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

////                                                              ////

////  eth_rxstatem.v                                              ////

////                                                              ////

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

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

////                                                              ////

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

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

////      - Novan Hartadi (novan@vlsi.itb.ac.id)                  ////

////      - Mahmud Galela (mgalela@vlsi.itb.ac.id)                ////

////                                                              ////

////  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 1.5  2002/01/23 10:28:16  mohor

// Link in the header changed.

//

// Revision 1.4  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 1.3  2001/10/18 12:07:11  mohor

// Status signals changed, Adress decoding changed, interrupt controller

// added.

//

// Revision 1.2  2001/09/11 14:17:00  mohor

// Few little NCSIM warnings fixed.

//

// 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 1.2  2001/07/03 12:55:41  mohor

// Minor changes because of the synthesys warnings.

//

//

// Revision 1.1  2001/06/27 21:26:19  mohor

// Initial release of the RxEthMAC module.

//

//

//

//

`include "timescale.v"

module eth_rxstatem (MRxClk, Reset, MRxDV, ByteCntEq0, ByteCntGreat2, Transmitting, MRxDEq5, MRxDEqD,

                     IFGCounterEq24, ByteCntMaxFrame, StateData, StateIdle, StatePreamble, StateSFD,

                     StateDrop

                    );

input         MRxClk;

input         Reset;

input         MRxDV;

input         ByteCntEq0;

input         ByteCntGreat2;

input         MRxDEq5;

input         Transmitting;

input         MRxDEqD;

input         IFGCounterEq24;

input         ByteCntMaxFrame;

output [1:0]  StateData;

output        StateIdle;

output        StateDrop;

output        StatePreamble;

output        StateSFD;

reg           StateData0;

reg           StateData1;

reg           StateIdle;

reg           StateDrop;

reg           StatePreamble;

reg           StateSFD;

wire          StartIdle;

wire          StartDrop;

wire          StartData0;

wire          StartData1;

wire          StartPreamble;

wire          StartSFD;

// Defining the next state

assign StartIdle = ~MRxDV & (StateDrop | StatePreamble | StateSFD | (|StateData));

assign StartPreamble = MRxDV & ~MRxDEq5 & (StateIdle & ~Transmitting);

assign StartSFD = MRxDV & MRxDEq5 & (StateIdle & ~Transmitting | StatePreamble);

assign StartData0 = MRxDV & (StateSFD & MRxDEqD & IFGCounterEq24 | StateData1);

assign StartData1 = MRxDV & StateData0 & (~ByteCntMaxFrame);

assign StartDrop = MRxDV & (StateIdle & Transmitting | StateSFD & ~IFGCounterEq24 &

                            MRxDEqD |  StateData0 &  ByteCntMaxFrame);

// Rx State Machine

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    begin

      StateIdle     <=  1'b0;

      StateDrop     <=  1'b1;

      StatePreamble <=  1'b0;

      StateSFD      <=  1'b0;

      StateData0    <=  1'b0;

      StateData1    <=  1'b0;

    end

  else

    begin

      if(StartPreamble | StartSFD | StartDrop)

        StateIdle <=  1'b0;

      else

      if(StartIdle)

        StateIdle <=  1'b1;

      if(StartIdle)

        StateDrop <=  1'b0;

      else

      if(StartDrop)

        StateDrop <=  1'b1;

      if(StartSFD | StartIdle | StartDrop)

        StatePreamble <=  1'b0;

      else

      if(StartPreamble)

        StatePreamble <=  1'b1;

      if(StartPreamble | StartIdle | StartData0 | StartDrop)

        StateSFD <=  1'b0;

      else

      if(StartSFD)

        StateSFD <=  1'b1;

      if(StartIdle | StartData1 | StartDrop)

        StateData0 <=  1'b0;

      else

      if(StartData0)

        StateData0 <=  1'b1;

      if(StartIdle | StartData0 | StartDrop)

        StateData1 <=  1'b0;

      else

      if(StartData1)

        StateData1 <=  1'b1;

    end

end

assign StateData[1:0] = {StateData1, StateData0};

endmodule