| /* |
| * |
| * 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. |
| * |
| */ |
| |
| using System; |
| |
| namespace Lucene.Net.Support |
| { |
| internal class CRC32 : IChecksum |
| { |
| private static readonly UInt32[] crcTable = InitializeCRCTable(); |
| |
| private static UInt32[] InitializeCRCTable() |
| { |
| UInt32[] crcTable = new UInt32[256]; |
| for (UInt32 n = 0; n < 256; n++) |
| { |
| UInt32 c = n; |
| for (int k = 8; --k >= 0; ) |
| { |
| if ((c & 1) != 0) |
| c = 0xedb88320 ^ (c >> 1); |
| else |
| c = c >> 1; |
| } |
| crcTable[n] = c; |
| } |
| return crcTable; |
| } |
| |
| private UInt32 crc = 0; |
| |
| public long Value => crc & 0xffffffffL; |
| |
| public void Reset() |
| { |
| crc = 0; |
| } |
| |
| public void Update(int bval) |
| { |
| UInt32 c = ~crc; |
| c = crcTable[(c ^ bval) & 0xff] ^ (c >> 8); |
| crc = ~c; |
| } |
| |
| public void Update(byte[] buf, int off, int len) |
| { |
| UInt32 c = ~crc; |
| while (--len >= 0) |
| c = crcTable[(c ^ buf[off++]) & 0xff] ^ (c >> 8); |
| crc = ~c; |
| } |
| |
| public void Update(byte[] buf) |
| { |
| Update(buf, 0, buf.Length); |
| } |
| } |
| } |