getvlc.c

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/************************************************************************
 *
 *  getvlc.c, variable length decoding for tmndecode (H.263 decoder)
  */


#include <stdio.h>

#include "config.h"
#include "tmndec.h"
#include "global.h"
#include "getvlc.h"

int getTMNMV()
{
  int code;

  if (getbits1())
  {
    return 0;
  }

  if ((code = showbits(12))>=512)
  {
    code = (code>>8) - 2;
    flushbits(TMNMVtab0[code].len);

    return TMNMVtab0[code].val;
  }

  if (code>=128)
  {
    code = (code>>2) -32;
    flushbits(TMNMVtab1[code].len);

    return TMNMVtab1[code].val;
  }

  if ((code-=5)<0)
  {
    if (!quiet)
      fprintf(stderr,"Invalid motion_vector code\n");
    fault=1;
    return 0;
  }

  flushbits(TMNMVtab2[code].len);

  return TMNMVtab2[code].val;
}


int getMCBPC()
{
  int code;

  code = showbits(9);

  if (code == 1) {
    /* macroblock stuffing */
    flushbits(9);
    return 255;
  }

  if (code == 0) {
    if (!quiet) 
      fprintf(stderr,"Invalid MCBPC code\n");
    fault = 1;
    return 0;
  }
    
  if (code>=256)
  {
    flushbits(1);
    return 0;
  }
    
  flushbits(MCBPCtab[code].len);

  return MCBPCtab[code].val;
}

int getMODB()
{
  int code;
  int MODB;

  code = showbits(2);

  if (code < 2) 
  {
    MODB = 0;
    flushbits(1);
  }
  else if (code == 2) 
  {
    MODB = 1;
    flushbits(2);
  }
  else 
  { /* code == 3 */
    MODB = 2;
    flushbits(2);
  }
  return MODB;
}


int getMCBPCintra()
{
  int code;

  code = showbits(9);

  if (code == 1) 
  {
    /* macroblock stuffing */
    flushbits(9);
    return 255;
  }

  if (code < 8) 
  {
    if (!quiet) 
      fprintf(stderr,"Invalid MCBPCintra code\n");
    fault = 1;
    return 0;
  }

  code >>= 3;
    
  if (code>=32)
  {
    flushbits(1);
    return 3;
  }

  flushbits(MCBPCtabintra[code].len);

  return MCBPCtabintra[code].val;
}

int getCBPY()
{
  int code;

  code = showbits(6);
  if (code < 2) 
  {
    if (!quiet) 
      fprintf(stderr,"Invalid CBPY code\n");
    fault = 1;
    return -1;
  }
    
  if (code>=48)
  {
    flushbits(2);
    return 0;
  }

  flushbits(CBPYtab[code].len);

  return CBPYtab[code].val;
}