xencode.c

Reference Implementation of G.711 standard and other voice codecs

	Description:	get file's mode.
	~~~~~~~~~~~~

	Variables:
	~~~~~~~~~~
	fp 	pointer to file of which the mode is wanted

	Exit values:
	~~~~~~~~~~~~
	S_????	file's access mode

	Author:	Simao Ferraz de Campos Neto -- CPqD/Telebras
	~~~~~~~  <[e-mail]>

	Date:	19/Mar/91-16:30
	~~~~~

	Version: 1.00
	~~~~~~~~

	Revision/Date/Author: none (yet)
	~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
int             get_mode(fp)
  FILE           *fp;
{
  struct stat     sbuf;

  /* figure out file mode */
  fstat(fileno(fp), &sbuf);
  return (sbuf.st_mode & 0777);
}
/* ........................... end of get_mode() ........................... */


/*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	int encode (FILE *in, FILE *out, long charno);
        ~~~~~~~~~~

	Description:
	~~~~~~~~~~~~
	Copy from in to out, encoding as it goes along, using the basic
	encoding scheme:
                          ENC(c) = (((c) & 077) + ' ')

	Variables:
	~~~~~~~~~~
	in 	pointer to file from which samples are taken
	out	pointer to file to which encoded samples are put
	charno	maximum number of chars to be written

	Routines:	- outenc
	~~~~~~~~~	- ENC

	Author:	unknown
	~~~~~~~

	Revision/Date/Author: 
	~~~~~~~~~~~~~~~~~~~~~ 
        19.Mar.91 v1.0 Adapted from public domain implementation
                       <[e-mail]>
        25.Sep.95 v1.1 Modified charno to reflect the number of bytes of the 
                       output file, instead of the number of bytes of the 
                       input file. <[e-mail]>

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
int             encode(in, out, charno)
  FILE           *in;
  FILE           *out;
  long            charno;
{
  char            buf[80];
  int             i, n;
  long            count = 0;

  /* Adjust input bytes to output bytes */
  charno = (long)(charno * 3 / 4);

  do
  {
    /* Find out, encode and write the no.of chars/line (upto 45) */
    n = fr(in, buf, 45);
    putc(ENC(n), out);

    /* Update CRCs for the block of data */
    crc_a = get_arc_crc(crc_a,(unsigned char *) buf, n);
    crc_c = get_ccitt_crc(crc_c, (unsigned char *) buf, n);
    crc_x = get_xmodem_crc(crc_x, (unsigned char *) buf, n);

    /* Encode the data from input and save to output, 3 at a time */
    for (i = 0; i < n; i += 3)
      outenc(&buf[i], out);

    /* New line after "n" chars are out */
    putc('\n', out);

    /* Updates counter of output samples */
    count += n;

  } while (n > 0 && count < charno);	/* i.e., not EOF, ... */
  if (count >= charno)
    fprintf(out, "`\n");

  return 0;
}
/* .......................... end of encode() .......................... */

/*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	int outenc (char *p, FILE *f);
        ~~~~~~~~~~

	Description:
	~~~~~~~~~~~~
	Output one group of 3 bytes, pointed at by p, on file f, using
	the basic encoding scheme:

                          ENC(c) = (((c) & 077) + ' ')

	Variables:
	~~~~~~~~~~
	p	pointer to array of 3 bytes to be coded and saved as 4
		[printable] bytes;
	f	pointer to file to which encoded samples are put

	Author:	unknown
	~~~~~~~

	Revision/Date/Author: Simao Ferraz de Campos Neto -- CPqD/Telebras
	~~~~~~~~~~~~~~~~~~~~~ <[e-mail]> -- 19/Mar/91-16:30

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
int outenc(p, f)
  char           *p;
  FILE           *f;
{
  int             c1, c2, c3, c4;

  c1 = *p >> 2;
  c2 = ((*p << 4) & 060) | ((p[1] >> 4) & 017);
  c3 = ((p[1] << 2) & 074) | ((p[2] >> 6) & 03);
  c4 = p[2] & 077;
  putc(ENC(c1), f);
  putc(ENC(c2), f);
  putc(ENC(c3), f);
  putc(ENC(c4), f);

  return 0;
}
/* ........................... end of outenc() ........................... */


/*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	int fr (FILE *fd, char *buf, int cnt);
	~~~~~~

	Description:
	~~~~~~~~~~~~
	Read upto cnt bytes from stream (file/device) pointed by fd and
	save in buffer buf. Similar to fread.

	Variables:
	~~~~~~~~~~
	fd 	pointer to file from which chars are read
	buf	pointer to char
	cnt	maximum number of chars to be read

	Author:	unknown
	~~~~~~~

	Revision/Date/Author: Simao Ferraz de Campos Neto -- CPqD/Telebras
	~~~~~~~~~~~~~~~~~~~~~ <[e-mail]> -- 19/Mar/91-16:30

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
int             fr(fd, buf, cnt)
  FILE           *fd;
  char           *buf;
  int             cnt;
{
  int             c, i;

  for (i = 0; i < cnt; i++)
  {
    c = getc(fd);
    if (c == EOF)
      return (i);
    buf[i] = c;
  }
  return (cnt);
}
/* ........................... end of fr() ........................... */


/*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	char *xcode_index (register char *sp, register char c);
	~~~~~~~~~~~

	Description:
	~~~~~~~~~~~~
	Locates the first occurence of c in stream sp and returns it;
	if c is not found, returns NULL.

	Variables:
	~~~~~~~~~~
	sp 	pointer to first ocurrence of c in ptr
	c	character to be located;

	Author:	unknown
	~~~~~~~

	Revision/Date/Author: Simao Ferraz de Campos Neto -- CPqD/Telebras
	~~~~~~~~~~~~~~~~~~~~~ <[e-mail]> -- 19/Mar/91-16:30

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#ifdef NULL
# undef NULL
#endif
#define	NULL	0
char           *xcode_index(sp, c)
  register char  *sp;
  register char   c;
{
  do
  {
    if (*sp == c)
      return (sp);
  } while (*sp++);
  return (NULL);
}
/* ........................... end of xcode_index() ........................... */


/*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	char *get_root (char *root, char *full_name);
	~~~~~~~~~~~~~~
	Description:
	~~~~~~~~~~~~
        Deletes file extension from a file name by  locating the last
        occurence of the extension mark (".") in the file  name pointed
        by "full_name" and copying upto that position, "full_name" to
        "root".

	Variables:
	~~~~~~~~~~
	root		file name without extension;
	full_name	file's full name;

	Exit values:
	~~~~~~~~~~~~
	Filename without extension; if given file name has no extension,
        the original name is returned.

	Original Author:
	~~~~~~~~~~~~~~~~
	Simao Ferraz de Campos Neto -- CPqD/Telebras

	Revision/Date/Author:
	~~~~~~~~~~~~~~~~~~~~~
        19.Mar.91 v1.0 1st release
        21.Jul.93 v2.0 Added removal of the path from the file name.<simao>
        25.Sep.95 v2.1 Added smarter handling of filenames with multiple '.' 
                       (allowed in Unix) <[e-mail]>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#if defined(VMS)
#define PATH_END ']'
#elif defined(MSDOS)
#define PATH_END '\\'
#else				/* Unix */
#define PATH_END '/'
#endif

char           *get_root(root, full_name)
  char           *root;
  char           *full_name;
{
  register char  *tmp = full_name;
#if (XENCODE==200)
  int             n;
#endif

  /* copy full-name to root buffer */
  strcpy(root, full_name);

  /* finds last occurence of a pointend of the path */
  tmp = (char *) strrchr(root, PATH_END);
  if (tmp == NULL)
    tmp = root; 		/* name starts with root, i.e., no path
				 * present */
  else
    tmp++;			/* move onto start of root name */

#if (XENCODE==200)
  /* finds last occurence of a point */
  n = (long) strcspn(tmp, ".");

  /* copy root from tmp to `root' */
  strncpy(root, tmp, n);
  root[n] = '\0';
#else
  /* finds last occurence of a dot */
  tmp = strrchr(tmp, '.');
  if (tmp) 
    *tmp = 0;
#endif

  /* returns the file name without extension */
  return (root);
}
#undef PATH_END
/* ........................... end of get_root() ........................... */


/*
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	char *get_extension (char *ext, char *full_name, int max_length);
	~~~~~~~~~~~~~~~~~~~

	Description:
	~~~~~~~~~~~~
        Locates the extension of a file name by  locating the last
        occurence of the extension mark (".") in the file name pointed
        by "full_name" and copying from that position (thus including
        the '.')  upto the name's end (limmited to max_length chars) to
        "ext".

	Variables:
	~~~~~~~~~~
	ext		file name's extension (with point);
	full_name	file's full name;
	max_length	maximum length allowed for the extension

	Exit values:
	~~~~~~~~~~~~
	Filename's extension; if given file name has no extension,
        a null-string is returned.

	Author:	Simao Ferraz de Campos Neto -- CPqD/Telebras
	~~~~~~~  <[e-mail]>

	Date:	19/Mar/91-16:30
	~~~~~

	Version: 1.00
	~~~~~~~~

	Revision/Date/Author: none (yet)
	~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
char           *get_extension(ext, full_name, max_length)
  char           *ext;
  char           *full_name;
  int             max_length;
{
  register char  *tmp, *end;

  /* finds last occurence of a point */
  if ((tmp = (char *) strrchr(full_name, '.')) == NULL)
  {
    /* if original file had no extension, returns a '.' */
    strcpy(ext, ".");
    return (NULL);
  }

  /* and string's end */
  end = (char *) strrchr(full_name, 0);

  /* copies the extension from the point, ... */
  strncpy(ext, tmp, max_length);

  /* ... and appends a '\0', if needed */
  if (max_length <= end - tmp)
    ext[max_length] = '\0';

  /* returns the file name's extension ('.' included!) */
  return (ext);
}
/* ......................... end of get_extension() ......................... */