pluto_hdl_adi/library/util_cdc/sync_event.v

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// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
//
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// In this HDL repository, there are many different and unique modules, consisting
// of various HDL (Verilog or VHDL) components. The individual modules are
// developed independently, and may be accompanied by separate and unique license
// terms.
//
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// The user should read each of these license terms, and understand the
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// freedoms and responsibilities that he or she has by using this source/core.
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//
// This core 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.
//
// Redistribution and use of source or resulting binaries, with or without modification
// of this file, are permitted under one of the following two license terms:
//
// 1. The GNU General Public License version 2 as published by the
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// Free Software Foundation, which can be found in the top level directory
// of this repository (LICENSE_GPL2), and also online at:
// <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
//
// OR
//
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// 2. An ADI specific BSD license, which can be found in the top level directory
// of this repository (LICENSE_ADIBSD), and also on-line at:
// https://github.com/analogdevicesinc/hdl/blob/master/LICENSE_ADIBSD
// This will allow to generate bit files and not release the source code,
// as long as it attaches to an ADI device.
//
// ***************************************************************************
// ***************************************************************************
`timescale 1ns/100ps
module sync_event #(
parameter NUM_OF_EVENTS = 1,
parameter ASYNC_CLK = 1
) (
input in_clk,
input [NUM_OF_EVENTS-1:0] in_event,
input out_clk,
output reg [NUM_OF_EVENTS-1:0] out_event
);
generate
if (ASYNC_CLK == 1) begin
wire out_toggle;
wire in_toggle;
reg out_toggle_d1 = 1'b0;
reg in_toggle_d1 = 1'b0;
sync_bits i_sync_out (
.in(in_toggle_d1),
.out_clk(out_clk),
.out_resetn(1'b1),
.out(out_toggle)
);
sync_bits i_sync_in (
.in(out_toggle_d1),
.out_clk(in_clk),
.out_resetn(1'b1),
.out(in_toggle)
);
wire in_ready = in_toggle == in_toggle_d1;
wire load_out = out_toggle ^ out_toggle_d1;
reg [NUM_OF_EVENTS-1:0] in_event_sticky = 'h00;
wire [NUM_OF_EVENTS-1:0] pending_events = in_event_sticky | in_event;
wire [NUM_OF_EVENTS-1:0] out_event_s;
always @(posedge in_clk) begin
if (in_ready == 1'b1) begin
in_event_sticky <= {NUM_OF_EVENTS{1'b0}};
if (|pending_events == 1'b1) begin
in_toggle_d1 <= ~in_toggle_d1;
end
end else begin
in_event_sticky <= pending_events;
end
end
if (NUM_OF_EVENTS > 1) begin
reg [NUM_OF_EVENTS-1:0] cdc_hold = 'h00;
always @(posedge in_clk) begin
if (in_ready == 1'b1) begin
cdc_hold <= pending_events;
end
end
assign out_event_s = cdc_hold;
end else begin
// When there is only one event, we know that it is set.
assign out_event_s = 1'b1;
end
always @(posedge out_clk) begin
if (load_out == 1'b1) begin
out_event <= out_event_s;
end else begin
out_event <= {NUM_OF_EVENTS{1'b0}};
end
out_toggle_d1 <= out_toggle;
end
end else begin
always @(*) begin
out_event <= in_event;
end
end
endgenerate
endmodule