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

////                                                              ////

////  ZBT RAM Model                                               ////

////                                                              ////

////                                                              ////

////  Description                                                 ////

////  Emulates the behaviour of the ZBT RAM                       ////

////                                                              ////

////  To Do:                                                      ////

////   - nothing really                                           ////

////                                                              ////

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

////      - Javier Castillo, jcastillo@opensocdesign.com          ////

////                                                              ////

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

////                                                              ////

//// Copyright (C) 2004 OpenCores                                 ////

////                                                              ////

//// 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 $

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

module zbtram(clk,nBW,nCS,nRW,data,address);

   input        clk;

   input [3:0]  nBW;

   input        nCS;

   input        nRW;

   inout [31:0] data;

   input [19:0] address;

   reg   [19:0] addr_var;

   reg   [31:0] mem['h0:'h10000];

   reg control;

   reg [31:0] data_t;

   assign #1 data = control ? data_t : 32'hZ;

   integer i,file;

   initial

   begin

      #1

      for(i='h0;i<'h10000;i=i+1)

        mem[i]=0;

      //Load RAM with a initial program

 /*   $display("Initializing RAM");

      $readmemh("./hex/or1k-des.hex", mem); */

      data_t=0;

      control=0;

      while(1)

      begin

          @(posedge clk)

          if(nRW==1)

          begin

            addr_var = address;

            control = 1;

            data_t = mem[addr_var];

            if(addr_var==0) data_t=0;

//          $display("Read %X from address %X",data_t,addr_var);   

          end

          else

          begin

            addr_var = address;

            control = 0;

            @(posedge clk)

            case(nBW)

             4'b0000:

               mem[addr_var] = data;

             4'b0111:

               mem[addr_var][31:24] = data[7:0];

             4'b1011:

               mem[addr_var][23:16] = data[7:0];

             4'b1101:

               mem[addr_var][15:8] = data[7:0];

             4'b1110:

               mem[addr_var][7:0] = data[7:0];

             4'b0011:

               mem[addr_var][31:16] = data[15:0];

             4'b1100:

               mem[addr_var][15:0] = data[15:0];

            endcase

            control = 1;

//            $display("%d: Write %X in address %X sel= %b",$time,mem[addr_var],addr_var,nBW);   

          end

       end

    end

endmodule