/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package java.util.zip;
import java.util.Arrays;
/**
* The CRC32 class is used to compute a CRC32 checksum from data provided as
* input value. See also {@link Adler32} which is almost as good, but cheaper.
*/
public class CRC32 implements Checksum {
private long crc = 0L;
long tbytes = 0L;
/**
* Returns the CRC32 checksum for all input received.
*
* @return The checksum for this instance.
*/
public long getValue() {
return crc;
}
/**
* Resets the CRC32 checksum to it initial state.
*/
public void reset() {
tbytes = crc = 0;
}
/**
* Updates this checksum with the byte value provided as integer.
*
* @param val
* represents the byte to update the checksum.
*/
public void update(int val) {
crc = updateByteImpl((byte) val, crc);
}
/**
* Updates this checksum with the bytes contained in buffer {@code buf}.
*
* @param buf
* the buffer holding the data to update the checksum with.
*/
public void update(byte[] buf) {
update(buf, 0, buf.length);
}
/**
* Update this {@code CRC32} checksum with the contents of {@code buf},
* starting from {@code offset} and reading {@code byteCount} bytes of data.
*/
public void update(byte[] buf, int offset, int byteCount) {
Arrays.checkOffsetAndCount(buf.length, offset, byteCount);
tbytes += byteCount;
crc = updateImpl(buf, offset, byteCount, crc);
}
private native long updateImpl(byte[] buf, int offset, int byteCount, long crc1);
private native long updateByteImpl(byte val, long crc1);
}