dly01_16.v 2.44 KB
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/*******************************************************************************
 * Module: dly01_16
 * Date:2014-05-30  
 * Author: Andrey Filippov
 * Description: Synchronous delay by 1-16 clock cycles with reset (will map to primitive)
 *
 * Copyright (c) 2014 Elphel, Inc.
 * dly01_16.v 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.
 *
 *  dly01_16.v 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/> .
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 *
 * Additional permission under GNU GPL version 3 section 7:
 * If you modify this Program, or any covered work, by linking or combining it
 * with independent modules provided by the FPGA vendor only (this permission
 * does not extend to any 3-rd party modules, "soft cores" or macros) under
 * different license terms solely for the purpose of generating binary "bitstream"
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 * files and/or simulating the code, the copyright holders of this Program give
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 * you the right to distribute the covered work without those independent modules
 * as long as the source code for them is available from the FPGA vendor free of
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 * charge, and there is no dependence on any encrypted modules for simulating of
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 * the combined code. This permission applies to you if the distributed code
 * contains all the components and scripts required to completely simulate it
 * with at least one of the Free Software programs.
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 *******************************************************************************/
`timescale 1ns/1ps

module  dly01_16(
    input       clk,
    input       rst,
    input [3:0] dly,
    input       din,
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    output      dout
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);
    reg [15:0] sr=0;
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`ifdef SHREG_SEQUENTIAL_RESET
    always @ (posedge clk) begin
        sr <= {sr[14:0], din & ~rst}; 
    end
`else 
//    always @ (posedge rst or posedge clk) begin
    always @ (posedge clk) begin
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       if (rst) sr <=0;
       else     sr <= {sr[14:0],din}; 
    end
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`endif
`ifdef SIMULATION
    assign dout = (|sr) ? ((&sr) ? 1'b1 : sr[dly]) :  1'b0 ;
`else
    assign dout =sr[dly];
`endif        
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endmodule