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[/] [spacewiresystemc/] [trunk/] [altera_work/] [spw_fifo_ulight/] [ulight_fifo/] [synthesis/] [submodules/] [altera_reset_synchronizer.v] - Rev 40
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// (C) 2001-2017 Intel Corporation. All rights reserved. // Your use of Intel Corporation's design tools, logic functions and other // software and tools, and its AMPP partner logic functions, and any output // files from any of the foregoing (including device programming or simulation // files), and any associated documentation or information are expressly subject // to the terms and conditions of the Intel Program License Subscription // Agreement, Intel FPGA IP License Agreement, or other applicable // license agreement, including, without limitation, that your use is for the // sole purpose of programming logic devices manufactured by Intel and sold by // Intel or its authorized distributors. Please refer to the applicable // agreement for further details. // $Id: //acds/rel/17.1std/ip/merlin/altera_reset_controller/altera_reset_synchronizer.v#1 $ // $Revision: #1 $ // $Date: 2017/07/30 $ // $Author: swbranch $ // ----------------------------------------------- // Reset Synchronizer // ----------------------------------------------- `timescale 1 ns / 1 ns module altera_reset_synchronizer #( parameter ASYNC_RESET = 1, parameter DEPTH = 2 ) ( input reset_in /* synthesis ALTERA_ATTRIBUTE = "SUPPRESS_DA_RULE_INTERNAL=R101" */, input clk, output reset_out ); // ----------------------------------------------- // Synchronizer register chain. We cannot reuse the // standard synchronizer in this implementation // because our timing constraints are different. // // Instead of cutting the timing path to the d-input // on the first flop we need to cut the aclr input. // // We omit the "preserve" attribute on the final // output register, so that the synthesis tool can // duplicate it where needed. // ----------------------------------------------- (*preserve*) reg [DEPTH-1:0] altera_reset_synchronizer_int_chain; reg altera_reset_synchronizer_int_chain_out; generate if (ASYNC_RESET) begin // ----------------------------------------------- // Assert asynchronously, deassert synchronously. // ----------------------------------------------- always @(posedge clk or posedge reset_in) begin if (reset_in) begin altera_reset_synchronizer_int_chain <= {DEPTH{1'b1}}; altera_reset_synchronizer_int_chain_out <= 1'b1; end else begin altera_reset_synchronizer_int_chain[DEPTH-2:0] <= altera_reset_synchronizer_int_chain[DEPTH-1:1]; altera_reset_synchronizer_int_chain[DEPTH-1] <= 0; altera_reset_synchronizer_int_chain_out <= altera_reset_synchronizer_int_chain[0]; end end assign reset_out = altera_reset_synchronizer_int_chain_out; end else begin // ----------------------------------------------- // Assert synchronously, deassert synchronously. // ----------------------------------------------- always @(posedge clk) begin altera_reset_synchronizer_int_chain[DEPTH-2:0] <= altera_reset_synchronizer_int_chain[DEPTH-1:1]; altera_reset_synchronizer_int_chain[DEPTH-1] <= reset_in; altera_reset_synchronizer_int_chain_out <= altera_reset_synchronizer_int_chain[0]; end assign reset_out = altera_reset_synchronizer_int_chain_out; end endgenerate endmodule