| /** |
| * 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 org.apache.hadoop.fs.azurebfs.utils; |
| |
| /** |
| * CRC64 implementation for AzureBlobFileSystem. |
| */ |
| public class CRC64 { |
| |
| private static final long POLY = 0x9a6c9329ac4bc9b5L; |
| private static final int TABLE_LENGTH = 256; |
| private static final long[] TABLE = new long[TABLE_LENGTH]; |
| |
| private long value = -1; |
| |
| /** |
| * @param input byte arrays. |
| * @return long value of the CRC-64 checksum of the data. |
| * */ |
| public long compute(byte[] input) { |
| init(); |
| for (int i = 0; i < input.length; i++) { |
| value = TABLE[(input[i] ^ (int) value) & 0xFF] ^ (value >>> 8); |
| } |
| return ~value; |
| } |
| |
| /* |
| * Initialize a table constructed from POLY (0x9a6c9329ac4bc9b5L). |
| * */ |
| private void init() { |
| value = -1; |
| for (int n = 0; n < TABLE_LENGTH; ++n) { |
| long crc = n; |
| for (int i = 0; i < 8; ++i) { |
| if ((crc & 1) == 1) { |
| crc = (crc >>> 1) ^ POLY; |
| } else { |
| crc >>>= 1; |
| } |
| } |
| TABLE[n] = crc; |
| } |
| } |
| } |