/*
* 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;
/**
* The CRC32 class is used to compute a CRC32 checksum from data provided as
* input value.
*/
public class CRC32 implements java.util.zip.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);
}
/**
* Updates this checksum with n bytes of data obtained from buffer {@code
* buf}, starting at offset {@code off}.
*
* @param buf
* the buffer to update the checksum.
* @param off
* the offset in {@code buf} to obtain data from.
* @param nbytes
* the number of bytes to read from {@code buf}.
*/
public void update(byte[] buf, int off, int nbytes) {
// avoid int overflow, check null buf
if (off <= buf.length && nbytes >= 0 && off >= 0
&& buf.length - off >= nbytes) {
tbytes += nbytes;
crc = updateImpl(buf, off, nbytes, crc);
} else {
throw new ArrayIndexOutOfBoundsException();
}
}
private native long updateImpl(byte[] buf, int off, int nbytes, long crc1);
private native long updateByteImpl(byte val, long crc1);
}
|