CRC32.java revision f7c6911047d63bc76292f55ce538da32818dd931
1f7c6911047d63bc76292f55ce538da32818dd931Jesse Wilson/* 2adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Licensed to the Apache Software Foundation (ASF) under one or more 3adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * contributor license agreements. See the NOTICE file distributed with 4adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * this work for additional information regarding copyright ownership. 5adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * The ASF licenses this file to You under the Apache License, Version 2.0 6adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * (the "License"); you may not use this file except in compliance with 7adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * the License. You may obtain a copy of the License at 8f7c6911047d63bc76292f55ce538da32818dd931Jesse Wilson * 9adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * http://www.apache.org/licenses/LICENSE-2.0 10f7c6911047d63bc76292f55ce538da32818dd931Jesse Wilson * 11adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Unless required by applicable law or agreed to in writing, software 12adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * distributed under the License is distributed on an "AS IS" BASIS, 13adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * See the License for the specific language governing permissions and 15adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * limitations under the License. 16adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 17adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 18adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Projectpackage java.util.zip; 19adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 20adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project/** 21adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * The CRC32 class is used to compute a CRC32 checksum from data provided as 22adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * input value. 23adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 24adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Projectpublic class CRC32 implements java.util.zip.Checksum { 25adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 26adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project private long crc = 0L; 27adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 28adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project long tbytes = 0L; 29adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 30adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 31adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Returns the CRC32 checksum for all input received. 32f7c6911047d63bc76292f55ce538da32818dd931Jesse Wilson * 33adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @return The checksum for this instance. 34adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 35adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public long getValue() { 36adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project return crc; 37adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 38adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 39adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 40adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Resets the CRC32 checksum to it initial state. 41adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 42adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public void reset() { 43adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project tbytes = crc = 0; 44adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 45adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 46adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 47adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 48adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Updates this checksum with the byte value provided as integer. 4957995e8186b54515d5a03bf2ab104c3dc247f1b6Jesse Wilson * 50adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param val 51adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * represents the byte to update the checksum. 52adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 53adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public void update(int val) { 54adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project crc = updateByteImpl((byte) val, crc); 55adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 56adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 57adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 58adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Updates this checksum with the bytes contained in buffer {@code buf}. 59f7c6911047d63bc76292f55ce538da32818dd931Jesse Wilson * 60adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param buf 61adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * the buffer holding the data to update the checksum with. 62adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 63adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public void update(byte[] buf) { 64adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project update(buf, 0, buf.length); 65adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 66adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 67adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 68adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Updates this checksum with n bytes of data obtained from buffer {@code 69adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * buf}, starting at offset {@code off}. 70f7c6911047d63bc76292f55ce538da32818dd931Jesse Wilson * 71adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param buf 72adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * the buffer to update the checksum. 73adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param off 74adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * the offset in {@code buf} to obtain data from. 75adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param nbytes 76adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * the number of bytes to read from {@code buf}. 77adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 78adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public void update(byte[] buf, int off, int nbytes) { 79adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project // avoid int overflow, check null buf 80adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project if (off <= buf.length && nbytes >= 0 && off >= 0 81adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project && buf.length - off >= nbytes) { 82adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project tbytes += nbytes; 83adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project crc = updateImpl(buf, off, nbytes, crc); 84adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } else { 85adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project throw new ArrayIndexOutOfBoundsException(); 86adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 87adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 88adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 89adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project private native long updateImpl(byte[] buf, int off, int nbytes, long crc1); 90adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 91adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project private native long updateByteImpl(byte val, long crc1); 92adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project} 93