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

////                                                              ////

////  eth_spram_256x32.v                                          ////

////                                                              ////

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

////  http://www.opencores.org/projects/ethmac/                   ////

////                                                              ////

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

////      - Igor Mohor (igorM@opencores.org)                      ////

////                                                              ////

////  All additional information is available in the Readme.txt   ////

////  file.                                                       ////

////                                                              ////

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

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//// Copyright (C) 2001, 2002 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. ////

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//// 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.                                               ////

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//// PURPOSE.  See the GNU Lesser General Public License for more ////

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

//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

// Revision 1.1  2002/07/23 16:36:09  mohor

// ethernet spram added. So far a generic ram and xilinx RAMB4 are used.

//

//

//

`include "eth_defines.v"

`include "timescale.v"

module eth_spram_256x32(

        // Generic synchronous single-port RAM interface

        clk, rst, ce, we, oe, addr, di, do

);

        //

        // Generic synchronous single-port RAM interface

        //

        input           clk;  // Clock, rising edge

        input           rst;  // Reset, active high

        input           ce;   // Chip enable input, active high

        input           we;   // Write enable input, active high

        input           oe;   // Output enable input, active high

        input  [7:0]    addr; // address bus inputs

        input  [31:0]   di;   // input data bus

        output [31:0]   do;   // output data bus

`ifdef ETH_XILINX_RAMB4

    RAMB4_S16 ram0

    (

        .DO      (do[15:0]),

        .ADDR    (addr),

        .DI      (di[15:0]),

        .EN      (ce),

        .CLK     (clk),

        .WE      (we),

        .RST     (rst)

    );

    RAMB4_S16 ram1

    (

        .DO      (do[31:16]),

        .ADDR    (addr),

        .DI      (di[31:16]),

        .EN      (ce),

        .CLK     (clk),

        .WE      (we),

        .RST     (rst)

    );

`else   // !ETH_XILINX_RAMB4

`ifdef  ETH_VIRTUAL_SILICON_RAM

  vs_hdsp_256x32 ram0

  (

        .CK       (clk),

        .CEN      (!ce),

        .WEN      (!we),

        .OEN      (!oe),

        .ADR      (addr),

        .DI       (di),

        .DOUT     (do)

  );

`else   // !ETH_VIRTUAL_SILICON_RAM

        //

        // Generic single-port synchronous RAM model

        //

        //

        // Generic RAM's registers and wires

        //

        reg  [31:0] mem [255:0];  // RAM content

        wire [31:0] q;          // RAM output

        reg  [7:0]  raddr;      // RAM read address

        //

        // Data output drivers

        //

        assign do = (oe & ce) ? q : {32{1'bz}};

        //

        // RAM read and write

        //

        // read operation

        always@(posedge clk)

        if (ce) // && !we)

                raddr <= #1 addr;    // read address needs to be registered to read clock

        assign #1 q = rst ? {32{1'b0}} : mem[raddr];

        // write operation

        always@(posedge clk)

                if (ce && we)

                        mem[addr] <= #1 di;

        // Task prints range of memory

        // *** Remember that tasks are non reentrant, don't call this task in parallel for multiple instantiations. 

        task print_ram;

        input [7:0] start;

        input [7:0] finish;

        integer rnum;

        begin

                for (rnum=start;rnum<=finish;rnum=rnum+1)

                        $display("Addr %h = %h",rnum,mem[rnum]);

        end

        endtask

`endif  // !ETH_VIRTUAL_SILICON_RAM

`endif  // !ETH_XILINX_RAMB4

endmodule