/* -*-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;
// DECODING PRIMITIVES: packet streaming layer
// This has two layers to place more of the multi-serialno and paging
// control in the application's hands. First, we expose a data buffer
// using ogg_decode_buffer(). The app either copies into the
// buffer, or passes it directly to read(), etc. We then call
// ogg_decode_wrote() to tell how many bytes we just added.
//
// Pages are returned (pointers into the buffer in ogg_sync_state)
// by ogg_decode_stream(). The page is then submitted to
// ogg_decode_page() along with the appropriate
// ogg_stream_state* (ie, matching serialno). We then get raw
// packets out calling ogg_stream_packet() with a
// ogg_stream_state. See the 'frame-prog.txt' docs for details and
// example code.
public class SyncState {
public byte[] data;
int storage;
int fill;
int returned;
int unsynced;
int headerbytes;
int bodybytes;
public int clear() {
data = null;
return (0);
}
public int buffer(int size) {
// first, clear out any space that has been previously returned
if (returned != 0) {
fill -= returned;
if (fill > 0) {
System.arraycopy(data, returned, data, 0, fill);
}
returned = 0;
}
if (size > storage - fill) {
// We need to extend the internal buffer
int newsize = size + fill + 4096; // an extra page to be nice
if (data != null) {
byte[] foo = new byte[newsize];
System.arraycopy(data, 0, foo, 0, data.length);
data = foo;
} else {
data = new byte[newsize];
}
storage = newsize;
}
return (fill);
}
public int wrote(int bytes) {
if (fill + bytes > storage)
return (-1);
fill += bytes;
return (0);
}
// sync the stream. This is meant to be useful for finding page
// boundaries.
//
// return values for this:
// -n) skipped n bytes
// 0) page not ready; more data (no bytes skipped)
// n) page synced at current location; page length n bytes
private Page pageseek = new Page();
private byte[] chksum = new byte[4];
public int pageseek(Page og) {
int page = returned;
int next;
int bytes = fill - returned;
if (headerbytes == 0) {
int _headerbytes, i;
if (bytes < 27)
return (0); // not enough for a header
/* verify capture pattern */
if (data[page] != 'O' || data[page + 1] != 'g' || data[page + 2] != 'g'
|| data[page + 3] != 'S') {
headerbytes = 0;
bodybytes = 0;
// search for possible capture
next = 0;
for (int ii = 0; ii < bytes - 1; ii++) {
if (data[page + 1 + ii] == 'O') {
next = page + 1 + ii;
break;
}
}
//next=memchr(page+1,'O',bytes-1);
if (next == 0)
next = fill;
returned = next;
return (-(next - page));
}
_headerbytes = (data[page + 26] & 0xff) + 27;
if (bytes < _headerbytes)
return (0); // not enough for header + seg table
// count up body length in the segment table
for (i = 0; i < (data[page + 26] & 0xff); i++) {
bodybytes += (data[page + 27 + i] & 0xff);
}
headerbytes = _headerbytes;
}
if (bodybytes + headerbytes > bytes)
return (0);
// The whole test page is buffered. Verify the checksum
synchronized (chksum) {
// Grab the checksum bytes, set the header field to zero
System.arraycopy(data, page + 22, chksum, 0, 4);
data[page + 22] = 0;
data[page + 23] = 0;
data[page + 24] = 0;
data[page + 25] = 0;
// set up a temp page struct and recompute the checksum
Page log = pageseek;
log.header_base = data;
log.header = page;
log.header_len = headerbytes;
log.body_base = data;
log.body = page + headerbytes;
log.body_len = bodybytes;
log.checksum();
// Compare
if (chksum[0] != data[page + 22] || chksum[1] != data[page + 23]
|| chksum[2] != data[page + 24] || chksum[3] != data[page + 25]) {
// D'oh. Mismatch! Corrupt page (or miscapture and not a page at all)
// replace the computed checksum with the one actually read in
System.arraycopy(chksum, 0, data, page + 22, 4);
// Bad checksum. Lose sync */
headerbytes = 0;
bodybytes = 0;
// search for possible capture
next = 0;
for (int ii = 0; ii < bytes - 1; ii++) {
if (data[page + 1 + ii] == 'O') {
next = page + 1 + ii;
break;
}
}
//next=memchr(page+1,'O',bytes-1);
if (next == 0)
next = fill;
returned = next;
return (-(next - page));
}
}
// yes, have a whole page all ready to go
{
page = returned;
if (og != null) {
og.header_base = data;
og.header = page;
og.header_len = headerbytes;
og.body_base = data;
og.body = page + headerbytes;
og.body_len = bodybytes;
}
unsynced = 0;
returned += (bytes = headerbytes + bodybytes);
headerbytes = 0;
bodybytes = 0;
return (bytes);
}
}
// sync the stream and get a page. Keep trying until we find a page.
// Supress 'sync errors' after reporting the first.
//
// return values:
// -1) recapture (hole in data)
// 0) need more data
// 1) page returned
//
// Returns pointers into buffered data; invalidated by next call to
// _stream, _clear, _init, or _buffer
public int pageout(Page og) {
// all we need to do is verify a page at the head of the stream
// buffer. If it doesn't verify, we look for the next potential
// frame
while (true) {
int ret = pageseek(og);
if (ret > 0) {
// have a page
return (1);
}
if (ret == 0) {
// need more data
return (0);
}
// head did not start a synced page... skipped some bytes
if (unsynced == 0) {
unsynced = 1;
return (-1);
}
// loop. keep looking
}
}
// clear things to an initial state. Good to call, eg, before seeking
public int reset() {
fill = 0;
returned = 0;
unsynced = 0;
headerbytes = 0;
bodybytes = 0;
return (0);
}
public void init() {
}
public int getDataOffset() {
return returned;
}
public int getBufferOffset() {
return fill;
}
}