/*!
 * <b>Module:</b> crc16_x16x12x5x0
 * @file crc16_x16x12x5x0.v
 * @date 2019-03-31  
 * @author Andrey Filippov
 *     
 * @brief calculates CRC x^16+x^12+x^5+x^0 16-bit parallel
 *
 * @copyright Copyright (c) 2019 Elphel, Inc.
 *
 * <b>License </b>
 *
 * crc16_x16x12x5x0.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.
 *
 * crc16_x16x12x5x0.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/> .
 *
 * 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"
 * files and/or simulating the code, the copyright holders of this Program give
 * 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
 * charge, and there is no dependence on any encrypted modules for simulating of
 * 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.
 */
`timescale 1ns/1ps

module crc16_x16x12x5x0(
    input         clk,
    input         srst,
    input         en,
    input  [15:0] din,
    output [15:0] dout
);
    reg [15:0] crc;
    assign dout = crc;
    always@ (posedge clk) begin
        if (srst) crc <= 0;
        else if (en) crc <= din ^ {
            crc[10]^crc[3]^crc[7]^crc[11],
            crc[14]^crc[9]^crc[2],
            crc[1]^crc[12]^crc[6]^crc[10]^crc[14]^crc[5]^crc[9],
            crc[12]^crc[7]^crc[0]^crc[4]^crc[15],
            crc[11]^crc[15]^crc[6]^crc[10]^crc[14],
            crc[10]^crc[14]^crc[5]^crc[9]^crc[13],
            crc[9]^crc[13]^crc[4]^crc[15]^crc[8]^crc[12],
            crc[8]^crc[12]^crc[3]^crc[14]^crc[7]^crc[11]^crc[15],
            crc[7]^crc[11]^crc[15]^crc[2]^crc[13],
            crc[1]^crc[12]^crc[5]^crc[9]^crc[13],
            crc[5]^crc[9]^crc[13]^crc[0]^crc[11]^crc[4]^crc[8]^crc[12],
            crc[4]^crc[15]^crc[8]^crc[12],
            crc[3]^crc[14]^crc[7]^crc[11]^crc[15],
            crc[2]^crc[13],
            crc[1]^crc[12]^crc[6]^crc[10]^crc[14]^crc[5]^crc[9]^crc[13],
            crc[0]^crc[11]^crc[4]^crc[8]^crc[12]        
        };
    end

endmodule