deacelpe.c

E729国际标准的语音编码

/* Version 1.1    Last modified: February 1998 */

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

 *  File deacelpe.c                                *

 *  ~~~~~~~~~~~~~~~~~~~~~~~                                  *

 *   Algebraic codebook decoder.                             *

 *----------------------------------------------------------*/
#include <stdlib.h>
#include <stdio.h>

#include "typedef.h"
#include "basic_op.h"
#include "ld8k.h"

/* local function */
static void dec_pulses(

  Word16 index,        /* (i)       : pulses index (4 or 7 bits)    */

  Word16 track,        /* (i)       : track of the pulses           */

  Word16 nb_of_pulses, /* (i)       : 1 or 2 pulses                 */

  Word16 cod[]         /* (i/o) Q13 : algebraic codebook excitation */

);






void Dec_ACELP_10i40_35bits(

  Word16 *index,  /* (i)     : 5 words index (positions & sign)      */

  Word16 cod[]    /* (o) Q13 : algebraic (fixed) codebook excitation */

)

{

  Word16 i, j;



  /* decode the positions and signs of pulses and build the codeword */



  for (i=0; i<L_SUBFR; i++) {

    cod[i] = 0;         

  }



  for (j=0; j<5; j++)

  {

    dec_pulses(index[j], j, 2, cod);

  }



  return;

}


void Dec_ACELP_12i40_44bits(

  Word16 *index,  /* (i)     : 5 words index (positions & sign)      */

  Word16 cod[]    /* (o) Q13 : algebraic (fixed) codebook excitation */

)

{

  Word16 i, j, track;



  /* decode the positions and signs of pulses and build the codeword */



  for (i=0; i<L_SUBFR; i++) {

    cod[i] = 0;         

  }



  track = shr(index[0], 10) & (Word16)7;

  if (track > 4) track = 4;



  for (j=0; j<2; j++)

  { 

    dec_pulses(index[j], track, 3, cod);



    track = add(track, 1);

    if (track > 4) track = 0;

  }



  for (j=2; j<5; j++)

  {

    dec_pulses(index[j], track, 2, cod);



    track = add(track, 1);

    if (track > 4) track = 0;

  }



  return;

}





static void dec_pulses(

  Word16 index,        /* (i)       : pulses index (4 or 7 bits)    */

  Word16 track,        /* (i)       : track of the pulses           */

  Word16 nb_of_pulses, /* (i)       : 1, 2 or 3 pulses              */

  Word16 cod[]         /* (i/o) Q13 : algebraic codebook excitation */

)

{

  Word16 i, pos1, pos2, pos3, sign;



  /* compute index i */

  i = extract_l(L_shr(L_mult((Word16)(index & (Word16)7), 5), 1));

  pos1 = add(i, track);         /* position of pulse 1 */



  i = shr(index, 3) & (Word16)1;

    

  if (i == 0) sign = 4096;          /* Q12 +1.0 */

  else sign = -4096;                /* Q12 -1.0 */



  cod[pos1] = sign;             



  if (nb_of_pulses >= 2)

  {

    /* compute index i */

    i = extract_l(L_shr(L_mult((Word16)(shr(index, 4) & (Word16)7), 5), 1));

    pos2 = add(i, track);       /* position of pulse 2 */



    if (sub(pos2,pos1) > 0)

    {

      sign = negate(sign);

    }



    cod[pos2] = add(cod[pos2], sign);

  }  



  if (nb_of_pulses == 3)

  {

    /* compute index i */

    i = extract_l(L_shr(L_mult((Word16)(shr(index, 7) & (Word16)7), 5), 1));

    pos3 = add(i, track);       /* position of pulse 2 */

    

    if (sub(pos3,pos2) > 0)

    {

      sign = negate(sign);

    }



    cod[pos3] = add(cod[pos3], sign);

  }  



  return;

}