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

////                                                              ////

////  MAC_tx_addr_add.v                                           ////

////                                                              ////

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

////  http://www.opencores.org/projects.cgi/wr_en/ethernet_tri_mode/////

////                                                              ////

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

////      - Jon Gao (gaojon@yahoo.com)                            ////

////                                                              ////

////                                                              ////

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

////                                                              ////

//// 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  2005/12/16 06:44:18  Administrator

// replaced tab with space.

// passed 9.6k length frame test.

//

// Revision 1.1.1.1  2005/12/13 01:51:45  Administrator

// no message

//                                           

module MAC_tx_addr_add (

Reset               ,

Clk                 ,

MAC_tx_addr_init    ,

MAC_tx_addr_rd      ,

MAC_tx_addr_data    ,

//CPU               ,

MAC_add_prom_data   ,

MAC_add_prom_add    ,

MAC_add_prom_wr

);

input           Reset               ;

input           Clk                 ;

input           MAC_tx_addr_rd      ;

input           MAC_tx_addr_init    ;

output  [7:0]   MAC_tx_addr_data    ;

                //CPU               ;

input   [7:0]   MAC_add_prom_data   ;

input   [2:0]   MAC_add_prom_add    ;

input           MAC_add_prom_wr     ;

//******************************************************************************   

//internal signals                                                              

//******************************************************************************

reg [2:0]       add_rd;

wire[2:0]       add_wr;

wire[7:0]       din;

wire[7:0]       dout;

wire            wr_en;

reg             MAC_add_prom_wr_dl1;

reg             MAC_add_prom_wr_dl2;

//******************************************************************************   

//write data from cpu to prom                                                              

//******************************************************************************

always @ (posedge Clk or posedge Reset)

    if (Reset)

        begin

        MAC_add_prom_wr_dl1     <=0;

        MAC_add_prom_wr_dl2     <=0;

        end

    else

        begin

        MAC_add_prom_wr_dl1     <=MAC_add_prom_wr;

        MAC_add_prom_wr_dl2     <=MAC_add_prom_wr_dl1;

        end

assign # 2 wr_en   =MAC_add_prom_wr_dl1&!MAC_add_prom_wr_dl2;

assign # 2 add_wr  =MAC_add_prom_add;

assign # 2 din     =MAC_add_prom_data;

//******************************************************************************   

//read data from cpu to prom                                                              

//******************************************************************************

always @ (posedge Clk or posedge Reset)

    if (Reset)

        add_rd       <=0;

    else if (MAC_tx_addr_init)

        add_rd       <=0;

    else if (MAC_tx_addr_rd)

        add_rd       <=add_rd + 1;

assign MAC_tx_addr_data=dout;

//******************************************************************************   

//b port for read ,a port for write .

//******************************************************************************

duram #(8,3,"M512","DUAL_PORT") U_duram(

.data_a         (din            ),

.wren_a         (wr_en          ),

.address_a      (add_wr         ),

.address_b      (add_rd         ),

.clock_a        (Clk            ),

.clock_b        (Clk            ),

.q_b            (dout           ));

endmodule