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

////                                                              ////

////  eth_macstatus.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 available in the Readme.txt   ////

////  file.                                                       ////

////                                                              ////

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

////                                                              ////

//// Copyright (C) 2001, 2002 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 1.16  2005/02/21 10:42:11  igorm

// Defer indication fixed.

//

// Revision 1.15  2003/01/30 13:28:19  tadejm

// Defer indication changed.

//

// Revision 1.14  2002/11/22 01:57:06  mohor

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

// synchronized.

//

// Revision 1.13  2002/11/13 22:30:58  tadejm

// Late collision is reported only when not in the full duplex.

// Sample is taken (for status) as soon as MRxDV is not valid (regardless

// of the received byte cnt).

//

// Revision 1.12  2002/09/12 14:50:16  mohor

// CarrierSenseLost bug fixed when operating in full duplex mode.

//

// Revision 1.11  2002/09/04 18:38:03  mohor

// CarrierSenseLost status is not set when working in loopback mode.

//

// Revision 1.10  2002/07/25 18:17:46  mohor

// InvalidSymbol generation changed.

//

// Revision 1.9  2002/04/22 13:51:44  mohor

// Short frame and ReceivedLengthOK were not detected correctly.

//

// Revision 1.8  2002/02/18 10:40:17  mohor

// Small fixes.

//

// Revision 1.7  2002/02/15 17:07:39  mohor

// Status was not written correctly when frames were discarted because of

// address mismatch.

//

// Revision 1.6  2002/02/11 09:18:21  mohor

// Tx status is written back to the BD.

//

// Revision 1.5  2002/02/08 16:21:54  mohor

// Rx status is written back to the BD.

//

// Revision 1.4  2002/01/23 10:28:16  mohor

// Link in the header changed.

//

// Revision 1.3  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 1.2  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.

//

//

//

//

//

`include "timescale.v"

module eth_macstatus(

                      MRxClk, Reset, ReceivedLengthOK, ReceiveEnd, ReceivedPacketGood, RxCrcError,

                      MRxErr, MRxDV, RxStateSFD, RxStateData, RxStatePreamble, RxStateIdle, Transmitting,

                      RxByteCnt, RxByteCntEq0, RxByteCntGreat2, RxByteCntMaxFrame,

                      InvalidSymbol, MRxD, LatchedCrcError, Collision, CollValid, RxLateCollision,

                      r_RecSmall, r_MinFL, r_MaxFL, ShortFrame, DribbleNibble, ReceivedPacketTooBig, r_HugEn,

                      LoadRxStatus, StartTxDone, StartTxAbort, RetryCnt, RetryCntLatched, MTxClk, MaxCollisionOccured,

                      RetryLimit, LateCollision, LateCollLatched, DeferIndication, DeferLatched, RstDeferLatched, TxStartFrm,

                      StatePreamble, StateData, CarrierSense, CarrierSenseLost, TxUsedData, LatchedMRxErr, Loopback,

                      r_FullD

                    );

input         MRxClk;

input         Reset;

input         RxCrcError;

input         MRxErr;

input         MRxDV;

input         RxStateSFD;

input   [1:0] RxStateData;

input         RxStatePreamble;

input         RxStateIdle;

input         Transmitting;

input  [15:0] RxByteCnt;

input         RxByteCntEq0;

input         RxByteCntGreat2;

input         RxByteCntMaxFrame;

input   [3:0] MRxD;

input         Collision;

input   [5:0] CollValid;

input         r_RecSmall;

input  [15:0] r_MinFL;

input  [15:0] r_MaxFL;

input         r_HugEn;

input         StartTxDone;

input         StartTxAbort;

input   [3:0] RetryCnt;

input         MTxClk;

input         MaxCollisionOccured;

input         LateCollision;

input         DeferIndication;

input         TxStartFrm;

input         StatePreamble;

input   [1:0] StateData;

input         CarrierSense;

input         TxUsedData;

input         Loopback;

input         r_FullD;

output        ReceivedLengthOK;

output        ReceiveEnd;

output        ReceivedPacketGood;

output        InvalidSymbol;

output        LatchedCrcError;

output        RxLateCollision;

output        ShortFrame;

output        DribbleNibble;

output        ReceivedPacketTooBig;

output        LoadRxStatus;

output  [3:0] RetryCntLatched;

output        RetryLimit;

output        LateCollLatched;

output        DeferLatched;

input         RstDeferLatched;

output        CarrierSenseLost;

output        LatchedMRxErr;

reg           ReceiveEnd;

reg           LatchedCrcError;

reg           LatchedMRxErr;

reg           LoadRxStatus;

reg           InvalidSymbol;

reg     [3:0] RetryCntLatched;

reg           RetryLimit;

reg           LateCollLatched;

reg           DeferLatched;

reg           CarrierSenseLost;

wire          TakeSample;

wire          SetInvalidSymbol; // Invalid symbol was received during reception in 100Mbps 

// Crc error

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    LatchedCrcError <= 1'b0;

  else

  if(RxStateSFD)

    LatchedCrcError <= 1'b0;

  else

  if(RxStateData[0])

    LatchedCrcError <= RxCrcError & ~RxByteCntEq0;

end

// LatchedMRxErr

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    LatchedMRxErr <= 1'b0;

  else

  if(MRxErr & MRxDV & (RxStatePreamble | RxStateSFD | (|RxStateData) | RxStateIdle & ~Transmitting))

    LatchedMRxErr <= 1'b1;

  else

    LatchedMRxErr <= 1'b0;

end

// ReceivedPacketGood

assign ReceivedPacketGood = ~LatchedCrcError;

// ReceivedLengthOK

assign ReceivedLengthOK = RxByteCnt[15:0] >= r_MinFL[15:0] & RxByteCnt[15:0] <= r_MaxFL[15:0];

// Time to take a sample

//assign TakeSample = |RxStateData     & ~MRxDV & RxByteCntGreat2  |

assign TakeSample = (|RxStateData)   & (~MRxDV)                    |

                      RxStateData[0] &   MRxDV & RxByteCntMaxFrame;

// LoadRxStatus

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    LoadRxStatus <= 1'b0;

  else

    LoadRxStatus <= TakeSample;

end

// ReceiveEnd

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    ReceiveEnd  <= 1'b0;

  else

    ReceiveEnd  <= LoadRxStatus;

end

// Invalid Symbol received during 100Mbps mode

assign SetInvalidSymbol = MRxDV & MRxErr & MRxD[3:0] == 4'he;

// InvalidSymbol

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    InvalidSymbol <= 1'b0;

  else

  if(LoadRxStatus & ~SetInvalidSymbol)

    InvalidSymbol <= 1'b0;

  else

  if(SetInvalidSymbol)

    InvalidSymbol <= 1'b1;

end

// Late Collision

reg RxLateCollision;

reg RxColWindow;

// Collision Window

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    RxLateCollision <= 1'b0;

  else

  if(LoadRxStatus)

    RxLateCollision <= 1'b0;

  else

  if(Collision & (~r_FullD) & (~RxColWindow | r_RecSmall))

    RxLateCollision <= 1'b1;

end

// Collision Window

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    RxColWindow <= 1'b1;

  else

  if(~Collision & RxByteCnt[5:0] == CollValid[5:0] & RxStateData[1])

    RxColWindow <= 1'b0;

  else

  if(RxStateIdle)

    RxColWindow <= 1'b1;

end

// ShortFrame

reg ShortFrame;

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    ShortFrame <= 1'b0;

  else

  if(LoadRxStatus)

    ShortFrame <= 1'b0;

  else

  if(TakeSample)

    ShortFrame <= RxByteCnt[15:0] < r_MinFL[15:0];

end

// DribbleNibble

reg DribbleNibble;

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    DribbleNibble <= 1'b0;

  else

  if(RxStateSFD)

    DribbleNibble <= 1'b0;

  else

  if(~MRxDV & RxStateData[1])

    DribbleNibble <= 1'b1;

end

reg ReceivedPacketTooBig;

always @ (posedge MRxClk or posedge Reset)

begin

  if(Reset)

    ReceivedPacketTooBig <= 1'b0;

  else

  if(LoadRxStatus)

    ReceivedPacketTooBig <= 1'b0;

  else

  if(TakeSample)

    ReceivedPacketTooBig <= ~r_HugEn & RxByteCnt[15:0] > r_MaxFL[15:0];

end

// Latched Retry counter for tx status

always @ (posedge MTxClk or posedge Reset)

begin

  if(Reset)

    RetryCntLatched <= 4'h0;

  else

  if(StartTxDone | StartTxAbort)

    RetryCntLatched <= RetryCnt;

end

// Latched Retransmission limit

always @ (posedge MTxClk or posedge Reset)

begin

  if(Reset)

    RetryLimit <= 1'h0;

  else

  if(StartTxDone | StartTxAbort)

    RetryLimit <= MaxCollisionOccured;

end

// Latched Late Collision

always @ (posedge MTxClk or posedge Reset)

begin

  if(Reset)

    LateCollLatched <= 1'b0;

  else

  if(StartTxDone | StartTxAbort)

    LateCollLatched <= LateCollision;

end

// Latched Defer state

always @ (posedge MTxClk or posedge Reset)

begin

  if(Reset)

    DeferLatched <= 1'b0;

  else

  if(DeferIndication)

    DeferLatched <= 1'b1;

  else

  if(RstDeferLatched)

    DeferLatched <= 1'b0;

end

// CarrierSenseLost

always @ (posedge MTxClk or posedge Reset)

begin

  if(Reset)

    CarrierSenseLost <= 1'b0;

  else

  if((StatePreamble | (|StateData)) & ~CarrierSense & ~Loopback & ~Collision & ~r_FullD)

    CarrierSenseLost <= 1'b1;

  else

  if(TxStartFrm)

    CarrierSenseLost <= 1'b0;

end

endmodule