|
| 1 | +/* |
| 2 | + * Licensed to the Apache Software Foundation (ASF) under one |
| 3 | + * or more contributor license agreements. See the NOTICE file |
| 4 | + * distributed with this work for additional information |
| 5 | + * regarding copyright ownership. The ASF licenses this file |
| 6 | + * to you under the Apache License, Version 2.0 (the |
| 7 | + * "License"); you may not use this file except in compliance |
| 8 | + * with the License. You may obtain a copy of the License at |
| 9 | + * |
| 10 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | + * |
| 12 | + * Unless required by applicable law or agreed to in writing, software |
| 13 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | + * See the License for the specific language governing permissions and |
| 16 | + * limitations under the License. |
| 17 | + * |
| 18 | + * Some portions of this file Copyright (c) 2004-2006 Intel Corportation |
| 19 | + * and licensed under the BSD license. |
| 20 | + */ |
| 21 | +package org.apache.hadoop.ozone.common; |
| 22 | + |
| 23 | +import org.apache.ratis.util.Preconditions; |
| 24 | + |
| 25 | +import java.nio.ByteBuffer; |
| 26 | +import java.util.zip.Checksum; |
| 27 | + |
| 28 | +/** |
| 29 | + * A sub-interface of {@link Checksum} |
| 30 | + * with a method to update checksum from a {@link ByteBuffer}. |
| 31 | + */ |
| 32 | +public interface ChecksumByteBuffer extends Checksum { |
| 33 | + /** |
| 34 | + * Updates the current checksum with the specified bytes in the buffer. |
| 35 | + * Upon return, the buffer's position will be equal to its limit. |
| 36 | + * |
| 37 | + * @param buffer the bytes to update the checksum with |
| 38 | + */ |
| 39 | + void update(ByteBuffer buffer); |
| 40 | + |
| 41 | + @Override |
| 42 | + default void update(byte[] b, int off, int len) { |
| 43 | + update(ByteBuffer.wrap(b, off, len).asReadOnlyBuffer()); |
| 44 | + } |
| 45 | + |
| 46 | + /** |
| 47 | + * An abstract class implementing {@link ChecksumByteBuffer} |
| 48 | + * with a 32-bit checksum and a lookup table. |
| 49 | + */ |
| 50 | + abstract class CrcIntTable implements ChecksumByteBuffer { |
| 51 | + /** Current CRC value with bit-flipped. */ |
| 52 | + private int crc; |
| 53 | + |
| 54 | + CrcIntTable() { |
| 55 | + reset(); |
| 56 | + Preconditions.assertTrue(getTable().length == 8 * (1 << 8)); |
| 57 | + } |
| 58 | + |
| 59 | + abstract int[] getTable(); |
| 60 | + |
| 61 | + @Override |
| 62 | + public final long getValue() { |
| 63 | + return (~crc) & 0xffffffffL; |
| 64 | + } |
| 65 | + |
| 66 | + @Override |
| 67 | + public final void reset() { |
| 68 | + crc = 0xffffffff; |
| 69 | + } |
| 70 | + |
| 71 | + @Override |
| 72 | + public final void update(int b) { |
| 73 | + crc = (crc >>> 8) ^ getTable()[(((crc ^ b) << 24) >>> 24)]; |
| 74 | + } |
| 75 | + |
| 76 | + @Override |
| 77 | + public final void update(ByteBuffer b) { |
| 78 | + crc = update(crc, b, getTable()); |
| 79 | + } |
| 80 | + |
| 81 | + private static int update(int crc, ByteBuffer b, int[] table) { |
| 82 | + for(; b.remaining() > 7;) { |
| 83 | + final int c0 = (b.get() ^ crc) & 0xff; |
| 84 | + final int c1 = (b.get() ^ (crc >>>= 8)) & 0xff; |
| 85 | + final int c2 = (b.get() ^ (crc >>>= 8)) & 0xff; |
| 86 | + final int c3 = (b.get() ^ (crc >>> 8)) & 0xff; |
| 87 | + crc = (table[0x700 + c0] ^ table[0x600 + c1]) |
| 88 | + ^ (table[0x500 + c2] ^ table[0x400 + c3]); |
| 89 | + |
| 90 | + final int c4 = b.get() & 0xff; |
| 91 | + final int c5 = b.get() & 0xff; |
| 92 | + final int c6 = b.get() & 0xff; |
| 93 | + final int c7 = b.get() & 0xff; |
| 94 | + |
| 95 | + crc ^= (table[0x300 + c4] ^ table[0x200 + c5]) |
| 96 | + ^ (table[0x100 + c6] ^ table[c7]); |
| 97 | + } |
| 98 | + |
| 99 | + // loop unroll - duff's device style |
| 100 | + switch (b.remaining()) { |
| 101 | + case 7: crc = (crc >>> 8) ^ table[((crc ^ b.get()) & 0xff)]; |
| 102 | + case 6: crc = (crc >>> 8) ^ table[((crc ^ b.get()) & 0xff)]; |
| 103 | + case 5: crc = (crc >>> 8) ^ table[((crc ^ b.get()) & 0xff)]; |
| 104 | + case 4: crc = (crc >>> 8) ^ table[((crc ^ b.get()) & 0xff)]; |
| 105 | + case 3: crc = (crc >>> 8) ^ table[((crc ^ b.get()) & 0xff)]; |
| 106 | + case 2: crc = (crc >>> 8) ^ table[((crc ^ b.get()) & 0xff)]; |
| 107 | + case 1: crc = (crc >>> 8) ^ table[((crc ^ b.get()) & 0xff)]; |
| 108 | + default: // noop |
| 109 | + } |
| 110 | + |
| 111 | + return crc; |
| 112 | + } |
| 113 | + } |
| 114 | +} |
0 commit comments