Thread: CRC algorithm

I have a code CRC but I don't know how to use it. Cause I don't know why the code is working
I new in Java programming.

can other tell me how the code is working and how to use it?

import java.util.zip.Checksum;
 
public class crc implements Checksum {
 
	public crc(){
		crc = 0;
	}
 
  private int crc;
 
 
  private static int[] crc_table = make_crc_table();
 
 
  private static int[] make_crc_table ()
  {
    int[] crc_table = new int[256];
    for (int n = 0; n < 256; n++)
      {
        int c = n;
        for (int k = 8;  --k >= 0; )
          {
            if ((c & 1) != 0)
                c = 0xedb88320 ^ (c >>> 1); 
            else
              c = c >>> 1;
          }
        crc_table[n] = c;
      }
    return crc_table;
  }
 
 
  public long getValue ()
  {
    return (long) crc & 0xffffffffL;
  }
 
  public void reset () { crc = 0; }
 
  public void update (int bval)
  {
    int c = ~crc;
    c = crc_table[(c ^ bval) & 0xff] ^ (c >>> 8);
    crc = ~c;
  }
 
  public void update (byte[] buf, int off, int len)
  {
    int c = ~crc;
 
    while (--len >= 0)
 
      c = crc_table[(c ^ buf[off++]) & 0xff] ^ (c >>> 8);
    crc = ~c;
  }
  public void printCRCTable(){
	  int count = 0;
	for(int printcrc :crc_table){
	}
  }
 
  public void update (byte[] buf) { update(buf, 0, buf.length); }
 
}

thanks for your attention