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

////                                                              ////

////  eth_transmitcontrol.v                                       ////

////                                                              ////

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

////  http://www.opencores.org/cores/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 1.2  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 1.1  2001/07/03 12:51:54  mohor

// Initial release of the MAC Control module.

//

//

//

//

//

//

`include "timescale.v"

module eth_transmitcontrol (MTxClk, TxReset, TxUsedDataIn, TxUsedDataOut, TxDoneIn, TxAbortIn,

                            TxStartFrmIn, TPauseRq, TxUsedDataOutDetected, TxFlow, DlyCrcEn,

                            TxPauseTV, MAC, TxCtrlStartFrm, TxCtrlEndFrm, SendingCtrlFrm, CtrlMux,

                            ControlData, WillSendControlFrame

                           );

parameter Tp = 1;

input         MTxClk;

input         TxReset;

input         TxUsedDataIn;

input         TxUsedDataOut;

input         TxDoneIn;

input         TxAbortIn;

input         TxStartFrmIn;

input         TPauseRq;

input         TxUsedDataOutDetected;

input         TxFlow;

input         DlyCrcEn;

input  [15:0] TxPauseTV;

input  [47:0] MAC;

output        TxCtrlStartFrm;

output        TxCtrlEndFrm;

output        SendingCtrlFrm;

output        CtrlMux;

output [7:0]  ControlData;

output        WillSendControlFrame;

reg           SendingCtrlFrm;

reg           CtrlMux;

reg           WillSendControlFrame;

reg    [3:0]  DlyCrcCnt;

reg    [5:0]  ByteCnt;

reg           ControlEnd_q;

reg    [7:0]  MuxedCtrlData;

reg           TxCtrlStartFrm;

reg           TxCtrlStartFrm_q;

reg           TxCtrlEndFrm;

reg    [7:0]  ControlData;

reg           TxUsedDataIn_q;

wire          IncrementDlyCrcCnt;

wire          ResetByteCnt;

wire          IncrementByteCnt;

wire          ControlEnd;

// A command for Sending the control frame is active (latched)

always @ (posedge MTxClk or posedge TxReset)

begin

  if(TxReset)

    WillSendControlFrame <= #Tp 1'b0;

  else

  if(TxCtrlEndFrm & CtrlMux)

    WillSendControlFrame <= #Tp 1'b0;

  else

  if(TPauseRq & TxFlow)

    WillSendControlFrame <= #Tp 1'b1;

end

// Generation of the transmit control packet start frame

always @ (posedge MTxClk or posedge TxReset)

begin

  if(TxReset)

    TxCtrlStartFrm <= #Tp 1'b0;

  else

  if(TxUsedDataIn_q & CtrlMux)

    TxCtrlStartFrm <= #Tp 1'b0;

  else

  if(WillSendControlFrame & ~TxUsedDataOut & (TxDoneIn | TxAbortIn | TxStartFrmIn | ~TxUsedDataOutDetected))

    TxCtrlStartFrm <= #Tp 1'b1;

end

// Generation of the transmit control packet end frame

always @ (posedge MTxClk or posedge TxReset)

begin

  if(TxReset)

    TxCtrlEndFrm <= #Tp 1'b0;

  else

  if(ControlEnd | ControlEnd_q)

    TxCtrlEndFrm <= #Tp 1'b1;

  else

    TxCtrlEndFrm <= #Tp 1'b0;

end

// Generation of the multiplexer signal (controls muxes for switching between

// normal and control packets)

always @ (posedge MTxClk or posedge TxReset)

begin

  if(TxReset)

    CtrlMux <= #Tp 1'b0;

  else

  if(WillSendControlFrame & ~TxUsedDataOut)

    CtrlMux <= #Tp 1'b1;

  else

  if(TxDoneIn)

    CtrlMux <= #Tp 1'b0;

end

// Generation of the Sending Control Frame signal (enables padding and CRC)

always @ (posedge MTxClk or posedge TxReset)

begin

  if(TxReset)

    SendingCtrlFrm <= #Tp 1'b0;

  else

  if(WillSendControlFrame & TxCtrlStartFrm)

    SendingCtrlFrm <= #Tp 1'b1;

  else

  if(TxDoneIn)

    SendingCtrlFrm <= #Tp 1'b0;

end

always @ (posedge MTxClk or posedge TxReset)

begin

  if(TxReset)

    TxUsedDataIn_q <= #Tp 1'b0;

  else

    TxUsedDataIn_q <= #Tp TxUsedDataIn;

end

always @ (posedge MTxClk)

begin

  ControlEnd_q     <= #Tp ControlEnd;

  TxCtrlStartFrm_q <= #Tp TxCtrlStartFrm;

end

assign IncrementDlyCrcCnt = CtrlMux & TxUsedDataIn &  ~DlyCrcCnt[2];

// Delayed CRC counter

always @ (posedge MTxClk or posedge TxReset)

begin

  if(TxReset)

    DlyCrcCnt <= #Tp 4'h0;

  else

  if(ResetByteCnt)

    DlyCrcCnt <= #Tp 4'h0;

  else

  if(IncrementDlyCrcCnt)

    DlyCrcCnt <= #Tp DlyCrcCnt + 1'b1;

end

assign ResetByteCnt = TxReset | (~TxCtrlStartFrm & (TxDoneIn | TxAbortIn));

assign IncrementByteCnt = CtrlMux & (TxCtrlStartFrm & ~TxCtrlStartFrm_q & ~TxUsedDataIn | TxUsedDataIn & ~ControlEnd);

// Byte counter

always @ (posedge MTxClk or posedge TxReset)

begin

  if(TxReset)

    ByteCnt <= #Tp 6'h0;

  else

  if(ResetByteCnt)

    ByteCnt <= #Tp 6'h0;

  else

  if(IncrementByteCnt & (~DlyCrcEn | DlyCrcEn & (&DlyCrcCnt[1:0])))

    ByteCnt <= #Tp (ByteCnt[5:0] ) + 1'b1;

end

assign ControlEnd = ByteCnt[5:0] == 6'h22;

// Control data generation (goes to the TxEthMAC module)

always @ (ByteCnt or DlyCrcEn or MAC or TxPauseTV or DlyCrcCnt)

begin

  case(ByteCnt)

    6'h0:    if(~DlyCrcEn | DlyCrcEn & (&DlyCrcCnt[1:0]))

               MuxedCtrlData[7:0] = 8'h01;                   // Reserved Multicast Address

             else

                                                         MuxedCtrlData[7:0] = 8'h0;

    6'h2:      MuxedCtrlData[7:0] = 8'h80;

    6'h4:      MuxedCtrlData[7:0] = 8'hC2;

    6'h6:      MuxedCtrlData[7:0] = 8'h00;

    6'h8:      MuxedCtrlData[7:0] = 8'h00;

    6'hA:      MuxedCtrlData[7:0] = 8'h01;

    6'hC:      MuxedCtrlData[7:0] = MAC[47:40];

    6'hE:      MuxedCtrlData[7:0] = MAC[39:32];

    6'h10:     MuxedCtrlData[7:0] = MAC[31:24];

    6'h12:     MuxedCtrlData[7:0] = MAC[23:16];

    6'h14:     MuxedCtrlData[7:0] = MAC[15:8];

    6'h16:     MuxedCtrlData[7:0] = MAC[7:0];

    6'h18:     MuxedCtrlData[7:0] = 8'h88;                   // Type/Length

    6'h1A:     MuxedCtrlData[7:0] = 8'h08;

    6'h1C:     MuxedCtrlData[7:0] = 8'h00;                   // Opcode

    6'h1E:     MuxedCtrlData[7:0] = 8'h01;

    6'h20:     MuxedCtrlData[7:0] = TxPauseTV[15:8];         // Pause timer value

    6'h22:     MuxedCtrlData[7:0] = TxPauseTV[7:0];

    default:   MuxedCtrlData[7:0] = 8'h0;

  endcase

end

// Latched Control data

always @ (posedge MTxClk or posedge TxReset)

begin

  if(TxReset)

    ControlData[7:0] <= #Tp 8'h0;

  else

  if(~ByteCnt[0])

    ControlData[7:0] <= #Tp MuxedCtrlData[7:0];

end

endmodule