ton_stab.cpp

实现3GPP的GSM中AMR语音的CODECS。

    state = pointer to pointer to structure type tonStabState.
    lsp   = pointer to unquantized LSPs of type Word16

 Outputs:
    pOverflow = 1 if there is an overflow else it is zero.

 Returns:
    None.

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

  Function:  check_lsp()
  Purpose:   Check the LSP's to detect resonances

------------------------------------------------------------------------------
 REQUIREMENTS

 None.

------------------------------------------------------------------------------
 REFERENCES

 ton_stab.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

Word16 check_lsp(tonStabState *st, // i/o : State struct
                 Word16 *lsp       // i   : unquantized LSP's
)
{
   Word16 i, dist, dist_min1, dist_min2, dist_th;

   // Check for a resonance:
   // Find minimum distance between lsp[i] and lsp[i+1]

   dist_min1 = MAX_16;
   for (i = 3; i < M-2; i++)
   {
      dist = sub(lsp[i], lsp[i+1]);

      if (sub(dist, dist_min1) < 0)
      {
         dist_min1 = dist;
      }
   }

   dist_min2 = MAX_16;
   for (i = 1; i < 3; i++)
   {
      dist = sub(lsp[i], lsp[i+1]);

      if (sub(dist, dist_min2) < 0)
      {
         dist_min2 = dist;
      }
   }

   if (sub(lsp[1], 32000) > 0)
   {
      dist_th = 600;
   }
   else if (sub(lsp[1], 30500) > 0)
   {
      dist_th = 800;
   }
   else
   {
      dist_th = 1100;
   }

   if (sub(dist_min1, 1500) < 0 ||
       sub(dist_min2, dist_th) < 0)
   {
      st->count = add(st->count, 1);
   }
   else
   {
      st->count = 0;
   }

   // Need 12 consecutive frames to set the flag
   if (sub(st->count, 12) >= 0)
   {
      st->count = 12;
      return 1;
   }
   else
   {
      return 0;
   }
}

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

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

Word16 check_lsp(tonStabState *st, /* i/o : State struct            */
                 Word16 *lsp,      /* i   : unquantized LSP's       */
                 Flag  *pOverflow
                )
{
    Word16 i;
    Word16 dist;
    Word16 dist_min1;
    Word16 dist_min2;
    Word16 dist_th;
    Word16 *p_lsp   = &lsp[3];
    Word16 *p_lsp_1 = &lsp[4];

    OSCL_UNUSED_ARG(pOverflow);
    /* Check for a resonance:                             */
    /* Find minimum distance between lsp[i] and lsp[i+1]  */

    dist_min1 = MAX_16;
    for (i = 3; i < M - 2; i++)
    {
        dist = *(p_lsp++) - *(p_lsp_1++);

        if (dist < dist_min1)
        {
            dist_min1 = dist;
        }
    }

    dist_min2 = MAX_16;
    p_lsp   = &lsp[1];
    p_lsp_1 = &lsp[2];

    for (i = 1; i < 3; i++)
    {
        dist = *(p_lsp++) - *(p_lsp_1++);

        if (dist < dist_min2)
        {
            dist_min2 = dist;
        }
    }

    if (lsp[1] > 32000)
    {
        dist_th = 600;
    }
    else if (lsp[1] > 30500)
    {
        dist_th = 800;
    }
    else
    {
        dist_th = 1100;
    }

    if ((dist_min1 < 1500) || (dist_min2 < dist_th))
    {
        st->count++;
    }
    else
    {
        st->count = 0;
    }

    /* Need 12 consecutive frames to set the flag */
    if (st->count >= 12)
    {
        st->count = 12;
        return 1;
    }
    else
    {
        return 0;
    }
}

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

/*
------------------------------------------------------------------------------
 FUNCTION NAME: check_gp_clipping
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    state = pointer to pointer to structure type tonStabState.
    g_pitch = pitch gain of type Word16

 Outputs:
    pOverflow = 1 if there is an overflow else it is zero.

 Returns:
    None.

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

  Function:   Check_Gp_Clipping()
  Purpose:    Verify that the sum of the last (N_FRAME+1) pitch
              gains is under a certain threshold.

------------------------------------------------------------------------------
 REQUIREMENTS

 None.

------------------------------------------------------------------------------
 REFERENCES

 ton_stab.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

Word16 check_gp_clipping(tonStabState *st, // i/o : State struct
                         Word16 g_pitch    // i   : pitch gain
)
{
   Word16 i, sum;

   sum = shr(g_pitch, 3);          // Division by 8
   for (i = 0; i < N_FRAME; i++)
   {
      sum = add(sum, st->gp[i]);
   }

   if (sub(sum, GP_CLIP) > 0)
   {
      return 1;
   }
   else
   {
      return 0;
   }
}

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

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

Word16 check_gp_clipping(tonStabState *st, /* i/o : State struct            */
                         Word16 g_pitch,   /* i   : pitch gain              */
                         Flag   *pOverflow
                        )
{
    Word16 i;
    Word16 sum;

    sum = shr(g_pitch, 3, pOverflow);        /* Division by 8 */
    for (i = 0; i < N_FRAME; i++)
    {
        sum = add(sum, st->gp[i], pOverflow);
    }

    if (sum > GP_CLIP)
    {
        return 1;
    }
    else
    {
        return 0;
    }
}

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

/*
------------------------------------------------------------------------------
 FUNCTION NAME: update_gp_clipping
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    state = pointer to pointer to structure type tonStabState.
    g_pitch = pitch gain of type Word16

 Outputs:
    pOverflow = 1 if there is an overflow else it is zero.

 Returns:
    None.

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

  Function:  Update_Gp_Clipping()
  Purpose:   Update past pitch gain memory

------------------------------------------------------------------------------
 REQUIREMENTS

 None.

------------------------------------------------------------------------------
 REFERENCES

 ton_stab.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

void update_gp_clipping(tonStabState *st, // i/o : State struct
                        Word16 g_pitch    // i   : pitch gain
)
{
   Copy(&st->gp[1], &st->gp[0], N_FRAME-1);
   st->gp[N_FRAME-1] = shr(g_pitch, 3);
}

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

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

void update_gp_clipping(tonStabState *st, /* i/o : State struct            */
                        Word16 g_pitch,   /* i   : pitch gain              */
                        Flag   *pOverflow
                       )
{
    OSCL_UNUSED_ARG(pOverflow);
    for (int i = 0; i < N_FRAME - 1; i++)
    {
        st->gp[i] = st->gp[i+1];
    }
    st->gp[N_FRAME-1] =  g_pitch >> 3;
}