module simple_gemac_tb;

     
   reg clk = 0;
   reg reset = 1;

   initial #1000 reset = 0;
   always #50 clk = ~clk;

   wire GMII_RX_DV, GMII_RX_ER, GMII_TX_EN, GMII_TX_ER, GMII_GTX_CLK;
   wire [7:0] GMII_RXD, GMII_TXD;

   wire rx_valid, rx_error, rx_ack;
   wire tx_ack;
   reg tx_valid = 0, tx_error = 0;
   
   wire [7:0] rx_data;
   reg [7:0] tx_data;
   
   reg [15:0] pause_time;
   reg pause_req     = 0;

//   reg GMII_RX_CLK;
//   always @(GMII_GTX_CLK)
//     GMII_RX_CLK     <= #30 GMII_GTX_CLK;
   
   wire GMII_RX_CLK  = GMII_GTX_CLK;

   // Loopback
   assign GMII_RX_DV  = GMII_TX_EN;
   assign GMII_RX_ER  = GMII_TX_ER;
   assign GMII_RXD    = GMII_TXD;
   
   simple_gemac simple_gemac
     (.clk125(clk),  .reset(reset),
      .GMII_GTX_CLK(GMII_GTX_CLK), .GMII_TX_EN(GMII_TX_EN),  
      .GMII_TX_ER(GMII_TX_ER), .GMII_TXD(GMII_TXD),
      .GMII_RX_CLK(GMII_RX_CLK), .GMII_RX_DV(GMII_RX_DV),  
      .GMII_RX_ER(GMII_RX_ER), .GMII_RXD(GMII_RXD),
      .pause_req(pause_req), .pause_time(pause_time),
      .rx_clk(rx_clk), .rx_data(rx_data),
      .rx_valid(rx_valid), .rx_error(rx_error), .rx_ack(rx_ack),
      .tx_clk(tx_clk), .tx_data(tx_data), 
      .tx_valid(tx_valid), .tx_error(tx_error), .tx_ack(tx_ack)
      );

   task SendFlowCtrl;
      input [15:0] fc_len;
      begin
	 $display("Sending Flow Control, quanta = %d, time = %d", fc_len,$time);
	 pause_time = fc_len;
	 @(posedge clk);
	 pause_req <= 1;
	 @(posedge clk);
	 pause_req <= 0;
      end
   endtask // SendFlowCtrl
   
   reg [31:0] count;
   task SendPacket;
      input [7:0] data_start;
      input [31:0] data_len;
      begin
	 $display("Sending Packet Len=%d, %d", data_len, $time);
	 count <= 1;
	 tx_data  <= data_start;
	 tx_error <= 0;
	 tx_valid <= 1;
	 while(~tx_ack)
	   @(posedge tx_clk);
	 $display("Packet Accepted, %d", $time);
	 while(count < data_len)
	   begin
	      tx_data <= tx_data + 1;
	      count   <= count + 1;
	      @(posedge clk);
	   end
	 tx_valid <= 0;
	 @(posedge tx_clk);
      end
   endtask // SendPacket
   	
   task SendPacketFromFile;
      input [31:0] data_len;
      begin
	 $display("Sending Packet From File Len=%d, %d",data_len,$time);
	 $readmemh( "test_packet.mem",pkt_rom );     
	 count 	  = 0;
	 tx_data  = pkt_rom[count];
	 tx_error = 0;
	 tx_valid = 1;
	 while(~tx_ack)
	   @(posedge tx_clk);
	 $display("Packet Accepted, %d",$time);
	 count = 1;
	 while(count < data_len)
	   begin
	      tx_data = pkt_rom[count];
	      count   = count + 1;
	      @(posedge clk);
	   end
	 tx_valid <= 0;
	 @(posedge tx_clk);
      end
   endtask // SendPacket
   	
   initial $dumpfile("simple_gemac_tb.vcd");
   initial $dumpvars(0,simple_gemac_tb);

   integer i; 
   reg [7:0] pkt_rom[0:65535];
   reg [1023:0] ROMFile;
   
   initial
     for (i=0;i<65536;i=i+1)
       pkt_rom[i] <= 8'h0;
      
   initial
     begin
	@(negedge reset);
	repeat (10)
	  @(posedge clk);
	SendFlowCtrl(16'h0007);  // Send flow control
	#30000;
	@(posedge clk);
	SendFlowCtrl(16'h0009);  // Increas flow control before it expires
	#10000;
	@(posedge clk);
	SendFlowCtrl(16'h0000);  // Cancel flow control befor it expires
	@(posedge clk);
	SendPacket(8'hAA,10);    // This packet gets dropped by the filters
	repeat (10)
	  @(posedge clk);
	SendPacketFromFile(60);  // The rest are valid packets
	repeat (10)
	  @(posedge clk);
	SendPacketFromFile(61);
	repeat (10)
	  @(posedge clk);
	SendPacketFromFile(62);
	repeat (10)
	  @(posedge clk);
	SendPacketFromFile(63);
	repeat (1)
	  @(posedge clk);
	SendPacketFromFile(64);
	repeat (10)
	  @(posedge clk);
	SendPacketFromFile(59);
	repeat (1)
	  @(posedge clk);
	SendPacketFromFile(58);
	#10000 $finish;
     end

   always @(posedge clk)
     if(GMII_TX_EN)
       $display("%x",GMII_TXD);
   
endmodule // simple_gemac_tb

/*
    if ( !$value$plusargs( "rom=%s", ROMFile ) )
        begin
           $display( "Using default ROM file, 'flash.rom'" );
           ROMFile = "flash.rom";
        end
      else
	$display( "Using %s as ROM file.", ROMFile);
      
      #1 $readmemh( ROMFile,rom );     
   end
 */