framing.c

betaplayer_0.096源码 tcpmp老版本

/********************************************************************
 *                                                                  *
 * 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 ([e-mail]).  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;

    if(!bs->outstanding){
      _ogg_free(bs);
      return;
    }

    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;
  }
}

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,