diff -r e353ca78d28b -r f7e49eff3708 misc/libtremor/framing.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/misc/libtremor/framing.c	Sun Apr 24 22:57:57 2011 +0200
@@ -0,0 +1,1126 @@
+/********************************************************************
+ *                                                                  *
+ * THIS FILE IS PART OF THE OggVorbis 'TREMOR' CODEC SOURCE CODE.   *
+ *                                                                  *
+ * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
+ * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
+ * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
+ *                                                                  *
+ * THE OggVorbis 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2003    *
+ * BY THE Xiph.Org FOUNDATION http://www.xiph.org/                  *
+ *                                                                  *
+ ********************************************************************
+
+ function: decode Ogg streams back into raw packets
+
+ note: The CRC code is directly derived from public domain code by
+ Ross Williams (ross@guest.adelaide.edu.au).  See docs/framing.html
+ for details.
+
+ ********************************************************************/
+
+#include <stdlib.h>
+#include <string.h>
+#include "ogg.h"
+#include "misc.h"
+
+
+/* A complete description of Ogg framing exists in docs/framing.html */
+
+/* basic, centralized Ogg memory management based on linked lists of
+   references to refcounted memory buffers.  References and buffers
+   are both recycled.  Buffers are passed around and consumed in
+   reference form. */
+
+static ogg_buffer_state *ogg_buffer_create(void){
+  ogg_buffer_state *bs=_ogg_calloc(1,sizeof(*bs));
+  return bs;
+}
+
+/* destruction is 'lazy'; there may be memory references outstanding,
+   and yanking the buffer state out from underneath would be
+   antisocial.  Dealloc what is currently unused and have
+   _release_one watch for the stragglers to come in.  When they do,
+   finish destruction. */
+
+/* call the helper while holding lock */
+static void _ogg_buffer_destroy(ogg_buffer_state *bs){
+  ogg_buffer *bt;
+  ogg_reference *rt;
+
+  if(bs->shutdown){
+
+    bt=bs->unused_buffers;
+    rt=bs->unused_references;
+
+    while(bt){
+      ogg_buffer *b=bt;
+      bt=b->ptr.next;
+      if(b->data)_ogg_free(b->data);
+      _ogg_free(b);
+    }
+    bs->unused_buffers=0;
+    while(rt){
+      ogg_reference *r=rt;
+      rt=r->next;
+      _ogg_free(r);
+    }
+    bs->unused_references=0;
+
+    if(!bs->outstanding)
+      _ogg_free(bs);
+
+  }
+}
+
+static void ogg_buffer_destroy(ogg_buffer_state *bs){
+  bs->shutdown=1;
+  _ogg_buffer_destroy(bs);
+}
+
+static ogg_buffer *_fetch_buffer(ogg_buffer_state *bs,long bytes){
+  ogg_buffer    *ob;
+  bs->outstanding++;
+
+  /* do we have an unused buffer sitting in the pool? */
+  if(bs->unused_buffers){
+    ob=bs->unused_buffers;
+    bs->unused_buffers=ob->ptr.next;
+
+    /* if the unused buffer is too small, grow it */
+    if(ob->size<bytes){
+      ob->data=_ogg_realloc(ob->data,bytes);
+      ob->size=bytes;
+    }
+  }else{
+    /* allocate a new buffer */
+    ob=_ogg_malloc(sizeof(*ob));
+    ob->data=_ogg_malloc(bytes<16?16:bytes);
+    ob->size=bytes;
+  }
+
+  ob->refcount=1;
+  ob->ptr.owner=bs;
+  return ob;
+}
+
+static ogg_reference *_fetch_ref(ogg_buffer_state *bs){
+  ogg_reference *or;
+  bs->outstanding++;
+
+  /* do we have an unused reference sitting in the pool? */
+  if(bs->unused_references){
+    or=bs->unused_references;
+    bs->unused_references=or->next;
+  }else{
+    /* allocate a new reference */
+    or=_ogg_malloc(sizeof(*or));
+  }
+
+  or->begin=0;
+  or->length=0;
+  or->next=0;
+  return or;
+}
+
+/* fetch a reference pointing to a fresh, initially continguous buffer
+   of at least [bytes] length */
+static ogg_reference *ogg_buffer_alloc(ogg_buffer_state *bs,long bytes){
+  ogg_buffer    *ob=_fetch_buffer(bs,bytes);
+  ogg_reference *or=_fetch_ref(bs);
+  or->buffer=ob;
+  return or;
+}
+
+/* enlarge the data buffer in the current link */
+static void ogg_buffer_realloc(ogg_reference *or,long bytes){
+  ogg_buffer    *ob=or->buffer;
+  
+  /* if the unused buffer is too small, grow it */
+  if(ob->size<bytes){
+    ob->data=_ogg_realloc(ob->data,bytes);
+    ob->size=bytes;
+  }
+}
+
+static void _ogg_buffer_mark_one(ogg_reference *or){
+  or->buffer->refcount++;
+}
+
+/* increase the refcount of the buffers to which the reference points */
+static void ogg_buffer_mark(ogg_reference *or){
+  while(or){
+    _ogg_buffer_mark_one(or);
+    or=or->next;
+  }
+}
+
+/* duplicate a reference (pointing to the same actual buffer memory)
+   and increment buffer refcount.  If the desired segment begins out
+   of range, NULL is returned; if the desired segment is simply zero
+   length, a zero length ref is returned.  Partial range overlap
+   returns the overlap of the ranges */
+static ogg_reference *ogg_buffer_sub(ogg_reference *or,long begin,long length){
+  ogg_reference *ret=0,*head=0;
+
+  /* walk past any preceeding fragments we don't want */
+  while(or && begin>=or->length){
+    begin-=or->length;
+    or=or->next;
+  }
+
+  /* duplicate the reference chain; increment refcounts */
+  while(or && length){
+    ogg_reference *temp=_fetch_ref(or->buffer->ptr.owner);
+    if(head)
+      head->next=temp;
+    else
+      ret=temp;
+    head=temp;
+    head->buffer=or->buffer;    
+    head->begin=or->begin+begin;
+    head->length=length;
+    if(head->length>or->length-begin)
+      head->length=or->length-begin;
+    
+    begin=0;
+    length-=head->length;
+    or=or->next;
+  }
+
+  ogg_buffer_mark(ret);
+  return ret;
+}
+
+ogg_reference *ogg_buffer_dup(ogg_reference *or){
+  ogg_reference *ret=0,*head=0;
+  /* duplicate the reference chain; increment refcounts */
+  while(or){
+    ogg_reference *temp=_fetch_ref(or->buffer->ptr.owner);
+    if(head)
+      head->next=temp;
+    else
+      ret=temp;
+    head=temp;
+    head->buffer=or->buffer;    
+    head->begin=or->begin;
+    head->length=or->length;
+    or=or->next;
+  }
+
+  ogg_buffer_mark(ret);
+  return ret;
+}
+
+/* split a reference into two references; 'return' is a reference to
+   the buffer preceeding pos and 'head'/'tail' are the buffer past the
+   split.  If pos is at or past the end of the passed in segment,
+   'head/tail' are NULL */
+static ogg_reference *ogg_buffer_split(ogg_reference **tail,
+                                ogg_reference **head,long pos){
+
+  /* walk past any preceeding fragments to one of:
+     a) the exact boundary that seps two fragments
+     b) the fragment that needs split somewhere in the middle */
+  ogg_reference *ret=*tail;
+  ogg_reference *or=*tail;
+
+  while(or && pos>or->length){
+    pos-=or->length;
+    or=or->next;
+  }
+
+  if(!or || pos==0){
+
+    return 0;
+    
+  }else{
+    
+    if(pos>=or->length){
+      /* exact split, or off the end? */
+      if(or->next){
+        
+        /* a split */
+        *tail=or->next;
+        or->next=0;
+        
+      }else{
+        
+        /* off or at the end */
+        *tail=*head=0;
+        
+      }
+    }else{
+      
+      /* split within a fragment */
+      long lengthA=pos;
+      long beginB=or->begin+pos;
+      long lengthB=or->length-pos;
+      
+      /* make a new reference to tail the second piece */
+      *tail=_fetch_ref(or->buffer->ptr.owner);
+      
+      (*tail)->buffer=or->buffer;
+      (*tail)->begin=beginB;
+      (*tail)->length=lengthB;
+      (*tail)->next=or->next;
+      _ogg_buffer_mark_one(*tail);
+      if(head && or==*head)*head=*tail;    
+      
+      /* update the first piece */
+      or->next=0;
+      or->length=lengthA;
+      
+    }
+  }
+  return ret;
+}
+
+static void ogg_buffer_release_one(ogg_reference *or){
+  ogg_buffer *ob=or->buffer;
+  ogg_buffer_state *bs=ob->ptr.owner;
+
+  ob->refcount--;
+  if(ob->refcount==0){
+    bs->outstanding--; /* for the returned buffer */
+    ob->ptr.next=bs->unused_buffers;
+    bs->unused_buffers=ob;
+  }
+  
+  bs->outstanding--; /* for the returned reference */
+  or->next=bs->unused_references;
+  bs->unused_references=or;
+
+  _ogg_buffer_destroy(bs); /* lazy cleanup (if needed) */
+
+}
+
+/* release the references, decrease the refcounts of buffers to which
+   they point, release any buffers with a refcount that drops to zero */
+static void ogg_buffer_release(ogg_reference *or){
+  while(or){
+    ogg_reference *next=or->next;
+    ogg_buffer_release_one(or);
+    or=next;
+  }
+}
+
+static ogg_reference *ogg_buffer_pretruncate(ogg_reference *or,long pos){
+  /* release preceeding fragments we don't want */
+  while(or && pos>=or->length){
+    ogg_reference *next=or->next;
+    pos-=or->length;
+    ogg_buffer_release_one(or);
+    or=next;
+  }
+  if (or) {
+    or->begin+=pos;
+    or->length-=pos;
+  }
+  return or;
+}
+
+static ogg_reference *ogg_buffer_walk(ogg_reference *or){
+  if(!or)return NULL;
+  while(or->next){
+    or=or->next;
+  }
+  return(or);
+}
+
+/* *head is appended to the front end (head) of *tail; both continue to
+   be valid pointers, with *tail at the tail and *head at the head */
+static ogg_reference *ogg_buffer_cat(ogg_reference *tail, ogg_reference *head){
+  if(!tail)return head;
+
+  while(tail->next){
+    tail=tail->next;
+  }
+  tail->next=head;
+  return ogg_buffer_walk(head);
+}
+
+static void _positionB(oggbyte_buffer *b,int pos){
+  if(pos<b->pos){
+    /* start at beginning, scan forward */
+    b->ref=b->baseref;
+    b->pos=0;
+    b->end=b->pos+b->ref->length;
+    b->ptr=b->ref->buffer->data+b->ref->begin;
+  }
+}
+
+static void _positionF(oggbyte_buffer *b,int pos){
+  /* scan forward for position */
+  while(pos>=b->end){
+    /* just seek forward */
+    b->pos+=b->ref->length;
+    b->ref=b->ref->next;
+    b->end=b->ref->length+b->pos;
+    b->ptr=b->ref->buffer->data+b->ref->begin;
+  }
+}
+
+static int oggbyte_init(oggbyte_buffer *b,ogg_reference *or){
+  memset(b,0,sizeof(*b));
+  if(or){
+    b->ref=b->baseref=or;
+    b->pos=0;
+    b->end=b->ref->length;
+    b->ptr=b->ref->buffer->data+b->ref->begin;  
+    return 0;
+  }else
+    return -1;
+}
+
+static void oggbyte_set4(oggbyte_buffer *b,ogg_uint32_t val,int pos){
+  int i;
+  _positionB(b,pos);
+  for(i=0;i<4;i++){
+    _positionF(b,pos);
+    b->ptr[pos-b->pos]=val;
+    val>>=8;
+    ++pos;
+  }
+}
+ 
+static unsigned char oggbyte_read1(oggbyte_buffer *b,int pos){
+  _positionB(b,pos);
+  _positionF(b,pos);
+  return b->ptr[pos-b->pos];
+}
+
+static ogg_uint32_t oggbyte_read4(oggbyte_buffer *b,int pos){
+  ogg_uint32_t ret;
+  _positionB(b,pos);
+  _positionF(b,pos);
+  ret=b->ptr[pos-b->pos];
+  _positionF(b,++pos);
+  ret|=b->ptr[pos-b->pos]<<8;
+  _positionF(b,++pos);
+  ret|=b->ptr[pos-b->pos]<<16;
+  _positionF(b,++pos);
+  ret|=b->ptr[pos-b->pos]<<24;
+  return ret;
+}
+
+static ogg_int64_t oggbyte_read8(oggbyte_buffer *b,int pos){
+  ogg_int64_t ret;
+  unsigned char t[7];
+  int i;
+  _positionB(b,pos);
+  for(i=0;i<7;i++){
+    _positionF(b,pos);
+    t[i]=b->ptr[pos++ -b->pos];
+  }
+
+  _positionF(b,pos);
+  ret=b->ptr[pos-b->pos];
+
+  for(i=6;i>=0;--i)
+    ret= ret<<8 | t[i];
+
+  return ret;
+}
+
+/* Now we get to the actual framing code */
+
+int ogg_page_version(ogg_page *og){
+  oggbyte_buffer ob;
+  oggbyte_init(&ob,og->header);
+  return oggbyte_read1(&ob,4);
+}
+
+int ogg_page_continued(ogg_page *og){
+  oggbyte_buffer ob;
+  oggbyte_init(&ob,og->header);
+  return oggbyte_read1(&ob,5)&0x01;
+}
+
+int ogg_page_bos(ogg_page *og){
+  oggbyte_buffer ob;
+  oggbyte_init(&ob,og->header);
+  return oggbyte_read1(&ob,5)&0x02;
+}
+
+int ogg_page_eos(ogg_page *og){
+  oggbyte_buffer ob;
+  oggbyte_init(&ob,og->header);
+  return oggbyte_read1(&ob,5)&0x04;
+}
+
+ogg_int64_t ogg_page_granulepos(ogg_page *og){
+  oggbyte_buffer ob;
+  oggbyte_init(&ob,og->header);
+  return oggbyte_read8(&ob,6);
+}
+
+ogg_uint32_t ogg_page_serialno(ogg_page *og){
+  oggbyte_buffer ob;
+  oggbyte_init(&ob,og->header);
+  return oggbyte_read4(&ob,14);
+}
+ 
+ogg_uint32_t ogg_page_pageno(ogg_page *og){
+  oggbyte_buffer ob;
+  oggbyte_init(&ob,og->header);
+  return oggbyte_read4(&ob,18);
+}
+
+/* returns the number of packets that are completed on this page (if
+   the leading packet is begun on a previous page, but ends on this
+   page, it's counted */
+
+/* NOTE:
+If a page consists of a packet begun on a previous page, and a new
+packet begun (but not completed) on this page, the return will be:
+  ogg_page_packets(page)   ==1, 
+  ogg_page_continued(page) !=0
+
+If a page happens to be a single packet that was begun on a
+previous page, and spans to the next page (in the case of a three or
+more page packet), the return will be: 
+  ogg_page_packets(page)   ==0, 
+  ogg_page_continued(page) !=0
+*/
+
+int ogg_page_packets(ogg_page *og){
+  int i;
+  int n;
+  int count=0;
+  oggbyte_buffer ob;
+  oggbyte_init(&ob,og->header);
+
+  n=oggbyte_read1(&ob,26);
+  for(i=0;i<n;i++)
+    if(oggbyte_read1(&ob,27+i)<255)count++;
+  return(count);
+}
+
+/* Static CRC calculation table.  See older code in CVS for dead
+   run-time initialization code. */
+
+static ogg_uint32_t crc_lookup[256]={
+  0x00000000,0x04c11db7,0x09823b6e,0x0d4326d9,
+  0x130476dc,0x17c56b6b,0x1a864db2,0x1e475005,
+  0x2608edb8,0x22c9f00f,0x2f8ad6d6,0x2b4bcb61,
+  0x350c9b64,0x31cd86d3,0x3c8ea00a,0x384fbdbd,
+  0x4c11db70,0x48d0c6c7,0x4593e01e,0x4152fda9,
+  0x5f15adac,0x5bd4b01b,0x569796c2,0x52568b75,
+  0x6a1936c8,0x6ed82b7f,0x639b0da6,0x675a1011,
+  0x791d4014,0x7ddc5da3,0x709f7b7a,0x745e66cd,
+  0x9823b6e0,0x9ce2ab57,0x91a18d8e,0x95609039,
+  0x8b27c03c,0x8fe6dd8b,0x82a5fb52,0x8664e6e5,
+  0xbe2b5b58,0xbaea46ef,0xb7a96036,0xb3687d81,
+  0xad2f2d84,0xa9ee3033,0xa4ad16ea,0xa06c0b5d,
+  0xd4326d90,0xd0f37027,0xddb056fe,0xd9714b49,
+  0xc7361b4c,0xc3f706fb,0xceb42022,0xca753d95,
+  0xf23a8028,0xf6fb9d9f,0xfbb8bb46,0xff79a6f1,
+  0xe13ef6f4,0xe5ffeb43,0xe8bccd9a,0xec7dd02d,
+  0x34867077,0x30476dc0,0x3d044b19,0x39c556ae,
+  0x278206ab,0x23431b1c,0x2e003dc5,0x2ac12072,
+  0x128e9dcf,0x164f8078,0x1b0ca6a1,0x1fcdbb16,
+  0x018aeb13,0x054bf6a4,0x0808d07d,0x0cc9cdca,
+  0x7897ab07,0x7c56b6b0,0x71159069,0x75d48dde,
+  0x6b93dddb,0x6f52c06c,0x6211e6b5,0x66d0fb02,
+  0x5e9f46bf,0x5a5e5b08,0x571d7dd1,0x53dc6066,
+  0x4d9b3063,0x495a2dd4,0x44190b0d,0x40d816ba,
+  0xaca5c697,0xa864db20,0xa527fdf9,0xa1e6e04e,
+  0xbfa1b04b,0xbb60adfc,0xb6238b25,0xb2e29692,
+  0x8aad2b2f,0x8e6c3698,0x832f1041,0x87ee0df6,
+  0x99a95df3,0x9d684044,0x902b669d,0x94ea7b2a,
+  0xe0b41de7,0xe4750050,0xe9362689,0xedf73b3e,
+  0xf3b06b3b,0xf771768c,0xfa325055,0xfef34de2,
+  0xc6bcf05f,0xc27dede8,0xcf3ecb31,0xcbffd686,
+  0xd5b88683,0xd1799b34,0xdc3abded,0xd8fba05a,
+  0x690ce0ee,0x6dcdfd59,0x608edb80,0x644fc637,
+  0x7a089632,0x7ec98b85,0x738aad5c,0x774bb0eb,
+  0x4f040d56,0x4bc510e1,0x46863638,0x42472b8f,
+  0x5c007b8a,0x58c1663d,0x558240e4,0x51435d53,
+  0x251d3b9e,0x21dc2629,0x2c9f00f0,0x285e1d47,
+  0x36194d42,0x32d850f5,0x3f9b762c,0x3b5a6b9b,
+  0x0315d626,0x07d4cb91,0x0a97ed48,0x0e56f0ff,
+  0x1011a0fa,0x14d0bd4d,0x19939b94,0x1d528623,
+  0xf12f560e,0xf5ee4bb9,0xf8ad6d60,0xfc6c70d7,
+  0xe22b20d2,0xe6ea3d65,0xeba91bbc,0xef68060b,
+  0xd727bbb6,0xd3e6a601,0xdea580d8,0xda649d6f,
+  0xc423cd6a,0xc0e2d0dd,0xcda1f604,0xc960ebb3,
+  0xbd3e8d7e,0xb9ff90c9,0xb4bcb610,0xb07daba7,
+  0xae3afba2,0xaafbe615,0xa7b8c0cc,0xa379dd7b,
+  0x9b3660c6,0x9ff77d71,0x92b45ba8,0x9675461f,
+  0x8832161a,0x8cf30bad,0x81b02d74,0x857130c3,
+  0x5d8a9099,0x594b8d2e,0x5408abf7,0x50c9b640,
+  0x4e8ee645,0x4a4ffbf2,0x470cdd2b,0x43cdc09c,
+  0x7b827d21,0x7f436096,0x7200464f,0x76c15bf8,
+  0x68860bfd,0x6c47164a,0x61043093,0x65c52d24,
+  0x119b4be9,0x155a565e,0x18197087,0x1cd86d30,
+  0x029f3d35,0x065e2082,0x0b1d065b,0x0fdc1bec,
+  0x3793a651,0x3352bbe6,0x3e119d3f,0x3ad08088,
+  0x2497d08d,0x2056cd3a,0x2d15ebe3,0x29d4f654,
+  0xc5a92679,0xc1683bce,0xcc2b1d17,0xc8ea00a0,
+  0xd6ad50a5,0xd26c4d12,0xdf2f6bcb,0xdbee767c,
+  0xe3a1cbc1,0xe760d676,0xea23f0af,0xeee2ed18,
+  0xf0a5bd1d,0xf464a0aa,0xf9278673,0xfde69bc4,
+  0x89b8fd09,0x8d79e0be,0x803ac667,0x84fbdbd0,
+  0x9abc8bd5,0x9e7d9662,0x933eb0bb,0x97ffad0c,
+  0xafb010b1,0xab710d06,0xa6322bdf,0xa2f33668,
+  0xbcb4666d,0xb8757bda,0xb5365d03,0xb1f740b4};
+
+ogg_sync_state *ogg_sync_create(void){
+  ogg_sync_state *oy=_ogg_calloc(1,sizeof(*oy));
+  memset(oy,0,sizeof(*oy));
+  oy->bufferpool=ogg_buffer_create();
+  return oy;
+}
+
+int ogg_sync_destroy(ogg_sync_state *oy){
+  if(oy){
+    ogg_sync_reset(oy);
+    ogg_buffer_destroy(oy->bufferpool);
+    memset(oy,0,sizeof(*oy));
+    _ogg_free(oy);
+  }
+  return OGG_SUCCESS;
+}
+
+unsigned char *ogg_sync_bufferin(ogg_sync_state *oy, long bytes){
+
+  /* [allocate and] expose a buffer for data submission.
+
+     If there is no head fragment
+       allocate one and expose it
+     else
+       if the current head fragment has sufficient unused space
+         expose it
+       else
+         if the current head fragment is unused
+           resize and expose it
+         else
+           allocate new fragment and expose it
+  */
+
+  /* base case; fifo uninitialized */
+  if(!oy->fifo_head){
+    oy->fifo_head=oy->fifo_tail=ogg_buffer_alloc(oy->bufferpool,bytes);
+    return oy->fifo_head->buffer->data;
+  }
+  
+  /* space left in current fragment case */
+  if(oy->fifo_head->buffer->size-
+     oy->fifo_head->length-
+     oy->fifo_head->begin >= bytes)
+    return oy->fifo_head->buffer->data+
+      oy->fifo_head->length+oy->fifo_head->begin;
+
+  /* current fragment is unused, but too small */
+  if(!oy->fifo_head->length){
+    ogg_buffer_realloc(oy->fifo_head,bytes);
+    return oy->fifo_head->buffer->data+oy->fifo_head->begin;
+  }
+  
+  /* current fragment used/full; get new fragment */
+  {
+    ogg_reference *new=ogg_buffer_alloc(oy->bufferpool,bytes);
+    oy->fifo_head->next=new;
+    oy->fifo_head=new;
+  }
+  return oy->fifo_head->buffer->data;
+}
+
+int ogg_sync_wrote(ogg_sync_state *oy, long bytes){ 
+  if(!oy->fifo_head)return OGG_EINVAL;
+  if(oy->fifo_head->buffer->size-oy->fifo_head->length-oy->fifo_head->begin < 
+     bytes)return OGG_EINVAL;
+  oy->fifo_head->length+=bytes;
+  oy->fifo_fill+=bytes;
+  return OGG_SUCCESS;
+}
+
+static ogg_uint32_t _checksum(ogg_reference *or, int bytes){
+  ogg_uint32_t crc_reg=0;
+  int j,post;
+
+  while(or){
+    unsigned char *data=or->buffer->data+or->begin;
+    post=(bytes<or->length?bytes:or->length);
+    for(j=0;j<post;++j)
+      crc_reg=(crc_reg<<8)^crc_lookup[((crc_reg >> 24)&0xff)^data[j]];
+    bytes-=j;
+    or=or->next;
+  }
+
+  return crc_reg;
+}
+
+
+/* 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
+   
+*/
+
+long ogg_sync_pageseek(ogg_sync_state *oy,ogg_page *og){
+  oggbyte_buffer page;
+  long           bytes,ret=0;
+
+  ogg_page_release(og);
+
+  bytes=oy->fifo_fill;
+  oggbyte_init(&page,oy->fifo_tail);
+
+  if(oy->headerbytes==0){
+    if(bytes<27)goto sync_out; /* not enough for even a minimal header */
+    
+    /* verify capture pattern */
+    if(oggbyte_read1(&page,0)!=(int)'O' ||
+       oggbyte_read1(&page,1)!=(int)'g' ||
+       oggbyte_read1(&page,2)!=(int)'g' ||
+       oggbyte_read1(&page,3)!=(int)'S'    ) goto sync_fail;
+
+    oy->headerbytes=oggbyte_read1(&page,26)+27;
+  }
+  if(bytes<oy->headerbytes)goto sync_out; /* not enough for header +
+                                             seg table */
+  if(oy->bodybytes==0){
+    int i;
+    /* count up body length in the segment table */
+    for(i=0;i<oy->headerbytes-27;i++)
+      oy->bodybytes+=oggbyte_read1(&page,27+i);
+  }
+  
+  if(oy->bodybytes+oy->headerbytes>bytes)goto sync_out;
+
+  /* we have what appears to be a complete page; last test: verify
+     checksum */
+  {
+    ogg_uint32_t chksum=oggbyte_read4(&page,22);
+    oggbyte_set4(&page,0,22);
+
+    /* Compare checksums; memory continues to be common access */
+    if(chksum!=_checksum(oy->fifo_tail,oy->bodybytes+oy->headerbytes)){
+      
+      /* D'oh.  Mismatch! Corrupt page (or miscapture and not a page
+         at all). replace the computed checksum with the one actually
+         read in; remember all the memory is common access */
+      
+      oggbyte_set4(&page,chksum,22);
+      goto sync_fail;
+    }
+    oggbyte_set4(&page,chksum,22);
+  }
+
+  /* We have a page.  Set up page return. */
+  if(og){
+    /* set up page output */
+    og->header=ogg_buffer_split(&oy->fifo_tail,&oy->fifo_head,oy->headerbytes);
+    og->header_len=oy->headerbytes;
+    og->body=ogg_buffer_split(&oy->fifo_tail,&oy->fifo_head,oy->bodybytes);
+    og->body_len=oy->bodybytes;
+  }else{
+    /* simply advance */
+    oy->fifo_tail=
+      ogg_buffer_pretruncate(oy->fifo_tail,oy->headerbytes+oy->bodybytes);
+    if(!oy->fifo_tail)oy->fifo_head=0;
+  }
+  
+  ret=oy->headerbytes+oy->bodybytes;
+  oy->unsynced=0;
+  oy->headerbytes=0;
+  oy->bodybytes=0;
+  oy->fifo_fill-=ret;
+
+  return ret;
+  
+ sync_fail:
+
+  oy->headerbytes=0;
+  oy->bodybytes=0;
+  oy->fifo_tail=ogg_buffer_pretruncate(oy->fifo_tail,1);
+  ret--;
+  
+  /* search forward through fragments for possible capture */
+  while(oy->fifo_tail){
+    /* invariant: fifo_cursor points to a position in fifo_tail */
+    unsigned char *now=oy->fifo_tail->buffer->data+oy->fifo_tail->begin;
+    unsigned char *next=memchr(now, 'O', oy->fifo_tail->length);
+      
+    if(next){
+      /* possible capture in this segment */
+      long bytes=next-now;
+      oy->fifo_tail=ogg_buffer_pretruncate(oy->fifo_tail,bytes);
+      ret-=bytes;
+      break;
+    }else{
+      /* no capture.  advance to next segment */
+      long bytes=oy->fifo_tail->length;
+      ret-=bytes;
+      oy->fifo_tail=ogg_buffer_pretruncate(oy->fifo_tail,bytes);
+    }
+  }
+  if(!oy->fifo_tail)oy->fifo_head=0;
+  oy->fifo_fill+=ret;
+
+ sync_out:
+  return ret;
+}
+
+/* sync the stream and get a page.  Keep trying until we find a page.
+   Supress 'sync errors' after reporting the first.
+
+   return values:
+   OGG_HOLE) 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 */
+
+int ogg_sync_pageout(ogg_sync_state *oy, ogg_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(1){
+    long ret=ogg_sync_pageseek(oy,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(!oy->unsynced){
+      oy->unsynced=1;
+      return OGG_HOLE;
+    }
+
+    /* loop. keep looking */
+
+  }
+}
+
+/* clear things to an initial state.  Good to call, eg, before seeking */
+int ogg_sync_reset(ogg_sync_state *oy){
+
+  ogg_buffer_release(oy->fifo_tail);
+  oy->fifo_tail=0;
+  oy->fifo_head=0;
+  oy->fifo_fill=0;
+
+  oy->unsynced=0;
+  oy->headerbytes=0;
+  oy->bodybytes=0;
+  return OGG_SUCCESS;
+}
+
+ogg_stream_state *ogg_stream_create(int serialno){
+  ogg_stream_state *os=_ogg_calloc(1,sizeof(*os));
+  os->serialno=serialno;
+  os->pageno=-1;
+  return os;
+} 
+
+int ogg_stream_destroy(ogg_stream_state *os){
+  if(os){
+    ogg_buffer_release(os->header_tail);
+    ogg_buffer_release(os->body_tail);
+    memset(os,0,sizeof(*os));    
+    _ogg_free(os);
+  }
+  return OGG_SUCCESS;
+} 
+
+
+#define FINFLAG 0x80000000UL
+#define FINMASK 0x7fffffffUL
+
+static void _next_lace(oggbyte_buffer *ob,ogg_stream_state *os){
+  /* search ahead one lace */
+  os->body_fill_next=0;
+  while(os->laceptr<os->lacing_fill){
+    int val=oggbyte_read1(ob,27+os->laceptr++);
+    os->body_fill_next+=val;
+    if(val<255){
+      os->body_fill_next|=FINFLAG;
+      os->clearflag=1;
+      break;
+    }
+  }
+}
+
+static void _span_queued_page(ogg_stream_state *os){ 
+  while( !(os->body_fill&FINFLAG) ){
+    
+    if(!os->header_tail)break;
+
+    /* first flush out preceeding page header (if any).  Body is
+       flushed as it's consumed, so that's not done here. */
+
+    if(os->lacing_fill>=0)
+      os->header_tail=ogg_buffer_pretruncate(os->header_tail,
+                                             os->lacing_fill+27);
+    os->lacing_fill=0;
+    os->laceptr=0;
+    os->clearflag=0;
+
+    if(!os->header_tail){
+      os->header_head=0;
+      break;
+    }else{
+      
+      /* process/prepare next page, if any */
+
+      long pageno;
+      oggbyte_buffer ob;
+      ogg_page og;               /* only for parsing header values */
+      og.header=os->header_tail; /* only for parsing header values */
+      pageno=ogg_page_pageno(&og);
+
+      oggbyte_init(&ob,os->header_tail);
+      os->lacing_fill=oggbyte_read1(&ob,26);
+      
+      /* are we in sequence? */
+      if(pageno!=os->pageno){
+        if(os->pageno==-1) /* indicates seek or reset */
+          os->holeflag=1;  /* set for internal use */
+        else
+          os->holeflag=2;  /* set for external reporting */
+
+        os->body_tail=ogg_buffer_pretruncate(os->body_tail,
+                                             os->body_fill);
+        if(os->body_tail==0)os->body_head=0;
+        os->body_fill=0;
+
+      }
+    
+      if(ogg_page_continued(&og)){
+        if(os->body_fill==0){
+          /* continued packet, but no preceeding data to continue */
+          /* dump the first partial packet on the page */
+          _next_lace(&ob,os);   
+          os->body_tail=
+            ogg_buffer_pretruncate(os->body_tail,os->body_fill_next&FINMASK);
+          if(os->body_tail==0)os->body_head=0;
+          /* set span flag */
+          if(!os->spanflag && !os->holeflag)os->spanflag=2;
+        }
+      }else{
+        if(os->body_fill>0){
+          /* preceeding data to continue, but not a continued page */
+          /* dump body_fill */
+          os->body_tail=ogg_buffer_pretruncate(os->body_tail,
+                                               os->body_fill);
+          if(os->body_tail==0)os->body_head=0;
+          os->body_fill=0;
+
+          /* set espan flag */
+          if(!os->spanflag && !os->holeflag)os->spanflag=2;
+        }
+      }
+
+      if(os->laceptr<os->lacing_fill){
+        os->granulepos=ogg_page_granulepos(&og);
+
+        /* get current packet size & flag */
+        _next_lace(&ob,os);
+        os->body_fill+=os->body_fill_next; /* addition handles the flag fine;
+                                             unsigned on purpose */
+        /* ...and next packet size & flag */
+        _next_lace(&ob,os);
+
+      }
+      
+      os->pageno=pageno+1;
+      os->e_o_s=ogg_page_eos(&og);
+      os->b_o_s=ogg_page_bos(&og);
+    
+    }
+  }
+}
+
+/* add the incoming page to the stream state; we decompose the page
+   into packet segments here as well. */
+
+int ogg_stream_pagein(ogg_stream_state *os, ogg_page *og){
+
+  int serialno=ogg_page_serialno(og);
+  int version=ogg_page_version(og);
+
+  /* check the serial number */
+  if(serialno!=os->serialno){
+    ogg_page_release(og);
+    return OGG_ESERIAL;
+  }
+  if(version>0){
+    ogg_page_release(og);
+    return OGG_EVERSION;
+  }
+
+  /* add to fifos */
+  if(!os->body_tail){
+    os->body_tail=og->body;
+    os->body_head=ogg_buffer_walk(og->body);
+  }else{
+    os->body_head=ogg_buffer_cat(os->body_head,og->body);
+  }
+  if(!os->header_tail){
+    os->header_tail=og->header;
+    os->header_head=ogg_buffer_walk(og->header);
+    os->lacing_fill=-27;
+  }else{
+    os->header_head=ogg_buffer_cat(os->header_head,og->header);
+  }
+
+  memset(og,0,sizeof(*og));
+  return OGG_SUCCESS;
+}
+
+int ogg_stream_reset(ogg_stream_state *os){
+
+  ogg_buffer_release(os->header_tail);
+  ogg_buffer_release(os->body_tail);
+  os->header_tail=os->header_head=0;
+  os->body_tail=os->body_head=0;
+
+  os->e_o_s=0;
+  os->b_o_s=0;
+  os->pageno=-1;
+  os->packetno=0;
+  os->granulepos=0;
+
+  os->body_fill=0;
+  os->lacing_fill=0;
+
+  os->holeflag=0;
+  os->spanflag=0;
+  os->clearflag=0;
+  os->laceptr=0;
+  os->body_fill_next=0;
+
+  return OGG_SUCCESS;
+}
+
+int ogg_stream_reset_serialno(ogg_stream_state *os,int serialno){
+  ogg_stream_reset(os);
+  os->serialno=serialno;
+  return OGG_SUCCESS;
+}
+
+static int _packetout(ogg_stream_state *os,ogg_packet *op,int adv){
+
+  ogg_packet_release(op);
+  _span_queued_page(os);
+
+  if(os->holeflag){
+    int temp=os->holeflag;
+    if(os->clearflag)
+      os->holeflag=0;
+    else
+      os->holeflag=1;
+    if(temp==2){
+      os->packetno++;
+      return OGG_HOLE;
+    }
+  }
+  if(os->spanflag){
+    int temp=os->spanflag;
+    if(os->clearflag)
+      os->spanflag=0;
+    else
+      os->spanflag=1;
+    if(temp==2){
+      os->packetno++;
+      return OGG_SPAN;
+    }
+  }
+
+  if(!(os->body_fill&FINFLAG)) return 0;
+  if(!op && !adv)return 1; /* just using peek as an inexpensive way
+                               to ask if there's a whole packet
+                               waiting */
+  if(op){
+    op->b_o_s=os->b_o_s;
+    if(os->e_o_s && os->body_fill_next==0)
+      op->e_o_s=os->e_o_s;
+    else
+      op->e_o_s=0;
+    if( (os->body_fill&FINFLAG) && !(os->body_fill_next&FINFLAG) )
+      op->granulepos=os->granulepos;
+    else
+      op->granulepos=-1;
+    op->packetno=os->packetno;
+  }
+
+  if(adv){
+    oggbyte_buffer ob;
+    oggbyte_init(&ob,os->header_tail);
+
+    /* split the body contents off */
+    if(op){
+      op->packet=ogg_buffer_split(&os->body_tail,&os->body_head,
+				  os->body_fill&FINMASK);
+      op->bytes=os->body_fill&FINMASK;
+    }else{
+      os->body_tail=ogg_buffer_pretruncate(os->body_tail,
+					   os->body_fill&FINMASK);
+      if(os->body_tail==0)os->body_head=0;
+    }
+
+    /* update lacing pointers */
+    os->body_fill=os->body_fill_next;
+    _next_lace(&ob,os);
+  }else{
+    if(op){
+      op->packet=ogg_buffer_sub(os->body_tail,0,os->body_fill&FINMASK);
+      op->bytes=os->body_fill&FINMASK;
+    }
+  }
+  
+  if(adv){
+    os->packetno++;
+    os->b_o_s=0;
+  }
+
+  return 1;
+}
+
+int ogg_stream_packetout(ogg_stream_state *os,ogg_packet *op){
+  return _packetout(os,op,1);
+}
+
+int ogg_stream_packetpeek(ogg_stream_state *os,ogg_packet *op){
+  return _packetout(os,op,0);
+}
+
+int ogg_packet_release(ogg_packet *op) {
+  if(op){
+    ogg_buffer_release(op->packet);
+    memset(op, 0, sizeof(*op));
+  }
+  return OGG_SUCCESS;
+}
+
+int ogg_page_release(ogg_page *og) {
+  if(og){
+    ogg_buffer_release(og->header);
+    ogg_buffer_release(og->body);
+    memset(og, 0, sizeof(*og));
+  }
+  return OGG_SUCCESS;
+}
+
+void ogg_page_dup(ogg_page *dup,ogg_page *orig){
+  dup->header_len=orig->header_len;
+  dup->body_len=orig->body_len;
+  dup->header=ogg_buffer_dup(orig->header);
+  dup->body=ogg_buffer_dup(orig->body);
+}
+