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

////                                                              ////

//// WISHBONE SD Card Controller IP Core                          ////

////                                                              ////

//// edge_detect.v                                                ////

////                                                              ////

//// This file is part of the WISHBONE SD Card                    ////

//// Controller IP Core project                                   ////

//// http://opencores.org/project,sd_card_controller              ////

////                                                              ////

//// Description                                                  ////

//// Signal edge detection. If input signal transitions between   ////

//// two states, output signal is generated for one clock cycle.  ////

////                                                              ////

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

////     - Marek Czerski, ma.czerski@gmail.com                    ////

////                                                              ////

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

////                                                              ////

//// Copyright (C) 2013 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                     ////

////                                                              ////

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

module edge_detect (

    input rst,

    input clk,

    input sig,

    output rise,

    output fall

);

reg [1:0] sig_reg;

always @(posedge clk or posedge rst)

    if (rst == 1'b1)

        sig_reg <= 2'b00;

    else

        sig_reg <= {sig_reg[0], sig};

assign rise = sig_reg[0] == 1'b1 && sig_reg[1] == 1'b0 ? 1'b1 : 1'b0;

assign fall = sig_reg[0] == 1'b0 && sig_reg[1] == 1'b1 ? 1'b1 : 1'b0;

endmodule