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

//   ____  ____

//  /   /\/   /

// /___/  \  /    Vendor: Xilinx

// \   \   \/     Version: 3.0

//  \   \         Application: MIG

//  /   /         Filename: ddr2_usr_addr_fifo.v

// /___/   /\     Date Last Modified: $Date: 2008/12/23 14:26:01 $

// \   \  /  \    Date Created: Mon Aug 28 2006

//  \___\/\___\

//

//Device: Virtex-5

//Design Name: DDR2

//Purpose:

//   This module instantiates the block RAM based FIFO to store the user

//   address and the command information. Also calculates potential bank/row

//   conflicts by comparing the new address with last address issued.

//Reference:

//Revision History:

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

`timescale 1ns/1ps

module ddr2_usr_addr_fifo #

  (

   // Following parameters are for 72-bit RDIMM design (for ML561 Reference 

   // board design). Actual values may be different. Actual parameters values 

   // are passed from design top module ddr2_mig module. Please refer to

   // the ddr2_mig module for actual values.

   parameter BANK_WIDTH    = 2,

   parameter COL_WIDTH     = 10,

   parameter CS_BITS       = 0,

   parameter ROW_WIDTH     = 14

   )

  (

   input          clk0,

    input         rst0,

    input         usr_clk,

   input [2:0]    app_af_cmd,

   input [30:0]   app_af_addr,

   input          app_af_wren,

   input          ctrl_af_rden,

   output [2:0]   af_cmd,

   output [30:0]  af_addr,

   output         af_empty,

   output         app_af_afull

   );

  wire [35:0]     fifo_data_out;

   reg            rst_r;

  always @(posedge clk0)

     rst_r <= rst0;

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

  assign af_cmd      = fifo_data_out[33:31];

  assign af_addr     = fifo_data_out[30:0];

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

  FIFO36 #

    (

     .ALMOST_EMPTY_OFFSET     (13'h0007),

     .ALMOST_FULL_OFFSET      (13'h000F),

     .DATA_WIDTH              (36),

     .DO_REG                  (1),

     .EN_SYN                  ("FALSE"), // changed to FALSE - jb

     .FIRST_WORD_FALL_THROUGH ("FALSE")

     )

    u_af

      (

       .ALMOSTEMPTY (),

       .ALMOSTFULL  (app_af_afull),

       .DO          (fifo_data_out[31:0]),

       .DOP         (fifo_data_out[35:32]),

       .EMPTY       (af_empty),

       .FULL        (),

       .RDCOUNT     (),

       .RDERR       (),

       .WRCOUNT     (),

       .WRERR       (),

       .DI          ({app_af_cmd[0],app_af_addr}),

       .DIP         ({2'b00,app_af_cmd[2:1]}),

       .RDCLK       (clk0),

       .RDEN        (ctrl_af_rden),

       .RST         (rst_r),

       //.WRCLK       (clk0),

       .WRCLK       (usr_clk),

       .WREN        (app_af_wren)

       );

endmodule