aboutsummaryrefslogtreecommitdiffstats
path: root/usrp2/gpmc/cross_clock_reader.v
blob: a8366badc36e0b5438dc5b25ca2e44981fcd3529 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
//
// Copyright 2011-2012 Ettus Research LLC
//
// 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 3 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, see <http://www.gnu.org/licenses/>.
//

module cross_clock_reader
    #(
        parameter WIDTH = 1,
        parameter DEFAULT = 0
    )
    (
        input clk, input rst,
        input [WIDTH-1:0] in,
        output reg [WIDTH-1:0] out
    );

    reg [WIDTH-1:0] shadow0, shadow1;

    always @(posedge clk) begin
        if (rst) begin
            out <= DEFAULT;
            shadow0 <= DEFAULT;
            shadow1 <= DEFAULT;
        end
        else if (shadow0 == shadow1) begin
            out <= shadow1;
        end
        shadow0 <= in;
        shadow1 <= shadow0;
    end

endmodule //cross_clock_reader