187 lines
7.7 KiB
C
187 lines
7.7 KiB
C
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/***********************************************************************
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Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of Internet Society, IETF or IETF Trust, nor the
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names of specific contributors, may be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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***********************************************************************/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "SigProc_FLP.h"
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#include "tuning_parameters.h"
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#include "define.h"
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#define MAX_FRAME_SIZE 384 /* subfr_length * nb_subfr = ( 0.005 * 16000 + 16 ) * 4 = 384*/
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/* Compute reflection coefficients from input signal */
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silk_float silk_burg_modified_FLP( /* O returns residual energy */
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silk_float A[], /* O prediction coefficients (length order) */
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const silk_float x[], /* I input signal, length: nb_subfr*(D+L_sub) */
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const silk_float minInvGain, /* I minimum inverse prediction gain */
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const opus_int subfr_length, /* I input signal subframe length (incl. D preceding samples) */
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const opus_int nb_subfr, /* I number of subframes stacked in x */
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const opus_int D /* I order */
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)
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{
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opus_int k, n, s, reached_max_gain;
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double C0, invGain, num, nrg_f, nrg_b, rc, Atmp, tmp1, tmp2;
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const silk_float *x_ptr;
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double C_first_row[ SILK_MAX_ORDER_LPC ], C_last_row[ SILK_MAX_ORDER_LPC ];
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double CAf[ SILK_MAX_ORDER_LPC + 1 ], CAb[ SILK_MAX_ORDER_LPC + 1 ];
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double Af[ SILK_MAX_ORDER_LPC ];
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celt_assert( subfr_length * nb_subfr <= MAX_FRAME_SIZE );
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/* Compute autocorrelations, added over subframes */
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C0 = silk_energy_FLP( x, nb_subfr * subfr_length );
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silk_memset( C_first_row, 0, SILK_MAX_ORDER_LPC * sizeof( double ) );
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for( s = 0; s < nb_subfr; s++ ) {
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x_ptr = x + s * subfr_length;
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for( n = 1; n < D + 1; n++ ) {
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C_first_row[ n - 1 ] += silk_inner_product_FLP( x_ptr, x_ptr + n, subfr_length - n );
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}
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}
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silk_memcpy( C_last_row, C_first_row, SILK_MAX_ORDER_LPC * sizeof( double ) );
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/* Initialize */
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CAb[ 0 ] = CAf[ 0 ] = C0 + FIND_LPC_COND_FAC * C0 + 1e-9f;
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invGain = 1.0f;
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reached_max_gain = 0;
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for( n = 0; n < D; n++ ) {
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/* Update first row of correlation matrix (without first element) */
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/* Update last row of correlation matrix (without last element, stored in reversed order) */
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/* Update C * Af */
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/* Update C * flipud(Af) (stored in reversed order) */
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for( s = 0; s < nb_subfr; s++ ) {
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x_ptr = x + s * subfr_length;
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tmp1 = x_ptr[ n ];
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tmp2 = x_ptr[ subfr_length - n - 1 ];
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for( k = 0; k < n; k++ ) {
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C_first_row[ k ] -= x_ptr[ n ] * x_ptr[ n - k - 1 ];
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C_last_row[ k ] -= x_ptr[ subfr_length - n - 1 ] * x_ptr[ subfr_length - n + k ];
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Atmp = Af[ k ];
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tmp1 += x_ptr[ n - k - 1 ] * Atmp;
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tmp2 += x_ptr[ subfr_length - n + k ] * Atmp;
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}
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for( k = 0; k <= n; k++ ) {
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CAf[ k ] -= tmp1 * x_ptr[ n - k ];
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CAb[ k ] -= tmp2 * x_ptr[ subfr_length - n + k - 1 ];
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}
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}
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tmp1 = C_first_row[ n ];
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tmp2 = C_last_row[ n ];
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for( k = 0; k < n; k++ ) {
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Atmp = Af[ k ];
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tmp1 += C_last_row[ n - k - 1 ] * Atmp;
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tmp2 += C_first_row[ n - k - 1 ] * Atmp;
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}
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CAf[ n + 1 ] = tmp1;
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CAb[ n + 1 ] = tmp2;
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/* Calculate nominator and denominator for the next order reflection (parcor) coefficient */
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num = CAb[ n + 1 ];
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nrg_b = CAb[ 0 ];
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nrg_f = CAf[ 0 ];
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for( k = 0; k < n; k++ ) {
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Atmp = Af[ k ];
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num += CAb[ n - k ] * Atmp;
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nrg_b += CAb[ k + 1 ] * Atmp;
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nrg_f += CAf[ k + 1 ] * Atmp;
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}
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silk_assert( nrg_f > 0.0 );
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silk_assert( nrg_b > 0.0 );
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/* Calculate the next order reflection (parcor) coefficient */
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rc = -2.0 * num / ( nrg_f + nrg_b );
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silk_assert( rc > -1.0 && rc < 1.0 );
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/* Update inverse prediction gain */
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tmp1 = invGain * ( 1.0 - rc * rc );
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if( tmp1 <= minInvGain ) {
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/* Max prediction gain exceeded; set reflection coefficient such that max prediction gain is exactly hit */
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rc = sqrt( 1.0 - minInvGain / invGain );
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if( num > 0 ) {
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/* Ensure adjusted reflection coefficients has the original sign */
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rc = -rc;
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}
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invGain = minInvGain;
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reached_max_gain = 1;
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} else {
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invGain = tmp1;
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}
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/* Update the AR coefficients */
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for( k = 0; k < (n + 1) >> 1; k++ ) {
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tmp1 = Af[ k ];
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tmp2 = Af[ n - k - 1 ];
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Af[ k ] = tmp1 + rc * tmp2;
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Af[ n - k - 1 ] = tmp2 + rc * tmp1;
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}
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Af[ n ] = rc;
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if( reached_max_gain ) {
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/* Reached max prediction gain; set remaining coefficients to zero and exit loop */
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for( k = n + 1; k < D; k++ ) {
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Af[ k ] = 0.0;
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}
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break;
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}
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/* Update C * Af and C * Ab */
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for( k = 0; k <= n + 1; k++ ) {
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tmp1 = CAf[ k ];
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CAf[ k ] += rc * CAb[ n - k + 1 ];
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CAb[ n - k + 1 ] += rc * tmp1;
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}
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}
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if( reached_max_gain ) {
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/* Convert to silk_float */
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for( k = 0; k < D; k++ ) {
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A[ k ] = (silk_float)( -Af[ k ] );
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}
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/* Subtract energy of preceding samples from C0 */
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for( s = 0; s < nb_subfr; s++ ) {
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C0 -= silk_energy_FLP( x + s * subfr_length, D );
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}
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/* Approximate residual energy */
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nrg_f = C0 * invGain;
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} else {
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/* Compute residual energy and store coefficients as silk_float */
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nrg_f = CAf[ 0 ];
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tmp1 = 1.0;
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for( k = 0; k < D; k++ ) {
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Atmp = Af[ k ];
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nrg_f += CAf[ k + 1 ] * Atmp;
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tmp1 += Atmp * Atmp;
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A[ k ] = (silk_float)(-Atmp);
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}
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nrg_f -= FIND_LPC_COND_FAC * C0 * tmp1;
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}
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/* Return residual energy */
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return (silk_float)nrg_f;
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}
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