1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package java.util.zip; 19 20 import java.util.Arrays; 21 22 /** 23 * The Adler-32 class is used to compute the {@code Adler32} checksum from a set 24 * of data. Compared to {@link CRC32} it trades reliability for speed. 25 * Refer to RFC 1950 for the specification. 26 */ 27 public class Adler32 implements Checksum { 28 29 private long adler = 1; 30 31 /** 32 * Returns the {@code Adler32} checksum for all input received. 33 * 34 * @return The checksum for this instance. 35 */ getValue()36 public long getValue() { 37 return adler; 38 } 39 40 /** 41 * Reset this instance to its initial checksum. 42 */ reset()43 public void reset() { 44 adler = 1; 45 } 46 47 /** 48 * Update this {@code Adler32} checksum with the single byte provided as 49 * argument. 50 * 51 * @param i 52 * the byte to update checksum with. 53 */ update(int i)54 public void update(int i) { 55 adler = updateByteImpl(i, adler); 56 } 57 58 /** 59 * Update this {@code Adler32} checksum using the contents of {@code buf}. 60 * 61 * @param buf 62 * bytes to update checksum with. 63 */ update(byte[] buf)64 public void update(byte[] buf) { 65 update(buf, 0, buf.length); 66 } 67 68 /** 69 * Update this {@code Adler32} checksum with the contents of {@code buf}, 70 * starting from {@code offset} and reading {@code byteCount} bytes of data. 71 */ update(byte[] buf, int offset, int byteCount)72 public void update(byte[] buf, int offset, int byteCount) { 73 Arrays.checkOffsetAndCount(buf.length, offset, byteCount); 74 adler = updateImpl(buf, offset, byteCount, adler); 75 } 76 updateImpl(byte[] buf, int offset, int byteCount, long adler1)77 private native long updateImpl(byte[] buf, int offset, int byteCount, long adler1); 78 updateByteImpl(int val, long adler1)79 private native long updateByteImpl(int val, long adler1); 80 } 81