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/* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
/* JOrbis
* Copyright (C) 2000 ymnk, JCraft,Inc.
*
* Written by: 2000 ymnk<ymnk@jcraft.com>
*
* Many thanks to
* Monty <monty@xiph.org> and
* The XIPHOPHORUS Company http://www.xiph.org/ .
* JOrbis has been based on their awesome works, Vorbis codec.
*
* This program 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 program 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 program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
package com.jcraft.jogg;
public class Page {
private static int[] crc_lookup = new int[256];
static {
for (int i = 0; i < crc_lookup.length; i++) {
crc_lookup[i] = crc_entry(i);
}
}
private static int crc_entry(int index) {
int r = index << 24;
for (int i = 0; i < 8; i++) {
if ((r & 0x80000000) != 0) {
r = (r << 1) ^ 0x04c11db7; /*
* The same as the ethernet generator polynomial, although we use an
* unreflected alg and an init/final of 0, not 0xffffffff
*/
} else {
r <<= 1;
}
}
return (r & 0xffffffff);
}
public byte[] header_base;
public int header;
public int header_len;
public byte[] body_base;
public int body;
public int body_len;
int version() {
return header_base[header + 4] & 0xff;
}
int continued() {
return (header_base[header + 5] & 0x01);
}
public int bos() {
return (header_base[header + 5] & 0x02);
}
public int eos() {
return (header_base[header + 5] & 0x04);
}
public long granulepos() {
long foo = header_base[header + 13] & 0xff;
foo = (foo << 8) | (header_base[header + 12] & 0xff);
foo = (foo << 8) | (header_base[header + 11] & 0xff);
foo = (foo << 8) | (header_base[header + 10] & 0xff);
foo = (foo << 8) | (header_base[header + 9] & 0xff);
foo = (foo << 8) | (header_base[header + 8] & 0xff);
foo = (foo << 8) | (header_base[header + 7] & 0xff);
foo = (foo << 8) | (header_base[header + 6] & 0xff);
return (foo);
}
public int serialno() {
return (header_base[header + 14] & 0xff) | ((header_base[header + 15] & 0xff) << 8)
| ((header_base[header + 16] & 0xff) << 16) | ((header_base[header + 17] & 0xff) << 24);
}
int pageno() {
return (header_base[header + 18] & 0xff) | ((header_base[header + 19] & 0xff) << 8)
| ((header_base[header + 20] & 0xff) << 16) | ((header_base[header + 21] & 0xff) << 24);
}
void checksum() {
int crc_reg = 0;
for (int i = 0; i < header_len; i++) {
crc_reg = (crc_reg << 8) ^ crc_lookup[((crc_reg >>> 24) & 0xff) ^ (header_base[header + i] & 0xff)];
}
for (int i = 0; i < body_len; i++) {
crc_reg = (crc_reg << 8) ^ crc_lookup[((crc_reg >>> 24) & 0xff) ^ (body_base[body + i] & 0xff)];
}
header_base[header + 22] = (byte) crc_reg;
header_base[header + 23] = (byte) (crc_reg >>> 8);
header_base[header + 24] = (byte) (crc_reg >>> 16);
header_base[header + 25] = (byte) (crc_reg >>> 24);
}
public Page copy() {
return copy(new Page());
}
public Page copy(Page p) {
byte[] tmp = new byte[header_len];
System.arraycopy(header_base, header, tmp, 0, header_len);
p.header_len = header_len;
p.header_base = tmp;
p.header = 0;
tmp = new byte[body_len];
System.arraycopy(body_base, body, tmp, 0, body_len);
p.body_len = body_len;
p.body_base = tmp;
p.body = 0;
return p;
}
}
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