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#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include "main.h"

#include "stack_alloc.h"

/**********************************************************/

/* Core decoder. Performs inverse NSQ operation LTP + LPC */

/**********************************************************/

void silk_decode_core(

    silk_decoder_state          *psDec,                         /* I/O  Decoder state                               */

    silk_decoder_control        *psDecCtrl,                     /* I    Decoder control                             */

    opus_int16                  xq[],                           /* O    Decoded speech                              */

    const opus_int16            pulses[ MAX_FRAME_LENGTH ],     /* I    Pulse signal                                */

    int                         arch                            /* I    Run-time architecture                       */

)

{

    opus_int   i, k, lag = 0, start_idx, sLTP_buf_idx, NLSF_interpolation_flag, signalType;

    opus_int16 *A_Q12, *B_Q14, *pxq, A_Q12_tmp[ MAX_LPC_ORDER ];

    VARDECL( opus_int16, sLTP );

    VARDECL( opus_int32, sLTP_Q15 );

    opus_int32 LTP_pred_Q13, LPC_pred_Q10, Gain_Q10, inv_gain_Q31, gain_adj_Q16, rand_seed, offset_Q10;

    opus_int32 *pred_lag_ptr, *pexc_Q14, *pres_Q14;

    VARDECL( opus_int32, res_Q14 );

    VARDECL( opus_int32, sLPC_Q14 );

    SAVE_STACK;

    silk_assert( psDec->prev_gain_Q16 != 0 );

    ALLOC( sLTP, psDec->ltp_mem_length, opus_int16 );

    ALLOC( sLTP_Q15, psDec->ltp_mem_length + psDec->frame_length, opus_int32 );

    ALLOC( res_Q14, psDec->subfr_length, opus_int32 );

    ALLOC( sLPC_Q14, psDec->subfr_length + MAX_LPC_ORDER, opus_int32 );

    offset_Q10 = silk_Quantization_Offsets_Q10[ psDec->indices.signalType >> 1 ][ psDec->indices.quantOffsetType ];

    if( psDec->indices.NLSFInterpCoef_Q2 < 1 << 2 ) {

        NLSF_interpolation_flag = 1;

    } else {

        NLSF_interpolation_flag = 0;

    }

    /* Decode excitation */

    rand_seed = psDec->indices.Seed;

    for( i = 0; i < psDec->frame_length; i++ ) {

        rand_seed = silk_RAND( rand_seed );

        psDec->exc_Q14[ i ] = silk_LSHIFT( (opus_int32)pulses[ i ], 14 );

        if( psDec->exc_Q14[ i ] > 0 ) {

            psDec->exc_Q14[ i ] -= QUANT_LEVEL_ADJUST_Q10 << 4;

        } else

        if( psDec->exc_Q14[ i ] < 0 ) {

            psDec->exc_Q14[ i ] += QUANT_LEVEL_ADJUST_Q10 << 4;

        }

        psDec->exc_Q14[ i ] += offset_Q10 << 4;

        if( rand_seed < 0 ) {

           psDec->exc_Q14[ i ] = -psDec->exc_Q14[ i ];

        }

        rand_seed = silk_ADD32_ovflw( rand_seed, pulses[ i ] );

    }

    /* Copy LPC state */

    silk_memcpy( sLPC_Q14, psDec->sLPC_Q14_buf, MAX_LPC_ORDER * sizeof( opus_int32 ) );

    pexc_Q14 = psDec->exc_Q14;

    pxq      = xq;

    sLTP_buf_idx = psDec->ltp_mem_length;

    /* Loop over subframes */

    for( k = 0; k < psDec->nb_subfr; k++ ) {

        pres_Q14 = res_Q14;

        A_Q12 = psDecCtrl->PredCoef_Q12[ k >> 1 ];

        /* Preload LPC coeficients to array on stack. Gives small performance gain */

        silk_memcpy( A_Q12_tmp, A_Q12, psDec->LPC_order * sizeof( opus_int16 ) );

        B_Q14        = &psDecCtrl->LTPCoef_Q14[ k * LTP_ORDER ];

        signalType   = psDec->indices.signalType;

        Gain_Q10     = silk_RSHIFT( psDecCtrl->Gains_Q16[ k ], 6 );

        inv_gain_Q31 = silk_INVERSE32_varQ( psDecCtrl->Gains_Q16[ k ], 47 );

        /* Calculate gain adjustment factor */

        if( psDecCtrl->Gains_Q16[ k ] != psDec->prev_gain_Q16 ) {

            gain_adj_Q16 =  silk_DIV32_varQ( psDec->prev_gain_Q16, psDecCtrl->Gains_Q16[ k ], 16 );

            /* Scale short term state */

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

                sLPC_Q14[ i ] = silk_SMULWW( gain_adj_Q16, sLPC_Q14[ i ] );

            }

        } else {

            gain_adj_Q16 = (opus_int32)1 << 16;

        }

        /* Save inv_gain */

        silk_assert( inv_gain_Q31 != 0 );

        psDec->prev_gain_Q16 = psDecCtrl->Gains_Q16[ k ];

        /* Avoid abrupt transition from voiced PLC to unvoiced normal decoding */

        if( psDec->lossCnt && psDec->prevSignalType == TYPE_VOICED &&

            psDec->indices.signalType != TYPE_VOICED && k < MAX_NB_SUBFR/2 ) {

            silk_memset( B_Q14, 0, LTP_ORDER * sizeof( opus_int16 ) );

            B_Q14[ LTP_ORDER/2 ] = SILK_FIX_CONST( 0.25, 14 );

            signalType = TYPE_VOICED;

            psDecCtrl->pitchL[ k ] = psDec->lagPrev;

        }

        if( signalType == TYPE_VOICED ) {

            /* Voiced */

            lag = psDecCtrl->pitchL[ k ];

            /* Re-whitening */

            if( k == 0 || ( k == 2 && NLSF_interpolation_flag ) ) {

                /* Rewhiten with new A coefs */

                start_idx = psDec->ltp_mem_length - lag - psDec->LPC_order - LTP_ORDER / 2;

                celt_assert( start_idx > 0 );

                if( k == 2 ) {

                    silk_memcpy( &psDec->outBuf[ psDec->ltp_mem_length ], xq, 2 * psDec->subfr_length * sizeof( opus_int16 ) );

                }

                silk_LPC_analysis_filter( &sLTP[ start_idx ], &psDec->outBuf[ start_idx + k * psDec->subfr_length ],

                    A_Q12, psDec->ltp_mem_length - start_idx, psDec->LPC_order, arch );

                /* After rewhitening the LTP state is unscaled */

                if( k == 0 ) {

                    /* Do LTP downscaling to reduce inter-packet dependency */

                    inv_gain_Q31 = silk_LSHIFT( silk_SMULWB( inv_gain_Q31, psDecCtrl->LTP_scale_Q14 ), 2 );

                }

                for( i = 0; i < lag + LTP_ORDER/2; i++ ) {

                    sLTP_Q15[ sLTP_buf_idx - i - 1 ] = silk_SMULWB( inv_gain_Q31, sLTP[ psDec->ltp_mem_length - i - 1 ] );

                }

            } else {

                /* Update LTP state when Gain changes */

                if( gain_adj_Q16 != (opus_int32)1 << 16 ) {

                    for( i = 0; i < lag + LTP_ORDER/2; i++ ) {

                        sLTP_Q15[ sLTP_buf_idx - i - 1 ] = silk_SMULWW( gain_adj_Q16, sLTP_Q15[ sLTP_buf_idx - i - 1 ] );

                    }

                }

            }

        }

        /* Long-term prediction */

        if( signalType == TYPE_VOICED ) {

            /* Set up pointer */

            pred_lag_ptr = &sLTP_Q15[ sLTP_buf_idx - lag + LTP_ORDER / 2 ];

            for( i = 0; i < psDec->subfr_length; i++ ) {

                /* Unrolled loop */

                /* Avoids introducing a bias because silk_SMLAWB() always rounds to -inf */

                LTP_pred_Q13 = 2;

                LTP_pred_Q13 = silk_SMLAWB( LTP_pred_Q13, pred_lag_ptr[  0 ], B_Q14[ 0 ] );

                LTP_pred_Q13 = silk_SMLAWB( LTP_pred_Q13, pred_lag_ptr[ -1 ], B_Q14[ 1 ] );

                LTP_pred_Q13 = silk_SMLAWB( LTP_pred_Q13, pred_lag_ptr[ -2 ], B_Q14[ 2 ] );

                LTP_pred_Q13 = silk_SMLAWB( LTP_pred_Q13, pred_lag_ptr[ -3 ], B_Q14[ 3 ] );

                LTP_pred_Q13 = silk_SMLAWB( LTP_pred_Q13, pred_lag_ptr[ -4 ], B_Q14[ 4 ] );

                pred_lag_ptr++;

                /* Generate LPC excitation */

                pres_Q14[ i ] = silk_ADD_LSHIFT32( pexc_Q14[ i ], LTP_pred_Q13, 1 );

                /* Update states */

                sLTP_Q15[ sLTP_buf_idx ] = silk_LSHIFT( pres_Q14[ i ], 1 );

                sLTP_buf_idx++;

            }

        } else {

            pres_Q14 = pexc_Q14;

        }

        for( i = 0; i < psDec->subfr_length; i++ ) {

            /* Short-term prediction */

            celt_assert( psDec->LPC_order == 10 || psDec->LPC_order == 16 );

            /* Avoids introducing a bias because silk_SMLAWB() always rounds to -inf */

            LPC_pred_Q10 = silk_RSHIFT( psDec->LPC_order, 1 );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i -  1 ], A_Q12_tmp[ 0 ] );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i -  2 ], A_Q12_tmp[ 1 ] );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i -  3 ], A_Q12_tmp[ 2 ] );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i -  4 ], A_Q12_tmp[ 3 ] );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i -  5 ], A_Q12_tmp[ 4 ] );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i -  6 ], A_Q12_tmp[ 5 ] );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i -  7 ], A_Q12_tmp[ 6 ] );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i -  8 ], A_Q12_tmp[ 7 ] );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i -  9 ], A_Q12_tmp[ 8 ] );

            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 10 ], A_Q12_tmp[ 9 ] );

            if( psDec->LPC_order == 16 ) {

                LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 11 ], A_Q12_tmp[ 10 ] );

                LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 12 ], A_Q12_tmp[ 11 ] );

                LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 13 ], A_Q12_tmp[ 12 ] );

                LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 14 ], A_Q12_tmp[ 13 ] );

                LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 15 ], A_Q12_tmp[ 14 ] );

                LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14[ MAX_LPC_ORDER + i - 16 ], A_Q12_tmp[ 15 ] );

            }

            /* Add prediction to LPC excitation */

            sLPC_Q14[ MAX_LPC_ORDER + i ] = silk_ADD_SAT32( pres_Q14[ i ], silk_LSHIFT_SAT32( LPC_pred_Q10, 4 ) );

            /* Scale with gain */

            pxq[ i ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( silk_SMULWW( sLPC_Q14[ MAX_LPC_ORDER + i ], Gain_Q10 ), 8 ) );

        }

        /* Update LPC filter state */

        silk_memcpy( sLPC_Q14, &sLPC_Q14[ psDec->subfr_length ], MAX_LPC_ORDER * sizeof( opus_int32 ) );

        pexc_Q14 += psDec->subfr_length;

        pxq      += psDec->subfr_length;

    }

    /* Save LPC state */

    silk_memcpy( psDec->sLPC_Q14_buf, sLPC_Q14, MAX_LPC_ORDER * sizeof( opus_int32 ) );

    RESTORE_STACK;

}