C++ silk_LSHIFT函数代码示例

/* High-pass filter with cutoff frequency adaptation based on pitch lag statistics */
void silk_HP_variable_cutoff(silk_encoder_state_Fxx state_Fxx[]	/* I/O  Encoder states                              */
    )
{
	int quality_Q15;
	int32_t pitch_freq_Hz_Q16, pitch_freq_log_Q7, delta_freq_Q7;
	silk_encoder_state *psEncC1 = &state_Fxx[0].sCmn;

	/* Adaptive cutoff frequency: estimate low end of pitch frequency range */
	if (psEncC1->prevSignalType == TYPE_VOICED) {
		/* difference, in log domain */
		pitch_freq_Hz_Q16 =
		    silk_DIV32_16(silk_LSHIFT
				  (silk_MUL(psEncC1->fs_kHz, 1000), 16),
				  psEncC1->prevLag);
		pitch_freq_log_Q7 = silk_lin2log(pitch_freq_Hz_Q16) - (16 << 7);

		/* adjustment based on quality */
		quality_Q15 = psEncC1->input_quality_bands_Q15[0];
		pitch_freq_log_Q7 =
		    silk_SMLAWB(pitch_freq_log_Q7,
				silk_SMULWB(silk_LSHIFT(-quality_Q15, 2),
					    quality_Q15),
				pitch_freq_log_Q7 -
				(silk_lin2log
				 (SILK_FIX_CONST(VARIABLE_HP_MIN_CUTOFF_HZ, 16))
				 - (16 << 7)));

		/* delta_freq = pitch_freq_log - psEnc->variable_HP_smth1; */
		delta_freq_Q7 =
		    pitch_freq_log_Q7 -
		    silk_RSHIFT(psEncC1->variable_HP_smth1_Q15, 8);
		if (delta_freq_Q7 < 0) {
			/* less smoothing for decreasing pitch frequency, to track something close to the minimum */
			delta_freq_Q7 = silk_MUL(delta_freq_Q7, 3);
		}

		/* limit delta, to reduce impact of outliers in pitch estimation */
		delta_freq_Q7 =
		    silk_LIMIT_32(delta_freq_Q7,
				  -SILK_FIX_CONST(VARIABLE_HP_MAX_DELTA_FREQ,
						  7),
				  SILK_FIX_CONST(VARIABLE_HP_MAX_DELTA_FREQ,
						 7));

		/* update smoother */
		psEncC1->variable_HP_smth1_Q15 =
		    silk_SMLAWB(psEncC1->variable_HP_smth1_Q15,
				silk_SMULBB(psEncC1->speech_activity_Q8,
					    delta_freq_Q7),
				SILK_FIX_CONST(VARIABLE_HP_SMTH_COEF1, 16));

		/* limit frequency range */
		psEncC1->variable_HP_smth1_Q15 =
		    silk_LIMIT_32(psEncC1->variable_HP_smth1_Q15,
				  silk_LSHIFT(silk_lin2log
					      (VARIABLE_HP_MIN_CUTOFF_HZ), 8),
				  silk_LSHIFT(silk_lin2log
					      (VARIABLE_HP_MAX_CUTOFF_HZ), 8));
	}
}

static OPUS_INLINE void silk_A2NLSF_init(
     const opus_int32    *a_Q16,
     opus_int32          *P,
     opus_int32          *Q,
     const opus_int      dd
)
{
    opus_int k;

    /* Convert filter coefs to even and odd polynomials */
    P[dd] = silk_LSHIFT( 1, 16 );
    Q[dd] = silk_LSHIFT( 1, 16 );
    for( k = 0; k < dd; k++ ) {
        P[ k ] = -a_Q16[ dd - k - 1 ] - a_Q16[ dd + k ];    /* Q16 */
        Q[ k ] = -a_Q16[ dd - k - 1 ] + a_Q16[ dd + k ];    /* Q16 */
    }

    /* Divide out zeros as we have that for even filter orders, */
    /* z =  1 is always a root in Q, and                        */
    /* z = -1 is always a root in P                             */
    for( k = dd; k > 0; k-- ) {
        P[ k - 1 ] -= P[ k ];
        Q[ k - 1 ] += Q[ k ];
    }

    /* Transform polynomials from cos(n*f) to cos(f)^n */
    silk_A2NLSF_trans_poly( P, dd );
    silk_A2NLSF_trans_poly( Q, dd );
}

/* uses SMLAWB(), requiring armv5E and higher.                          */
opus_int32 silk_schur(                              /* O    Returns residual energy                                     */
    opus_int16                  *rc_Q15,            /* O    reflection coefficients [order] Q15                         */
    const opus_int32            *c,                 /* I    correlations [order+1]                                      */
    const opus_int32            order               /* I    prediction order                                            */
)
{
    opus_int        k, n, lz;
    opus_int32    C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ];
    opus_int32    Ctmp1, Ctmp2, rc_tmp_Q15;

    silk_assert( order==6||order==8||order==10||order==12||order==14||order==16 );

    /* Get number of leading zeros */
    lz = silk_CLZ32( c[ 0 ] );

    /* Copy correlations and adjust level to Q30 */
    if( lz < 2 ) {
        /* lz must be 1, so shift one to the right */
        for( k = 0; k < order + 1; k++ ) {
            C[ k ][ 0 ] = C[ k ][ 1 ] = silk_RSHIFT( c[ k ], 1 );
        }
    } else if( lz > 2 ) {
        /* Shift to the left */
        lz -= 2;
        for( k = 0; k < order + 1; k++ ) {
            C[ k ][ 0 ] = C[ k ][ 1 ] = silk_LSHIFT( c[ k ], lz );
        }
    } else {
        /* No need to shift */
        for( k = 0; k < order + 1; k++ ) {
            C[ k ][ 0 ] = C[ k ][ 1 ] = c[ k ];
        }
    }

    for( k = 0; k < order; k++ ) {

        /* Get reflection coefficient */
        rc_tmp_Q15 = -silk_DIV32_16( C[ k + 1 ][ 0 ], silk_max_32( silk_RSHIFT( C[ 0 ][ 1 ], 15 ), 1 ) );

        /* Clip (shouldn't happen for properly conditioned inputs) */
        rc_tmp_Q15 = silk_SAT16( rc_tmp_Q15 );

        /* Store */
        rc_Q15[ k ] = (opus_int16)rc_tmp_Q15;

        /* Update correlations */
        for( n = 0; n < order - k; n++ ) {
            Ctmp1 = C[ n + k + 1 ][ 0 ];
            Ctmp2 = C[ n ][ 1 ];
            C[ n + k + 1 ][ 0 ] = silk_SMLAWB( Ctmp1, silk_LSHIFT( Ctmp2, 1 ), rc_tmp_Q15 );
            C[ n ][ 1 ]         = silk_SMLAWB( Ctmp2, silk_LSHIFT( Ctmp1, 1 ), rc_tmp_Q15 );
        }
    }

    /* return residual energy */
    return C[ 0 ][ 1 ];
}

/* Uses SMULL(), available on armv4                                     */
opus_int32 silk_schur64(                            /* O    returns residual energy                                     */
    opus_int32                  rc_Q16[],           /* O    Reflection coefficients [order] Q16                         */
    const opus_int32            c[],                /* I    Correlations [order+1]                                      */
    opus_int32                  order               /* I    Prediction order                                            */
)
{
    opus_int   k, n;
    opus_int32 C[ SILK_MAX_ORDER_LPC + 1 ][ 2 ];
    opus_int32 Ctmp1_Q30, Ctmp2_Q30, rc_tmp_Q31;

    silk_assert( order==6||order==8||order==10||order==12||order==14||order==16 );

    /* Check for invalid input */
    if( c[ 0 ] <= 0 ) {
        silk_memset( rc_Q16, 0, order * sizeof( opus_int32 ) );
        return 0;
    }

    for( k = 0; k < order + 1; k++ ) {
        C[ k ][ 0 ] = C[ k ][ 1 ] = c[ k ];
    }

    for( k = 0; k < order; k++ ) {
        /* Check that we won't be getting an unstable rc, otherwise stop here. */
        if (silk_abs_int32(C[ k + 1 ][ 0 ]) >= C[ 0 ][ 1 ]) {
           if ( C[ k + 1 ][ 0 ] > 0 ) {
              rc_Q16[ k ] = -SILK_FIX_CONST( .99f, 16 );
           } else {
              rc_Q16[ k ] = SILK_FIX_CONST( .99f, 16 );
           }
           k++;
           break;
        }

        /* Get reflection coefficient: divide two Q30 values and get result in Q31 */
        rc_tmp_Q31 = silk_DIV32_varQ( -C[ k + 1 ][ 0 ], C[ 0 ][ 1 ], 31 );

        /* Save the output */
        rc_Q16[ k ] = silk_RSHIFT_ROUND( rc_tmp_Q31, 15 );

        /* Update correlations */
        for( n = 0; n < order - k; n++ ) {
            Ctmp1_Q30 = C[ n + k + 1 ][ 0 ];
            Ctmp2_Q30 = C[ n ][ 1 ];

            /* Multiply and add the highest int32 */
            C[ n + k + 1 ][ 0 ] = Ctmp1_Q30 + silk_SMMUL( silk_LSHIFT( Ctmp2_Q30, 1 ), rc_tmp_Q31 );
            C[ n ][ 1 ]         = Ctmp2_Q30 + silk_SMMUL( silk_LSHIFT( Ctmp1_Q30, 1 ), rc_tmp_Q31 );
        }
    }

    for(; k < order; k++ ) {
       rc_Q16[ k ] = 0;
    }

    return silk_max_32( 1, C[ 0 ][ 1 ] );
}

/* Glues concealed frames with new good received frames */
void silk_PLC_glue_frames(
    silk_decoder_state                  *psDec,             /* I/O decoder state        */
    opus_int16                          frame[],            /* I/O signal               */
    opus_int                            length              /* I length of signal       */
)
{
    opus_int   i, energy_shift;
    opus_int32 energy;
    silk_PLC_struct *psPLC;
    psPLC = &psDec->sPLC;

    if( psDec->lossCnt ) {
        /* Calculate energy in concealed residual */
        silk_sum_sqr_shift( &psPLC->conc_energy, &psPLC->conc_energy_shift, frame, length );

        psPLC->last_frame_lost = 1;
    } else {
        if( psDec->sPLC.last_frame_lost ) {
            /* Calculate residual in decoded signal if last frame was lost */
            silk_sum_sqr_shift( &energy, &energy_shift, frame, length );

            /* Normalize energies */
            if( energy_shift > psPLC->conc_energy_shift ) {
                psPLC->conc_energy = silk_RSHIFT( psPLC->conc_energy, energy_shift - psPLC->conc_energy_shift );
            } else if( energy_shift < psPLC->conc_energy_shift ) {
                energy = silk_RSHIFT( energy, psPLC->conc_energy_shift - energy_shift );
            }

            /* Fade in the energy difference */
            if( energy > psPLC->conc_energy ) {
                opus_int32 frac_Q24, LZ;
                opus_int32 gain_Q16, slope_Q16;

                LZ = silk_CLZ32( psPLC->conc_energy );
                LZ = LZ - 1;
                psPLC->conc_energy = silk_LSHIFT( psPLC->conc_energy, LZ );
                energy = silk_RSHIFT( energy, silk_max_32( 24 - LZ, 0 ) );

                frac_Q24 = silk_DIV32( psPLC->conc_energy, silk_max( energy, 1 ) );

                gain_Q16 = silk_LSHIFT( silk_SQRT_APPROX( frac_Q24 ), 4 );
                slope_Q16 = silk_DIV32_16( ( (opus_int32)1 << 16 ) - gain_Q16, length );
                /* Make slope 4x steeper to avoid missing onsets after DTX */
                slope_Q16 = silk_LSHIFT( slope_Q16, 2 );

                for( i = 0; i < length; i++ ) {
                    frame[ i ] = silk_SMULWB( gain_Q16, frame[ i ] );
                    gain_Q16 += slope_Q16;
                    if( gain_Q16 > (opus_int32)1 << 16 ) {
                        break;
                    }
                }
            }
        }
        psPLC->last_frame_lost = 0;
    }
}

/* Prefilter for finding Quantizer input signal */
static OPUS_INLINE void silk_prefilt_FIX(
        silk_prefilter_state_FIX *P,                         /* I/O  state                               */
        opus_int32 st_res_Q12[],               /* I    short term residual signal          */
        opus_int32 xw_Q3[],                    /* O    prefiltered signal                  */
        opus_int32 HarmShapeFIRPacked_Q12,     /* I    Harmonic shaping coeficients        */
        opus_int Tilt_Q14,                   /* I    Tilt shaping coeficient             */
        opus_int32 LF_shp_Q14,                 /* I    Low-frequancy shaping coeficients   */
        opus_int lag,                        /* I    Lag for harmonic shaping            */
        opus_int length                      /* I    Length of signals                   */
) {
    opus_int i, idx, LTP_shp_buf_idx;
    opus_int32 n_LTP_Q12, n_Tilt_Q10, n_LF_Q10;
    opus_int32 sLF_MA_shp_Q12, sLF_AR_shp_Q12;
    opus_int16 *LTP_shp_buf;

    /* To speed up use temp variables instead of using the struct */
    LTP_shp_buf = P->sLTP_shp;
    LTP_shp_buf_idx = P->sLTP_shp_buf_idx;
    sLF_AR_shp_Q12 = P->sLF_AR_shp_Q12;
    sLF_MA_shp_Q12 = P->sLF_MA_shp_Q12;

    for (i = 0; i < length; i++) {
        if (lag > 0) {
            /* unrolled loop */
            silk_assert(HARM_SHAPE_FIR_TAPS == 3);
            idx = lag + LTP_shp_buf_idx;
            n_LTP_Q12 = silk_SMULBB(LTP_shp_buf[(idx - HARM_SHAPE_FIR_TAPS / 2 - 1) & LTP_MASK],
                                    HarmShapeFIRPacked_Q12);
            n_LTP_Q12 = silk_SMLABT(n_LTP_Q12,
                                    LTP_shp_buf[(idx - HARM_SHAPE_FIR_TAPS / 2) & LTP_MASK],
                                    HarmShapeFIRPacked_Q12);
            n_LTP_Q12 = silk_SMLABB(n_LTP_Q12,
                                    LTP_shp_buf[(idx - HARM_SHAPE_FIR_TAPS / 2 + 1) & LTP_MASK],
                                    HarmShapeFIRPacked_Q12);
        } else {
            n_LTP_Q12 = 0;
        }

        n_Tilt_Q10 = silk_SMULWB(sLF_AR_shp_Q12, Tilt_Q14);
        n_LF_Q10 = silk_SMLAWB(silk_SMULWT(sLF_AR_shp_Q12, LF_shp_Q14), sLF_MA_shp_Q12, LF_shp_Q14);

        sLF_AR_shp_Q12 = silk_SUB32(st_res_Q12[i], silk_LSHIFT(n_Tilt_Q10, 2));
        sLF_MA_shp_Q12 = silk_SUB32(sLF_AR_shp_Q12, silk_LSHIFT(n_LF_Q10, 2));

        LTP_shp_buf_idx = (LTP_shp_buf_idx - 1) & LTP_MASK;
        LTP_shp_buf[LTP_shp_buf_idx] = (opus_int16) silk_SAT16(
                silk_RSHIFT_ROUND(sLF_MA_shp_Q12, 12));

        xw_Q3[i] = silk_RSHIFT_ROUND(silk_SUB32(sLF_MA_shp_Q12, n_LTP_Q12), 9);
    }

    /* Copy temp variable back to state */
    P->sLF_AR_shp_Q12 = sLF_AR_shp_Q12;
    P->sLF_MA_shp_Q12 = sLF_MA_shp_Q12;
    P->sLTP_shp_buf_idx = LTP_shp_buf_idx;
}

/* Find least-squares prediction gain for one signal based on another and quantize it */
int32_t silk_stereo_find_predictor(	/* O    Returns predictor in Q13                    */
					     int32_t * ratio_Q14,	/* O    Ratio of residual and mid energies          */
					     const int16_t x[],	/* I    Basis signal                                */
					     const int16_t y[],	/* I    Target signal                               */
					     int32_t mid_res_amp_Q0[],	/* I/O  Smoothed mid, residual norms                */
					     int length,	/* I    Number of samples                           */
					     int smooth_coef_Q16	/* I    Smoothing coefficient                       */
    )
{
	int scale, scale1, scale2;
	int32_t nrgx, nrgy, corr, pred_Q13, pred2_Q10;

	/* Find  predictor */
	silk_sum_sqr_shift(&nrgx, &scale1, x, length);
	silk_sum_sqr_shift(&nrgy, &scale2, y, length);
	scale = silk_max_int(scale1, scale2);
	scale = scale + (scale & 1);	/* make even */
	nrgy = silk_RSHIFT32(nrgy, scale - scale2);
	nrgx = silk_RSHIFT32(nrgx, scale - scale1);
	nrgx = silk_max_int(nrgx, 1);
	corr = silk_inner_prod_aligned_scale(x, y, scale, length);
	pred_Q13 = silk_DIV32_varQ(corr, nrgx, 13);
	pred_Q13 = silk_LIMIT(pred_Q13, -(1 << 14), 1 << 14);
	pred2_Q10 = silk_SMULWB(pred_Q13, pred_Q13);

	/* Faster update for signals with large prediction parameters */
	smooth_coef_Q16 =
	    (int) silk_max_int(smooth_coef_Q16, silk_abs(pred2_Q10));

	/* Smoothed mid and residual norms */
	assert(smooth_coef_Q16 < 32768);
	scale = silk_RSHIFT(scale, 1);
	mid_res_amp_Q0[0] =
	    silk_SMLAWB(mid_res_amp_Q0[0],
			silk_LSHIFT(silk_SQRT_APPROX(nrgx),
				    scale) - mid_res_amp_Q0[0],
			smooth_coef_Q16);
	/* Residual energy = nrgy - 2 * pred * corr + pred^2 * nrgx */
	nrgy = silk_SUB_LSHIFT32(nrgy, silk_SMULWB(corr, pred_Q13), 3 + 1);
	nrgy = silk_ADD_LSHIFT32(nrgy, silk_SMULWB(nrgx, pred2_Q10), 6);
	mid_res_amp_Q0[1] =
	    silk_SMLAWB(mid_res_amp_Q0[1],
			silk_LSHIFT(silk_SQRT_APPROX(nrgy),
				    scale) - mid_res_amp_Q0[1],
			smooth_coef_Q16);

	/* Ratio of smoothed residual and mid norms */
	*ratio_Q14 =
	    silk_DIV32_varQ(mid_res_amp_Q0[1], silk_max(mid_res_amp_Q0[0], 1),
			    14);
	*ratio_Q14 = silk_LIMIT(*ratio_Q14, 0, 32767);

	return pred_Q13;
}

/* Control SNR of redidual quantizer */
opus_int silk_control_SNR(
        silk_encoder_state *psEncC,                        /* I/O  Pointer to Silk encoder state               */
        opus_int32 TargetRate_bps                  /* I    Target max bitrate (bps)                    */
) {
    opus_int k, ret = SILK_NO_ERROR;
    opus_int32 frac_Q6;
    const opus_int32 *rateTable;

    /* Set bitrate/coding quality */
    TargetRate_bps = silk_LIMIT(TargetRate_bps, MIN_TARGET_RATE_BPS, MAX_TARGET_RATE_BPS);
    if (TargetRate_bps != psEncC->TargetRate_bps) {
        psEncC->TargetRate_bps = TargetRate_bps;

        /* If new TargetRate_bps, translate to SNR_dB value */
        if (psEncC->fs_kHz == 8) {
            rateTable = silk_TargetRate_table_NB;
        } else if (psEncC->fs_kHz == 12) {
            rateTable = silk_TargetRate_table_MB;
        } else {
            rateTable = silk_TargetRate_table_WB;
        }

        /* Reduce bitrate for 10 ms modes in these calculations */
        if (psEncC->nb_subfr == 2) {
            TargetRate_bps -= REDUCE_BITRATE_10_MS_BPS;
        }

        /* Find bitrate interval in table and interpolate */
        for (k = 1; k < TARGET_RATE_TAB_SZ; k++) {
            if (TargetRate_bps <= rateTable[k]) {
                frac_Q6 = silk_DIV32(silk_LSHIFT(TargetRate_bps - rateTable[k - 1], 6),
                                     rateTable[k] - rateTable[k - 1]);
                psEncC->SNR_dB_Q7 = silk_LSHIFT(silk_SNR_table_Q1[k - 1], 6) + silk_MUL(frac_Q6,
                                                                                        silk_SNR_table_Q1[k] -
                                                                                        silk_SNR_table_Q1[
                                                                                                k -
                                                                                                1]);
                break;
            }
        }

        /* Reduce coding quality whenever LBRR is enabled, to free up some bits */
        if (psEncC->LBRR_enabled) {
            psEncC->SNR_dB_Q7 = silk_SMLABB(psEncC->SNR_dB_Q7, 12 - psEncC->LBRR_GainIncreases,
                                            SILK_FIX_CONST(-0.25, 7));
        }
    }

    return ret;
}

/* Polynomial evaluation          */
static OPUS_INLINE opus_int32 silk_A2NLSF_eval_poly( /* return the polynomial evaluation, in Q16     */
    opus_int32          *p,                     /* I    Polynomial, Q16                         */
    const opus_int32    x,                      /* I    Evaluation point, Q12                   */
    const opus_int      dd                      /* I    Order                                   */
)
{
    opus_int   n;
    opus_int32 x_Q16, y32;

    y32 = p[ dd ];                                  /* Q16 */
    x_Q16 = silk_LSHIFT( x, 4 );

    if ( opus_likely( 8 == dd ) )
    {
        y32 = (opus_int32) silk_SMLAWW( p[ 7 ], y32, x_Q16 );
        y32 = (opus_int32) silk_SMLAWW( p[ 6 ], y32, x_Q16 );
        y32 = (opus_int32) silk_SMLAWW( p[ 5 ], y32, x_Q16 );
        y32 = (opus_int32) silk_SMLAWW( p[ 4 ], y32, x_Q16 );
        y32 = (opus_int32) silk_SMLAWW( p[ 3 ], y32, x_Q16 );
        y32 = (opus_int32) silk_SMLAWW( p[ 2 ], y32, x_Q16 );
        y32 = (opus_int32) silk_SMLAWW( p[ 1 ], y32, x_Q16 );
        y32 = (opus_int32) silk_SMLAWW( p[ 0 ], y32, x_Q16 );
    }
    else
    {
        for( n = dd - 1; n >= 0; n-- ) {
            y32 = (opus_int32) silk_SMLAWW( p[ n ], y32, x_Q16 );    /* Q16 */
        }
    }
    return y32;
}

/* Gains scalar dequantization, uniform on log scale */
void silk_gains_dequant(
    opus_int32                  gain_Q16[ MAX_NB_SUBFR ],       /* O    quantized gains                             */
    const opus_int8             ind[ MAX_NB_SUBFR ],            /* I    gain indices                                */
    opus_int8                   *prev_ind,                      /* I/O  last index in previous frame                */
    const opus_int              conditional,                    /* I    first gain is delta coded if 1              */
    const opus_int              nb_subfr                        /* I    number of subframes                          */
)
{
    opus_int   k, ind_tmp, double_step_size_threshold;

    for( k = 0; k < nb_subfr; k++ ) {
        if( k == 0 && conditional == 0 ) {
            /* Gain index is not allowed to go down more than 16 steps (~21.8 dB) */
            *prev_ind = silk_max_int( ind[ k ], *prev_ind - 16 );
        } else {
            /* Delta index */
            ind_tmp = ind[ k ] + MIN_DELTA_GAIN_QUANT;

            /* Accumulate deltas */
            double_step_size_threshold = 2 * MAX_DELTA_GAIN_QUANT - N_LEVELS_QGAIN + *prev_ind;
            if( ind_tmp > double_step_size_threshold ) {
                *prev_ind += silk_LSHIFT( ind_tmp, 1 ) - double_step_size_threshold;
            } else {
                *prev_ind += ind_tmp;
            }
        }
        *prev_ind = silk_LIMIT_int( *prev_ind, 0, N_LEVELS_QGAIN - 1 );

        /* Scale and convert to linear scale */
        gain_Q16[ k ] = silk_log2lin( silk_min_32( silk_SMULWB( INV_SCALE_Q16, *prev_ind ) + OFFSET, 3967 ) ); /* 3967 = 31 in Q7 */
    }
}

void silk_NLSF_decode(
          opus_int16            *pNLSF_Q15,                     /* O    Quantized NLSF vector [ LPC_ORDER ]         */
          opus_int8             *NLSFIndices,                   /* I    Codebook path vector [ LPC_ORDER + 1 ]      */
    const silk_NLSF_CB_struct   *psNLSF_CB                      /* I    Codebook object                             */
)
{
    opus_int         i;
    opus_uint8       pred_Q8[  MAX_LPC_ORDER ];
    opus_int16       ec_ix[    MAX_LPC_ORDER ];
    opus_int16       res_Q10[  MAX_LPC_ORDER ];
    opus_int32       NLSF_Q15_tmp;
    const opus_uint8 *pCB_element;
    const opus_int16 *pCB_Wght_Q9;

    /* Unpack entropy table indices and predictor for current CB1 index */
    silk_NLSF_unpack( ec_ix, pred_Q8, psNLSF_CB, NLSFIndices[ 0 ] );

    /* Predictive residual dequantizer */
    silk_NLSF_residual_dequant( res_Q10, &NLSFIndices[ 1 ], pred_Q8, psNLSF_CB->quantStepSize_Q16, psNLSF_CB->order );

    /* Apply inverse square-rooted weights to first stage and add to output */
    pCB_element = &psNLSF_CB->CB1_NLSF_Q8[ NLSFIndices[ 0 ] * psNLSF_CB->order ];
    pCB_Wght_Q9 = &psNLSF_CB->CB1_Wght_Q9[ NLSFIndices[ 0 ] * psNLSF_CB->order ];
    for( i = 0; i < psNLSF_CB->order; i++ ) {
        NLSF_Q15_tmp = silk_ADD_LSHIFT32( silk_DIV32_16( silk_LSHIFT( (opus_int32)res_Q10[ i ], 14 ), pCB_Wght_Q9[ i ] ), (opus_int16)pCB_element[ i ], 7 );
        pNLSF_Q15[ i ] = (opus_int16)silk_LIMIT( NLSF_Q15_tmp, 0, 32767 );
    }

    /* NLSF stabilization */
    silk_NLSF_stabilize( pNLSF_Q15, psNLSF_CB->deltaMin_Q15, psNLSF_CB->order );
}

/* Processing of gains */
void silk_process_gains_FIX(
    silk_encoder_state_FIX          *psEnc,                                 /* I/O  Encoder state                                                               */
    silk_encoder_control_FIX        *psEncCtrl,                             /* I/O  Encoder control                                                             */
    opus_int                        condCoding                              /* I    The type of conditional coding to use                                       */
)
{
    silk_shape_state_FIX *psShapeSt = &psEnc->sShape;
    opus_int     k;
    opus_int32   s_Q16, InvMaxSqrVal_Q16, gain, gain_squared, ResNrg, ResNrgPart, quant_offset_Q10;

    /* Gain reduction when LTP coding gain is high */
    if( psEnc->sCmn.indices.signalType == TYPE_VOICED ) {
        /*s = -0.5f * silk_sigmoid( 0.25f * ( psEncCtrl->LTPredCodGain - 12.0f ) ); */
        s_Q16 = -silk_sigm_Q15( silk_RSHIFT_ROUND( psEncCtrl->LTPredCodGain_Q7 - SILK_FIX_CONST( 12.0, 7 ), 4 ) );
        for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
            psEncCtrl->Gains_Q16[ k ] = silk_SMLAWB( psEncCtrl->Gains_Q16[ k ], psEncCtrl->Gains_Q16[ k ], s_Q16 );
        }
    }

    /* Limit the quantized signal */
    /* InvMaxSqrVal = pow( 2.0f, 0.33f * ( 21.0f - SNR_dB ) ) / subfr_length; */
    InvMaxSqrVal_Q16 = silk_DIV32_16( silk_log2lin(
        silk_SMULWB( SILK_FIX_CONST( 21 + 16 / 0.33, 7 ) - psEnc->sCmn.SNR_dB_Q7, SILK_FIX_CONST( 0.33, 16 ) ) ), psEnc->sCmn.subfr_length );

    for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
        /* Soft limit on ratio residual energy and squared gains */
        ResNrg     = psEncCtrl->ResNrg[ k ];
        ResNrgPart = silk_SMULWW( ResNrg, InvMaxSqrVal_Q16 );
        if( psEncCtrl->ResNrgQ[ k ] > 0 ) {
            ResNrgPart = silk_RSHIFT_ROUND( ResNrgPart, psEncCtrl->ResNrgQ[ k ] );
        } else {
            if( ResNrgPart >= silk_RSHIFT( silk_int32_MAX, -psEncCtrl->ResNrgQ[ k ] ) ) {
                ResNrgPart = silk_int32_MAX;
            } else {
                ResNrgPart = silk_LSHIFT( ResNrgPart, -psEncCtrl->ResNrgQ[ k ] );
            }
        }
        gain = psEncCtrl->Gains_Q16[ k ];
        gain_squared = silk_ADD_SAT32( ResNrgPart, silk_SMMUL( gain, gain ) );
        if( gain_squared < silk_int16_MAX ) {
            /* recalculate with higher precision */
            gain_squared = silk_SMLAWW( silk_LSHIFT( ResNrgPart, 16 ), gain, gain );
            silk_assert( gain_squared > 0 );
            gain = silk_SQRT_APPROX( gain_squared );                    /* Q8   */
            gain = silk_min( gain, silk_int32_MAX >> 8 );
            psEncCtrl->Gains_Q16[ k ] = silk_LSHIFT_SAT32( gain, 8 );   /* Q16  */
        } else {

/* Convert int32 coefficients to int16 coefs and make sure there's no wrap-around */
void silk_LPC_fit(
    opus_int16                  *a_QOUT,            /* O    Output signal                                               */
    opus_int32                    *a_QIN,             /* I/O  Input signal                                                */
    const opus_int              QOUT,               /* I    Input Q domain                                              */
    const opus_int              QIN,                /* I    Input Q domain                                              */
    const opus_int              d                   /* I    Filter order                                                */
)
{
    opus_int    i, k, idx = 0;
    opus_int32    maxabs, absval, chirp_Q16;

    /* Limit the maximum absolute value of the prediction coefficients, so that they'll fit in int16 */
    for( i = 0; i < 10; i++ ) {
        /* Find maximum absolute value and its index */
        maxabs = 0;
        for( k = 0; k < d; k++ ) {
            absval = silk_abs( a_QIN[k] );
            if( absval > maxabs ) {
                maxabs = absval;
                idx    = k;
            }
        }
        maxabs = silk_RSHIFT_ROUND( maxabs, QIN - QOUT );

        if( maxabs > silk_int16_MAX ) {
            /* Reduce magnitude of prediction coefficients */
            maxabs = silk_min( maxabs, 163838 );  /* ( silk_int32_MAX >> 14 ) + silk_int16_MAX = 163838 */
            chirp_Q16 = SILK_FIX_CONST( 0.999, 16 ) - silk_DIV32( silk_LSHIFT( maxabs - silk_int16_MAX, 14 ),
                                        silk_RSHIFT32( silk_MUL( maxabs, idx + 1), 2 ) );
            silk_bwexpander_32( a_QIN, d, chirp_Q16 );
        } else {
            break;
        }
    }

    if( i == 10 ) {
        /* Reached the last iteration, clip the coefficients */
        for( k = 0; k < d; k++ ) {
            a_QOUT[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( a_QIN[ k ], QIN - QOUT ) );
            a_QIN[ k ] = silk_LSHIFT( (opus_int32)a_QOUT[ k ], QIN - QOUT );
        }
    } else {
        for( k = 0; k < d; k++ ) {
            a_QOUT[ k ] = (opus_int16)silk_RSHIFT_ROUND( a_QIN[ k ], QIN - QOUT );
        }
    }
}

void silk_PLC_Reset(
    silk_decoder_state                  *psDec              /* I/O Decoder state        */
)
{
    psDec->sPLC.pitchL_Q8 = silk_LSHIFT( psDec->frame_length, 8 - 1 );
    psDec->sPLC.prevGain_Q16[ 0 ] = SILK_FIX_CONST( 1, 16 );
    psDec->sPLC.prevGain_Q16[ 1 ] = SILK_FIX_CONST( 1, 16 );
    psDec->sPLC.subfr_length = 20;
    psDec->sPLC.nb_subfr = 2;
}

/* Step up function, converts reflection coefficients to prediction coefficients */
void silk_k2a(
    opus_int32                  *A_Q24,             /* O    Prediction coefficients [order] Q24                         */
    const opus_int16            *rc_Q15,            /* I    Reflection coefficients [order] Q15                         */
    const opus_int32            order               /* I    Prediction order                                            */
)
{
    opus_int   k, n;
    opus_int32 Atmp[ SILK_MAX_ORDER_LPC ];

    for( k = 0; k < order; k++ ) {
        for( n = 0; n < k; n++ ) {
            Atmp[ n ] = A_Q24[ n ];
        }
        for( n = 0; n < k; n++ ) {
            A_Q24[ n ] = silk_SMLAWB( A_Q24[ n ], silk_LSHIFT( Atmp[ k - n - 1 ], 1 ), rc_Q15[ k ] );
        }
        A_Q24[ k ] = -silk_LSHIFT( (opus_int32)rc_Q15[ k ], 9 );
    }
}