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/*

    This file is part of Blue8.

    Foobar 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 3 of the License, or

    (at your option) any later version.

    Foobar 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 Blue8.  If not, see <http://www.gnu.org/licenses/>.

    Blue8 by Al Williams alw@al-williams.com

*/

// this synchronizes a "switch" which may be async and

// long, and this outputs a single pulse. The switch is assmed

// to already be debounced

module switchsync(clk,d,q);

input clk,d;

output q;

reg q;

reg s0;

initial q=0;

initial s0=0;

always @(posedge clk) begin

  if (s0==1'b0 && d==1'b1) q=1'b1; else q=1'b0;

  s0=d;

end

endmodule