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A Java parser for SIE files that can read files of version 1 to 4 (including 4i)
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/*
MIT License

Copyright (c) 2015 Johan Idstam
Modifications by Per Nyfelt Copyright (c) 2016 Alipsa HB

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

package alipsa.sieparser;

import java.util.ArrayList;
import java.util.List;

/**
 * This is an implementation of the CRC algorithm published in the Sie specification
 */
public class SieCRC32 {
    public boolean Started = false;
    private static long CRC32_POLYNOMIAL = 0xEDB88320;
    private long[] CRCTable = new long[256];
    private long crc;

    public SieCRC32()  {
        createCrcTable();
    }

    private void createCrcTable() {
        int i;
        long j;
        long crc;
        for (i = 0; i <= 255; i++) {
            crc = i;
            for (j = 8; j > 0; j--) {
                if ((crc & 1) == 1) {
                    crc = (crc >> 1) ^ CRC32_POLYNOMIAL;
                } else {
                    crc >>= 1;
                }
            }
            CRCTable[i] = crc;
        }
    }

    // start CRC-calculation
    public void start() throws Exception {
        crc = 0xFFFFFFFF;
        Started = true;
    }

    public void addData(SieDataItem item) throws Exception {
        List buffer = new ArrayList<>();
        buffer.addAll(Encoding.getBytes(item.getItemType()));
        for (String d : item.getData()) {
            String foo = d.replace("{", "").replace("}", "");
            buffer.addAll(Encoding.getBytes(foo));
        }
        cRC_accumulate(buffer);
    }

    public long checksum() throws Exception {
        return (~crc);
    }

    private void cRC_accumulate(List buffer) throws Exception {
        long temp1;
        long temp2;
        for (Byte p : buffer) {
            temp1 = (crc >> 8) & 0x00FFFFFF;
            temp2 = CRCTable[((int) crc ^ p.byteValue()) & 0xff];
            crc = temp1 ^ temp2;
        }
    }

}