package org.kc7bfi.jflac.util;
/**
* libFLAC - Free Lossless Audio Codec library
* Copyright (C) 2000,2001,2002,2003 Josh Coalson
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/**
* Utility class to calculate 16-bit CRC.
*
* @author kc7bfi
*/
public final class CRC16 {
// CRC-16, poly = x^16 + x^15 + x^2 + x^0, init = 0
private static final short[] CRC16_TABLE =
new short[]{
(short) 0x0000,
(short) 0x8005,
(short) 0x800f,
(short) 0x000a,
(short) 0x801b,
(short) 0x001e,
(short) 0x0014,
(short) 0x8011,
(short) 0x8033,
(short) 0x0036,
(short) 0x003c,
(short) 0x8039,
(short) 0x0028,
(short) 0x802d,
(short) 0x8027,
(short) 0x0022,
(short) 0x8063,
(short) 0x0066,
(short) 0x006c,
(short) 0x8069,
(short) 0x0078,
(short) 0x807d,
(short) 0x8077,
(short) 0x0072,
(short) 0x0050,
(short) 0x8055,
(short) 0x805f,
(short) 0x005a,
(short) 0x804b,
(short) 0x004e,
(short) 0x0044,
(short) 0x8041,
(short) 0x80c3,
(short) 0x00c6,
(short) 0x00cc,
(short) 0x80c9,
(short) 0x00d8,
(short) 0x80dd,
(short) 0x80d7,
(short) 0x00d2,
(short) 0x00f0,
(short) 0x80f5,
(short) 0x80ff,
(short) 0x00fa,
(short) 0x80eb,
(short) 0x00ee,
(short) 0x00e4,
(short) 0x80e1,
(short) 0x00a0,
(short) 0x80a5,
(short) 0x80af,
(short) 0x00aa,
(short) 0x80bb,
(short) 0x00be,
(short) 0x00b4,
(short) 0x80b1,
(short) 0x8093,
(short) 0x0096,
(short) 0x009c,
(short) 0x8099,
(short) 0x0088,
(short) 0x808d,
(short) 0x8087,
(short) 0x0082,
(short) 0x8183,
(short) 0x0186,
(short) 0x018c,
(short) 0x8189,
(short) 0x0198,
(short) 0x819d,
(short) 0x8197,
(short) 0x0192,
(short) 0x01b0,
(short) 0x81b5,
(short) 0x81bf,
(short) 0x01ba,
(short) 0x81ab,
(short) 0x01ae,
(short) 0x01a4,
(short) 0x81a1,
(short) 0x01e0,
(short) 0x81e5,
(short) 0x81ef,
(short) 0x01ea,
(short) 0x81fb,
(short) 0x01fe,
(short) 0x01f4,
(short) 0x81f1,
(short) 0x81d3,
(short) 0x01d6,
(short) 0x01dc,
(short) 0x81d9,
(short) 0x01c8,
(short) 0x81cd,
(short) 0x81c7,
(short) 0x01c2,
(short) 0x0140,
(short) 0x8145,
(short) 0x814f,
(short) 0x014a,
(short) 0x815b,
(short) 0x015e,
(short) 0x0154,
(short) 0x8151,
(short) 0x8173,
(short) 0x0176,
(short) 0x017c,
(short) 0x8179,
(short) 0x0168,
(short) 0x816d,
(short) 0x8167,
(short) 0x0162,
(short) 0x8123,
(short) 0x0126,
(short) 0x012c,
(short) 0x8129,
(short) 0x0138,
(short) 0x813d,
(short) 0x8137,
(short) 0x0132,
(short) 0x0110,
(short) 0x8115,
(short) 0x811f,
(short) 0x011a,
(short) 0x810b,
(short) 0x010e,
(short) 0x0104,
(short) 0x8101,
(short) 0x8303,
(short) 0x0306,
(short) 0x030c,
(short) 0x8309,
(short) 0x0318,
(short) 0x831d,
(short) 0x8317,
(short) 0x0312,
(short) 0x0330,
(short) 0x8335,
(short) 0x833f,
(short) 0x033a,
(short) 0x832b,
(short) 0x032e,
(short) 0x0324,
(short) 0x8321,
(short) 0x0360,
(short) 0x8365,
(short) 0x836f,
(short) 0x036a,
(short) 0x837b,
(short) 0x037e,
(short) 0x0374,
(short) 0x8371,
(short) 0x8353,
(short) 0x0356,
(short) 0x035c,
(short) 0x8359,
(short) 0x0348,
(short) 0x834d,
(short) 0x8347,
(short) 0x0342,
(short) 0x03c0,
(short) 0x83c5,
(short) 0x83cf,
(short) 0x03ca,
(short) 0x83db,
(short) 0x03de,
(short) 0x03d4,
(short) 0x83d1,
(short) 0x83f3,
(short) 0x03f6,
(short) 0x03fc,
(short) 0x83f9,
(short) 0x03e8,
(short) 0x83ed,
(short) 0x83e7,
(short) 0x03e2,
(short) 0x83a3,
(short) 0x03a6,
(short) 0x03ac,
(short) 0x83a9,
(short) 0x03b8,
(short) 0x83bd,
(short) 0x83b7,
(short) 0x03b2,
(short) 0x0390,
(short) 0x8395,
(short) 0x839f,
(short) 0x039a,
(short) 0x838b,
(short) 0x038e,
(short) 0x0384,
(short) 0x8381,
(short) 0x0280,
(short) 0x8285,
(short) 0x828f,
(short) 0x028a,
(short) 0x829b,
(short) 0x029e,
(short) 0x0294,
(short) 0x8291,
(short) 0x82b3,
(short) 0x02b6,
(short) 0x02bc,
(short) 0x82b9,
(short) 0x02a8,
(short) 0x82ad,
(short) 0x82a7,
(short) 0x02a2,
(short) 0x82e3,
(short) 0x02e6,
(short) 0x02ec,
(short) 0x82e9,
(short) 0x02f8,
(short) 0x82fd,
(short) 0x82f7,
(short) 0x02f2,
(short) 0x02d0,
(short) 0x82d5,
(short) 0x82df,
(short) 0x02da,
(short) 0x82cb,
(short) 0x02ce,
(short) 0x02c4,
(short) 0x82c1,
(short) 0x8243,
(short) 0x0246,
(short) 0x024c,
(short) 0x8249,
(short) 0x0258,
(short) 0x825d,
(short) 0x8257,
(short) 0x0252,
(short) 0x0270,
(short) 0x8275,
(short) 0x827f,
(short) 0x027a,
(short) 0x826b,
(short) 0x026e,
(short) 0x0264,
(short) 0x8261,
(short) 0x0220,
(short) 0x8225,
(short) 0x822f,
(short) 0x022a,
(short) 0x823b,
(short) 0x023e,
(short) 0x0234,
(short) 0x8231,
(short) 0x8213,
(short) 0x0216,
(short) 0x021c,
(short) 0x8219,
(short) 0x0208,
(short) 0x820d,
(short) 0x8207,
(short) 0x0202};
/**
* Update the CRC with the byte data.
*
* @param data The byte data
* @param crc The starting CRC value
* @return The updated CRC value
*/
public static short update(byte data, short crc) {
crc = (short) ((crc << 8) ^ CRC16_TABLE[((crc >> 8) ^ data) & 0xff]);
return crc;
}
/**
* Update the CRC with the byte array data.
*
* @param data The byte array data
* @param len The byte array length
* @param crc The starting CRC value
* @return The updated CRC value
*/
public static short updateBlock(byte[] data, int len, short crc) {
for (int i = 0; i < len; i++)
crc = (short) ((crc << 8) ^ CRC16_TABLE[(crc >> 8) ^ data[i]]);
return crc;
}
/**
* Calculate the CRC over a byte array.
*
* @param data The byte data
* @param len The byte array length
* @return The calculated CRC value
*/
public static short calc(byte[] data, int len) {
short crc = 0;
for (int i = 0; i < len; i++)
crc = (short) ((crc << 8) ^ CRC16_TABLE[(crc >> 8) ^ data[i]]);
return crc;
}
}