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#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "main_FIX.h"

#include "stack_alloc.h"

#include "tuning_parameters.h"

/* Finds LPC vector from correlations, and converts to NLSF */

void silk_find_LPC_FIX(

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

    opus_int16                      NLSF_Q15[],                             /* O    NLSFs                                                                       */

    const opus_int16                x[],                                    /* I    Input signal                                                                */

    const opus_int32                minInvGain_Q30                          /* I    Inverse of max prediction gain                                              */

)

{

    opus_int     k, subfr_length;

    opus_int32   a_Q16[ MAX_LPC_ORDER ];

    opus_int     isInterpLower, shift;

    opus_int32   res_nrg0, res_nrg1;

    opus_int     rshift0, rshift1;

    /* Used only for LSF interpolation */

    opus_int32   a_tmp_Q16[ MAX_LPC_ORDER ], res_nrg_interp, res_nrg, res_tmp_nrg;

    opus_int     res_nrg_interp_Q, res_nrg_Q, res_tmp_nrg_Q;

    opus_int16   a_tmp_Q12[ MAX_LPC_ORDER ];

    opus_int16   NLSF0_Q15[ MAX_LPC_ORDER ];

    SAVE_STACK;

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

    /* Default: no interpolation */

    psEncC->indices.NLSFInterpCoef_Q2 = 4;

    /* Burg AR analysis for the full frame */

    silk_burg_modified( &res_nrg, &res_nrg_Q, a_Q16, x, minInvGain_Q30, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder, psEncC->arch );

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

        VARDECL( opus_int16, LPC_res );

        /* Optimal solution for last 10 ms */

        silk_burg_modified( &res_tmp_nrg, &res_tmp_nrg_Q, a_tmp_Q16, x + 2 * subfr_length, minInvGain_Q30, subfr_length, 2, psEncC->predictLPCOrder, psEncC->arch );

        /* 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 */

        shift = res_tmp_nrg_Q - res_nrg_Q;

        if( shift >= 0 ) {

            if( shift < 32 ) {

                res_nrg = res_nrg - silk_RSHIFT( res_tmp_nrg, shift );

            }

        } else {

            silk_assert( shift > -32 );

            res_nrg   = silk_RSHIFT( res_nrg, -shift ) - res_tmp_nrg;

            res_nrg_Q = res_tmp_nrg_Q;

        }

        /* Convert to NLSFs */

        silk_A2NLSF( NLSF_Q15, a_tmp_Q16, psEncC->predictLPCOrder );

        ALLOC( LPC_res, 2 * subfr_length, opus_int16 );

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

        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( a_tmp_Q12, NLSF0_Q15, psEncC->predictLPCOrder, psEncC->arch );

            /* Calculate residual energy with NLSF interpolation */

            silk_LPC_analysis_filter( LPC_res, x, a_tmp_Q12, 2 * subfr_length, psEncC->predictLPCOrder, psEncC->arch );

            silk_sum_sqr_shift( &res_nrg0, &rshift0, LPC_res + psEncC->predictLPCOrder,                subfr_length - psEncC->predictLPCOrder );

            silk_sum_sqr_shift( &res_nrg1, &rshift1, LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder );

            /* Add subframe energies from first half frame */

            shift = rshift0 - rshift1;

            if( shift >= 0 ) {

                res_nrg1         = silk_RSHIFT( res_nrg1, shift );

                res_nrg_interp_Q = -rshift0;

            } else {

                res_nrg0         = silk_RSHIFT( res_nrg0, -shift );

                res_nrg_interp_Q = -rshift1;

            }

            res_nrg_interp = silk_ADD32( res_nrg0, res_nrg1 );

            /* Compare with first half energy without NLSF interpolation, or best interpolated value so far */

            shift = res_nrg_interp_Q - res_nrg_Q;

            if( shift >= 0 ) {

                if( silk_RSHIFT( res_nrg_interp, shift ) < res_nrg ) {

                    isInterpLower = silk_TRUE;

                } else {

                    isInterpLower = silk_FALSE;

                }

            } else {

                if( -shift < 32 ) {

                    if( res_nrg_interp < silk_RSHIFT( res_nrg, -shift ) ) {

                        isInterpLower = silk_TRUE;

                    } else {

                        isInterpLower = silk_FALSE;

                    }

                } else {

                    isInterpLower = silk_FALSE;

                }

            }

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

            if( isInterpLower == silk_TRUE ) {

                /* Interpolation has lower residual energy */

                res_nrg   = res_nrg_interp;

                res_nrg_Q = res_nrg_interp_Q;

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

            }

        }

    }

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

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

        silk_A2NLSF( NLSF_Q15, a_Q16, psEncC->predictLPCOrder );

    }

    celt_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 || ( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) );

    RESTORE_STACK;

}