| /* |
| * 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 Adler-32 class is used to compute the {@code Adler32} checksum from a set |
| * of data. Compared to the CRC-32 algorithm it trades reliabilty for speed. |
| * Refer to RFC 1950 for the specification. |
| * |
| * @see CRC32 |
| */ |
| public class Adler32 implements java.util.zip.Checksum { |
| |
| private long adler = 1; |
| |
| /** |
| * Returns the {@code Adler32} checksum for all input received. |
| * |
| * @return The checksum for this instance. |
| */ |
| public long getValue() { |
| return adler; |
| } |
| |
| /** |
| * Reset this instance to its initial checksum. |
| */ |
| public void reset() { |
| adler = 1; |
| } |
| |
| /** |
| * Update this {@code Adler32} checksum with the single byte provided as |
| * argument. |
| * |
| * @param i |
| * the byte to update checksum with. |
| */ |
| public void update(int i) { |
| adler = updateByteImpl(i, adler); |
| } |
| |
| /** |
| * Update this {@code Adler32} checksum using the contents of {@code buf}. |
| * |
| * @param buf |
| * bytes to update checksum with. |
| */ |
| public void update(byte[] buf) { |
| update(buf, 0, buf.length); |
| } |
| |
| /** |
| * Update this {@code Adler32} checksum with the contents of {@code buf}, |
| * starting from the offset provided and reading n bytes of data. |
| * |
| * @param buf |
| * buffer to obtain data from. |
| * @param off |
| * offset in {@code buf} to start reading from. |
| * @param nbytes |
| * number of bytes from {@code buf} to use. |
| * @throws ArrayIndexOutOfBoundsException |
| * if {@code offset > buf.length} or {@code nbytes} is negative |
| * or {@code offset + nbytes > buf.length}. |
| */ |
| 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) { |
| adler = updateImpl(buf, off, nbytes, adler); |
| } else { |
| throw new ArrayIndexOutOfBoundsException(); |
| } |
| } |
| |
| private native long updateImpl(byte[] buf, int off, int nbytes, long adler1); |
| |
| private native long updateByteImpl(int val, long adler1); |
| } |