Subversion Repositories bluespec-h264

/*!

 ************************************************************************

 * \file  nal.c

 *

 * \brief

 *    Converts Encapsulated Byte Sequence Packets (EBSP) to Raw Byte

 *    Sequence Packets (RBSP), and then onto String Of Data Bits (SODB)

 *

 * \author

 *    Main contributors (see contributors.h for copyright, address and affiliation details)

 *    - Shankar L. Regunathan <shanre@microsoft.com>

 ************************************************************************

 */

#include "contributors.h"

#include <assert.h>

#include <stdlib.h>

#include <math.h>

#include <string.h>

#include "defines.h"

#include "global.h"

 /*!

 ************************************************************************

 * \brief

 *    Converts RBSP to string of data bits

 * \param streamBuffer

 *          pointer to buffer containing data

 *  \param last_byte_pos

 *          position of the last byte containing data.

 * \return last_byte_pos

 *          position of the last byte pos. If the last-byte was entirely a stuffing byte,

 *          it is removed, and the last_byte_pos is updated.

 *

************************************************************************/

int RBSPtoSODB(byte *streamBuffer, int last_byte_pos)

{

  int ctr_bit, bitoffset;

  bitoffset = 0;

  //find trailing 1

  ctr_bit = (streamBuffer[last_byte_pos-1] & (0x01<<bitoffset));   // set up control bit

  while (ctr_bit==0)

  {                 // find trailing 1 bit

    bitoffset++;

    if(bitoffset == 8)

    {

      if(last_byte_pos == 0)

        printf(" Panic: All zero data sequence in RBSP \n");

      assert(last_byte_pos != 0);

      last_byte_pos -= 1;

      bitoffset = 0;

    }

    ctr_bit= streamBuffer[last_byte_pos-1] & (0x01<<(bitoffset));

  }

  // We keep the stop bit for now

/*  if (remove_stop)

  {

    streamBuffer[last_byte_pos-1] -= (0x01<<(bitoffset));

    if(bitoffset == 7)

      return(last_byte_pos-1);

    else

      return(last_byte_pos);

  }

*/

  return(last_byte_pos);

}

/*!

************************************************************************

* \brief

*    Converts Encapsulated Byte Sequence Packets to RBSP

* \param streamBuffer

*    pointer to data stream

* \param end_bytepos

*    size of data stream

* \param begin_bytepos

*    Position after beginning

************************************************************************/

int EBSPtoRBSP(byte *streamBuffer, int end_bytepos, int begin_bytepos)

{

  int i, j, count;

  count = 0;

  if(end_bytepos < begin_bytepos)

    return end_bytepos;

  j = begin_bytepos;

  for(i = begin_bytepos; i < end_bytepos; i++)

  { //starting from begin_bytepos to avoid header information

    if(count == ZEROBYTES_SHORTSTARTCODE && streamBuffer[i] == 0x03)

    {

      i++;

      count = 0;

    }

    streamBuffer[j] = streamBuffer[i];

    if(streamBuffer[i] == 0x00)

      count++;

    else

      count = 0;

    j++;

  }

  return j;

}