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

////                                                              ////

////  Tubo 8051 cores common library Module                       ////

////                                                              ////

////  This file is part of the Turbo 8051 cores project           ////

////  http://www.opencores.org/cores/turbo8051/                   ////

////                                                              ////

////  Description                                                 ////

////  Turbo 8051 definitions.                                     ////

////                                                              ////

////  To Do:                                                      ////

////    nothing                                                   ////

////                                                              ////

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

////      - Dinesh Annayya, dinesha@opencores.org                 ////

////                                                              ////

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

////                                                              ////

//// Copyright (C) 2000 Authors and OPENCORES.ORG                 ////

////                                                              ////

//// 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                     ////

////                                                              ////

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

module toggle_sync (in_clk,

                    in_rst_n,

                    out_clk,

                    out_rst_n,

                    in,

                    out_req,

                    out_ack);

   output   out_req;

   input    in_clk, in_rst_n, out_clk, out_rst_n, in, out_ack;

   reg      in_flag, out_flag;

   always @ (posedge in_clk or negedge in_rst_n)

      if (~in_rst_n)

         in_flag <= 1'b0;

      else

         in_flag <= (in) ? ~in_flag : in_flag;

   always @ (posedge out_clk or negedge out_rst_n)

      if (~out_rst_n)

         out_flag <= 1'b0;

      else

         out_flag <= (out_ack & out_req) ? ~out_flag : out_flag;

   wire     raw_req_pend;

   assign raw_req_pend = in_flag ^ out_flag;

   reg      s1_out_req, s2_out_req;

   always @ (posedge out_clk or negedge out_rst_n)

      if (~out_rst_n) begin

         s1_out_req <= 1'b0;

         s2_out_req <= 1'b0;

      end // if (~out_rst_n)

      else begin

         s1_out_req <= ~out_ack & raw_req_pend;

         s2_out_req <= ~out_ack & s1_out_req;

      end // else: !if(~out_rst_n)

   wire out_req;

   assign out_req = s2_out_req;

endmodule // toggle_sync