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////  dbg_comm_vpi.v                                              ////

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////                                                              ////

////  This file is part of the SoC/OpenRISC Development Interface ////

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

////                                                              ////

////                                                              ////

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

////       Igor Mohor (igorm@opencores.org)                       ////

////       Gyorgy Jeney (nog@sdf.lonestar.net)                    ////

////       Nathan Yawn (nathan.yawn@opencores.org)                ////

////       Raul Fajardo (rfajardo@gmail.com)                      ////

////                                                              ////

////                                                              ////

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

////                                                              ////

//// Copyright (C) 2000-2011 Authors                              ////

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//// 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                     ////

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

//

// CVS Revision History

//

// $Log: dbg_comm_vpi.v,v $

// Revision 1.2.1  2009/09/08 14:57  rfajardo

// Changed clock and reset outputs to inputs for minsoc

//

// $Log: dbg_comm_vpi.v,v $

// Revision 1.2  2009/05/17 20:55:57  Nathan

// Changed email address to opencores.org

//

// Revision 1.1  2008/07/26 17:33:20  Nathan

// Added debug comm module for use with VPI / network communication.

//

// Revision 1.1  2002/03/28 19:59:54  lampret

// Added bench directory

//

// Revision 1.1.1.1  2001/11/04 18:51:07  lampret

// First import.

//

// Revision 1.3  2001/09/24 14:06:13  mohor

// Changes connected to the OpenRISC access (SPR read, SPR write).

//

// Revision 1.2  2001/09/20 10:10:30  mohor

// Working version. Few bugs fixed, comments added.

//

// Revision 1.1.1.1  2001/09/13 13:49:19  mohor

// Initial official release.

//

//

//

//

//

`include "timescale.v"

`define JP_PORT "4567"

`define TIMEOUT_COUNT 6'd5  // 1/2 of a TCK clock will be this many SYS_CLK ticks.  Must be less than 6 bits. 

  module dbg_comm_vpi (

                       SYS_CLK,

                       P_TMS,

                       P_TCK,

                       P_TRST,

                       P_TDI,

                       P_TDO

                       );

   //parameter Tp = 20;

   input     SYS_CLK;

   output    P_TMS;

   output    P_TCK;

   output    P_TRST;

   output    P_TDI;

   input     P_TDO;

   reg [4:0] memory;  // [0:0];

   wire      P_TCK;

   wire      P_TRST;

   wire      P_TDI;

   wire      P_TMS;

   wire      P_TDO;

   reg [3:0] in_word_r;

   reg [5:0] clk_count;

   // Handle commands from the upper level

   initial

     begin

        in_word_r = 5'b0;

        memory = 5'b0;

        $jp_init(`JP_PORT);

        #5500;  // Wait until reset is complete

        while(1)

          begin

             #1;

             $jp_in(memory);  // This will not change memory[][] if no command has been sent from jp

             if(memory[4])  // was memory[0][4]

               begin

                  in_word_r = memory[3:0];

                  memory = memory & 4'b1111;

                  clk_count = 6'b000000;  // Reset the timeout clock in case jp wants to wait for a timeout / half TCK period

               end

          end

     end

   // Send the output bit to the upper layer

   always @ (P_TDO)

     begin

        $jp_out(P_TDO);

     end

   assign P_TCK  = in_word_r[0];

   assign P_TRST = in_word_r[1];

   assign P_TDI  = in_word_r[2];

   assign P_TMS  = in_word_r[3];

   // Send timeouts / wait periods to the upper layer

   always @ (posedge SYS_CLK)

     begin

        if(clk_count < `TIMEOUT_COUNT) clk_count[5:0] = clk_count[5:0] + 1;

        else if(clk_count == `TIMEOUT_COUNT) begin

           $jp_wait_time();

           clk_count[5:0] = clk_count[5:0] + 1;

        end

        // else it's already timed out, don't do anything

     end

endmodule