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#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "main_FLP.h"

#define MAX_ITERATIONS_RESIDUAL_NRG         10

#define REGULARIZATION_FACTOR               1e-8f

/* Residual energy: nrg = wxx - 2 * wXx * c + c' * wXX * c */

silk_float silk_residual_energy_covar_FLP(                              /* O    Weighted residual energy                    */

    const silk_float                *c,                                 /* I    Filter coefficients                         */

    silk_float                      *wXX,                               /* I/O  Weighted correlation matrix, reg. out       */

    const silk_float                *wXx,                               /* I    Weighted correlation vector                 */

    const silk_float                wxx,                                /* I    Weighted correlation value                  */

    const opus_int                  D                                   /* I    Dimension                                   */

)

{

    opus_int   i, j, k;

    silk_float tmp, nrg = 0.0f, regularization;

    /* Safety checks */

    celt_assert( D >= 0 );

    regularization = REGULARIZATION_FACTOR * ( wXX[ 0 ] + wXX[ D * D - 1 ] );

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

        nrg = wxx;

        tmp = 0.0f;

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

            tmp += wXx[ i ] * c[ i ];

        }

        nrg -= 2.0f * tmp;

        /* compute c' * wXX * c, assuming wXX is symmetric */

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

            tmp = 0.0f;

            for( j = i + 1; j < D; j++ ) {

                tmp += matrix_c_ptr( wXX, i, j, D ) * c[ j ];

            }

            nrg += c[ i ] * ( 2.0f * tmp + matrix_c_ptr( wXX, i, i, D ) * c[ i ] );

        }

        if( nrg > 0 ) {

            break;

        } else {

            /* Add white noise */

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

                matrix_c_ptr( wXX, i, i, D ) +=  regularization;

            }

            /* Increase noise for next run */

            regularization *= 2.0f;

        }

    }

    if( k == MAX_ITERATIONS_RESIDUAL_NRG ) {

        silk_assert( nrg == 0 );

        nrg = 1.0f;

    }

    return nrg;

}

/* Calculates residual energies of input subframes where all subframes have LPC_order   */

/* of preceding samples                                                                 */

void silk_residual_energy_FLP(

    silk_float                      nrgs[ MAX_NB_SUBFR ],               /* O    Residual energy per subframe                */

    const silk_float                x[],                                /* I    Input signal                                */

    silk_float                      a[ 2 ][ MAX_LPC_ORDER ],            /* I    AR coefs for each frame half                */

    const silk_float                gains[],                            /* I    Quantization gains                          */

    const opus_int                  subfr_length,                       /* I    Subframe length                             */

    const opus_int                  nb_subfr,                           /* I    number of subframes                         */

    const opus_int                  LPC_order                           /* I    LPC order                                   */

)

{

    opus_int     shift;

    silk_float   *LPC_res_ptr, LPC_res[ ( MAX_FRAME_LENGTH + MAX_NB_SUBFR * MAX_LPC_ORDER ) / 2 ];

    LPC_res_ptr = LPC_res + LPC_order;

    shift = LPC_order + subfr_length;

    /* Filter input to create the LPC residual for each frame half, and measure subframe energies */

    silk_LPC_analysis_filter_FLP( LPC_res, a[ 0 ], x + 0 * shift, 2 * shift, LPC_order );

    nrgs[ 0 ] = ( silk_float )( gains[ 0 ] * gains[ 0 ] * silk_energy_FLP( LPC_res_ptr + 0 * shift, subfr_length ) );

    nrgs[ 1 ] = ( silk_float )( gains[ 1 ] * gains[ 1 ] * silk_energy_FLP( LPC_res_ptr + 1 * shift, subfr_length ) );

    if( nb_subfr == MAX_NB_SUBFR ) {

        silk_LPC_analysis_filter_FLP( LPC_res, a[ 1 ], x + 2 * shift, 2 * shift, LPC_order );

        nrgs[ 2 ] = ( silk_float )( gains[ 2 ] * gains[ 2 ] * silk_energy_FLP( LPC_res_ptr + 0 * shift, subfr_length ) );

        nrgs[ 3 ] = ( silk_float )( gains[ 3 ] * gains[ 3 ] * silk_energy_FLP( LPC_res_ptr + 1 * shift, subfr_length ) );

    }

}