source: other-projects/trunk/7z-ant/src/SevenZip/CRC.java@ 17387

// SevenZip/CRC.java

package SevenZip;

public class CRC
{
    static public int[] Table = new int[256];
    
    static
    {
        for (int i = 0; i < 256; i++)
        {
            int r = i;
            for (int j = 0; j < 8; j++)
                if ((r & 1) != 0)
                    r = (r >>> 1) ^ 0xEDB88320;
                else
                    r >>>= 1;
            Table[i] = r;
        }
    }
    
    int _value = -1;
    
    public void Init()
    {
        _value = -1;
    }
    
    public void Update(byte[] data, int offset, int size)
    {
        for (int i = 0; i < size; i++)
            _value = Table[(_value ^ data[offset + i]) & 0xFF] ^ (_value >>> 8);
    }
    
    public void Update(byte[] data)
    {
        int size = data.length;
        for (int i = 0; i < size; i++)
            _value = Table[(_value ^ data[i]) & 0xFF] ^ (_value >>> 8);
    }
    
    public void UpdateByte(int b)
    {
        _value = Table[(_value ^ b) & 0xFF] ^ (_value >>> 8);
    }
    
    public int GetDigest()
    {
        return _value ^ (-1);
    }
}