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

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

#include "global.h"
#include "vlc.h"
#include "elements.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 UsedBits;      // for internal statistics, is adjusted by se_v, ue_v, u_1

// Note that all NA values are filled with 0

//! for the linfo_levrun_inter routine
const byte NTAB1[4][8][2] =
{
  {{1,0},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0}},
  {{1,1},{1,2},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0}},
  {{2,0},{1,3},{1,4},{1,5},{0,0},{0,0},{0,0},{0,0}},
  {{3,0},{2,1},{2,2},{1,6},{1,7},{1,8},{1,9},{4,0}},
};
const byte LEVRUN1[16]=
{
  4,2,2,1,1,1,1,1,1,1,0,0,0,0,0,0,
};


const byte NTAB2[4][8][2] =
{
  {{1,0},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0}},
  {{1,1},{2,0},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0}},
  {{1,2},{3,0},{4,0},{5,0},{0,0},{0,0},{0,0},{0,0}},
  {{1,3},{1,4},{2,1},{3,1},{6,0},{7,0},{8,0},{9,0}},
};

//! for the linfo_levrun__c2x2 routine
const byte LEVRUN3[4] =
{
  2,1,0,0
};
const byte NTAB3[2][2][2] =
{
  {{1,0},{0,0}},
  {{2,0},{1,1}},
};

/*! 
 *************************************************************************************
 * \brief
 *    ue_v, reads an ue(v) syntax element, the length in bits is stored in 
 *    the global UsedBits variable
 *
 * \param tracestring
 *    the string for the trace file
 *
 * \param bitstream
 *    the stream to be read from
 *
 * \return
 *    the value of the coded syntax element
 *
 *************************************************************************************
 */
int ue_v (char *tracestring, Bitstream *bitstream)
{
  SyntaxElement symbol, *sym=&symbol;

  assert (bitstream->streamBuffer != NULL);
  sym->type = SE_HEADER;
  sym->mapping = linfo_ue;   // Mapping rule
  SYMTRACESTRING(tracestring);
  readSyntaxElement_VLC (sym, bitstream);
  UsedBits+=sym->len;
  return sym->value1;
}


/*! 
 *************************************************************************************
 * \brief
 *    ue_v, reads an se(v) syntax element, the length in bits is stored in 
 *    the global UsedBits variable
 *
 * \param tracestring
 *    the string for the trace file
 *
 * \param bitstream
 *    the stream to be read from
 *
 * \return
 *    the value of the coded syntax element
 *
 *************************************************************************************
 */
int se_v (char *tracestring, Bitstream *bitstream)
{
  SyntaxElement symbol, *sym=&symbol;

  assert (bitstream->streamBuffer != NULL);
  sym->type = SE_HEADER;
  sym->mapping = linfo_se;   // Mapping rule: signed integer
  SYMTRACESTRING(tracestring);
  readSyntaxElement_VLC (sym, bitstream);
  UsedBits+=sym->len;
  return sym->value1;
}


/*! 
 *************************************************************************************
 * \brief
 *    ue_v, reads an u(v) syntax element, the length in bits is stored in 
 *    the global UsedBits variable
 *
 * \param LenInBits
 *    length of the syntax element
 *
 * \param tracestring
 *    the string for the trace file
 *
 * \param bitstream
 *    the stream to be read from
 *
 * \return
 *    the value of the coded syntax element
 *
 *************************************************************************************
 */
int u_v (int LenInBits, char*tracestring, Bitstream *bitstream)
{
  SyntaxElement symbol, *sym=&symbol;

  assert (bitstream->streamBuffer != NULL);
  sym->type = SE_HEADER;
  sym->mapping = linfo_ue;   // Mapping rule
  sym->len = LenInBits;
  SYMTRACESTRING(tracestring);
  readSyntaxElement_FLC (sym, bitstream);
  UsedBits+=sym->len;
  return sym->inf;
};

                
/*! 
 *************************************************************************************
 * \brief
 *    ue_v, reads an u(1) syntax element, the length in bits is stored in 
 *    the global UsedBits variable
 *
 * \param tracestring
 *    the string for the trace file
 *
 * \param bitstream
 *    the stream to be read from
 *
 * \return
 *    the value of the coded syntax element
 *
 *************************************************************************************
 */
int u_1 (char *tracestring, Bitstream *bitstream)
{
  return u_v (1, tracestring, bitstream);
}



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

/*!
 ************************************************************************
 * \brief
 *    mapping rule for se(v) syntax elements
 * \par Input:
 *    lenght and info
 * \par Output:
 *    signed mvd
 ************************************************************************
 */
void linfo_se(int len,  int info, int *value1, int *dummy)
{
  int n;
  n = (int)pow(2,(len/2))+info-1;
  *value1 = (n+1)/2;
  if((n & 0x01)==0)                           // lsb is signed bit
    *value1 = -*value1;
}


/*!
 ************************************************************************
 * \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_ue(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_ue(len,info,&cbp_idx,dummy);
    *cbp=NCBP[cbp_idx][1];
}

/*!
 ************************************************************************
 * \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=max(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_c2x2(int len, int info, int *level, int *irun)
{
  int l2;
  int inf;

  if (len<=5)
  {
    l2=max(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
 *    read next UVLC codeword from UVLC-partition and
 *    map it to the corresponding syntax element
 ************************************************************************
 */
int readSyntaxElement_VLC(SyntaxElement *sym, Bitstream *currStream)
{
  int frame_bitoffset = currStream->frame_bitoffset;
  byte *buf = currStream->streamBuffer;
  int BitstreamLengthInBytes = currStream->bitstream_length;

  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);
#endif

  return 1;
}


/*!
 ************************************************************************
 * \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;

  return (readSyntaxElement_VLC(sym, currStream));
}

/*!
 ************************************************************************
 * \brief
 *    read next VLC codeword for 4x4 Intra Prediction Mode and
 *    map it to the corresponding Intra Prediction Direction
 ************************************************************************
 */
int readSyntaxElement_Intra4x4PredictionMode(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;

  sym->len = GetVLCSymbol_IntraMode (buf, frame_bitoffset, &(sym->inf), BitstreamLengthInBytes);

  if (sym->len == -1)
    return -1;

  currStream->frame_bitoffset += sym->len;
  sym->value1                  = sym->len == 1 ? -1 : sym->inf;

#if TRACE
  tracebits2(sym->tracestring, sym->len, sym->value1);
#endif

  return 1;
}

int GetVLCSymbol_IntraMode (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;

  //First bit
  if (ctr_bit)
  {
    *info = 0;
    return bitcounter;
  }
  else
    len=4;

  // 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
}


/*!
 ************************************************************************
 * \brief
 *    test if bit buffer contains only stop bit
 *
 * \param buffer
 *    buffer containing VLC-coded data bits
 * \param totbitoffset