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

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////  eth_outputcontrol.v                                         ////

////                                                              ////

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

////  http://www.opencores.org/project,ethmac                     ////

////                                                              ////

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

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

////                                                              ////

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

////  file.                                                       ////

////                                                              ////

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

////                                                              ////

//// Copyright (C) 2001 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 1.3  2002/01/23 10:28:16  mohor

// Link in the header changed.

//

// Revision 1.2  2001/10/19 08:43:51  mohor

// eth_timescale.v changed to timescale.v This is done because of the

// simulation of the few cores in a one joined project.

//

// Revision 1.1  2001/08/06 14:44:29  mohor

// A define FPGA added to select between Artisan RAM (for ASIC) and Block Ram (For Virtex).

// Include files fixed to contain no path.

// File names and module names changed ta have a eth_ prologue in the name.

// File eth_timescale.v is used to define timescale

// All pin names on the top module are changed to contain _I, _O or _OE at the end.

// Bidirectional signal MDIO is changed to three signals (Mdc_O, Mdi_I, Mdo_O

// and Mdo_OE. The bidirectional signal must be created on the top level. This

// is done due to the ASIC tools.

//

// Revision 1.1  2001/07/30 21:23:42  mohor

// Directory structure changed. Files checked and joind together.

//

// Revision 1.3  2001/06/01 22:28:56  mohor

// This files (MIIM) are fully working. They were thoroughly tested. The testbench is not updated.

//

//

`include "timescale.v"

module eth_outputcontrol(Clk, Reset, InProgress, ShiftedBit, BitCounter, WriteOp, NoPre, MdcEn_n, Mdo, MdoEn);

input         Clk;                // Host Clock

input         Reset;              // General Reset

input         WriteOp;            // Write Operation Latch (When asserted, write operation is in progress)

input         NoPre;              // No Preamble (no 32-bit preamble)

input         InProgress;         // Operation in progress

input         ShiftedBit;         // This bit is output of the shift register and is connected to the Mdo signal

input   [6:0] BitCounter;         // Bit Counter

input         MdcEn_n;            // MII Management Data Clock Enable signal is asserted for one Clk period before Mdc falls.

output        Mdo;                // MII Management Data Output

output        MdoEn;              // MII Management Data Output Enable

wire          SerialEn;

reg           MdoEn_2d;

reg           MdoEn_d;

reg           MdoEn;

reg           Mdo_2d;

reg           Mdo_d;

reg           Mdo;                // MII Management Data Output

// Generation of the Serial Enable signal (enables the serialization of the data)

assign SerialEn =  WriteOp & InProgress & ( BitCounter>31 | ( ( BitCounter == 0 ) & NoPre ) )

                | ~WriteOp & InProgress & (( BitCounter>31 & BitCounter<46 ) | ( ( BitCounter == 0 ) & NoPre ));

// Generation of the MdoEn signal

always @ (posedge Clk or posedge Reset)

begin

  if(Reset)

    begin

      MdoEn_2d <=  1'b0;

      MdoEn_d <=  1'b0;

      MdoEn <=  1'b0;

    end

  else

    begin

      if(MdcEn_n)

        begin

          MdoEn_2d <=  SerialEn | InProgress & BitCounter<32;

          MdoEn_d <=  MdoEn_2d;

          MdoEn <=  MdoEn_d;

        end

    end

end

// Generation of the Mdo signal.

always @ (posedge Clk or posedge Reset)

begin

  if(Reset)

    begin

      Mdo_2d <=  1'b0;

      Mdo_d <=  1'b0;

      Mdo <=  1'b0;

    end

  else

    begin

      if(MdcEn_n)

        begin

          Mdo_2d <=  ~SerialEn & BitCounter<32;

          Mdo_d <=  ShiftedBit | Mdo_2d;

          Mdo <=  Mdo_d;

        end

    end

end

endmodule