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

////                                                              ////

////  eth_rxaddrcheck.v                                           ////

////                                                              ////

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

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

////                                                              ////

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

////      - Bill Dittenhofer (billditt@aol.com)                   ////

////                                                              ////

////  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: eth_rxaddrcheck.v,v $

// Revision 1.9  2002/11/22 01:57:06  mohor

// Rx Flow control fixed. CF flag added to the RX buffer descriptor. RxAbort

// synchronized.

//

// Revision 1.8  2002/11/19 17:34:52  mohor

// AddressMiss status is connecting to the Rx BD. AddressMiss is identifying

// that a frame was received because of the promiscous mode.

//

// Revision 1.7  2002/09/04 18:41:06  mohor

// Bug when last byte of destination address was not checked fixed.

//

// Revision 1.6  2002/03/20 15:14:11  mohor

// When in promiscous mode some frames were not received correctly. Fixed.

//

// Revision 1.5  2002/03/02 21:06:32  mohor

// Log info was missing.

//

//

// Revision 1.1  2002/02/08 12:51:54  ditt

// Initial release of the ethernet addresscheck module.

//

//

//

//

//

`include "timescale.v"

module eth_rxaddrcheck(MRxClk,  Reset, RxData, Broadcast ,r_Bro ,r_Pro,

                       ByteCntEq2, ByteCntEq3, ByteCntEq4, ByteCntEq5,

                       ByteCntEq6, ByteCntEq7, HASH0, HASH1,

                       CrcHash,    CrcHashGood, StateData, RxEndFrm,

                       Multicast, MAC, RxAbort, AddressMiss, PassAll,

                       ControlFrmAddressOK

                      );

parameter Tp = 1;

  input        MRxClk;

  input        Reset;

  input [7:0]  RxData;

  input        Broadcast;

  input        r_Bro;

  input        r_Pro;

  input        ByteCntEq2;

  input        ByteCntEq3;

  input        ByteCntEq4;

  input        ByteCntEq5;

  input        ByteCntEq6;

  input        ByteCntEq7;

  input [31:0] HASH0;

  input [31:0] HASH1;

  input [5:0]  CrcHash;

  input        CrcHashGood;

  input        Multicast;

  input [47:0] MAC;

  input [1:0]  StateData;

  input        RxEndFrm;

  input        PassAll;

  input        ControlFrmAddressOK;

  output       RxAbort;

  output       AddressMiss;

 wire BroadcastOK;

 wire ByteCntEq2;

 wire ByteCntEq3;

 wire ByteCntEq4;

 wire ByteCntEq5;

 wire RxAddressInvalid;

 wire RxCheckEn;

 wire HashBit;

 wire [31:0] IntHash;

 reg [7:0]  ByteHash;

 reg MulticastOK;

 reg UnicastOK;

 reg RxAbort;

 reg AddressMiss;

assign RxAddressInvalid = ~(UnicastOK | BroadcastOK | MulticastOK | r_Pro);

assign BroadcastOK = Broadcast & ~r_Bro;

assign RxCheckEn   = | StateData;

 // Address Error Reported at end of address cycle

 // RxAbort clears after one cycle

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    RxAbort <= #Tp 1'b0;

  else if(RxAddressInvalid & ByteCntEq7 & RxCheckEn)

    RxAbort <= #Tp 1'b1;

  else

    RxAbort <= #Tp 1'b0;

end

// This ff holds the "Address Miss" information that is written to the RX BD status.

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    AddressMiss <= #Tp 1'b0;

  else if(ByteCntEq7 & RxCheckEn)

    AddressMiss <= #Tp (~(UnicastOK | BroadcastOK | MulticastOK | (PassAll & ControlFrmAddressOK)));

end

// Hash Address Check, Multicast

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    MulticastOK <= #Tp 1'b0;

  else if(RxEndFrm | RxAbort)

    MulticastOK <= #Tp 1'b0;

  else if(CrcHashGood & Multicast)

    MulticastOK <= #Tp HashBit;

end

// Address Detection (unicast)

// start with ByteCntEq2 due to delay of addres from RxData

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    UnicastOK <= #Tp 1'b0;

  else

  if(RxCheckEn & ByteCntEq2)

    UnicastOK <= #Tp   RxData[7:0] == MAC[47:40];

  else

  if(RxCheckEn & ByteCntEq3)

    UnicastOK <= #Tp ( RxData[7:0] == MAC[39:32]) & UnicastOK;

  else

  if(RxCheckEn & ByteCntEq4)

    UnicastOK <= #Tp ( RxData[7:0] == MAC[31:24]) & UnicastOK;

  else

  if(RxCheckEn & ByteCntEq5)

    UnicastOK <= #Tp ( RxData[7:0] == MAC[23:16]) & UnicastOK;

  else

  if(RxCheckEn & ByteCntEq6)

    UnicastOK <= #Tp ( RxData[7:0] == MAC[15:8])  & UnicastOK;

  else

  if(RxCheckEn & ByteCntEq7)

    UnicastOK <= #Tp ( RxData[7:0] == MAC[7:0])   & UnicastOK;

  else

  if(RxEndFrm | RxAbort)

    UnicastOK <= #Tp 1'b0;

end

assign IntHash = (CrcHash[5])? HASH1 : HASH0;

always@(CrcHash or IntHash)

begin

  case(CrcHash[4:3])

    2'b00: ByteHash = IntHash[7:0];

    2'b01: ByteHash = IntHash[15:8];

    2'b10: ByteHash = IntHash[23:16];

    2'b11: ByteHash = IntHash[31:24];

  endcase

end

assign HashBit = ByteHash[CrcHash[2:0]];

endmodule