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#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "define.h"

#include "main_FLP.h"

#include "tuning_parameters.h"

/* LPC analysis */

void silk_find_LPC_FLP(

    silk_encoder_state              *psEncC,                            /* I/O  Encoder state                               */

    opus_int16                      NLSF_Q15[],                         /* O    NLSFs                                       */

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

    const silk_float                minInvGain,                         /* I    Inverse of max prediction gain              */

    int                             arch

)

{

    opus_int    k, subfr_length;

    silk_float  a[ MAX_LPC_ORDER ];

    /* Used only for NLSF interpolation */

    silk_float  res_nrg, res_nrg_2nd, res_nrg_interp;

    opus_int16  NLSF0_Q15[ MAX_LPC_ORDER ];

    silk_float  a_tmp[ MAX_LPC_ORDER ];

    silk_float  LPC_res[ MAX_FRAME_LENGTH + MAX_NB_SUBFR * MAX_LPC_ORDER ];

    subfr_length = psEncC->subfr_length + psEncC->predictLPCOrder;

    /* Default: No interpolation */

    psEncC->indices.NLSFInterpCoef_Q2 = 4;

    /* Burg AR analysis for the full frame */

    res_nrg = silk_burg_modified_FLP( a, x, minInvGain, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder, arch );

    if( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) {

        /* Optimal solution for last 10 ms; subtract residual energy here, as that's easier than        */

        /* adding it to the residual energy of the first 10 ms in each iteration of the search below    */

        res_nrg -= silk_burg_modified_FLP( a_tmp, x + ( MAX_NB_SUBFR / 2 ) * subfr_length, minInvGain, subfr_length, MAX_NB_SUBFR / 2, psEncC->predictLPCOrder, arch );

        /* Convert to NLSFs */

        silk_A2NLSF_FLP( NLSF_Q15, a_tmp, psEncC->predictLPCOrder );

        /* Search over interpolation indices to find the one with lowest residual energy */

        res_nrg_2nd = silk_float_MAX;

        for( k = 3; k >= 0; k-- ) {

            /* Interpolate NLSFs for first half */

            silk_interpolate( NLSF0_Q15, psEncC->prev_NLSFq_Q15, NLSF_Q15, k, psEncC->predictLPCOrder );

            /* Convert to LPC for residual energy evaluation */

            silk_NLSF2A_FLP( a_tmp, NLSF0_Q15, psEncC->predictLPCOrder, psEncC->arch );

            /* Calculate residual energy with LSF interpolation */

            silk_LPC_analysis_filter_FLP( LPC_res, a_tmp, x, 2 * subfr_length, psEncC->predictLPCOrder );

            res_nrg_interp = (silk_float)(

                silk_energy_FLP( LPC_res + psEncC->predictLPCOrder,                subfr_length - psEncC->predictLPCOrder ) +

                silk_energy_FLP( LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder ) );

            /* Determine whether current interpolated NLSFs are best so far */

            if( res_nrg_interp < res_nrg ) {

                /* Interpolation has lower residual energy */

                res_nrg = res_nrg_interp;

                psEncC->indices.NLSFInterpCoef_Q2 = (opus_int8)k;

            } else if( res_nrg_interp > res_nrg_2nd ) {

                /* No reason to continue iterating - residual energies will continue to climb */

                break;

            }

            res_nrg_2nd = res_nrg_interp;

        }

    }

    if( psEncC->indices.NLSFInterpCoef_Q2 == 4 ) {

        /* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */

        silk_A2NLSF_FLP( NLSF_Q15, a, psEncC->predictLPCOrder );

    }

    celt_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 ||

        ( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) );

}