g726.c

G.726协议的C源码

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_adda(dqln, y, dql)
  short          *dqln, *y, *dql;
{
  *dql = (*dqln + (*y >> 2)) & 4095;

}
/* ....................... end of G726_adda() ....................... */


/*
 ----------------------------------------------------------------------

        void G726_antilog (short *dql, short *dqs, short *dq);
        ~~~~~~~~~~~~~~~~~

        Description:
        ~~~~~~~~~~~~

        Convert quantized difference signal from the  logarithmic to
        the linear domain.

 	Inputs:   dql, dqs
 	Output:   dq

        Return value:  none.
        ~~~~~~~~~~~~~

        Prototype:   in g726.h
        ~~~~~~~~~~

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_antilog(dql, dqs, dq)
  short          *dql, *dqs, *dq;
{
  long            dqmag;
  long            ds, dmn, dex, dqt;

  /* Extract 4-bit exponent */
  ds = (*dql >> 11);
  dex = (*dql >> 7) & 15;

  /* Extract 7-bit mantissa */
  dmn = *dql & 127;

  dqt = dmn + 128;

  /* Convert mantissa to linear using the approx. 2**x = 1+x */
  dqmag = ds ? 0 : ((dqt << 7) >> (14 - dex));

  /* Attach sign bit to signed mag. word */
  *dq = (short) (*dqs << 15) + dqmag;
}
/* ..................... end of G726_antilog() ..................... */


/*
 ----------------------------------------------------------------------

        void G726_reconst (short rate, short *i, short *dqln, short *dqs);
        ~~~~~~~~~~~~~~~~~

        Description:
        ~~~~~~~~~~~~

        Reconstruction of quantized difference signal  in the
        logarithmic domain.

 	Inputs:   i, rate
 	Outputs:  dqln, dqs

        Return value:  none.
        ~~~~~~~~~~~~~

        Prototype:   in g726.h
        ~~~~~~~~~~

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_reconst(rate, i, dqln, dqs)
  short          *i, *dqln, *dqs;
  short           rate;
{
  if (rate == 4)
  {
    /* Initialized data */
    static short    tab[16] = {2048, 4, 135, 213, 273, 323, 373, 425,
    425, 373, 323, 273, 213, 135, 4, 2048};

    /* Extract sign */
    *dqs = (*i >> 3);

    /* Table look-up */
    *dqln = tab[*i];
  }				/* ............... end of 32 kbit part
				 * ................. */

  else if (rate == 3)
  {
    /* Initialized data */
    static short    tab[8] = {2048, 135, 273, 373, 373, 273, 135, 2048};

    *dqs = (*i >> 2);

    /* Table look-up */
    *dqln = tab[*i];

  }				/* ............... end of 24 kbit part
				 * ................. */


  else if (rate == 2)
  {
    /* Initialized data */
    static short    tab[4] = {116, 365, 365, 116};

    *dqs = (*i >> 1);

    /* Table look-up */
    *dqln = tab[*i];

  }				/* ............... end of 16 kbit part
				 * ................. */
  else
  {
    /* Initialized data */
    static short    tab[32] = {2048, 4030, 28, 104, 169, 224, 274, 318, 358, 395, 429,
      459, 488, 514, 539, 566, 566, 539, 514, 488, 459, 429, 395, 358, 318, 274, 224,
    169, 104, 28, 4030, 2048};

    *dqs = (*i >> 4);

    /* Table look-up */
    *dqln = tab[*i];

  }				/* ................ end of 40 kbit part
				 * ................... */


}
/* ....................... end of G726_reconst() ....................... */


/*
 ----------------------------------------------------------------------

        void G726_delaya (short *r, short *x, short *y);
        ~~~~~~~~~~~~~~~~

        Description:
        ~~~~~~~~~~~~

        Memory block.

 	Inputs:    r, x
 	Output:    y

        Return value:  none.
        ~~~~~~~~~~~~~

        Prototype:   in g726.h
        ~~~~~~~~~~

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_delaya(r, x, y)
  short          *r, *x, *y;
{
  *y = (*r == 0) ? *x : 0;

}
/* ....................... end of G726_delaya() ....................... */


/*
 ----------------------------------------------------------------------

        void G726_delayb (short *r, short *x, short *y);
        ~~~~~~~~~~~~~~~~

        Description:
        ~~~~~~~~~~~~

        Memory block.

 	Inputs:    r, x
 	Output:    y

        Return value:  none.
        ~~~~~~~~~~~~~

        Prototype:   in g726.h
        ~~~~~~~~~~

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_delayb(r, x, y)
  short          *r, *x, *y;
{
  *y = (*r == 0) ? *x : 544;

}
/* ....................... end of G726_delayb() ....................... */


/*
 ----------------------------------------------------------------------

        void G726_delayc (short *r, long *x, long *y);
        ~~~~~~~~~~~~~~~~

        Description:
        ~~~~~~~~~~~~

        Memory block.

 	Inputs:    r, x
 	Output:    y

        Return value:  none.
        ~~~~~~~~~~~~~

        Prototype:   in g726.h
        ~~~~~~~~~~

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_delayc(r, x, y)
  short          *r;
  long           *x, *y;
{
  *y = (*r == 0) ? *x : 34816;

}
/* ....................... end of G726_delayc() ....................... */


/*
 ----------------------------------------------------------------------

        void G726_delayd (short *r, short *x, short *y);
        ~~~~~~~~~~~~~~~~

        Description:
        ~~~~~~~~~~~~

        Memory block

 	Inputs:   r, x
 	Output:   y

        Return value:          none.
        ~~~~~~~~~~~~~

        Prototype:   in g726.h
        ~~~~~~~~~~

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_delayd(r, x, y)
  short          *r, *x, *y;
{
  *y = (*r == 0) ? *x : 32;

}
/* ....................... end of G726_delayd() ....................... */


/*
 ----------------------------------------------------------------------

        void G726_filtd (short *wi, short *y, short *yut);
        ~~~~~~~~~~~~~~~

        Description:
        ~~~~~~~~~~~~

        Update of fast quantizer scale factor.

 	Inputs: wi, y
 	Output: yut

        Return value:  none.
        ~~~~~~~~~~~~~

        Prototype:   in g726.h
        ~~~~~~~~~~

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_filtd(wi, y, yut)
  short          *wi, *y, *yut;
{
  long            difs, difsx;
  long            y1;
  long            wi1, dif;

  /* Compute difference */
  wi1 = *wi;
  y1 = *y;
  dif = ((wi1 << 5) + 131072 - y1) & 131071;
  difs = (dif >> 16);

  /* Time constant is 1/32; sign extension */
  difsx = (difs == 0) ? (dif >> 5) : ((dif >> 5) + 4096);

  *yut = (short) ((y1 + difsx) & 8191);

}
/* ....................... end of G726_filte() ....................... */


/*
 ----------------------------------------------------------------------

        void G726_filte (short *yup, long *yl, long *ylp);
        ~~~~~~~~~~~~~~~

        Description:
        ~~~~~~~~~~~~

        Update of slow quantizer scale factor.


 	Inputs:  yup, yl
 	Output:  ylp

        Return value:  none.
        ~~~~~~~~~~~~~

        Prototype:   in g726.h
        ~~~~~~~~~~

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_filte(yup, yl, ylp)
  short          *yup;
  long           *yl, *ylp;
{
  long            difs, difsx;
  long            dif, dif1, yup1;

  /* Compute difference */
  yup1 = *yup;
  dif1 = 1048576 - *yl;
  dif = (yup1 + (dif1 >> 6)) & 16383;
  difs = (dif >> 13);

  /* Sign extension */
  difsx = (difs == 0) ? dif : (dif + 507904);

  *ylp = (*yl + difsx) & 524287;

}
/* ....................... end of G726_filte() ....................... */


/*
 ----------------------------------------------------------------------

        void G726_functw (short rate, short *i, short *wi);
        ~~~~~~~~~~~~~~~~

        Description:
        ~~~~~~~~~~~~

        Map quantizer output into logarithmic version  of scale factor
        multiplier.

 	Inputs: i, rate
 	Output: wi

        Return value:  none.
        ~~~~~~~~~~~~~

        Prototype:   in g726.h
        ~~~~~~~~~~

        History:
        ~~~~~~~~
        31.Jan.91 v1.0f Release of 1st Fortran version to UGST.
        		<[e-mail]>
        13.Feb.92 v1.0c 1st version in C translated from Fortran (f2c)
        		<[e-mail]>

 ----------------------------------------------------------------------
*/
void            G726_functw(rate, i, wi)
  short          *i, *wi;
  short           rate;
{
  if (rate == 4)
  {
    /* Initialized data */
    static short    tab[8] = {4084, 18, 41, 64, 112, 198, 355, 1122};
    short           im, is;

    is = (*i >> 3);

    im = (is == 0) ? (*i & 7) : ((15 - *i) & 7);

    /* Scale factor multiplier */
    *wi = tab[im];


  }				/* ................. end of 32 kbit part
				 * .............. */





  else if (rate == 3)
  {

    /* Initialized data */
    static short    tab[4] = {4092, 30, 137, 582};
    short           im, is;


    is = (*i >> 2);

    im = (is == 0) ? (*i & 3) : ((7 - *i) & 3);

    *wi = tab[im];



  }				/* ................. end of 24 kbit part
				 * .............. */





  else if (rate == 2)
  {
    /* Initialized data */
    static short    tab[2] = {4074, 439};
    short           im, is;


    is = (*i >> 1);

    im = (is == 0) ? (*i & 1) : ((3 - *i) & 1);

    *wi = tab[im];

  }				/* ................. end of 16 kbit part
				 * .............. */





  else