xsync_fpge/source/src/zutils/zutils_edge_detecter.v

module zutils_edge_detecter (
    input clk,  //clock input
    input rst_n,  //asynchronous reset input, low active
    input wire in_signal,
    output in_signal_last,
    output in_signal_rising_edge,
    output in_signal_falling_edge,
    output in_signal_edge
);

  reg in_signal_last = 0;
  reg in_signal_rising_edge = 0;
  reg in_signal_falling_edge = 0;
  reg in_signal_edge = 0;



  always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
      in_signal_last <= 0;
    end else begin
      in_signal_last <= in_signal;
    end
  end

  always @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
      in_signal_rising_edge  <= 0;
      in_signal_falling_edge <= 0;
      in_signal_edge         <= 0;
    end else begin
      if (in_signal_last == 0 && in_signal == 1) begin
        in_signal_rising_edge  <= 1;
        in_signal_falling_edge <= 0;
        in_signal_edge         <= 1;
      end else if (in_signal_last == 1 && in_signal == 0) begin
        in_signal_rising_edge  <= 0;
        in_signal_falling_edge <= 1;
        in_signal_edge         <= 1;
      end else begin
        in_signal_rising_edge  <= 0;
        in_signal_falling_edge <= 0;
        in_signal_edge         <= 0;
      end
    end
  end
endmodule