/*
***********************************************************************
* COPYRIGHT AND WARRANTY INFORMATION
*
* Copyright 2001, International Telecommunications Union, Geneva
*
* DISCLAIMER OF WARRANTY
*
* These software programs are available to the user without any
* license fee or royalty on an "as is" basis. The ITU disclaims
* any and all warranties, whether express, implied, or
* statutory, including any implied warranties of merchantability
* or of fitness for a particular purpose.  In no event shall the
* contributor or the ITU be liable for any incidental, punitive, or
* consequential damages of any kind whatsoever arising from the
* use of these programs.
*
* This disclaimer of warranty extends to the user of these programs
* and user's customers, employees, agents, transferees, successors,
* and assigns.
*
* The ITU does not represent or warrant that the programs furnished
* hereunder are free of infringement of any third-party patents.
* Commercial implementations of ITU-T Recommendations, including
* shareware, may be subject to royalty fees to patent holders.
* Information regarding the ITU-T patent policy is available from
* the ITU Web site at http://www.itu.int.
*
* THIS IS NOT A GRANT OF PATENT RIGHTS - SEE THE ITU-T PATENT POLICY.
************************************************************************
*/

/*!
 ************************************************************************
 * \file uvlc.c
 *
 * \brief
 *    UVLC support functions
 *
 * \author
 *    Main contributors (see contributors.h for copyright, address and affiliation details)
 *    - Inge Lille-Langøy               <inge.lille-langoy@telenor.com>
 *    - Detlev Marpe                    <marpe@hhi.de>
 *    - Gabi Blaettermann               <blaetter@hhi.de>
 ************************************************************************
 */
#include "contributors.h"

#include <math.h>
#include <stdlib.h>
#include <memory.h>
#include <string.h>

#include "global.h"
#include "uvlc.h"
#include "elements.h"
#include "bitsbuf.h"
#include "header.h"
#include "golomb_dec.h"


// A little trick to avoid those horrible #if TRACE all over the source code
#if TRACE
#define SYMTRACESTRING(s) strncpy(sym.tracestring,s,TRACESTRING_SIZE)
#else
#define SYMTRACESTRING(s) // do nothing
#endif

extern void tracebits(const char *trace_str,  int len,  int info,int value1,
    int value2) ;

/*!
 ************************************************************************
 * \brief
 *    linfo
 * \par Input:
 *    lenght and info
 * \par Output:
 *    number in the code table
 ************************************************************************
 */
void linfo(int len, int info, int *value1, int *dummy)
{
  *value1 = (int)pow(2,(len/2))+info-1; // *value1 = (int)(2<<(len>>1))+info-1;
}

/*!
 ************************************************************************
 * \par Input:
 *    lenght and info
 * \par Output:
 *    signed mvd
 ************************************************************************
 */
void linfo_mvd(int len, int info, int *signed_mvd, int *dummy)
{
  int n;
  n = (int)pow(2,(len/2))+info-1;
  *signed_mvd = (n+1)/2;
  if((n & 0x01)==0)                           // lsb is signed bit
    *signed_mvd = -*signed_mvd;
}

/*!
 ************************************************************************
 * \par Input:
 *    lenght and info
 * \par Output:
 *    cbp (intra)
 ************************************************************************
 */
void linfo_cbp_intra(int len,int info,int *cbp, int *dummy)
{
  extern const byte NCBP[48][2];
    int cbp_idx;
  linfo(len,info,&cbp_idx,dummy);
    *cbp=NCBP[cbp_idx][0];
}

/*!
 ************************************************************************
 * \par Input:
 *    lenght and info
 * \par Output:
 *    cbp (inter)
 ************************************************************************
 */
void linfo_cbp_inter(int len,int info,int *cbp, int *dummy)
{
  extern const byte NCBP[48][2];
  int cbp_idx;
  linfo(len,info,&cbp_idx,dummy);
    *cbp=NCBP[cbp_idx][1];
}

/*!
 ************************************************************************
 * \par Input:
 *    lenght and info
 * \par Output:
 *    signed mvd
 ************************************************************************
 */
void linfo_dquant(int len,  int info, int *signed_dquant, int *dummy)
{
  int n;
  n = (int)pow(2,(len/2))+info-1;
  *signed_dquant = (n+1)/2;
  if((n & 0x01)==0)                           // lsb is signed bit
    *signed_dquant = -*signed_dquant;
}

/*!
 ************************************************************************
 * \par Input:
 *    lenght and info
 * \par Output:
 *    level, run
 ************************************************************************
 */
void linfo_levrun_inter(int len, int info, int *level, int *irun)
{
  int l2;
  int inf;
  if (len<=9)
  {
    l2=mmax(0,len/2-1);
    inf=info/2;
    *level=NTAB1[l2][inf][0];
    *irun=NTAB1[l2][inf][1];
    if ((info&0x01)==1)
      *level=-*level;                   // make sign
  }
  else                                  // if len > 9, skip using the array
  {
    *irun=(info&0x1e)>>1;
    *level = LEVRUN1[*irun] + info/32 + (int)pow(2,len/2 - 5);
    if ((info&0x01)==1)
      *level=-*level;
  }
    if (len == 1) // EOB
        *level = 0;
}

/*!
 ************************************************************************
 * \par Input:
 *    lenght and info
 * \par Output:
 *    level, run
 ************************************************************************
 */
void linfo_levrun_intra(int len, int info, int *level,  int *irun)
{
  int l2;
  int inf;

  if (len<=9)
  {
    l2=mmax(0,len/2-1);
    inf=info/2;
    *level=NTAB2[l2][inf][0];
    *irun=NTAB2[l2][inf][1];
    if ((info&0x01)==1)
      *level=-*level;                 // make sign
  }
  else                                  // if len > 9, skip using the array
  {
    *irun=(info&0x0e)>>1;
    *level = LEVRUN2[*irun] + info/16 + (int)pow(2,len/2-4) -1;
    if ((info&0x01)==1)
      *level=-*level;
  }
    if (len == 1) // EOB
        *level = 0;
}


/*!
 ************************************************************************
 * \par Input:
 *    lenght and info
 * \par Output:
 *    level, run
 ************************************************************************
 */
void linfo_levrun_c2x2(int len, int info, int *level, int *irun)
{
  int l2;
  int inf;

  if (len<=5)
  {
    l2=mmax(0,len/2-1);
    inf=info/2;
    *level=NTAB3[l2][inf][0];
    *irun=NTAB3[l2][inf][1];
    if ((info&0x01)==1)
      *level=-*level;                 // make sign
  }
  else                                  // if len > 5, skip using the array
  {
    *irun=(info&0x06)>>1;
    *level = LEVRUN3[*irun] + info/8 + (int)pow(2,len/2 - 3);
    if ((info&0x01)==1)
      *level=-*level;
  }
  if (len == 1) // EOB
    *level = 0;
}


/*!
 ************************************************************************
 * \brief
 *    readSliceUVLC
 *
 * \par
 *    Slice Headers can start on every byte aligned position, provided zero-stuffing.
 *    This is implemented here in such a way that a slice header can be trailed by
 *    any number of 0 bits.
 *
 * \return
 *    readSliceUVLC returns -1 in case of problems, or oen of SOP, SOS, EOS in case of success
 ************************************************************************
 */
int readSliceUVLC(struct img_par *img, struct inp_par *inp)
{
  Slice *currSlice = img->currentSlice;
  DataPartition *dP;
  Bitstream *currStream = currSlice->partArr[0].bitstream;
  int *partMap = assignSE2partition[currSlice->dp_mode];
  SyntaxElement sym;
  int dummy;
  byte *buf = currStream->streamBuffer;
  
  int len;
  int newframe = 0;   //WYK: Oct. 8, 2001, change the method to find a new frame
  int startcodeprefix_len; //number of bytes taken by start code prefix

  currStream->frame_bitoffset = 0;
  
  memset (buf, 0xff, MAX_CODED_FRAME_SIZE);   // this prevents a buffer full with zeros
  currStream->bitstream_length = GetOneSliceIntoSourceBitBuffer(img, inp, buf, &startcodeprefix_len);
  if (currStream->bitstream_length > startcodeprefix_len)  // More than just a start code
  {
    if(inp->Encapsulated_NAL_Payload)
    {
      currStream->bitstream_length = EBSPtoRBSP(buf, currStream->bitstream_length, startcodeprefix_len);
      currStream->bitstream_length = RBSPtoSODB(buf, currStream->bitstream_length);
    }
    sym.type = SE_HEADER;
#if TRACE
    strncpy(sym.tracestring, "\nHeaderinfo", TRACESTRING_SIZE);
#endif
    if(img->type == B_IMG_1 || img->type == B_IMG_MULT)
      dP = &(currSlice->partArr[partMap[SE_BFRAME]]);
    else
      dP = &(currSlice->partArr[partMap[sym.type]]);
    len = startcodeprefix_len * 8;
    
    currStream->frame_bitoffset +=len;
    
    // read the slice header
    dummy = SliceHeader(img,inp);
    
    //WYK: Oct. 8, 2001, change the method to find a new frame
    if(img->tr != img->tr_old)
      newframe = 1;
    else 
      newframe = 0;
    img->tr_old = img->tr;
    
    // PLUS2, 7/7 temp fix for AFF
    if(img->structure != img->structure_old)		
      newframe |= 1;
/*    else
      newframe = 0;  */
	  img->structure_old = img->structure; 

  // if the TR of current slice is not identical to the TR  of previous received slice, we have a new frame
    if(newframe)
      return SOP;
    else
      return SOS;
    
  }
  else    // less than four bytes in file -> cannot be a slice
    return EOS;
  return 0;
}


/*!
 ************************************************************************
 * \brief
 *    read next UVLC codeword from UVLC-partition and
 *    map it to the corresponding syntax element
 ************************************************************************
 */
int readSyntaxElement_UVLC(SyntaxElement *sym, struct img_par *img, struct inp_par *inp, struct datapartition *dP)
{
  Bitstream   *currStream = dP->bitstream;
  int frame_bitoffset = currStream->frame_bitoffset;
  byte *buf = currStream->streamBuffer;
  int BitstreamLengthInBytes = currStream->bitstream_length;

  if( sym->golomb_maxlevels && (sym->type==SE_LUM_DC_INTRA||sym->type==SE_LUM_AC_INTRA||sym->type==SE_LUM_DC_INTER||sym->type==SE_LUM_AC_INTER) )
    return readSyntaxElement_GOLOMB(sym,img,inp,dP);

  sym->len =  GetVLCSymbol (buf, frame_bitoffset, &(sym->inf), BitstreamLengthInBytes);
  if (sym->len == -1)
    return -1;
  currStream->frame_bitoffset += sym->len;
  sym->mapping(sym->len,sym->inf,&(sym->value1),&(sym->value2));

#if TRACE
  tracebits(sym->tracestring, sym->len, sym->inf, sym->value1, sym->value2);
#endif

  return 1;
}

/*!
 ************************************************************************
 * \brief
 *    read a fixed codeword from UVLC-partition and
 *    map it to the corresponding syntax element
 ************************************************************************
 */
int readSyntaxElement_fixed(SyntaxElement *sym, struct img_par *img, struct inp_par *inp, struct datapartition *dP)
{
  Bitstream   *currStream = dP->bitstream;
  int totbitoffset = currStream->frame_bitoffset;
  byte *buffer = currStream->streamBuffer;
  int bytecount = currStream->bitstream_length;

  int *info = &(sym->inf);
  register int inf;
  long byteoffset;      // byte from start of buffer
  int bitoffset;      // bit from start of byte
  int bitcounter = 1;
  int info_bit;

  byteoffset = totbitoffset/8;
  bitoffset = 7-(totbitoffset%8);

  inf = 0;
  for (info_bit = 0; info_bit < sym->len; info_bit ++)
  {
    bitcounter ++;
    bitoffset -= 1;
    if (bitoffset < 0)
    {                 // finished with current byte ?
      bitoffset = bitoffset+8;
      byteoffset++;
    }
    if (byteoffset > bytecount)
    {
      return -1;
    }
    inf=(inf<<1);
    if(buffer[byteoffset] & (0x01<<(bitoffset)))
      inf |=1;
  }

  *info = inf;
  currStream->frame_bitoffset += sym->len;

#if TRACE
  tracebits(sym->tracestring, sym->len, sym->inf, sym->value1, sym->value2);
#endif

  return bitcounter;           // return absolute offset in bit from start of frame
}

/*!
 ************************************************************************
 * \brief
 *    Check if there are symbols for the next MB
 ************************************************************************
 */
int uvlc_startcode_follows(struct img_par *img, struct inp_par *inp)
{
  Slice *currSlice = img->currentSlice;
  int dp_Nr = assignSE2partition[currSlice->dp_mode][SE_MBTYPE];
  DataPartition *dP = &(currSlice->partArr[dp_Nr]);
  Bitstream   *currStream = dP->bitstream;
  byte *buf = currStream->streamBuffer;
  int frame_bitoffset = currStream->frame_bitoffset;
  int info;
// printf ("uvlc_startcode_follows returns %d\n", (-1 == GetVLCSymbol (buf, frame_bitoffset, &info, currStream->bitstream_length)));
  if (-1 == GetVLCSymbol (buf, frame_bitoffset, &info, currStream->bitstream_length))
    return TRUE;
  else
    return FALSE;
}

#ifdef _EXP_GOLOMB
/*!
 ************************************************************************
 * \brief
 *  Moves the read pointer of the partition forward by one symbol
 *
 * \param byte buffer[]
 *    containing VLC-coded data bits
 * \param int totbitoffset
 *    bit offset from start of partition
 * \param int type
 *    expected data type (Partiotion ID)
 * \return  int info, len
 *    Length and Value of the next symbol
 *
 * \note
 *    As in both nal_bits.c and nal_part.c all data of one partition, slice,
 *    picture was already read into a buffer, there is no need to read any data
 *    here again.
 * \par
 *    GetVLCInfo was extracted because there should be only one place in the
 *    source code that has knowledge about symbol extraction, regardless of
 *    the number of different NALs.
 * \par
 *    This function could (and should) be optimized considerably
 * \par
 *    If it is ever decided to have different VLC tables for different symbol
 *    types, then this would be the place for the implementation
 * \par
 *    An alternate VLC table is implemented based on exponential Golomb codes.
 *    The define _EXP_GOLOMB selects between the UVLC and the exponential Golomb codes.
 *    The encoder must have a matching define selected.
 *  
 ************************************************************************
 */
int GetVLCSymbol (byte buffer[],int totbitoffset,int *info, int bytecount)
{

  register int inf;
  long byteoffset;      // byte from start of buffer
  int bitoffset;      // bit from start of byte
  int ctr_bit=0;      // control bit for current bit posision
  int bitcounter=1;
  int len;
  int info_bit;

  byteoffset= totbitoffset/8;
  bitoffset= 7-(totbitoffset%8);
  ctr_bit = (buffer[byteoffset] & (0x01<<bitoffset));   // set up control bit

  len=1;
  while (ctr_bit==0)
  {                 // find leading 1 bit
    len++;
    bitoffset-=1;           
    bitcounter++;
    if (bitoffset<0)
    {                 // finish with current byte ?
      bitoffset=bitoffset+8;
      byteoffset++;
    }
    ctr_bit=buffer[byteoffset] & (0x01<<(bitoffset));
  }
    // make infoword
  inf=0;                          // shortest possible code is 1, then info is always 0
  for(info_bit=0;(info_bit<(len-1)); info_bit++)
  {
    bitcounter++;
    bitoffset-=1;
    if (bitoffset<0)
    {                 // finished with current byte ?
      bitoffset=bitoffset+8;
      byteoffset++;
    }
    if (byteoffset > bytecount)
    {
      return -1;
    }
    inf=(inf<<1);
    if(buffer[byteoffset] & (0x01<<(bitoffset)))
      inf |=1;
  }

  *info = inf;
  return bitcounter;           // return absolute offset in bit from start of frame
}
#else
/*!
 ************************************************************************
 * \brief
 *  Moves the read pointer of the partition forward by one symbol
 *
 * \param byte buffer[]
 *    containing VLC-coded data bits
 * \param int totbitoffset
 *    bit offset from start of partition
 * \param int type
 *    expected data type (Partiotion ID)
 * \return  int info, len
 *    Length and Value of the next symbol
 *
 * \note
 *    As in both nal_bits.c and nal_part.c all data of one partition, slice,
 *    picture was already read into a buffer, there is no need to read any data
 *    here again.
 * \par
 *    GetVLCInfo was extracted because there should be only one place in the
 *    source code that has knowledge about symbol extraction, regardless of
 *    the number of different NALs.
 * \par
 *    This function could (and should) be optimized considerably
 * \par
 *    If it is ever decided to have different VLC tables for different symbol
 *    types, then this would be the place for the implementation
 ************************************************************************
 */
int GetVLCSymbol (byte buffer[],int totbitoffset,int *info, int bytecount)
{

  register int inf;
  long byteoffset;      // byte from start of buffer
  int bitoffset;      // bit from start of byte
  int ctr_bit=0;      // control bit for current bit posision
  int bitcounter=1;

  byteoffset= totbitoffset/8;
  bitoffset= 7-(totbitoffset%8);
  ctr_bit = (buffer[byteoffset] & (0x01<<bitoffset));   // set up control bit

  inf=0;                          // shortest possible code is 1, then info is always 0

  while (ctr_bit==0)
  {                 // repeate until next 0, ref. VLC
    bitoffset-=2;           // from MSB to LSB
    if (bitoffset<0)
    {                 // finish with current byte ?
      bitoffset=bitoffset+8;
      byteoffset++;
    }

    ctr_bit=buffer[byteoffset] & (0x01<<(bitoffset));

    // make infoword

    if(bitoffset>=7)                  // first bit in new byte
      if (buffer[byteoffset-1] & (0x01))        // check last (info)bit of last byte
        inf = ((inf << 1) | 0x01);          // multiply with 2 and add 1, ref VLC
      else
        inf = (inf << 1);             // multiply with 2

    else
      if (buffer[byteoffset] & (0x01<<(bitoffset+1))) // check infobit
        inf = ((inf << 1) | 0x01);
      else
        inf = (inf << 1);
    bitcounter+=2;
    if (byteoffset > bytecount)
    {
      return -1;
    }
  }
  *info = inf;
  return bitcounter;           // return absolute offset in bit from start of frame
}
#endif


extern void tracebits2(const char *trace_str,  int len,  int info) ;


/*!
 ************************************************************************
 * \brief
 *    code from bitstream (2d tables)
 ************************************************************************
 */

int code_from_bitstream_2d(SyntaxElement *sym,  
                           DataPartition *dP,
                           int *lentab,
                           int *codtab,
                           int tabwidth,
                           int tabheight,
                           int *code)
{
  Bitstream   *currStream = dP->bitstream;
  int frame_bitoffset = currStream->frame_bitoffset;
  byte *buf = currStream->streamBuffer;
  int BitstreamLengthInBytes = currStream->bitstream_length;

  int i,j;
  int len, cod;

  // this VLC decoding method is not optimized for speed
  for (j = 0; j < tabheight; j++) {
    for (i = 0; i < tabwidth; i++)
    {
      len = lentab[i];
      if (!len)
        continue;
      cod = codtab[i];

      if ((ShowBits(buf, frame_bitoffset, BitstreamLengthInBytes, len) == cod))
      {
        sym->value1 = i;
        sym->value2 = j;
        currStream->frame_bitoffset += len; // move bitstream pointer
        sym->len = len;
        goto found_code;
      }
    }
    lentab += tabwidth;
    codtab += tabwidth;
  }
  
  return -1;  // failed to find code

found_code:

  *code = cod;

  return 0;
}


/*!
 ************************************************************************
 * \brief
 *    read FLC codeword from UVLC-partition 
 ************************************************************************
 */
int readSyntaxElement_FLC(SyntaxElement *sym, struct datapartition *dP)
{
  Bitstream   *currStream = dP->bitstream;
  int frame_bitoffset = currStream->frame_bitoffset;
  byte *buf = currStream->streamBuffer;
  int BitstreamLengthInBytes = currStream->bitstream_length;

  if ((GetBits(buf, frame_bitoffset, &(sym->inf), BitstreamLengthInBytes, sym->len)) < 0)
    return -1;

  currStream->frame_bitoffset += sym->len; // move bitstream pointer
  sym->value1 = sym->inf;

#if TRACE
  tracebits2(sym->tracestring, sym->len, sym->inf);
#endif

  return 1;
}



/*!
 ************************************************************************
 * \brief
 *    read NumCoeff/TrailingOnes codeword from UVLC-partition 
 ************************************************************************
 */

int readSyntaxElement_NumCoeffTrailingOnes(SyntaxElement *sym,  DataPartition *dP,
                                           char *type)
{
  Bitstream   *currStream = dP->bitstream;
  int frame_bitoffset = currStream->frame_bitoffset;
  byte *buf = currStream->streamBuffer;
  int BitstreamLengthInBytes = currStream->bitstream_length;

  int vlcnum, retval;
  int code, *ct, *lt;

  int lentab[3][4][17] = 
  {
    {   // 0702
      { 1, 6, 8, 9,10,11,13,13,13,14,14,15,15,16,16,16,16},
      { 0, 2, 6, 8, 9,10,11,13,13,14,14,15,15,15,16,16,16},
      { 0, 0, 3, 7, 8, 9,10,11,13,13,14,14,15,15,16,16,16},
      { 0, 0, 0, 5, 6, 7, 8, 9,10,11,13,14,14,15,15,16,16},
    },                                                 
    {                                                  
      { 2, 6, 6, 7, 8, 8, 9,11,11,12,12,12,13,13,13,14,14},
      { 0, 2, 5, 6, 6, 7, 8, 9,11,11,12,12,13,13,14,14,14},
      { 0, 0, 3, 6, 6, 7, 8, 9,11,11,12,12,13,13,13,14,14},
      { 0, 0, 0, 4, 4, 5, 6, 6, 7, 9,11,11,12,13,13,13,14},
    },                                                 
    {                                                  
      { 4, 6, 6, 6, 7, 7, 7, 7, 8, 8, 9, 9, 9,10,10,10,10},
      { 0, 4, 5, 5, 5, 5, 6, 6, 7, 8, 8, 9, 9, 9,10,10,10},
      { 0, 0, 4, 5, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,10,10,10},
      { 0, 0, 0, 4, 4, 4, 4, 4, 5, 6, 7, 8, 8, 9,10,10,10},
    },

  };

  int codtab[3][4][17] = 
  {
    {
      { 1, 5, 7, 7, 7, 7,15,11, 8,15,11,15,11,15,11, 7,4}, 
      { 0, 1, 4, 6, 6, 6, 6,14,10,14,10,14,10, 1,14,10,6}, 
      { 0, 0, 1, 5, 5, 5, 5, 5,13, 9,13, 9,13, 9,13, 9,5}, 
      { 0, 0, 0, 3, 3, 4, 4, 4, 4, 4,12,12, 8,12, 8,12,8},
    },
    {
      { 3,11, 7, 7, 7, 4, 7,15,11,15,11, 8,15,11, 7, 9,7}, 
      { 0, 2, 7,10, 6, 6, 6, 6,14,10,14,10,14,10,11, 8,6}, 
      { 0, 0, 3, 9, 5, 5, 5, 5,13, 9,13, 9,13, 9, 6,10,5}, 
      { 0, 0, 0, 5, 4, 6, 8, 4, 4, 4,12, 8,12,12, 8, 1,4},
    },
    {
      {15,15,11, 8,15,11, 9, 8,15,11,15,11, 8,13, 9, 5,1}, 
      { 0,14,15,12,10, 8,14,10,14,14,10,14,10, 7,12, 8,4},
      { 0, 0,13,14,11, 9,13, 9,13,10,13, 9,13, 9,11, 7,3},
      { 0, 0, 0,12,11,10, 9, 8,13,12,12,12, 8,12,10, 6,2},
    },
  };

  vlcnum = sym->value1;

  if (vlcnum == 3)
  {
    // read 6 bit FLC
    code = ShowBits(buf, frame_bitoffset, BitstreamLengthInBytes, 6);
    currStream->frame_bitoffset += 6;
    sym->value2 = code & 3;
    sym->value1 = (code >> 2);

    if (!sym->value1 && sym->value2 == 3)
    {
      // #c = 0, #t1 = 3 =>  #c = 0
      sym->value2 = 0;
    }
    else
      sym->value1++;

    sym->len = 6;

    retval = 0;
  }
  else

  {
    lt = &lentab[vlcnum][0][0];
    ct = &codtab[vlcnum][0][0];
    retval = code_from_bitstream_2d(sym, dP, lt, ct, 17, 4, &code);
  }

  if (retval)
  {
    printf("ERROR: failed to find NumCoeff/TrailingOnes\n");
    exit(-1);
  }

#if TRACE
  snprintf(sym->tracestring, 
    TRACESTRING_SIZE, "%s # c & tr.1s vlc=%d #c=%d #t1=%d",
           type, vlcnum, sym->value1, sym->value2);
  tracebits2(sym->tracestring, sym->len, code);

#endif

  return retval;
}


/*!
 ************************************************************************
 * \brief
 *    read NumCoeff/TrailingOnes codeword from UVLC-partition ChromaDC
 ************************************************************************
 */
int readSyntaxElement_NumCoeffTrailingOnesChromaDC(SyntaxElement *sym,  DataPartition *dP)
{
  int retval;
  int code, *ct, *lt;

  int lentab[4][5] = 
  {
    { 2, 6, 6, 6, 6,},          
    { 0, 1, 6, 7, 8,}, 
    { 0, 0, 3, 7, 8,}, 
    { 0, 0, 0, 6, 7,},
  };

  int codtab[4][5] = 
  {
    {1,7,4,3,2},
    {0,1,6,3,3},
    {0,0,1,2,2},
    {0,0,0,5,0},
  };



  lt = &lentab[0][0];
  ct = &codtab[0][0];

  retval = code_from_bitstream_2d(sym, dP, lt, ct, 5, 4, &code);

  if (retval)
  {
    printf("ERROR: failed to find NumCoeff/TrailingOnes ChromaDC\n");
    exit(-1);
  }


#if TRACE
    snprintf(sym->tracestring, 
      TRACESTRING_SIZE, "ChrDC # c & tr.1s  #c=%d #t1=%d",
              sym->value1, sym->value2);
    tracebits2(sym->tracestring, sym->len, code);

#endif

  return retval;
}




/*!
 ************************************************************************
 * \brief
 *    read Level VLC0 codeword from UVLC-partition 
 ************************************************************************
 */
int readSyntaxElement_Level_VLC0(SyntaxElement *sym, struct datapartition *dP)
{
  Bitstream   *currStream = dP->bitstream;
  int frame_bitoffset = currStream->frame_bitoffset;
  byte *buf = currStream->streamBuffer;
  int BitstreamLengthInBytes = currStream->bitstream_length;
  int len, sign, level, code;

  len = 0;
  while (!ShowBits(buf, frame_bitoffset+len, BitstreamLengthInBytes, 1))
    len++;

  len++;
  code = 1;
  frame_bitoffset += len;

  if (len < 15)
  {
    sign = len % 2;
    level = (len-1) / 2 + 1;
  }
  else if (len == 15)
  {
    // escape code
    code = (code << 4) | ShowBits(buf, frame_bitoffset, BitstreamLengthInBytes, 4);
    len += 4;
    frame_bitoffset += 4;
    sign = (code & 1);
    level = ((code >> 1) & 0x7) + 8;
  }
  else if (len == 16)
  {
    // escape code
    code = (code << 12) | ShowBits(buf, frame_bitoffset, BitstreamLengthInBytes, 12);
    len += 12;
    frame_bitoffset += 12;
    sign =  (code & 1);
    level = ((code >> 1) & 0x7ff) + 16;
  }
  else
  {
    printf("ERROR reading Level code\n");
    exit(-1);
  }

  if (!sign) 
    level = -level;

  sym->inf = level;
  sym->len = len;

#if TRACE
  tracebits2(sym->tracestring, sym->len, code);
#endif
  currStream->frame_bitoffset = frame_bitoffset;
  return 0;

}

/*!
 ************************************************************************
 * \brief
 *    read Level VLC codeword from UVLC-partition 
 ************************************************************************
 */
int readSyntaxElement_Level_VLCN(SyntaxElement *sym, int vlc, struct datapartition *dP)	 
{

	Bitstream   *currStream = dP->bitstream;
	int frame_bitoffset = currStream->frame_bitoffset;
	byte *buf = currStream->streamBuffer;
	int BitstreamLengthInBytes = currStream->bitstream_length;

	int levabs, sign;
	int len = 0;


	int numPrefix;
	int suffix = 0;
	int shift = vlc-1;
	int escape = (15<<shift)+1;

	// read pre zeros
	numPrefix = 0;
	while (!ShowBits(buf, frame_bitoffset+numPrefix, BitstreamLengthInBytes, 1))
		numPrefix++;


	len = numPrefix+1;

	if (numPrefix < 15)
	{
		levabs = (numPrefix<<shift) + 1;

		// read (vlc-1) bits -> suffix
		if (vlc-1)
		{
			levabs += ShowBits(buf, frame_bitoffset+len, BitstreamLengthInBytes, vlc-1);
			len += (vlc-1);
		}

		// read 1 bit -> sign
		sign = ShowBits(buf, frame_bitoffset+len, BitstreamLengthInBytes, 1);
		len ++;
	}
	else	// escape
	{
		// read 11 bits -> levabs
		// levabs += escape
		levabs = ShowBits(buf, frame_bitoffset+len, BitstreamLengthInBytes, 11) + escape;
		len+=11;

		// read 1 bit -> sign
		sign = ShowBits(buf, frame_bitoffset+len, BitstreamLengthInBytes, 1);
		len++;
	}

	sym->inf = (sign)?-levabs:levabs;
	currStream->frame_bitoffset = frame_bitoffset+len;

	return 0;
}

/*!
 ************************************************************************
 * \brief
 *    read Total Zeros codeword from UVLC-partition 
 ************************************************************************
 */
int readSyntaxElement_TotalZeros(SyntaxElement *sym,  DataPartition *dP)
{
  int vlcnum, retval;
  int code, *ct, *lt;

  int lentab[TOTRUN_NUM][16] = 
  {
    
    { 1,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9},  
    { 3,3,3,3,3,4,4,4,4,5,5,6,6,6,6},  
    { 4,3,3,3,4,4,3,3,4,5,5,6,5,6},  
    { 5,3,4,4,3,3,3,4,3,4,5,5,5},  
    { 4,4,4,3,3,3,3,3,4,5,4,5},  
    { 6,5,3,3,3,3,3,3,4,3,6},  
    { 6,5,3,3,3,2,3,4,3,6},  
    { 6,4,5,3,2,2,3,3,6},  
    { 6,6,4,2,2,3,2,5},  
    { 5,5,3,2,2,2,4},  
    { 4,4,3,3,1,3},  
    { 4,4,2,1,3},  
    { 3,3,1,2},  
    { 2,2,1},  
    { 1,1},  
  };

  int codtab[TOTRUN_NUM][16] = 
  {
    {1,3,2,3,2,3,2,3,2,3,2,3,2,3,2,1},
    {7,6,5,4,3,5,4,3,2,3,2,3,2,1,0},
    {5,7,6,5,4,3,4,3,2,3,2,1,1,0},
    {3,7,5,4,6,5,4,3,3,2,2,1,0},
    {5,4,3,7,6,5,4,3,2,1,1,0},
    {1,1,7,6,5,4,3,2,1,1,0},
    {1,1,5,4,3,3,2,1,1,0},
    {1,1,1,3,3,2,2,1,0},
    {1,0,1,3,2,1,1,1,},
    {1,0,1,3,2,1,1,},
    {0,1,1,2,1,3},
    {0,1,1,1,1},
    {0,1,1,1},
    {0,1,1},
    {0,1},  
  };
  vlcnum = sym->value1;

  lt = &lentab[vlcnum][0];
  ct = &codtab[vlcnum][0];

  retval = code_from_bitstream_2d(sym, dP, lt, ct, 16, 1, &code);

  if (retval)
  {
    printf("ERROR: failed to find Total Zeros\n");
    exit(-1);
  }


#if TRACE
    tracebits2(sym->tracestring, sym->len, code);

#endif

  return retval;
}    

/*!
 ************************************************************************
 * \brief
 *    read Total Zeros Chroma DC codeword from UVLC-partition 
 ************************************************************************
 */
int readSyntaxElement_TotalZerosChromaDC(SyntaxElement *sym,  DataPartition *dP)
{
  int vlcnum, retval;
  int code, *ct, *lt;

  int lentab[3][4] = 
  {
    { 1, 2, 3, 3,},
    { 1, 2, 2, 0,},
    { 1, 1, 0, 0,}, 
  };

  int codtab[3][4] = 
  {
    { 1, 1, 1, 0,},
    { 1, 1, 0, 0,},
    { 1, 0, 0, 0,},
  };

  vlcnum = sym->value1;

  lt = &lentab[vlcnum][0];
  ct = &codtab[vlcnum][0];

  retval = code_from_bitstream_2d(sym, dP, lt, ct, 4, 1, &code);

  if (retval)
  {
    printf("ERROR: failed to find Total Zeros\n");
    exit(-1);
  }


#if TRACE
    tracebits2(sym->tracestring, sym->len, code);

#endif

  return retval;
}    


/*!
 ************************************************************************
 * \brief
 *    read  Run codeword from UVLC-partition 
 ************************************************************************
 */
int readSyntaxElement_Run(SyntaxElement *sym,  DataPartition *dP)
{
  int vlcnum, retval;
  int code, *ct, *lt;

  int lentab[TOTRUN_NUM][16] = 
  {
    {1,1},
    {1,2,2},
    {2,2,2,2},
    {2,2,2,3,3},
    {2,2,3,3,3,3},
    {2,3,3,3,3,3,3},
    {3,3,3,3,3,3,3,4,5,6,7,8,9,10,11},
  };

  int codtab[TOTRUN_NUM][16] = 
  {
    {1,0},
    {1,1,0},
    {3,2,1,0},
    {3,2,1,1,0},
    {3,2,3,2,1,0},
    {3,0,1,3,2,5,4},
    {7,6,5,4,3,2,1,1,1,1,1,1,1,1,1},
  };

  vlcnum = sym->value1;

  lt = &lentab[vlcnum][0];
  ct = &codtab[vlcnum][0];

  retval = code_from_bitstream_2d(sym, dP, lt, ct, 16, 1, &code);

  if (retval)
  {
    printf("ERROR: failed to find Run\n");
    exit(-1);
  }


#if TRACE
    tracebits2(sym->tracestring, sym->len, code);
#endif

  return retval;
}    


/*!
 ************************************************************************
 * \brief
 *  Reads bits from the bitstream buffer
 *
 * \param byte buffer[]
 *    containing VLC-coded data bits
 * \param int totbitoffset
 *    bit offset from start of partition
 * \param int bytecount
 *    total bytes in bitstream
 * \param int numbits
 *    number of bits to read
 *
 ************************************************************************
 */


int GetBits (byte buffer[],int totbitoffset,int *info, int bytecount, 
				     int numbits)
{

  register int inf;
  long byteoffset;      // byte from start of buffer
  int bitoffset;      // bit from start of byte

  int bitcounter=numbits;

  byteoffset= totbitoffset/8;
  bitoffset= 7-(totbitoffset%8);

  inf=0;
  while (numbits)
  {
	  inf <<=1;
	  inf |= (buffer[byteoffset] & (0x01<<bitoffset))>>bitoffset;
	  numbits--;
	  bitoffset--;
	  if (bitoffset < 0)
	  {
		  byteoffset++;
		  bitoffset += 8;
        if (byteoffset > bytecount)
        {
          return -1;
        }
	  }
  }

  *info = inf;
  return bitcounter;           // return absolute offset in bit from start of frame
}	  

/*!
 ************************************************************************
 * \brief
 *  Reads bits from the bitstream buffer
 *
 * \param byte buffer[]
 *    containing VLC-coded data bits
 * \param int totbitoffset
 *    bit offset from start of partition
 * \param int bytecount
 *    total bytes in bitstream
 * \param int numbits
 *    number of bits to read
 *
 ************************************************************************
 */

int ShowBits (byte buffer[],int totbitoffset,int bytecount, int numbits)
{

  register int inf;
  long byteoffset;      // byte from start of buffer
  int bitoffset;      // bit from start of byte

  int bitcounter=numbits;

  byteoffset= totbitoffset/8;
  bitoffset= 7-(totbitoffset%8);

  inf=0;
  while (numbits)
  {
	  inf <<=1;
	  inf |= (buffer[byteoffset] & (0x01<<bitoffset))>>bitoffset;
	  numbits--;
	  bitoffset--;
	  if (bitoffset < 0)
	  {
		  byteoffset++;
		  bitoffset += 8;
        if (byteoffset > bytecount)
        {
          return -1;
        }
	  }
  }

  return inf;           // return absolute offset in bit from start of frame
}	  



