Log2_norm( x <<exp, exp, exponent, fraction );
}


/*
 * Pow2
 *
 *
 * Parameters:
 *    exponent          I: Integer part. (range: 0<=val<=30)
 *    fraction          O: Fractional part. (range: 0.0<=val<1.0)
 *
 * Function:
 *    pow(2.0, exponent.fraction)
 *
 *    The function Pow2(L_x) is approximated by a table and linear interpolation.
 *
 *    i = bit10-b15 of fraction, 0 <= i <= 31
 *    a = biT0-b9   of fraction
 *    x = table[i]<<16 - (table[i] - table[i+1]) * a * 2
 *    x = L_x >> (30-exponent) (with rounding)
 *
 * Returns:
 *    result (range: 0<=val<=0x7fffffff)
 */
static Word32 Pow2( Word32 exponent, Word32 fraction )
{
   Word32 i, a, tmp, x, exp;


   /* Extract b10-b16 of fraction */
   i = fraction >> 10;

   /* Extract b0-b9 of fraction */
   a = ( fraction << 5 ) & 0x7fff;

   /* table[i] << 16 */
   x = pow2_table[i] << 16;

   /* table[i] - table[i+1] */
   tmp = pow2_table[i] - pow2_table[i + 1];

   /* L_x -= tmp*a*2 */
   x -= ( tmp * a ) << 1;

   if ( exponent >= -1 ) {
      exp = ( 30 - exponent );

      /* Rounding */
      if ( ( x & ( ( Word32 )1 << ( exp - 1 ) ) ) != 0 ) {
         x = ( x >> exp ) + 1;
      }
      else
         x = x >> exp;
   }
   else
      x = 0;
   return( x );
}


/*
 * Build_CN_code
 *
 *
 * Parameters:
 *    seed              B: Old CN generator shift register state
 *    cod               O: Generated CN fixed codebook vector
 *
 * Function:
 *    Generate CN fixed codebook vector
 *
 * Returns:
 *    void
 */
static void Build_CN_code( Word32 *seed, Word32 cod[] )
{
   Word32 i, j, k;


   memset( cod, 0, L_SUBFR <<2 );

   for ( k = 0; k < 10; k++ ) {
      i = pseudonoise( seed, 2 );   /* generate pulse position */
      i = ( i * 20 ) >> 1;
      i = ( i + k );
      j = pseudonoise( seed, 1 );   /* generate sign           */

      if ( j > 0 ) {
         cod[i] = 4096;
      }
      else {
         cod[i] = -4096;
      }
   }
   return;
}


/*
 * Build_CN_param
 *
 *
 * Parameters:
 *    seed              B: Old CN generator shift register state
 *    nParam            I: number of params
 *    paramSizeTable    I: size of params
 *    parm              O: CN Generated params
 *
 * Function:
 *    Generate parameters for comfort noise generation
 *
 * Returns:
 *    void
 */
static void Build_CN_param( Word16 *seed, enum Mode mode, Word16 parm[] )
{
   Word32 i;
   const Word32 *p;


   *seed = ( Word16 )( ( *seed * 31821 ) + 13849L );
   p = &window_200_40[ * seed & 0x7F];

   switch ( mode ) {
      case MR122:
         for ( i = 0; i < PRMNO_MR122; i++ ) {
            parm[i] = ( Word16 )( *p++ & ~( 0xFFFF << bitno_MR122[i] ) );
         }
         break;

      case MR102:
         for ( i = 0; i < PRMNO_MR102; i++ ) {
            parm[i] = ( Word16 )( *p++ & ~( 0xFFFF << bitno_MR102[i] ) );
         }
         break;

      case MR795:
         for ( i = 0; i < PRMNO_MR795; i++ ) {
            parm[i] = ( Word16 )( *p++ & ~( 0xFFFF << bitno_MR795[i] ) );
         }
         break;

      case MR74:
         for ( i = 0; i < PRMNO_MR74; i++ ) {
            parm[i] = ( Word16 )( *p++ & ~( 0xFFFF << bitno_MR74[i] ) );
         }
         break;

      case MR67:
         for ( i = 0; i < PRMNO_MR67; i++ ) {
            parm[i] = ( Word16 )( *p++ & ~( 0xFFFF << bitno_MR67[i] ) );
         }
         break;

      case MR59:
         for ( i = 0; i < PRMNO_MR59; i++ ) {
            parm[i] = ( Word16 )( *p++ & ~( 0xFFFF << bitno_MR59[i] ) );
         }
         break;

      case MR515:
         for ( i = 0; i < PRMNO_MR515; i++ ) {
            parm[i] = ( Word16 )( *p++ & ~( 0xFFFF << bitno_MR515[i] ) );
         }
         break;

      case MR475:
         for ( i = 0; i < PRMNO_MR475; i++ ) {
            parm[i] = ( Word16 )( *p++ & ~( 0xFFFF << bitno_MR475[i] ) );
         }
         break;
   }
}


/*
 * Syn_filt
 *
 *
 * Parameters:
 *    a                 I: prediction coefficients [M+1]
 *    x                 I: input signal
 *    y                 O: output signal
 *    lg                I: size of filtering
 *    mem               B: memory associated with this filtering
 *    update            I: 0=no update, 1=update of memory.
 *
 * Function:
 *    Perform synthesis filtering through 1/A(z).
 *
 * Returns:
 *    void
 */
static Word32 Syn_filt( Word32 a[], Word32 x[], Word32 y[], Word32 lg, Word32 mem[]
      , Word32 update )
{
   Word32 tmp[50];   /* malloc is slow */
   Word32 s, a0, overflow = 0;
   Word32 *yy, *yy_limit;


   /* Copy mem[] to yy[] */
   memcpy( tmp, mem, 40 );
   yy = tmp + M;
   yy_limit = yy + lg;
   a0 = a[0];

   /* Do the filtering. */
   while ( yy < yy_limit ) {

      s = *x++ * a0;
      s -= yy[-1] * a[1];
      s -= yy[-2] * a[2];
      s -= yy[-3] * a[3];
      s -= yy[-4] * a[4];
      s -= yy[-5] * a[5];
      s -= yy[-6] * a[6];
      s -= yy[-7] * a[7];
      s -= yy[-8] * a[8];
      s -= yy[-9] * a[9];
      s -= yy[-10] * a[10];
      if ( labs( s ) < 0x7ffffff )
         *yy = ( s + 0x800L ) >> 12;
      else if ( s > 0 ) {
         *yy = 32767;
         overflow = 1;
      }
      else {
         *yy = -32768;
         overflow = 1;
      }
      yy++;
   }
   memcpy( y, &tmp[M], lg <<2 );

   /* Update of memory if update==1 */
   if ( update ) {
      memcpy( mem, &y[lg - M], 40 );
   }
   return overflow;
}

/*
 * Syn_filt_overflow
 *
 *
 * Parameters:
 *    a                 I: prediction coefficients [M+1]
 *    x                 I: input signal
 *    y                 O: output signal
 *    lg                I: size of filtering
 *    mem               B: memory associated with this filtering
 *    update            I: 0=no update, 1=update of memory.
 *
 * Function:
 *    Perform synthesis filtering through 1/A(z).
 *    Saturate after every multiplication.
 * Returns:
 *    void
 */
static void Syn_filt_overflow( Word32 a[], Word32 x[], Word32 y[], Word32 lg, Word32 mem[]
      , Word32 update )
{
   Word32 tmp[50];   /* malloc is slow */
   Word32 i, j, s, a0;
   Word32 *yy;


   /* Copy mem[] to yy[] */
   memcpy( tmp, mem, 40 );
   yy = tmp + M;
   a0 = a[0];

   /* Do the filtering. */
   for ( i = 0; i < lg; i++ ) {
      s = x[i] * a0;

      for ( j = 1; j <= M; j++ ) {
         s -= a[j] * yy[ - j];
         if (s > 1073741823){
            s = 1073741823;
         }
         else if ( s < -1073741824) {
            s = -1073741824;
         }
      }

      if ( labs( s ) < 0x7FFE800 )
         *yy = ( s + 0x800L ) >> 12;
      else if ( s > 0 ) {
         *yy = 32767;
      }
      else {
         *yy = -32768;
      }
      yy++;
   }
   memcpy( y, &tmp[M], lg <<2 );

   /* Update of memory if update==1 */
   if ( update ) {
      memcpy( mem, &y[lg - M], 40 );
   }
   return;
}

/*
 * dtx_dec
 *
 *
 * Parameters:
 *    st                            B: DTX state struct
 *    mem_syn                       I: AMR decoder state
 *    lsfState                      B: LSF state struct
 *    pred_state->past_qua_en       O: table of past quantized energies
 *    pred_state->past_qua_en_MR122 O: table of past quantized energies MR122
 *    averState->hangVar            O:
 *    averState->hangCount          O: hangover variable
 *    new_state                     I: new DTX state
 *    mode                          I: AMR mode
 *    parm                          I: vector of synthesis parameters
 *    synth                         O: synthesised speech
 *    A_t                           O: decoded LP filter in 4 subframes
 *
 * Function:
 *    DTX
 *
 * Returns:
 *    void
 */
static void dtx_dec( dtx_decState *st, Word32 *mem_syn, D_plsfState *lsfState,
      gc_predState *pred_state, Cb_gain_averageState *averState, enum
      DTXStateType new_state, enum Mode mode, Word16 parm[], Word32 synth[],
      Word32 A_t[] )
{
   Word32 ex[L_SUBFR], acoeff[11], acoeff_variab[M + 1], lsp_int[M];
   Word32 refl[M], lsf[M], lsf_int[M], lsf_int_variab[M], lsp_int_variab[M];
   Word32 i, j, int_fac, log_en_int, pred_err, log_pg_e, log_pg_m, log_pg;
   Word32 negative, lsf_mean, lsf_variab_index, lsf_variab_factor, ptr;
   Word16 log_en_index, log_en_int_e, log_en_int_m, level, ma_pred_init,
         tmp_int_length;


   if ( ( st->dtxHangoverAdded != 0 ) & ( st->sid_frame != 0 ) ) {
      /*
       * sidFirst after dtx hangover period
       * or sidUpd after dtxhangover
       */
      /* set log_en_adjust to correct value */
      st->log_en_adjust = dtx_log_en_adjust[mode];
      ptr = st->lsf_hist_ptr + M;

      if ( ptr == 80 ) {
         ptr = 0;
      }
      memcpy( &st->lsf_hist[ptr], &st->lsf_hist[st->lsf_hist_ptr], M <<2 );
      ptr = st->log_en_hist_ptr + 1;

      if ( ptr == DTX_HIST_SIZE ) {
         ptr = 0;
      }
      st->log_en_hist[ptr] = st->log_en_hist[st->log_en_hist_ptr];   /* Q11 */

      /*
       * compute mean log energy and lsp
       * from decoded signal (SID_FIRST)
       */
      st->log_en = 0;
      memset( lsf, 0, M <<2 );

      /* average energy and lsp */
      for ( i = 0; i < DTX_HIST_SIZE; i++ ) {
         st->log_en = st->log_en + ( st->log_en_hist[i] >> 3 );

         for ( j = 0; j < M; j++ ) {
            lsf[j] += st->lsf_hist[i * M + j];
         }
      }

      for ( j = 0; j < M; j++ ) {
         lsf[j] = lsf[j] >> 3;   /* divide by 8 */
      }
      Lsf_lsp( lsf, st->lsp );

      /*
       * make log_en speech coder mode independent
       * added again later before synthesis
       */
      st->log_en = st->log_en - st->log_en_adjust;

      /* compute lsf variability vector */
      memcpy( st->lsf_hist_mean, st->lsf_hist, 80 <<2 );

      for ( i = 0; i < M; i++ ) {
         lsf_mean = 0;

         /* compute mean lsf */
         for ( j = 0; j < 8; j++ ) {
            lsf_mean += st->lsf_hist_mean[i + j * M];
         }
         lsf_mean = lsf_mean >> 3;

         /*
          * subtract mean and limit to within reasonable limits
          * moreover the upper lsf's are attenuated
          */
         for ( j = 0; j < 8; j++ ) {
            /* subtract mean */
            st->lsf_hist_mean[i + j * M] = st->lsf_hist_mean[i + j * M] -
                  lsf_mean;

            /* attenuate deviation from mean, especially for upper lsf's */
            st->lsf_hist_mean[i + j * M] = ( st->lsf_hist_mean[i + j * M] *
                  lsf_hist_mean_scale[i] ) >> 15;

            /* limit the deviation */
            if ( st->lsf_hist_mean[i + j * M] < 0 ) {
               negative = 1;
            }
            else {
               negative = 0;
            }
            st->lsf_hist_mean[i + j * M] = labs( st->lsf_hist_mean[i + j * M] );

            /* apply soft limit */
            if ( st->lsf_hist_mean[i + j * M] > 655 ) {
               st->lsf_hist_mean[i + j * M] = 655 + ( ( st->lsf_hist_mean[i + j
                     * M] - 655 ) >> 2 );
            }

            /* apply hard limit */
            if ( st->lsf_hist_mean[i + j * M] > 1310 ) {
               st->lsf_hist_mean[i + j * M] = 1310;
            }

            if ( negative != 0 ) {
               st->lsf_hist_mean[i + j * M] = -st->lsf_hist_mean[i + j * M];
            }
         }
      }
   }

   if ( st->sid_frame != 0 ) {
      /*
       * Set old SID parameters, always shift
       * even if there is no new valid_data
       */
      memcpy( st->lsp_old, st->lsp, M <<2 );
      st->old_log_en = st->log_en;

      if ( st->valid_data != 0 ) /* new data available (no CRC) */ {
      /* Compute interpolation factor, since the division only works
       * for values of since_last_sid < 32 we have to limit the
       * interpolation to 32 frames
       */
         tmp_int_length = st->since_last_sid;
         st->since_last_sid = 0;

         if ( tmp_int_length > 32 ) {
            tmp_int_length = 32;
         }

         if ( tmp_int_length >= 2 ) {
            st->true_sid_period_inv = 0x2000000 / ( tmp_int_length
                  << 10 );
         }
         else {
            st->true_sid_period_inv = 16384;   /* 0.5 it Q15 */
         }
         memcpy( lsfState->past_r_q, &past_rq_init[parm[0] * M], M <<2 );
         D_plsf_3( lsfState, MRDTX, 0, &parm[1], st->lsp );

         /* reset for next speech frame */
         memset( lsfState->past_r_q, 0, M <<2 );
         log_en_index = parm[4];

         /* Q11 and divide by 4 */
         st->log_en = ( Word16 )( log_en_index << 9 );

         /* Subtract 2.5 in Q11 */
         st->log_en = ( Word16 )( st->log_en - 5120 );

         /* Index 0 is reserved for silence */
         if ( log_en_index == 0 ) {
            st->log_en = MIN_16;
         }

         /*
          * no interpolation at startup after coder reset
          * or when SID_UPD has been received right after SPEECH
          */
         if ( ( st->data_updated == 0 ) || ( st->dtxGlobalState == SPEECH ) ) {
            memcpy( st->lsp_old, st->lsp, M <<2 );
            st->old_log_en = st->log_en;
         }
      }   /* endif valid_data */

      /* initialize gain predictor memory of other modes */
      ma_pred_init = ( Word16 )( ( st->log_en >> 1 ) - 9000 );

      if ( ma_pred_init > 0 ) {
         ma_pred_init = 0;
      }

      if ( ma_pred_init < - 14436 ) {
         ma_pred_init = -14436;
      }
      pred_state->past_qua_en[0] = ma_pred_init;
      pred_state->past_qua_en[1] = ma_pred_init;
      pred_state->past_qua_en[2] = ma_pred_init;
      pred_state->past_qua_en[3] = ma_pred_init;

      /* past_qua_en for other modes than MR122 */
      ma_pred_init = ( Word16 )( ( 5443*ma_pred_init ) >> 15 );

      /* scale down by factor 20*log10(2) in Q15 */
      pred_state->past_qua_en_MR122[0] = ma_pred_init;
      pred_state->past_qua_en_MR122[1] = ma_pred_init;
      pred_state->past_qua_en_MR122[2] = ma_pred_init;
      pred_state->past_qua_en_MR122[3] = ma_pred_init;
   }   /* endif sid_frame */

   /*
    * CN generation
    * recompute level adjustment factor Q11
    * st->log_en_adjust = 0.9*st->log_en_adjust +
    *                     0.1*dtx_log_en_adjust[mode]);
    */
   st->log_en_adjust = ( Word16 )( ( ( st->log_en_adjust * 29491 ) >> 15 ) + ( (
         ( dtx_log_en_adjust[mode] << 5 ) * 3277 ) >> 20 ) );

   /* Interpolate SID info */
   /* Q10 */
   if ( st->since_last_sid > 30 )
      int_fac = 32767;
   else
      int_fac = ( Word16 )( (st->since_last_sid + 1) << 10 );

   /* Q10 * Q15 -> Q10 */
   int_fac = ( int_fac * st->true_sid_period_inv ) >> 15;

   /* Maximize to 1.0 in Q10 */
   if ( int_fac > 1024 ) {
      int_fac = 1024;
   }

   /* Q10 -> Q14 */
   int_fac = ( Word16 )( int_fac << 4 );

   /* Q14 * Q11->Q26 */
   log_en_int = ( int_fac * st->log_en ) << 1;

   for ( i = 0; i < M; i++ ) {
      /* Q14 * Q15 -> Q14 */
      lsp_int[i] = ( int_fac * st->lsp[i] ) >> 15;
   }

   /* 1-k in Q14 */
   int_fac = 16384 - int_fac;