_txen)
                eth_stim_tx_loop_keep_polling = 0;
              else if (eth_stim_detected_packet_tx)
                begin
                   // Wait until the eth_phy has finished receiving it
                   while (eth_phy0.mtxen_i === 1'b1)
                     #10;
 
                   $display("(%t) Check TX packet: bd %d: 0x%h",$time,
                            expected_txbd, ethmac_txbd_lenstat);
 
                   // Check the TXBD, see if the packet transmitted OK
                   if (ethmac_txbd_lenstat[8] | ethmac_txbd_lenstat[3])
                     begin
                        // Error occured
                        `TIME;
                        $display("*E TX Error of packet %0d detected.",
                                 num_tx_packets);
                        $display(" TX BD %0d = 0x%h", expected_txbd,
                                 ethmac_txbd_lenstat);
                        if (ethmac_txbd_lenstat[8])
                          $display(" Underrun in MAC during TX");
                        if (ethmac_txbd_lenstat[3])
                          $display(" Retransmission limit hit");
 
                        $finish;
                     end
                   else
                     begin
                        // Packet was OK, let's compare the contents we 
                        // received with those that were meant to be transmitted
                        if (eth_stim_check_tx_packet_contents)
                          begin
                             check_tx_packet(expected_txbd);
                             expected_txbd = (expected_txbd + 1) &
                                             num_tx_bds_mask;
                             num_tx_packets = num_tx_packets + 1;
                             eth_stim_detected_packet_tx = 0;
                          end
                     end
                end
           end // while (eth_stim_tx_loop_keep_polling)
     end // always @ (posedge ethmac_txen)
 
 
 
 
`ifdef XILINX_DDR2
   // Gets word from correct bank
   task get_32bitword_from_xilinx_ddr2;
      input [31:0] addr;
      output [31:0] insn;
      reg [16*8-1:0] ddr2_array_line0,ddr2_array_line1,ddr2_array_line2,
                     ddr2_array_line3;
      integer        word_in_line_num;
      begin
        // Get our 4 128-bit chunks (8 half-words in each!! Confused yet?), 
        // 16 words total
         gen_cs[0].gen[0].u_mem0.memory_read(addr[28:27],addr[26:13],
                                             {addr[12:6],3'd0},
                                             ddr2_array_line0);
         gen_cs[0].gen[1].u_mem0.memory_read(addr[28:27],addr[26:13],
                                             {addr[12:6],3'd0},
                                             ddr2_array_line1);
         gen_cs[0].gen[2].u_mem0.memory_read(addr[28:27],addr[26:13],
                                             {addr[12:6],3'd0},
                                             ddr2_array_line2);
         gen_cs[0].gen[3].u_mem0.memory_read(addr[28:27],addr[26:13],
                                             {addr[12:6],3'd0},
                                             ddr2_array_line3);
         case (addr[5:2])
           4'h0:
             begin
                insn[15:0] = ddr2_array_line0[15:0];
                insn[31:16] = ddr2_array_line1[15:0];
             end
           4'h1:
             begin
                insn[15:0] = ddr2_array_line2[15:0];
                insn[31:16] = ddr2_array_line3[15:0];
             end
           4'h2:
             begin
                insn[15:0] = ddr2_array_line0[31:16];
                insn[31:16] = ddr2_array_line1[31:16];
             end
           4'h3:
             begin
                insn[15:0] = ddr2_array_line2[31:16];
                insn[31:16] = ddr2_array_line3[31:16];
             end
           4'h4:
             begin
                insn[15:0] = ddr2_array_line0[47:32];
                insn[31:16] = ddr2_array_line1[47:32];
             end
           4'h5:
             begin
                insn[15:0] = ddr2_array_line2[47:32];
                insn[31:16] = ddr2_array_line3[47:32];
             end
           4'h6:
             begin
                insn[15:0] = ddr2_array_line0[63:48];
                insn[31:16] = ddr2_array_line1[63:48];
             end
           4'h7:
             begin
                insn[15:0] = ddr2_array_line2[63:48];
                insn[31:16] = ddr2_array_line3[63:48];
             end
           4'h8:
             begin
                insn[15:0] = ddr2_array_line0[79:64];
                insn[31:16] = ddr2_array_line1[79:64];
             end
           4'h9:
             begin
                insn[15:0] = ddr2_array_line2[79:64];
                insn[31:16] = ddr2_array_line3[79:64];
             end
           4'ha:
             begin
                insn[15:0] = ddr2_array_line0[95:80];
                insn[31:16] = ddr2_array_line1[95:80];
             end
           4'hb:
             begin
                insn[15:0] = ddr2_array_line2[95:80];
                insn[31:16] = ddr2_array_line3[95:80];
             end
           4'hc:
             begin
                insn[15:0] = ddr2_array_line0[111:96];
                insn[31:16] = ddr2_array_line1[111:96];
             end
           4'hd:
             begin
                insn[15:0] = ddr2_array_line2[111:96];
                insn[31:16] = ddr2_array_line3[111:96];
             end
           4'he:
             begin
                insn[15:0] = ddr2_array_line0[127:112];
                insn[31:16] = ddr2_array_line1[127:112];
             end
           4'hf:
             begin
                insn[15:0] = ddr2_array_line2[127:112];
                insn[31:16] = ddr2_array_line3[127:112];
             end
         endcase // case (addr[5:2])
      end
   endtask
 
   task get_byte_from_xilinx_ddr2;
      input [31:0] addr;
      output [7:0] data_byte;
      reg [31:0]   word;
      begin
         get_32bitword_from_xilinx_ddr2(addr, word);
         case (addr[1:0])
           2'b00:
             data_byte = word[31:24];
           2'b01:
             data_byte = word[23:16];
           2'b10:
             data_byte = word[15:8];
           2'b11:
             data_byte = word[7:0];
         endcase // case (addr[1:0])
      end
   endtask // get_byte_from_xilinx_ddr2
 
`endif
 
`ifdef XILINX_DDR2
   task sync_controller_cache_xilinx_ddr;
      begin
         // Sync cache (writeback dirty lines) with external memory
         dut.xilinx_ddr2_0.xilinx_ddr2_if0.do_sync;
         // Wait for it to occur.
         while (dut.xilinx_ddr2_0.xilinx_ddr2_if0.sync)
           #100;
 
         // Wait just incase writeback of all data hasn't fully occurred.
         // 4uS, in case RAM needs to refresh while writing back.
         #4_000_000;
 
 
      end
   endtask // sync_controller_cache_xilinx_ddr
`endif
 
 
   //
   // Check packet TX'd by MAC was good
   // 
   task check_tx_packet;
      input [31:0] tx_bd_num;
 
      reg [31:0]   tx_bd_addr;
      reg [7:0]    phy_byte;
 
      reg [31:0]   txpnt_wb; // Pointer in array to where data should be
      reg [24:0]   txpnt_sdram; // Index in array of shorts for data in SDRAM 
                                // part
      reg [21:0]   buffer;
      reg [7:0]    sdram_byte;
      reg [31:0]   tx_len_bd;
 
      integer      i;
      integer      failure;
      begin
         failure = 0;
 
         get_bd_lenstat(tx_bd_num, tx_len_bd);
 
         tx_len_bd = {15'd0,tx_len_bd[31:16]};
 
         // Check, if length didn't have to be padded, that
         // amount transmitted was correct
         if ((tx_len_bd > 60)&(tx_len_bd != (eth_phy0.tx_len-4)))
           begin
              $display("*E TX packet sent length, %0d != length in TX BD, %0d",
                       eth_phy0.tx_len-4, tx_len_bd);
              #100;
              $finish;
           end
 
`ifdef XILINX_DDR2
         sync_controller_cache_xilinx_ddr;
`endif
 
         get_bd_addr(tx_bd_num, tx_bd_addr);
 
         // We're never going to be using more than about 256K of receive buffer
         // so let's lop off the top bit of the address pointer - we only want
         // the offset from the base of the memory bank
         txpnt_wb = {14'd0,tx_bd_addr[17:0]};
         txpnt_sdram = tx_bd_addr[24:0];
 
         // Variable we'll use for index in the PHY's TX buffer
         buffer = 0; // Start of TX data
 
         for (i=0;i<tx_len_bd;i=i+1)
           begin
              //$display("Checking address in tx bd 0x%0h",txpnt_sdram);
              sdram_byte = 8'hx;
`ifdef RAM_WB
              sdram_byte = dut.ram_wb0.ram_wb_b3_0.get_mem8(txpnt_sdram);
`else
 `ifdef VERSATILE_SDRAM
              sdram0.get_byte(txpnt_sdram,sdram_byte);
 `else
  `ifdef XILINX_DDR2
              get_byte_from_xilinx_ddr2(txpnt_sdram, sdram_byte);
  `else
              $display(" * Error: sdram_byte was %x", sdram_byte);
 
              $display(" * eth_stim needs to be able to access the main memory to check packet rx/tx");
              $finish;
 
  `endif
 `endif
`endif
 
              phy_byte = eth_phy0.tx_mem[buffer];
              // Debugging output
              //$display("txpnt_sdram = 0x%h, sdram_byte = 0x%h, buffer = 0x%h, phy_byte = 0x%h", txpnt_sdram,  sdram_byte, buffer, phy_byte);
 
              if (phy_byte !== sdram_byte)
                begin
                   `TIME;
                   $display("*E Wrong byte (%d) of TX packet! ram = %h, phy = %h",buffer, sdram_byte, phy_byte);
                   failure = 1;
                end
 
              buffer = buffer + 1;
 
              txpnt_sdram = txpnt_sdram+1;
 
           end // for (i=0;i<tx_len_bd;i=i+1)
 
         if (failure)
           begin
              #100
                `TIME;
              $display("*E Error transmitting packet %0d (%0d bytes). Finishing simulation", num_tx_packets, tx_len_bd);
              get_bd_lenstat(tx_bd_num, tx_len_bd);
              $display("   TXBD lenstat: 0x%0h",tx_len_bd);
              $display("   TXBD address: 0x%0h",tx_bd_addr);
              $finish;
           end
         else
           begin
              #1 $display( "(%0t)(%m) TX packet %0d: %0d bytes in memory OK!",$time,num_tx_packets, tx_len_bd);
 
           end
 
 
      end
   endtask // check_tx_packet
 
 
   // Local buffer of "sent" data to the ethernet MAC, we will check against
   // Size of our local buffer in bytes
   parameter eth_rx_sent_circbuf_size = (16*1024);
   parameter eth_rx_sent_circbuf_size_mask = eth_rx_sent_circbuf_size - 1;
   integer eth_rx_sent_circbuf_fill_ptr = 0;
   integer eth_rx_sent_circbuf_read_ptr = 0;
   // The actual buffer
   reg [7:0] eth_rx_sent_circbuf [0:eth_rx_sent_circbuf_size-1];
 
 
   //
   // Task to send a set of packets
   //
   task send_packet_loop;
      input [31:0] num_packets;
      input [31:0] length;
      input [1:0]  length_change; // 0 = none, 1 = incr, 2 = decrement
      input [31:0] length_change_size; // Size to change by
      input        speed;
      input [31:0] back_to_back_delay; // #delay setting between packets
      input [47:0] dst_mac;
      input [47:0] src_mac;
      input        random_fill;
      input        random_errors;
      input [31:0] random_error_mod;
      input        dont_confirm_rx;
      integer      j, k;
      reg          error_this_time;
      integer      error_type; // 0 = rxerr, 1=bad preamble 2=bad crc 3=TODO
      reg [31:0]   rx_bd_lenstat;
      begin
         error_type = 0;
         error_this_time = 0;
 
         if (num_packets == 0)
           // Loop forever when num_packets is 0
           num_packets = 32'h7fffffff;
 
 
         if (speed & !(eth_phy0.control_bit14_10[13] === 1'b1))
           begin
              // write to phy's control register for 100Mbps
              eth_phy0.control_bit14_10 = 5'b01000; // bit 13 set - speed 100
              // Swapping speeds, give some delay
              #10000;
           end
         else if (!speed & !(eth_phy0.control_bit14_10[13] === 1'b0))
           begin
              eth_phy0.control_bit14_10 = 5'b00000; // bit 13 reset - speed 10
              // Swapping speeds, give some delay
              #10000;
           end
 
         eth_phy0.control_bit8_0   = 9'h1_00;
 
         for(j=0;j<num_packets | length <32;j=j+1)
           begin
              eth_stim_rx_packet_length = length[15:0]; // Bytes
              st_data = 8'h0F;
 
              // setup RX packet in buffer - length is without CRC
              set_rx_packet(0, eth_stim_rx_packet_length, 1'b0, dst_mac,
                            src_mac, 16'h0D0E, st_data, random_fill);
 
              set_rx_addr_type(0, dst_mac, src_mac, 16'h0D0E);
 
              // Error type 2 is cause CRC error
              append_rx_crc(0, eth_stim_rx_packet_length, 1'b0,
                            (error_type==2));
 
              if (error_this_time)
                begin
                   if (error_type == 0)
                     // RX ERR assert during transmit
                     eth_phy0.send_rx_packet(64'h0055_5555_5555_5555, 4'h7,
                                             8'hD5, 0,
                                             eth_stim_rx_packet_length+4,
                                             1'b0, 1'b1);
                   else if (error_type == 1)
                     // Incorrect preamble
                     eth_phy0.send_rx_packet(64'h0055_5f55_5555_5555, 4'h7,
                                             8'hD5, 0,
                                             eth_stim_rx_packet_length+4,
                                             1'b0, 1'b0);
                   else
                     // Normal datapacket
                     eth_phy0.send_rx_packet(64'h0055_5555_5555_5555, 4'h7,
                                             8'hD5, 0,
                                             eth_stim_rx_packet_length+4,
                                             1'b0, 1'b0);
                end
              else
                eth_phy0.send_rx_packet(64'h0055_5555_5555_5555, 4'h7, 8'hD5,
                                        0, eth_stim_rx_packet_length+4, 1'b0,
                                        1'b0);
 
 
              // if RX enable still set (might have gone low during this packet
              if (ethmac_rxen)
                begin
                   if (error_this_time || dont_confirm_rx) begin
                     // Put in dummy length, checking function will skip...
                     rx_packet_lengths[(eth_rx_num_packets_sent& 12'h3ff)]=32'heeeeeeee;
 
                      for(k=0;k<length;k=k+1)
                      // skip data  in verify buffer
                        eth_rx_sent_circbuf_read_ptr = (eth_rx_sent_circbuf_read_ptr+1)&
                                                       eth_rx_sent_circbuf_size_mask;
 
                   end
                   else
                     rx_packet_lengths[(eth_rx_num_packets_sent & 12'h3ff)] = length;
 
                   eth_rx_num_packets_sent = eth_rx_num_packets_sent + 1;
 
                end // if (ethmac_rxen)
              else
                begin
                   // Force the loop to finish up                  
                   j = num_packets;
                end
 
 
              // Inter-packet gap
              #back_to_back_delay;
 
              // Update length
              if (length_change == 2'b01)
                length = length + length_change_size;
 
              if ((length_change == 2'b10) &&
                  ((length - length_change_size) > 32))
                length = length - length_change_size;
 
              // Increment error type
              if (error_this_time)
                error_type = error_type + 1;
              if (error_type > 3)
                error_type = 0;
 
 
              // Check if we should put in an error this time
              if (j%random_error_mod == 0)
                error_this_time = 1;
              else
                error_this_time = 0;
 
              eth_phy0.rx_err(0);
 
              // Now wait to check if we have filled up all the RX BDs and
              // the this packet would start writing over them. Only really an
              // issue when doing minimum IPG tests.
              while(((eth_rx_num_packets_sent+1) - eth_rx_num_packets_checked)
                    == num_rx_bds)
                #100;
 
 
           end // for (j=0;j<num_packets | length <32;j=j+1)
      end
   endtask // send_packet_loop
 
   /*
    TASKS for set and check RX packets:
    -----------------------------------
    set_rx_packet
    (rxpnt[31:0], len[15:0], plus_nibble, d_addr[47:0], s_addr[47:0], type_len[15:0], start_data[7:0]);
    check_rx_packet
    (rxpnt_phy[31:0], rxpnt_wb[31:0], len[15:0], plus_nibble, successful_nibble, failure[31:0]);
    */
   task set_rx_packet;
      input  [31:0] rxpnt; // pointer to place in in the phy rx buffer we'll start at
      input [15:0]  len;
      input         plus_dribble_nibble; // if length is longer for one nibble
      input [47:0]  eth_dest_addr;
      input [47:0]  eth_source_addr;
      input [15:0]  eth_type_len;
      input [7:0]   eth_start_data;
      input         random_fill;
      integer       i, sd;
      reg [47:0]    dest_addr;
      reg [47:0]    source_addr;
      reg [15:0]    type_len;
      reg [21:0]    buffer;
      reg           delta_t;
 
      begin
         buffer = rxpnt[21:0];
         dest_addr = eth_dest_addr;
         source_addr = eth_source_addr;
         type_len = eth_type_len;
         sd = eth_start_data;
         delta_t = 0;
         for(i = 0; i < len; i = i + 1)
           begin
              if (i < 6)
                begin
                   eth_phy0.rx_mem[buffer] = dest_addr[47:40];
                   dest_addr = dest_addr << 8;
                end
              else if (i < 12)
                begin
                   eth_phy0.rx_mem[buffer] = source_addr[47:40];
                   source_addr = source_addr << 8;
                end
              else if (i < 14)
                begin
                   eth_phy0.rx_mem[buffer] = type_len[15:8];
                   type_len = type_len << 8;
                end
              else
                begin
                   if (random_fill)
                     begin
                        if (lfsr_last_byte == 0)
                          eth_phy0.rx_mem[buffer] = lfsr[15:8];
                        if (lfsr_last_byte == 1)
                          eth_phy0.rx_mem[buffer] = lfsr[23:16];
                        if (lfsr_last_byte == 2)
                          eth_phy0.rx_mem[buffer] = lfsr[31:24];
                        if (lfsr_last_byte == 3)
                          begin
                             eth_phy0.rx_mem[buffer] = lfsr[7:0];
                             lfsr = {lfsr[30:0],(((lfsr[31] ^ lfsr[6]) ^
                                                  lfsr[5]) ^ lfsr[1])};
                             lfsr_last_byte =  0;
                          end
                        else
                          lfsr_last_byte = lfsr_last_byte + 1;
 
                     end // if (random_fill)               
                   else
                     eth_phy0.rx_mem[buffer] = sd[7:0];
                   sd = sd + 1;
                end // else: !if(i < 14)
 
              // Update our local buffer
              eth_rx_sent_circbuf[eth_rx_sent_circbuf_fill_ptr]
                = eth_phy0.rx_mem[buffer];
              eth_rx_sent_circbuf_fill_ptr = (eth_rx_sent_circbuf_fill_ptr+1)&
                                             eth_rx_sent_circbuf_size_mask;
 
              buffer = buffer + 1;
           end // for (i = 0; i < len; i = i + 1)
 
         delta_t = !delta_t;
         if (plus_dribble_nibble)
           eth_phy0.rx_mem[buffer] = {4'h0, 4'hD /*sd[3:0]*/};
         delta_t = !delta_t;
      end
   endtask // set_rx_packet
 
 
 
 
   task set_rx_addr_type;
      input  [31:0] rxpnt;
      input [47:0]  eth_dest_addr;
      input [47:0]  eth_source_addr;
      input [15:0]  eth_type_len;
      integer       i;
      reg [47:0]    dest_addr;
      reg [47:0]    source_addr;
      reg [15:0]    type_len;
      reg [21:0]    buffer;
      reg           delta_t;
      begin
         buffer = rxpnt[21:0];
         dest_addr = eth_dest_addr;
         source_addr = eth_source_addr;
         type_len = eth_type_len;
         delta_t = 0;
         for(i = 0; i < 14; i = i + 1)
           begin
              if (i < 6)
                begin
                   eth_phy0.rx_mem[buffer] = dest_addr[47:40];
                   dest_addr = dest_addr << 8;
                end
              else if (i < 12)
                begin
                   eth_phy0.rx_mem[buffer] = source_addr[47:40];
                   source_addr = source_addr << 8;
                end
              else // if (i < 14)
                begin
                   eth_phy0.rx_mem[buffer] = type_len[15:8];
                   type_len = type_len << 8;
                end
              buffer = buffer + 1;
           end
         delta_t = !delta_t;
      end
   endtask // set_rx_addr_type
 
 
   // Check if we're using a synthesized version of eth module
`ifdef ethmac_IS_GATELEVEL
 
   // Get the length/status register of the ethernet buffer descriptor
   task get_bd_lenstat;
      input [31:0] bd_num;// Number of ethernet BD to check
      output [31:0] bd_lenstat;
 `ifdef ACTEL
      reg [8:0]    tmp;
      integer      raddr;
 `endif
      begin
 `ifdef ACTEL
 
         // Pull from the Actel memory model
         raddr = `ETH_BD_RAM_PATH.\mem_tile.I_1 .get_address((bd_num*2));
 
         tmp = `ETH_BD_RAM_PATH.\mem_tile.I_1 .MEM_512_9[(raddr*2)];
         bd_lenstat[8:0] = tmp[8:0];
 
         tmp = `ETH_BD_RAM_PATH.\mem_tile.I_1 .MEM_512_9[(raddr*2)+1];
         bd_lenstat[17:9] = tmp[8:0];
 
         raddr = `ETH_BD_RAM_PATH.\mem_tile_0.I_1 .get_address((bd_num*2));
 
         tmp = `ETH_BD_RAM_PATH.\mem_tile_0.I_1 .MEM_512_9[(raddr*2)];
         bd_lenstat[26:18] = tmp[8:0];
 
         tmp = `ETH_BD_RAM_PATH.\mem_tile_0.I_1 .MEM_512_9[(raddr*2)+1];
         bd_lenstat[31:27] = tmp[4:0];
 
         //$display("(%t) read eth bd lenstat %h",$time, bd_lenstat);
 `endif
      end
   endtask // get_bd_lenstat
 
   // Get the length/status register of the ethernet buffer descriptor
   task get_bd_addr;
      input [31:0] bd_num;// Number of the ethernet BD to check
      output [31:0] bd_addr;
 `ifdef ACTEL
      reg [8:0]    tmp;
      integer       raddr;
 `endif
      begin
 `ifdef ACTEL
         // Pull from the Actel memory model
         raddr = `ETH_BD_RAM_PATH.\mem_tile.I_1 .get_address((bd_num*2)+1);
 
         tmp = `ETH_BD_RAM_PATH.\mem_tile.I_1 .MEM_512_9[(raddr*2)];
         bd_addr[8:0] = tmp[8:0];
 
         tmp = `ETH_BD_RAM_PATH.\mem_tile.I_1 .MEM_512_9[(raddr*2)+1];
         bd_addr[17:9] = tmp[8:0];
 
         raddr = `ETH_BD_RAM_PATH.\mem_tile_0.I_1 .get_address((bd_num*2)+1);
 
         tmp = `ETH_BD_RAM_PATH.\mem_tile_0.I_1 .MEM_512_9[(raddr*2)];
         bd_addr[26:18] = tmp[8:0];
 
         tmp = `ETH_BD_RAM_PATH.\mem_tile_0.I_1 .MEM_512_9[(raddr*2)+1];
         bd_addr[31:27] = tmp[4:0];
 
         //$display("(%t) read eth bd%d addr %h",$time,bd_num, bd_addr);
 `endif
      end
   endtask // get_bd_addr
 
`else // !`ifdef ethmac_IS_GATELEVEL
 
   // Get the length/status register of the ethernet buffer descriptor
   task get_bd_lenstat;
      input [31:0] bd_num;// Number of ethernet BD to check
      output [31:0] bd_lenstat;
      begin
         bd_lenstat = `ETH_BD_RAM_PATH.mem[(bd_num*2)];
      end
   endtask // get_bd_lenstat
 
   // Get the length/status register of the ethernet buffer descriptor
   task get_bd_addr;
      input [31:0] bd_num;// Number of the ethernet BD to check
      output [31:0] bd_addr;
      begin
         bd_addr = `ETH_BD_RAM_PATH.mem[((bd_num*2)+1)];
         //$display("(%t) read eth bd%d addr %h",$time,bd_num, bd_addr);
      end
   endtask // get_bd_addr
`endif
 
   // Always block triggered by finishing of transmission of new packet from 
   // send_packet_loop
   integer eth_rx_packet_length_to_check;
 
   always @*
     begin
        // Loop here until:
        // 1 - packets sent is not equal to packets checked (ie. some to check)
        // 2 - we're explicitly disabled for some reason
        // 3 - Receive has been disabled in the MAC
        while((eth_rx_num_packets_sent == eth_rx_num_packets_checked) ||
              !eth_stim_check_rx_packet_contents || !(ethmac_rxen===1'b1))
          #1000;
 
        eth_rx_packet_length_to_check
          = rx_packet_lengths[(eth_rx_num_packets_checked & 12'h3ff)];
 
        if ( eth_rx_packet_length_to_check !==  32'heeeeeeee)
          check_rx_packet(expected_rxbd, 0, eth_rx_packet_length_to_check);
 
        eth_rx_num_packets_checked = eth_rx_num_packets_checked + 1;
 
        expected_rxbd = expected_rxbd + 1;
 
        // Wrap
        if (expected_rxbd == (num_tx_bds + num_rx_bds))
          expected_rxbd = num_tx_bds;
     end
 
   task check_rx_packet;
 
      input [31:0] rx_bd_num;
      input [31:0] rxpnt_phy; // Pointer in array of data in PHY
      input [31:0] len;
 
      reg [31:0]   rx_bd_lenstat;
      reg [31:0]   rx_bd_addr;
      reg [7:0]    phy_byte;
 
      reg [31:0]   rxpnt_wb; // Pointer in array to where data should be
      reg [24:0]   rxpnt_sdram; // byte address from CPU in RAM
      reg [15:0]   sdram_short;
      reg [7:0]    sdram_byte;
 
      integer      i;
      integer      failure;
 
      begin
 
         failure = 0;
 
         // Wait until the buffer descriptor indicates the packet has been 
         // received...
         get_bd_lenstat(rx_bd_num, rx_bd_lenstat);
         while (rx_bd_lenstat & 32'h00008000)// Check Empty bit
           begin
              #10;
              get_bd_lenstat(rx_bd_num, rx_bd_lenstat);
              //$display("(%t) check_rx_packet: poll bd %d: 0x%h",$time,
                //        rx_bd_num, rx_bd_lenstat);
           end
 
 
         // Delay some time - takes a bit for the Wishbone FSM to pipe out the
         // packet over Wishbone and into whatever memory it's going into
         #Td_rx_packet_check;
 
`ifdef XILINX_DDR2
         sync_controller_cache_xilinx_ddr;
`endif
 
         // Ok, buffer filled, let's get its offset in memory
         get_bd_addr(rx_bd_num, rx_bd_addr);
 
         $display("(%t) Check RX packet: bd %d: 0x%h, addr 0x%h",$time,
                  rx_bd_num, rx_bd_lenstat, rx_bd_addr);
 
 
         // We're never going to be using more than about 256KB of receive buffer
         // so let's lop off the top bit of the address pointer - we only want
         // the offset from the base of the memory bank
 
         rxpnt_wb = {14'd0,rx_bd_addr[17:0]};
         rxpnt_sdram = rx_bd_addr[24:0];
 
 
         //$display("RAM pointer for BD is 0x%h, SDRAM addr is 0x%h", rx_bd_addr, rxpnt_sdram);
 
 
         for (i=0;i<len;i=i+1)
           begin
 
              sdram_byte = 8'hx;
 
`ifdef RAM_WB
              sdram_byte = dut.ram_wb0.ram_wb_b3_0.get_mem8(rxpnt_sdram);
`else
 `ifdef XILINX_DDR2
              get_byte_from_xilinx_ddr2(rxpnt_sdram, sdram_byte);
 `else
              $display(" * Error:");
 
              $display(" * eth_stim needs to be able to access the main memory to check packet rx/tx");
              $finish;
 `endif
`endif
 
              phy_byte = eth_rx_sent_circbuf[eth_rx_sent_circbuf_read_ptr];
 
              if (phy_byte !== sdram_byte)
                begin
//                 `TIME;                 
                   $display("*E Wrong byte (%5d) of RX packet %5d. phy mem = %h, ram = %h",
                            i, eth_rx_num_packets_checked, phy_byte, sdram_byte);
                   failure = 1;
                end
 
              eth_rx_sent_circbuf_read_ptr = (eth_rx_sent_circbuf_read_ptr+1)&
                                             eth_rx_sent_circbuf_size_mask;
 
              rxpnt_sdram = rxpnt_sdram+1;
 
           end // for (i=0;i<len;i=i+2)
 
         if (failure)
           begin
              #100
                `TIME;
              $display("*E Recieved packet %0d, length %0d bytes, had an error. Finishing simulation.", eth_rx_num_packets_checked, len);
              $finish;
           end
         else
           begin
              #1 $display( "(%0t)(%m) RX packet %0d: %0d bytes in memory OK!",$time,eth_rx_num_packets_checked, len);
 
           end
      end
   endtask // check_rx_packet
 
 
   //////////////////////////////////////////////////////////////
   // Ethernet CRC Basic tasks
   //////////////////////////////////////////////////////////////
 
   task append_rx_crc;
      input  [31:0] rxpnt_phy; // source
      input [15:0]  len; // length in bytes without CRC
      input         plus_dribble_nibble; // if length is longer for one nibble
      input         negated_crc; // if appended CRC is correct or not
      reg [31:0]    crc;
      reg [7:0]     tmp;
      reg [31:0]    addr_phy;
      reg           delta_t;
      begin
         addr_phy = rxpnt_phy + len;
         delta_t = 0;
         // calculate CRC from prepared packet
         paralel_crc_phy_rx(rxpnt_phy, {16'h0, len}, plus_dribble_nibble, crc);
         if (negated_crc)
           crc = ~crc;
         delta_t = !delta_t;
 
         if (plus_dribble_nibble)
           begin
              tmp = eth_phy0.rx_mem[addr_phy];
              eth_phy0.rx_mem[addr_phy]     = {crc[27:24], tmp[3:0]};
              eth_phy0.rx_mem[addr_phy + 1] = {crc[19:16], crc[31:28]};
              eth_phy0.rx_mem[addr_phy + 2] = {crc[11:8], crc[23:20]};
              eth_phy0.rx_mem[addr_phy + 3] = {crc[3:0], crc[15:12]};
              eth_phy0.rx_mem[addr_phy + 4] = {4'h0, crc[7:4]};
           end
         else
           begin
              eth_phy0.rx_mem[addr_phy]     = crc[31:24];
              eth_phy0.rx_mem[addr_phy + 1] = crc[23:16];
              eth_phy0.rx_mem[addr_phy + 2] = crc[15:8];
              eth_phy0.rx_mem[addr_phy + 3] = crc[7:0];
           end
      end
   endtask // append_rx_crc
 
   task append_rx_crc_delayed;
      input  [31:0] rxpnt_phy; // source
      input [15:0]  len; // length in bytes without CRC
      input         plus_dribble_nibble; // if length is longer for one nibble
      input         negated_crc; // if appended CRC is correct or not
      reg [31:0]    crc;
      reg [7:0]     tmp;
      reg [31:0]    addr_phy;
      reg           delta_t;
      begin
         addr_phy = rxpnt_phy + len;
         delta_t = 0;
         // calculate CRC from prepared packet
         paralel_crc_phy_rx(rxpnt_phy+4, {16'h0, len}-4, plus_dribble_nibble, crc);
         if (negated_crc)
           crc = ~crc;
         delta_t = !delta_t;
 
         if (plus_dribble_nibble)
           begin
              tmp = eth_phy0.rx_mem[addr_phy];
              eth_phy0.rx_mem[addr_phy]     = {crc[27:24], tmp[3:0]};
              eth_phy0.rx_mem[addr_phy + 1] = {crc[19:16], crc[31:28]};
              eth_phy0.rx_mem[addr_phy + 2] = {crc[11:8], crc[23:20]};
              eth_phy0.rx_mem[addr_phy + 3] = {crc[3:0], crc[15:12]};
              eth_phy0.rx_mem[addr_phy + 4] = {4'h0, crc[7:4]};
           end
         else
           begin
              eth_phy0.rx_mem[addr_phy]     = crc[31:24];
              eth_phy0.rx_mem[addr_phy + 1] = crc[23:16];
              eth_phy0.rx_mem[addr_phy + 2] = crc[15:8];
              eth_phy0.rx_mem[addr_phy + 3] = crc[7:0];
           end
      end
   endtask // append_rx_crc_delayed
 
 
   // paralel CRC calculating for PHY RX
   task paralel_crc_phy_rx;
      input  [31:0] start_addr; // start address
      input [31:0]  len; // length of frame in Bytes without CRC length
      input         plus_dribble_nibble; // if length is longer for one nibble
      output [31:0] crc_out;
      reg [21:0]    addr_cnt; // only 22 address lines
      integer       word_cnt;
      integer       nibble_cnt;
      reg [31:0]    load_reg;
      reg           delta_t;
      reg [31:0]    crc_next;
      reg [31:0]    crc;
      reg           crc_error;
      reg [3:0]     data_in;
      integer       i;
      begin
         #1 addr_cnt = start_addr[21:0];
         word_cnt = 24; // 27; // start of the frame - nibble granularity (MSbit first)
         crc = 32'hFFFF_FFFF; // INITIAL value
         delta_t = 0;
         // length must include 4 bytes of ZEROs, to generate CRC
         // get number of nibbles from Byte length (2^1 = 2)
         if (plus_dribble_nibble)
           nibble_cnt = ((len + 4) << 1) + 1'b1; // one nibble longer
         else
           nibble_cnt = ((len + 4) << 1);
         // because of MAGIC NUMBER nibbles are swapped [3:0] -> [0:3]
         load_reg[31:24] = eth_phy0.rx_mem[addr_cnt];
         addr_cnt = addr_cnt + 1;
         load_reg[23:16] = eth_phy0.rx_mem[addr_cnt];
         addr_cnt = addr_cnt + 1;
         load_reg[15: 8] = eth_phy0.rx_mem[addr_cnt];
         addr_cnt = addr_cnt + 1;
         load_reg[ 7: 0] = eth_phy0.rx_mem[addr_cnt];
         addr_cnt = addr_cnt + 1;
         while (nibble_cnt > 0)
           begin
              // wait for delta time
              delta_t = !delta_t;
              // shift data in
 
              if(nibble_cnt <= 8) // for additional 8 nibbles shift ZEROs in!
                data_in[3:0] = 4'h0;
              else
 
                data_in[3:0] = {load_reg[word_cnt], load_reg[word_cnt+1], load_reg[word_cnt+2], load_reg[word_cnt+3]};
              crc_next[0]  = (data_in[0] ^ crc[28]);
              crc_next[1]  = (data_in[1] ^ data_in[0] ^ crc[28]    ^ crc[29]);
              crc_next[2]  = (data_in[2] ^ data_in[1] ^ data_in[0] ^ crc[28]  ^ crc[29] ^ crc[30]);
              crc_next[3]  = (data_in[3] ^ data_in[2] ^ data_in[1] ^ crc[29]  ^ crc[30] ^ crc[31]);
              crc_next[4]  = (data_in[3] ^ data_in[2] ^ data_in[0] ^ crc[28]  ^ crc[30] ^ crc[31]) ^ crc[0];
              crc_next[5]  = (data_in[3] ^ data_in[1] ^ data_in[0] ^ crc[28]  ^ crc[29] ^ crc[31]) ^ crc[1];
              crc_next[6]  = (data_in[2] ^ data_in[1] ^ crc[29]    ^ crc[30]) ^ crc[ 2];
              crc_next[7]  = (data_in[3] ^ data_in[2] ^ data_in[0] ^ crc[28]  ^ crc[30] ^ crc[31]) ^ crc[3];
              crc_next[8]  = (data_in[3] ^ data_in[1] ^ data_in[0] ^ crc[28]  ^ crc[29] ^ crc[31]) ^ crc[4];
              crc_next[9]  = (data_in[2] ^ data_in[1] ^ crc[29]    ^ crc[30]) ^ crc[5];
              crc_next[10] = (data_in[3] ^ data_in[2] ^ data_in[0] ^ crc[28]  ^ crc[30] ^ crc[31]) ^ crc[6];
              crc_next[11] = (data_in[3] ^ data_in[1] ^ data_in[0] ^ crc[28]  ^ crc[29] ^ crc[31]) ^ crc[7];
              crc_next[12] = (data_in[2] ^ data_in[1] ^ data_in[0] ^ crc[28]  ^ crc[29] ^ crc[30]) ^ crc[8];
              crc_next[13] = (data_in[3] ^ data_in[2] ^ data_in[1] ^ crc[29]  ^ crc[30] ^ crc[31]) ^ crc[9];
              crc_next[14] = (data_in[3] ^ data_in[2] ^ crc[30]    ^ crc[31]) ^ crc[10];
              crc_next[15] = (data_in[3] ^ crc[31])   ^ crc[11];
              crc_next[16] = (data_in[0] ^ crc[28])   ^ crc[12];
              crc_next[17] = (data_in[1] ^ crc[29])   ^ crc[13];
              crc_next[18] = (data_in[2] ^ crc[30])   ^ crc[14];
              crc_next[19] = (data_in[3] ^ crc[31])   ^ crc[15];
              crc_next[20] =  crc[16];
              crc_next[21] =  crc[17];
              crc_next[22] = (data_in[0] ^ crc[28])   ^ crc[18];
              crc_next[23] = (data_in[1] ^ data_in[0] ^ crc[29]    ^ crc[28]) ^ crc[19];
              crc_next[24] = (data_in[2] ^ data_in[1] ^ crc[30]    ^ crc[29]) ^ crc[20];
              crc_next[25] = (data_in[3] ^ data_in[2] ^ crc[31]    ^ crc[30]) ^ crc[21];
              crc_next[26] = (data_in[3] ^ data_in[0] ^ crc[31]    ^ crc[28]) ^ crc[22];
              crc_next[27] = (data_in[1] ^ crc[29])   ^ crc[23];
              crc_next[28] = (data_in[2] ^ crc[30])   ^ crc[24];
              crc_next[29] = (data_in[3] ^ crc[31])   ^ crc[25];
              crc_next[30] =  crc[26];
              crc_next[31] =  crc[27];
 
              crc = crc_next;
              crc_error = crc[31:0] != 32'hc704dd7b;  // CRC not equal to magic number
              case (nibble_cnt)
                9: crc_out = {!crc[24], !crc[25], !crc[26], !crc[27], !crc[28], !crc[29], !crc[30], !crc[31],
                              !crc[16], !crc[17], !crc[18], !crc[19], !crc[20], !crc[21], !crc[22], !crc[23],
                              !crc[ 8], !crc[ 9], !crc[10], !crc[11], !crc[12], !crc[13], !crc[14], !crc[15],
                              !crc[ 0], !crc[ 1], !crc[ 2], !crc[ 3], !crc[ 4], !crc[ 5], !crc[ 6], !crc[ 7]};
                default: crc_out = crc_out;
              endcase
              // wait for delta time
              delta_t = !delta_t;
              // increment address and load new data
              if ((word_cnt+3) == 7)//4)
                begin
                   // because of MAGIC NUMBER nibbles are swapped [3:0] -> [0:3]
                   load_reg[31:24] = eth_phy0.rx_mem[addr_cnt];
                   addr_cnt = addr_cnt + 1;
                   load_reg[23:16] = eth_phy0.rx_mem[addr_cnt];
                   addr_cnt = addr_cnt + 1;
                   load_reg[15: 8] = eth_phy0.rx_mem[addr_cnt];
                   addr_cnt = addr_cnt + 1;
                   load_reg[ 7: 0] = eth_phy0.rx_mem[addr_cnt];
                   addr_cnt = addr_cnt + 1;
                end
              // set new load bit position
              if((word_cnt+3) == 31)
                word_cnt = 16;
              else if ((word_cnt+3) == 23)
                word_cnt = 8;
              else if ((word_cnt+3) == 15)
                word_cnt = 0;
              else if ((word_cnt+3) == 7)
                word_cnt = 24;
              else
                word_cnt = word_cnt + 4;// - 4;
              // decrement nibble counter
              nibble_cnt = nibble_cnt - 1;
              // wait for delta time
              delta_t = !delta_t;
           end // while
         #1;
      end
   endtask // paralel_crc_phy_rx
 
 
 
 

Line No.	Rev	Author	Line
1	44	julius	`//////////////////////////////////////////////////////////////////////`
2			`//// ////`
3	412	julius	`//// Ethernet MAC Stimulus ////`
4	44	julius	`//// ////`
5			`//// Description ////`
6			`//// Ethernet MAC stimulus tasks. Taken from the project ////`
7			`//// testbench in the ethmac core. ////`
8			`//// ////`
9			`//// To Do: ////`
10			`//// ////`
11			`//// ////`
12			`//// Author(s): ////`
13			`//// - Tadej Markovic, tadej@opencores.org ////`
14			`//// - Igor Mohor, igorM@opencores.org ////`
15	412	julius	`//// - Julius Baxter julius.baxter@orsoc.se ////`
16	44	julius	`//// ////`
17			`//// ////`
18			`//////////////////////////////////////////////////////////////////////`
19			`//// ////`
20			`//// Copyright (C) 2009 Authors and OPENCORES.ORG ////`
21			`//// ////`
22			`//// This source file may be used and distributed without ////`
23			`//// restriction provided that this copyright statement is not ////`
24			`//// removed from the file and that any derivative work contains ////`
25			`//// the original copyright notice and the associated disclaimer. ////`
26			`//// ////`
27			`//// This source file is free software; you can redistribute it ////`
28			`//// and/or modify it under the terms of the GNU Lesser General ////`
29			`//// Public License as published by the Free Software Foundation; ////`
30			`//// either version 2.1 of the License, or (at your option) any ////`
31			`//// later version. ////`
32			`//// ////`
33			`//// This source is distributed in the hope that it will be ////`
34			`//// useful, but WITHOUT ANY WARRANTY; without even the implied ////`
35			`//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////`
36			`//// PURPOSE. See the GNU Lesser General Public License for more ////`
37			`//// details. ////`
38			`//// ////`
39			`//// You should have received a copy of the GNU Lesser General ////`
40			`//// Public License along with this source; if not, download it ////`
41			`//// from http://www.opencores.org/lgpl.shtml ////`
42			`//// ////`
43			`//////////////////////////////////////////////////////////////////////`
44	412	julius	`define TIME $display("Time: %0t", $time)
45	44	julius
46	412	julius	`// Defines for ethernet test to trigger sending/receiving`
47			`// Is straight forward when using RTL design, but if using netlist then paths to`
48			`// the RX/TX enabled bits depend on synthesis tool, etc, but ones here appear to`
49			`// work with design put through Synplify, with hierarchy maintained.`
50			`define ETH_TOP dut.ethmac0
51			`define ETH_BD_RAM_PATH `ETH_TOP.wishbone.bd_ram
52			`define ETH_MODER_PATH `ETH_TOP.ethreg1.MODER_0
53	44	julius
54	412	julius	`ifdef RTL_SIM
55			`ifdef ethmac_IS_GATELEVEL
56			`define ETH_MODER_TXEN_BIT `ETH_MODER_PATH.r_TxEn;
57			`define ETH_MODER_RXEN_BIT `ETH_MODER_PATH.r_RxEn;
58			`else
59			`define ETH_MODER_TXEN_BIT `ETH_MODER_PATH.DataOut[1];
60			`define ETH_MODER_RXEN_BIT `ETH_MODER_PATH.DataOut[0];
61			`endif
62			`endif
63
64			`ifdef GATE_SIM
65			`define ETH_MODER_TXEN_BIT `ETH_MODER_PATH.r_TxEn;
66			`define ETH_MODER_RXEN_BIT `ETH_MODER_PATH.r_RxEn;
67			`endif
68
69			`reg [15:0] eth_stim_rx_packet_length;`
70	44	julius	`reg [7:0] st_data;`
71	412	julius	`reg [31:0] lfsr;`
72			`integer lfsr_last_byte;`
73
74			`// Is number of ethernet packets to send if doing the eth-rx test.`
75	480	julius	`parameter eth_stim_num_rx_only_num_packets = 12; // Set to 0 for continuous RX`
76			`parameter eth_stim_num_rx_only_packet_size = 60;`
77	412	julius	`parameter eth_stim_num_rx_only_packet_size_change = 2'b01; // 2'b01: Increment`
78	480	julius	`parameter eth_stim_num_rx_only_packet_size_change_amount = 127;`
79	485	julius	`parameter eth_stim_num_rx_only_IPG = 800_000; // ps`
80	412	julius
81			`// Do call/response test`
82			`reg eth_stim_do_rx_reponse_to_tx;`
83	530	julius	`reg eth_stim_do_overflow_test;`
84	412	julius
85			`parameter num_tx_bds = 16;`
86			`parameter num_tx_bds_mask = 4'hf;`
87			`parameter num_rx_bds = 16;`
88			`parameter num_rx_bds_mask = 4'hf;`
89			`parameter max_eth_packet_size = 16'h0600;`
90
91			`// If running eth-rxtxbig test (sending and receiving maximum packets), then`
92			`// set this parameter to the max packet size, otherwise min packet size`
93			`//parameter rx_while_tx_min_packet_size = max_eth_packet_size;`
94			`parameter rx_while_tx_min_packet_size = 32;`
95
96			`// Use the smallest possible IPG`
97			`parameter eth_stim_use_min_IPG = 0;`
98	485	julius	`parameter eth_stim_IPG_delay_max = 100_000_000; // Maximum 100 us`
99	412	julius	`//parameter eth_stim_IPG_delay_max = 100_000_000; // Maximum 100mS between packets`
100	480	julius	`parameter eth_stim_IPG_min_10mb = 9600_000; // 9.6 uS`
101			`parameter eth_stim_IPG_min_100mb = 800_000; // 860+~100 = 960 nS 100MBit min IPG`
102	412	julius	`parameter eth_stim_check_rx_packet_contents = 1;`
103			`parameter eth_stim_check_tx_packet_contents = 1;`
104
105			`parameter eth_inject_errors = 0;`
106
107			`// When running simulations where you don't want to feed packets to the design`
108			`// like this...`
109			`parameter eth_stim_disable_rx_stim = 0;`
110
111			`// Delay between seeing that the buffer descriptor for an RX packet says it's`
112			`// been received and ending up in the memory.`
113			`// For 25MHz sdram controller, use following:`
114			//parameter Td_rx_packet_check = (`BOARD_CLOCK_PERIOD * 2000);
115			`// For 64MHz sdram controller, use following:`
116			parameter Td_rx_packet_check = (`BOARD_CLOCK_PERIOD * 500);
117
118			`integer expected_rxbd;// init to 0`
119			`integer expected_txbd;`
120
121			`wire ethmac_rxen;`
122			`wire ethmac_txen;`
123			assign ethmac_rxen = eth_stim_disable_rx_stim ? 0 : `ETH_MODER_RXEN_BIT;
124			assign ethmac_txen = `ETH_MODER_TXEN_BIT;
125
126			`integer eth_rx_num_packets_sent = 0;`
127			`integer eth_rx_num_packets_checked = 0;`
128			`integer num_tx_packets = 1;`
129
130			`integer rx_packet_lengths [0:1023]; // Array of packet lengths`
131
132
133			`integer speed_loop;`
134
135			`// When txen is (re)enabled, the tx bd pointer goes back to 0`
136			`always @(posedge ethmac_txen)`
137			`expected_txbd = 0;`
138
139			`reg eth_stim_waiting;`
140
141	44	julius	`initial`
142			`begin`
143	412	julius	`#1;`
144			`//lfsr = 32'h84218421; // Init pseudo lfsr`
145			`lfsr = 32'h00700001; // Init pseudo lfsr`
146			`lfsr_last_byte = 0;`
147
148			`eth_stim_waiting = 1;`
149			`expected_rxbd = num_tx_bds; // init this here`
150	44	julius
151	412	julius	`eth_stim_do_rx_reponse_to_tx = 0;`
152	530	julius	`eth_stim_do_overflow_test = 0;`
153	44	julius
154	412	julius	`while (eth_stim_waiting) // Loop, waiting for enabling of MAC by software`
155			`begin`
156			`#100;`
157			`// If RX enable and not TX enable...`
158			`if(ethmac_rxen === 1'b1 & !(ethmac_txen===1'b1))`
159			`begin`
160			`if (eth_inject_errors)`
161			`begin`
162			`do_rx_only_stim(16, 64, 0, 0);`
163			`do_rx_only_stim(128, 64, 1'b1, 8);`
164			`do_rx_only_stim(256, 64, 1'b1, 4);`
165			`eth_stim_waiting = 0;`
166			`end`
167			`else`
168			`begin`
169			`//do_rx_only_stim(eth_stim_num_rx_only_num_packets,`
170			`//eth_stim_num_rx_only_packet_size, 0, 0);`
171	44	julius
172	412	julius	`// Call packet send loop directly. No error injection.`
173			`send_packet_loop(eth_stim_num_rx_only_num_packets,`
174			`eth_stim_num_rx_only_packet_size,`
175			`eth_stim_num_rx_only_packet_size_change,`
176			`eth_stim_num_rx_only_packet_size_change_amount,`
177			`eth_phy0.eth_speed, // Speed`
178			`eth_stim_num_rx_only_IPG, // IPG`
179			`48'h0012_3456_789a, 48'h0708_090A_0B0C, 1,`
180	530	julius	`0, 0, 0);`
181	412	julius
182			`eth_stim_waiting = 0;`
183			`end`
184			`end // if (ethmac_rxen === 1'b1 & !(ethmac_txen===1'b1))`
185			`// If both RX and TX enabled`
186			`else if (ethmac_rxen === 1'b1 & ethmac_txen===1'b1)`
187			`begin`
188			`// Both enabled - let's wait for the first packet transmitted`
189			`// to see what stimulus we should provide`
190			`while (num_tx_packets==1)`
191			`#1000;`
192
193			`$display("* ethmac RX/TX test request: %x", eth_phy0.tx_mem[0]);`
194
195			`// Check the first received byte's value`
196			`case (eth_phy0.tx_mem[0])`
197			`0:`
198			`begin`
199			`// kickoff call/response here`
200			`eth_stim_do_rx_reponse_to_tx = 1;`
201			`end`
202	530	julius	`1:`
203			`begin`
204			`// kickoff overflow test here`
205			`eth_stim_do_overflow_test = 1;`
206			`end`
207	412	julius	`default:`
208			`begin`
209			`do_rx_while_tx_stim(1400);`
210			`end`
211			`endcase // case (eth_phy0.tx_mem[0])`
212
213			`eth_stim_waiting = 0;`
214			`end`
215			`end // while (eth_stim_waiting)`
216	49	julius
217	412	julius	`end // initial begin`
218	49	julius
219	412	julius	`// Main Ethernet RX testing stimulus task.`
220			`// Sends a set of packets at both speeds`
221			`task do_rx_only_stim;`
222			`input [31:0] num_packets;`
223			`input [31:0] start_packet_size;`
224			`input inject_errors;`
225			`input [31:0] inject_errors_mod;`
226
227			`begin`
228
229			`for(speed_loop=1;speed_loop<3;speed_loop=speed_loop+1)`
230			`begin`
231
232			`send_packet_loop(num_packets, start_packet_size, 2'b01, 1,`
233			`speed_loop[0], 10000,`
234			`48'h0012_3456_789a, 48'h0708_090A_0B0C, 1,`
235	530	julius	`inject_errors, inject_errors_mod, 0);`
236	412	julius
237			`end`
238
239			`end`
240			`endtask // do_rx_stim`
241	44	julius
242	412	julius	`// Generate RX packets while there's TX going on`
243			`// Sends a set of packets at both speeds`
244			`task do_rx_while_tx_stim;`
245			`input [31:0] num_packets;`
246			`reg [31:0] IPG; // Inter-packet gap`
247			`reg [31:0] packet_size;`
248	44	julius
249	412	julius	`integer j;`
250			`begin`
251
252			`for(j=0;j<num_packets;j=j+1)`
253			`begin`
254			`// Determine delay between RX packets:`
255
256			`if (eth_stim_use_min_IPG)`
257			`begin`
258			`// Assign based on whether we're in 100mbit or 10mbit mode`
259			`IPG = eth_phy0.eth_speed ? eth_stim_IPG_min_100mb :`
260			`eth_stim_IPG_min_10mb;`
261			`// Add a little bit of variability`
262			`// Add up to 15`
263			`IPG = IPG + ($random & 32'h000000f);`
264			`end`
265			`else`
266			`begin`
267			`IPG = $random;`
268
269			`while (IPG > eth_stim_IPG_delay_max)`
270			`IPG = IPG / 2;`
271
272
273			`end`
274			`$display("do_rx_while_tx IPG = %0d", IPG);`
275			`// Determine size of next packet:`
276			`if (rx_while_tx_min_packet_size == max_eth_packet_size)`
277			`// We want to transmit biggest packets possible, easy case`
278			`packet_size = max_eth_packet_size - 4;`
279			`else`
280			`begin`
281			`// Constrained random sized packets`
282			`packet_size = $random;`
283
284			`while (packet_size > (max_eth_packet_size-4))`
285			`packet_size = packet_size / 2;`
286
287			`// Now divide by least significant bits of j`
288			`packet_size = packet_size / {29'd0,j[1:0],1'b1};`
289			`if (packet_size < 60)`
290			`packet_size = packet_size + 60;`
291			`end`
292
293			`$display("do_rx_while_tx packet_size = %0d", packet_size);`
294			`send_packet_loop(1, packet_size, 2'b01, 1, eth_phy0.eth_speed,`
295			`IPG, 48'h0012_3456_789a,`
296	530	julius	`48'h0708_090A_0B0C, 1, 1'b0, 0, 0);`
297	44	julius
298	412	julius	`// If RX enable went low, wait for it go high again`
299			`if (ethmac_rxen===1'b0)`
300			`begin`
301
302			`while (ethmac_rxen===1'b0)`
303			`begin`
304			`@(posedge ethmac_rxen);`
305			`#10000;`
306			`end`
307
308			`// RX disabled and when re-enabled we reset the buffer descriptor number`
309			`expected_rxbd = num_tx_bds;`
310	44	julius
311	412	julius	`end`
312
313			`end // for (j=0;j<num_packets;j=j+1)`
314			`end`
315			`endtask // do_rx_stim`
316	44	julius
317	412	julius	`// Registers used in detecting transmitted packets`
318			`reg eth_stim_tx_loop_keep_polling;`
319			`reg [31:0] ethmac_txbd_lenstat, ethmac_last_txbd_lenstat;`
320			`reg eth_stim_detected_packet_tx;`
321	44	julius
322	412	julius	`// If in call-response mode, whenever we receive a TX packet, we generate`
323			`// one and send it back`
324			`always @(negedge eth_stim_detected_packet_tx)`
325			`begin`
326			`if (eth_stim_do_rx_reponse_to_tx & ethmac_rxen)`
327			`// Continue if we are enabled`
328			`do_rx_response_to_tx();`
329			`end`
330	530	julius
331
332			`// If in call-response mode, whenever we receive a TX packet, we generate`
333			`// one and send it back`
334			`always @(posedge eth_stim_do_overflow_test)`
335			`begin`
336			`// Continue if we are enabled`
337			`do_overflow_stimulus();`
338			`end`
339	412	julius
340			`// Generate RX packet in rsponse to TX packet`
341			`task do_rx_response_to_tx;`
342			`//input unused;`
343
344			`reg [31:0] IPG; // Inter-packet gap`
345			`reg [31:0] packet_size;`
346
347			`integer j;`
348			`begin`
349	44	julius
350	412	julius	`// Get packet size test wants us to send`
351			`packet_size = {eth_phy0.tx_mem[0],eth_phy0.tx_mem[1],`
352			`eth_phy0.tx_mem[2],eth_phy0.tx_mem[3]};`
353
354	44	julius
355	412	julius	`IPG = {eth_phy0.tx_mem[4],eth_phy0.tx_mem[5],`
356			`eth_phy0.tx_mem[6],eth_phy0.tx_mem[7]};`
357
358
359			`$display("do_rx_response_to_tx IPG = %0d", IPG);`
360			`if (packet_size == 0)`
361			`begin`
362			`// Constrained random sized packets`
363			`packet_size = $random;`
364
365			`while (packet_size > (max_eth_packet_size-4))`
366			`packet_size = packet_size / 2;`
367
368			`if (packet_size < 60)`
369			`packet_size = packet_size + 60;`
370			`end`
371
372			`$display("do_rx_response_to_tx packet_size = %0d", packet_size);`
373			`send_packet_loop(1, packet_size, 2'b01, 1, eth_phy0.eth_speed,`
374			`IPG, 48'h0012_3456_789a,`
375	530	julius	`48'h0708_090A_0B0C, 1, 1'b0, 0, 0);`
376	412	julius
377			`// If RX enable went low, wait for it go high again`
378			`if (ethmac_rxen===1'b0)`
379			`begin`
380
381			`while (ethmac_rxen===1'b0)`
382			`begin`
383			`@(posedge ethmac_rxen);`
384			`#10000;`
385			`end`
386
387			`// RX disabled and when re-enabled we reset the buffer`
388			`// descriptor number`
389			`expected_rxbd = num_tx_bds;`
390	44	julius
391	412	julius	`end`
392	44	julius
393	412	julius	`end`
394			`endtask // do_rx_response_to_tx`
395
396	530	julius	`// Generate RX packet in rsponse to TX packet`
397			`task do_overflow_stimulus;`
398			`//input unused;`
399			`reg [31:0] IPG; // Inter-packet gap`
400			`reg [31:0] packet_size;`
401
402			`integer j;`
403
404			`begin`
405	412	julius
406	530	julius	`// Maximum packet size`
407			`packet_size = 1500;`
408
409			`// Minimum IPG`
410			`IPG = eth_stim_IPG_min_100mb;`
411
412			`$display("do_overflow_stimulus IPG = %0d", IPG);`
413
414
415			`$display("do_overflow_stimulus packetsize = %0d", packet_size);`
416
417			`send_packet_loop(num_rx_bds, packet_size, 2'b01, 1,`
418			`eth_phy0.eth_speed,`
419			`IPG, 48'h0012_3456_789a,`
420			`48'h0708_090A_0B0C, 1, 1'b0, 0, 0);`
421
422			`// This one should cause overflow, don't check it gets there OK`
423			`send_packet_loop(1, packet_size, 2'b01, 1,`
424			`eth_phy0.eth_speed,`
425			`IPG, 48'h0012_3456_789a,`
426			`48'h0708_090A_0B0C, 1, 1'b0, 0, 1);`
427
428			`// Wind back expected RXBD number`
429			`if (expected_rxbd == num_tx_bds)`
430			`expected_rxbd = num_tx_bds + num_rx_bds - 1;`
431			`else`
432			`expected_rxbd = expected_rxbd - 1;`
433
434			`// This one should cause overflow, don't check it gets there OK`
435			`send_packet_loop(1, packet_size, 2'b01, 1,`
436			`eth_phy0.eth_speed,`
437			`IPG, 48'h0012_3456_789a,`
438			`48'h0708_090A_0B0C, 1, 1'b0, 0, 1);`
439
440			`// Wind back expected RXBD number`
441			`if (expected_rxbd == num_tx_bds)`
442			`expected_rxbd = num_tx_bds + num_rx_bds - 1;`
443			`else`
444			`expected_rxbd = expected_rxbd - 1;`
445
446
447			`// This one should cause overflow, don't check it gets there OK`
448			`send_packet_loop(1, packet_size, 2'b01, 1,`
449			`eth_phy0.eth_speed,`
450			`IPG, 48'h0012_3456_789a,`
451			`48'h0708_090A_0B0C, 1, 1'b0, 0, 1);`
452
453			`// Wind back expected RXBD number`
454			`if (expected_rxbd == num_tx_bds)`
455			`expected_rxbd = num_tx_bds + num_rx_bds - 1;`
456			`else`
457			`expected_rxbd = expected_rxbd - 1;`
458
459
460			`// This one should cause overflow, don't check it gets there OK`
461			`send_packet_loop(1, packet_size, 2'b01, 1,`
462			`eth_phy0.eth_speed,`
463			`IPG, 48'h0012_3456_789a,`
464			`48'h0708_090A_0B0C, 1, 1'b0, 0, 1);`
465
466			`// Wind back expected RXBD number`
467			`if (expected_rxbd == num_tx_bds)`
468			`expected_rxbd = num_tx_bds + num_rx_bds - 1;`
469			`else`
470			`expected_rxbd = expected_rxbd - 1;`
471
472
473			`// Wait until a buffer descriptor becomes available`
474			while(`ETH_TOP.wishbone.RxBDRead==1'b1)
475			`#1000;`
476
477			`$display("%t: RxBDRead gone low",$time);`
478			`#10000;`
479
480
481
482			`send_packet_loop(1, packet_size, 2'b01, 1, eth_phy0.eth_speed,`
483			`IPG, 48'h0012_3456_789a,`
484			`48'h0708_090A_0B0C, 1, 1'b0, 0, 0);`
485
486
487			`// If RX enable went low, wait for it go high again`
488			`if (ethmac_rxen===1'b0)`
489			`begin`
490
491			`while (ethmac_rxen===1'b0)`
492			`begin`
493			`@(posedge ethmac_rxen);`
494			`#10000;`
495			`end`
496
497			`// RX disabled and when re-enabled we reset the buffer`
498			`// descriptor number`
499			`expected_rxbd = num_tx_bds;`
500

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