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

#include "SKP_Silk_main.h"

/* Decode parameters from payload */
void SKP_Silk_decode_parameters(
    SKP_Silk_decoder_state      *psDec,             /* I/O  State                                       */
    SKP_Silk_decoder_control    *psDecCtrl,         /* I/O  Decoder control                             */
    SKP_int                     q[],                /* O    Excitation signal                           */
    const SKP_int               fullDecoding        /* I    Flag to tell if only arithmetic decoding    */
)
{
    SKP_int   i, k, Ix, fs_kHz_dec, nBytesUsed;
    SKP_int   Ixs[ NB_SUBFR ];
    SKP_int   GainsIndices[ NB_SUBFR ];
    SKP_int   NLSFIndices[ NLSF_MSVQ_MAX_CB_STAGES ];
    SKP_int   pNLSF_Q15[ MAX_LPC_ORDER ], pNLSF0_Q15[ MAX_LPC_ORDER ];
    const SKP_int16 *cbk_ptr_Q14;
    const SKP_Silk_NLSF_CB_struct *psNLSF_CB = NULL;
    SKP_Silk_range_coder_state  *psRC = &psDec->sRC;

    /************************/
    /* Decode sampling rate */
    /************************/
    /* only done for first frame of packet */
    if( psDec->nFramesDecoded == 0 ) {
        SKP_Silk_range_decoder( &Ix, psRC, SKP_Silk_SamplingRates_CDF, SKP_Silk_SamplingRates_offset );

        /* check that sampling rate is supported */
        if( Ix < 0 || Ix > 3 ) {
            psRC->error = RANGE_CODER_ILLEGAL_SAMPLING_RATE;
            return;
        }
        fs_kHz_dec = SKP_Silk_SamplingRates_table[ Ix ];
        SKP_Silk_decoder_set_fs( psDec, fs_kHz_dec );
    }

    /*******************************************/
    /* Decode signal type and quantizer offset */
    /*******************************************/
    if( psDec->nFramesDecoded == 0 ) {
        /* first frame in packet: independent coding */
        SKP_Silk_range_decoder( &Ix, psRC, SKP_Silk_type_offset_CDF, SKP_Silk_type_offset_CDF_offset );
    } else {
        /* condidtional coding */
        SKP_Silk_range_decoder( &Ix, psRC, SKP_Silk_type_offset_joint_CDF[ psDec->typeOffsetPrev ], 
                SKP_Silk_type_offset_CDF_offset );
    }
    psDecCtrl->sigtype         = SKP_RSHIFT( Ix, 1 );
    psDecCtrl->QuantOffsetType = Ix & 1;
    psDec->typeOffsetPrev      = Ix;

    /****************/
    /* Decode gains */
    /****************/
    /* first subframe */    
    if( psDec->nFramesDecoded == 0 ) {
        /* first frame in packet: independent coding */
        SKP_Silk_range_decoder( &GainsIndices[ 0 ], psRC, SKP_Silk_gain_CDF[ psDecCtrl->sigtype ], SKP_Silk_gain_CDF_offset );
    } else {
        /* condidtional coding */
        SKP_Silk_range_decoder( &GainsIndices[ 0 ], psRC, SKP_Silk_delta_gain_CDF, SKP_Silk_delta_gain_CDF_offset );
    }

    /* remaining subframes */
    for( i = 1; i < NB_SUBFR; i++ ) {
        SKP_Silk_range_decoder( &GainsIndices[ i ], psRC, SKP_Silk_delta_gain_CDF, SKP_Silk_delta_gain_CDF_offset );
    }
    
    /* Dequant Gains */
    SKP_Silk_gains_dequant( psDecCtrl->Gains_Q16, GainsIndices, &psDec->LastGainIndex, psDec->nFramesDecoded );
    /****************/
    /* Decode NLSFs */
    /****************/
    /* Set pointer to NLSF VQ CB for the current signal type */
    psNLSF_CB = psDec->psNLSF_CB[ psDecCtrl->sigtype ];

    /* Arithmetically decode NLSF path */
    SKP_Silk_range_decoder_multi( NLSFIndices, psRC, psNLSF_CB->StartPtr, psNLSF_CB->MiddleIx, psNLSF_CB->nStages );

    /* From the NLSF path, decode an NLSF vector */
    SKP_Silk_NLSF_MSVQ_decode( pNLSF_Q15, psNLSF_CB, NLSFIndices, psDec->LPC_order );

    /************************************/
    /* Decode NLSF interpolation factor */
    /************************************/
    SKP_Silk_range_decoder( &psDecCtrl->NLSFInterpCoef_Q2, psRC, SKP_Silk_NLSF_interpolation_factor_CDF, 
        SKP_Silk_NLSF_interpolation_factor_offset );
    
    /* If just reset, e.g., because internal Fs changed, do not allow interpolation */
    /* improves the case of packet loss in the first frame after a switch           */
    if( psDec->first_frame_after_reset == 1 ) {
        psDecCtrl->NLSFInterpCoef_Q2 = 4;
    }

    if( fullDecoding ) {
        /* Convert NLSF parameters to AR prediction filter coefficients */
        SKP_Silk_NLSF2A_stable( psDecCtrl->PredCoef_Q12[ 1 ], pNLSF_Q15, psDec->LPC_order );

        if( psDecCtrl->NLSFInterpCoef_Q2 < 4 ) {
            /* Calculation of the interpolated NLSF0 vector from the interpolation factor, */ 
            /* the previous NLSF1, and the current NLSF1                                   */
            for( i = 0; i < psDec->LPC_order; i++ ) {
                pNLSF0_Q15[ i ] = psDec->prevNLSF_Q15[ i ] + SKP_RSHIFT( SKP_MUL( psDecCtrl->NLSFInterpCoef_Q2, 
                    ( pNLSF_Q15[ i ] - psDec->prevNLSF_Q15[ i ] ) ), 2 );
            }

            /* Convert NLSF parameters to AR prediction filter coefficients */
            SKP_Silk_NLSF2A_stable( psDecCtrl->PredCoef_Q12[ 0 ], pNLSF0_Q15, psDec->LPC_order );
        } else {
            /* Copy LPC coefficients for first half from second half */
            SKP_memcpy( psDecCtrl->PredCoef_Q12[ 0 ], psDecCtrl->PredCoef_Q12[ 1 ], 
                psDec->LPC_order * sizeof( SKP_int16 ) );
        }
    }

    SKP_memcpy( psDec->prevNLSF_Q15, pNLSF_Q15, psDec->LPC_order * sizeof( SKP_int ) );

    /* After a packet loss do BWE of LPC coefs */
    if( psDec->lossCnt ) {
        SKP_Silk_bwexpander( psDecCtrl->PredCoef_Q12[ 0 ], psDec->LPC_order, BWE_AFTER_LOSS_Q16 );
        SKP_Silk_bwexpander( psDecCtrl->PredCoef_Q12[ 1 ], psDec->LPC_order, BWE_AFTER_LOSS_Q16 );
    }

    if( psDecCtrl->sigtype == SIG_TYPE_VOICED ) {
        /*********************/
        /* Decode pitch lags */
        /*********************/
        /* Get lag index */
        if( psDec->fs_kHz == 8 ) {
            SKP_Silk_range_decoder( &Ixs[ 0 ], psRC, SKP_Silk_pitch_lag_NB_CDF,  SKP_Silk_pitch_lag_NB_CDF_offset );
        } else if( psDec->fs_kHz == 12 ) {
            SKP_Silk_range_decoder( &Ixs[ 0 ], psRC, SKP_Silk_pitch_lag_MB_CDF,  SKP_Silk_pitch_lag_MB_CDF_offset );
        } else if( psDec->fs_kHz == 16 ) {
            SKP_Silk_range_decoder( &Ixs[ 0 ], psRC, SKP_Silk_pitch_lag_WB_CDF,  SKP_Silk_pitch_lag_WB_CDF_offset );
        } else {
            SKP_Silk_range_decoder( &Ixs[ 0 ], psRC, SKP_Silk_pitch_lag_SWB_CDF, SKP_Silk_pitch_lag_SWB_CDF_offset );
        }
        
        /* Get countour index */
        if( psDec->fs_kHz == 8 ) {
            /* Less codevectors used in 8 khz mode */
            SKP_Silk_range_decoder( &Ixs[ 1 ], psRC, SKP_Silk_pitch_contour_NB_CDF, SKP_Silk_pitch_contour_NB_CDF_offset );
        } else {
            /* Joint for 12, 16, and 24 khz */
            SKP_Silk_range_decoder( &Ixs[ 1 ], psRC, SKP_Silk_pitch_contour_CDF, SKP_Silk_pitch_contour_CDF_offset );
        }
        
        /* Decode pitch values */
        SKP_Silk_decode_pitch( Ixs[ 0 ], Ixs[ 1 ], psDecCtrl->pitchL, psDec->fs_kHz );

        /********************/
        /* Decode LTP gains */
        /********************/
        /* Decode PERIndex value */
        SKP_Silk_range_decoder( &psDecCtrl->PERIndex, psRC, SKP_Silk_LTP_per_index_CDF, 
                SKP_Silk_LTP_per_index_CDF_offset );

        /* Decode Codebook Index */
        cbk_ptr_Q14 = SKP_Silk_LTP_vq_ptrs_Q14[ psDecCtrl->PERIndex ]; // set pointer to start of codebook
        
        for( k = 0; k < NB_SUBFR; k++ ) {
            SKP_Silk_range_decoder( &Ix, psRC, SKP_Silk_LTP_gain_CDF_ptrs[ psDecCtrl->PERIndex ], 
                SKP_Silk_LTP_gain_CDF_offsets[ psDecCtrl->PERIndex ] );

            for( i = 0; i < LTP_ORDER; i++ ) {
                psDecCtrl->LTPCoef_Q14[ SKP_SMULBB( k, LTP_ORDER ) + i ] = cbk_ptr_Q14[ SKP_SMULBB( Ix, LTP_ORDER ) + i ];
            }
        }

        /**********************/
        /* Decode LTP scaling */
        /**********************/
        SKP_Silk_range_decoder( &Ix, psRC, SKP_Silk_LTPscale_CDF, SKP_Silk_LTPscale_offset );
        psDecCtrl->LTP_scale_Q14 = SKP_Silk_LTPScales_table_Q14[ Ix ];
    } else {
        SKP_memset( psDecCtrl->pitchL,      0, NB_SUBFR * sizeof( SKP_int ) );
        SKP_memset( psDecCtrl->LTPCoef_Q14, 0, NB_SUBFR * LTP_ORDER * sizeof( SKP_int16 ) );
        psDecCtrl->PERIndex      = 0;
        psDecCtrl->LTP_scale_Q14 = 0;
    }

    /***************/
    /* Decode seed */
    /***************/
    SKP_Silk_range_decoder( &Ix, psRC, SKP_Silk_Seed_CDF, SKP_Silk_Seed_offset );
    psDecCtrl->Seed = ( SKP_int32 )Ix;
    /*********************************************/
    /* Decode quantization indices of excitation */
    /*********************************************/
    SKP_Silk_decode_pulses( psRC, psDecCtrl, q, psDec->frame_length );

    /*********************************************/
    /* Decode VAD flag                           */
    /*********************************************/
    SKP_Silk_range_decoder( &psDec->vadFlag, psRC, SKP_Silk_vadflag_CDF, SKP_Silk_vadflag_offset );

    /**************************************/
    /* Decode Frame termination indicator */
    /**************************************/
    SKP_Silk_range_decoder( &psDec->FrameTermination, psRC, SKP_Silk_FrameTermination_CDF, SKP_Silk_FrameTermination_offset );

    /****************************************/
    /* get number of bytes used so far      */
    /****************************************/
    SKP_Silk_range_coder_get_length( psRC, &nBytesUsed );
    psDec->nBytesLeft = psRC->bufferLength - nBytesUsed;
    if( psDec->nBytesLeft < 0 ) {
        psRC->error = RANGE_CODER_READ_BEYOND_BUFFER;
    }

    /****************************************/
    /* check remaining bits in last byte    */
    /****************************************/
    if( psDec->nBytesLeft == 0 ) {
        SKP_Silk_range_coder_check_after_decoding( psRC );
    }
}
