1 /* 2 * CRC64 3 * 4 * Author: Lasse Collin <lasse.collin (at) tukaani.org> 5 * 6 * This file has been put into the public domain. 7 * You can do whatever you want with this file. 8 */ 9 10 package org.tukaani.xz.check; 11 12 public class CRC64 extends Check { 13 private static final long poly = 0xC96C5795D7870F42L; 14 private static final long[] crcTable = new long[256]; 15 16 private long crc = -1; 17 18 static { 19 for (int b = 0; b < crcTable.length; ++b) { 20 long r = b; 21 for (int i = 0; i < 8; ++i) { 22 if ((r & 1) == 1) 23 r = (r >>> 1) ^ poly; 24 else 25 r >>>= 1; 26 } 27 28 crcTable[b] = r; 29 } 30 } 31 32 public CRC64() { 33 size = 8; 34 name = "CRC64"; 35 } 36 37 public void update(byte[] buf, int off, int len) { 38 int end = off + len; 39 40 while (off < end) 41 crc = crcTable[(buf[off++] ^ (int)crc) & 0xFF] ^ (crc >>> 8); 42 } 43 44 public byte[] finish() { 45 long value = ~crc; 46 crc = -1; 47 48 byte[] buf = new byte[8]; 49 for (int i = 0; i < buf.length; ++i) 50 buf[i] = (byte)(value >> (i * 8)); 51 52 return buf; 53 } 54 } 55
