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// vim: ts=4 sw=4 noexpandtab
/*
* Synchronize a signal to a clock
*
* Copyright (c) 2019 Michael Buesch <m@bues.ch>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
`ifndef SYNC_SIGNAL_MOD_V_
`define SYNC_SIGNAL_MOD_V_
module sync_signal(
input clk, /* clock */
input in, /* input signal */
output out, /* synchronized output signal */
output falling, /* synchronized falling edge output */
output rising, /* synchronized rising edge output */
);
reg [2:0] shiftreg;
initial begin
shiftreg <= 0;
end
always @(posedge clk) begin
shiftreg[2:1] <= shiftreg[1:0];
shiftreg[0] <= in;
end
assign out = shiftreg[1];
assign falling = shiftreg[2] & ~shiftreg[1];
assign rising = ~shiftreg[2] & shiftreg[1];
endmodule
`endif /* SYNC_SIGNAL_MOD_V_ */
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