package Common;
public class CRC {
public static final 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 UpdateByte(int b) {
_value = Table[(_value ^ b) & 0xFF] ^ (_value >>> 8);
}
public void UpdateUInt32(int v) {
for (int i = 0; i < 4; i++)
UpdateByte((v >> (8 * i)) & 0xFF );
}
public void UpdateUInt64(long v) {
for (int i = 0; i < 8; i++)
UpdateByte((int)((v >> (8 * i))) & 0xFF);
}
public int GetDigest() {
return _value ^ (-1);
}
public void Update(byte[] data, int size) {
for (int i = 0; i < size; i++)
_value = Table[(_value ^ data[i]) & 0xFF] ^ (_value >>> 8);
}
public void Update(byte[] data) {
for (int i = 0; i < data.length; i++)
_value = Table[(_value ^ data[i]) & 0xFF] ^ (_value >>> 8);
}
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 static int CalculateDigest(byte [] data, int size) {
CRC crc = new CRC();
crc.Update(data, size);
return crc.GetDigest();
}
public static boolean VerifyDigest(int digest, byte [] data, int size) {
return (CalculateDigest(data, size) == digest);
}
public String toString() {
return Integer.toHexString(GetDigest());
}
}