[Vorbis] how to arrange the codeword tree into array form

[Ashok]

hi,

i am porting ogg vorbis decoder on to a24- bit dsp
platform. i would like to know how he is arranging 
the binary tree into an array form. i think this 
process is done in _make_words in tremer code. i 
would be if some one could explain me the exact 
algorithm or where can i get it? 

i am attaching the code here for your reference.

static int _make_words(char *l,long n,ogg_uint32_t *r,long quantvals,
		       codebook *b, oggpack_buffer *opb,int maptype){
  long i,j,count=0;
  long top=0;
  ogg_uint32_t marker[33];

  if(n<2){
    r[0]=0x80000000;
  }else{
    memset(marker,0,sizeof(marker));
    
    for(i=0;i<n;i++){
      long length=l[i];
      if(length){
	ogg_uint32_t entry=marker[length];
	long chase=0;
	if(count && !entry)return -1; /* overpopulated tree! */
	
	/* chase the tree as far as it's already populated, fill in past */
	for(j=0;j<length-1;j++){
	  int bit=(entry>>(length-j-1))&1;
	  if(chase>=top){ 
	    top++;
	    r[chase*2]=top;
	    r[chase*2+1]=0;
	  }else
	    if(!r[chase*2+bit])
	      r[chase*2+bit]=top;
	  chase=r[chase*2+bit];
	}
	{	
	  int bit=(entry>>(length-j-1))&1;
	  if(chase>=top){ 
	    top++;
	    r[chase*2+1]=0;
	  }
	  r[chase*2+bit]= decpack(i,count++,quantvals,b,opb,maptype) | 
	    0x80000000;
	}

	/* Look to see if the next shorter marker points to the node
	   above. if so, update it and repeat.  */
	for(j=length;j>0;j--){          
	  if(marker[j]&1){
	    marker[j]=marker[j-1]<<1;
	    break;
	  }
	  marker[j]++;
	}
	
	/* prune the tree; the implicit invariant says all the longer
	   markers were dangling from our just-taken node.  Dangle them
	   from our *new* node. */
	for(j=length+1;j<33;j++)
	  if((marker[j]>>1) == entry){
	    entry=marker[j];
	    marker[j]=marker[j-1]<<1;
	  }else
	    break;
      }
    }
  }
  
  return 0;
}

regards
ashok.j.n.