softbit.c

Reference Implementation of G.711 standard and other voice codecs

  }

  /* Convert byte-oriented data to word16-oriented data */
  for (i=0; i<n; i++)
  {
    tmp = byte[i];
    if (tmp == 0x20 || tmp == 0x21) /* It is a frame sync/erasure word */
      patt[i] = 0x6B00 | tmp;
    else
      patt[i] = tmp;
  }

  /* Free memory and quit */
  free(byte);
  return(n);
}
/* ....................... End of read_byte() ....................... */


/* 
  -------------------------------------------------------------------------
  long save_g192 (short *patt, long n, FILE *F);
  ~~~~~~~~~~~~~~

  Save a G.192-compliant 16-bit serial bitstream error pattern.

  Parameter:
  ~~~~~~~~~~
  patt .... headerless G.192 array with the softbits representing 
            the bit error/frame erasure pattern
  n ....... number of softbits in the pattern
  F ....... pointer to FILE where the pattern should be saved

  Return value: 
  ~~~~~~~~~~~~~
  Returns a long with the number of shorts saved to a file. On error, 
  returns -1.

  Original author: <[e-mail]>
  ~~~~~~~~~~~~~~~~

  History:
  ~~~~~~~~
  13.Aug.97  v.1.0  Created.
  -------------------------------------------------------------------------
*/
long save_g192(patt, n, F)
short *patt;
long n;
FILE *F;
{
  /* Save words to file */
  return(fwrite(patt, sizeof(short), n, F)<n ? -1l : n);
}
/* ....................... End of save_g192() ....................... */


/* 
  -------------------------------------------------------------------------
  long save_bit (short *patt, long n, FILE *F);
  ~~~~~~~~~~~~~

  Save a headerless G.192 error pattern as a bit-oriented file where the
  LSb corresponds to the bit that occurs first in time.

  Parameter:
  ~~~~~~~~~~
  patt .... headerless G.192 array with the softbits representing
            the bit error/frame erasure pattern
  n ....... number of softbits in the pattern
  F ....... pointer to FILE where the pattern should be saved

  Return value: 
  ~~~~~~~~~~~~~
  Returns a long with the number of shorts saved to a file. On error, 
  returns -1.

  Original author: <[e-mail]>
  ~~~~~~~~~~~~~~~~

  History:
  ~~~~~~~~
  15.Aug.97  v.1.0  Created.
  -------------------------------------------------------------------------
*/
#define IS_ONE(x)  ((x) && G192_ONE)
long save_bit(patt, n, F)
short *patt;
long n;
FILE *F;
{
  char *bits;
  short one, *p = patt;
  long i, j, k, nbytes;
  char register tmp;

  /* Skip function if no samples are to be read */
  if (n==0)
    return(0);

  /* Calculate number of bytes necessary in the compact bitstream */
  if (n%8)
  {
    fprintf(stderr, "The number of errors is not byte-aligned. \n");
    fprintf(stderr, "Zero insertion will be used and need to be \n");
    fprintf(stderr, "accounted for by the error-insertion program!\n");
  }
  nbytes= (long)(ceil(n/8.0));

  /* Allocate memory */
  if ((bits = (char *)calloc(nbytes, sizeof(char)))==NULL)
    HARAKIRI ("Cannot allocate memory to save compact binary bitstream\n", 6);
  
  /* Reset memory to zero */
  memset(bits, 0, nbytes);

  /* Scan to determine whether it is a bit error or a frame erasure array */
  switch(*p)
  {
  case G192_ZERO:
  case G192_ONE: /* Bit error */
    one = G192_ONE;
    break;
  case G192_SYNC:
  case G192_FER: /* Frame erasure */
    one = G192_FER;
    break;
  }

  /* Convert byte-oriented to compact bit oriented data */
  for (i=j=0; j<nbytes; j++)
  {
    /* Get 1st bit ... */
    tmp = (*p++==one) ? 1 : 0;
 
    /* Compact all the other bits ... */
    for (k=1; k<8 && i<n; k++, i++)
    {
      tmp += (unsigned char)( ( (*p++) == one ? 1 : 0) << k);
    }
 
    /* Save word as short */
    bits[j] = tmp;
  }

  /* Save words to file */
  i = fwrite(bits, sizeof(char), nbytes, F);

  /* Free memory and quit */
  free(bits);
  return(n<i ? -1l : n);
}
/* ....................... End of save_bit() ....................... */


/* 
  -------------------------------------------------------------------------
  long save_byte (short *patt, long n, FILE *F);
  ~~~~~~~~~~~~~~~

  Save a G.192 error pattern as a byte-oriented serial bitstream
  error pattern by writing to file only the lower byte of each 16-bit
  word. The follwoing map is used:
  0x007F -> 0x7F ('0' softbit)
  0x0081 -> 0x81 ('1' softbit)
  0x0021 -> 0x21 (Frame OK)
  0x0020 -> 0x20 (Frame erasure)
  NOTE: The user is responsible for having only these four values in
        the input array. The code will NOT check for compliance.

  Parameter:
  ~~~~~~~~~~
  patt .... char array with the softbits representing the bit
            error/frame erasure pattern
  n ....... number of softbits in the pattern
  F ....... pointer to FILE where the pattern should be saved

  Return value: 
  ~~~~~~~~~~~~~
  Returns a long with the number of shorts saved to a file. On error, 
  returns -1.

  Original author: <[e-mail]>
  ~~~~~~~~~~~~~~~~

  History:
  ~~~~~~~~
  15.Aug.97  v.1.0  Created.
  ------------------------------------------------------------------------- 
*/
long save_byte(patt, n, F)
short *patt;
long n;
FILE *F;
{
  char *byte;
  long i;

  /* Skip function if no samples are to be read */
  if (n==0)
    return(0);

  /* Allocate memory */
  if ((byte = (char *)calloc(n, sizeof(char)))==NULL)
    HARAKIRI ("Cannot allocate memory to save data as byte bitstream\n", 6);
  
  /* Convert word16-oriented data to byte-oriented data */
  /* NO compliance verification is performed, for performance reasons */
  for (i=0; i<n; i++)
    byte[i] = (unsigned char)(patt[i] & 0x00FF);

  /* Save words to file */
  i = fwrite(byte, sizeof(char), n, F);

  /* Free memory and quit */
  free(byte);
  return(n<i ? -1l : n);
}
/* ....................... End of save_byte() ....................... */


/*
  ---------------------------------------------------------------------------
  char *format_str (int fmt);
  ~~~~~~~~~~~~~~~~~

  Function to return a string with the description of the current
  bitstream format (g192, byte, or bit).

  Parameters:
  fmt ... integer with the bitstream format

  Returned value:
  ~~~~~~~~~~~~~~~
  Returns a pointer to the format string, or a NULL pointer
  if fmt is invalid. 

  Original author: <[e-mail]>
  ~~~~~~~~~~~~~~~~

  History:
  ~~~~~~~~
  21.Aug.97  v1.00 created
  ---------------------------------------------------------------------------
*/
char *format_str(fmt)
int fmt;
{
  switch(fmt)
  {
  case byte:
    return "byte";
    break;
  case g192:
    return "g192";
    break;
  case compact:
    return "bit";
    break;
  }
  return "";
}
/* ....................... End of format_str() ....................... */ 


/*
  ---------------------------------------------------------------------------
  char *type_str (int type);
  ~~~~~~~~~~~~~~

  Function to return a string with the description of the current
  bitstream format (g192, byte, or bit).

  Parameters:
  type ... integer with the bitstream format

  Returned value:
  ~~~~~~~~~~~~~~~
  Returns a pointer to the format string, or a NULL pointer
  if type is invalid. 

  Original author: <[e-mail]>
  ~~~~~~~~~~~~~~~~

  History:
  ~~~~~~~~
  21.Aug.97  v1.00 created
  ---------------------------------------------------------------------------
*/
char *type_str(type)
int type;
{
  switch(type)
  {
  case BER:
    return "BER";
    break;
  case FER:
    return "FER";
    break;
  }
  return "";
}
/* ....................... End of type_str() ....................... */ 


/*
  --------------------------------------------------------------------------
  char check_eid_format (FILE *F, char *file, char *type);
  ~~~~~~~~~~~~~~~~~~~~~

  Function that checks the format (g192, byte, bit) in a given
  bitstream, and tries to guess the type of data (bit stream or frame
  erasure pattern)

  Parameter:
  ~~~~~~~~~~
  F ...... FILE * structure to file to be checked
  file ... name of file to be checked
  type ... pointer to guessed data type (FER or BER) in file

  Returned value:
  ~~~~~~~~~~~~~~~
  Returns the data format (g192, byte, bit) found in file.

  Original author: <[e-mail]>
  ~~~~~~~~~~~~~~~~

  History:
  ~~~~~~~~
  15.Aug.97  v.1.0  Created.
  01.Jun.05  v.1.1  Bug correction: switch is made on the "unsigned short" value
					(v.1.0: "unsigned" only). <Cyril Guillaum