squeezelite-esp32/components/spotify/cspot/bell/external/opus/silk/float/pitch_analysis_core_FLP.c

/***********************************************************************
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#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

/*****************************************************************************
* Pitch analyser function
******************************************************************************/
#include "SigProc_FLP.h"
#include "SigProc_FIX.h"
#include "pitch_est_defines.h"
#include "pitch.h"

#define SCRATCH_SIZE        22

/************************************************************/
/* Internally used functions                                */
/************************************************************/
static void silk_P_Ana_calc_corr_st3(
    silk_float cross_corr_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ], /* O 3 DIM correlation array */
    const silk_float    frame[],            /* I vector to correlate                                            */
    opus_int            start_lag,          /* I start lag                                                      */
    opus_int            sf_length,          /* I sub frame length                                               */
    opus_int            nb_subfr,           /* I number of subframes                                            */
    opus_int            complexity,         /* I Complexity setting                                             */
    int                 arch                /* I Run-time architecture                                          */
);

static void silk_P_Ana_calc_energy_st3(
    silk_float energies_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ], /* O 3 DIM correlation array */
    const silk_float    frame[],            /* I vector to correlate                                            */
    opus_int            start_lag,          /* I start lag                                                      */
    opus_int            sf_length,          /* I sub frame length                                               */
    opus_int            nb_subfr,           /* I number of subframes                                            */
    opus_int            complexity          /* I Complexity setting                                             */
);

/************************************************************/
/* CORE PITCH ANALYSIS FUNCTION                             */
/************************************************************/
opus_int silk_pitch_analysis_core_FLP(      /* O    Voicing estimate: 0 voiced, 1 unvoiced                      */
    const silk_float    *frame,             /* I    Signal of length PE_FRAME_LENGTH_MS*Fs_kHz                  */
    opus_int            *pitch_out,         /* O    Pitch lag values [nb_subfr]                                 */
    opus_int16          *lagIndex,          /* O    Lag Index                                                   */
    opus_int8           *contourIndex,      /* O    Pitch contour Index                                         */
    silk_float          *LTPCorr,           /* I/O  Normalized correlation; input: value from previous frame    */
    opus_int            prevLag,            /* I    Last lag of previous frame; set to zero is unvoiced         */
    const silk_float    search_thres1,      /* I    First stage threshold for lag candidates 0 - 1              */
    const silk_float    search_thres2,      /* I    Final threshold for lag candidates 0 - 1                    */
    const opus_int      Fs_kHz,             /* I    sample frequency (kHz)                                      */
    const opus_int      complexity,         /* I    Complexity setting, 0-2, where 2 is highest                 */
    const opus_int      nb_subfr,           /* I    Number of 5 ms subframes                                    */
    int                 arch                /* I    Run-time architecture                                       */
)
{
    opus_int   i, k, d, j;
    silk_float frame_8kHz[  PE_MAX_FRAME_LENGTH_MS * 8 ];
    silk_float frame_4kHz[  PE_MAX_FRAME_LENGTH_MS * 4 ];
    opus_int16 frame_8_FIX[ PE_MAX_FRAME_LENGTH_MS * 8 ];
    opus_int16 frame_4_FIX[ PE_MAX_FRAME_LENGTH_MS * 4 ];
    opus_int32 filt_state[ 6 ];
    silk_float threshold, contour_bias;
    silk_float C[ PE_MAX_NB_SUBFR][ (PE_MAX_LAG >> 1) + 5 ];
    opus_val32 xcorr[ PE_MAX_LAG_MS * 4 - PE_MIN_LAG_MS * 4 + 1 ];
    silk_float CC[ PE_NB_CBKS_STAGE2_EXT ];
    const silk_float *target_ptr, *basis_ptr;
    double    cross_corr, normalizer, energy, energy_tmp;
    opus_int   d_srch[ PE_D_SRCH_LENGTH ];
    opus_int16 d_comp[ (PE_MAX_LAG >> 1) + 5 ];
    opus_int   length_d_srch, length_d_comp;
    silk_float Cmax, CCmax, CCmax_b, CCmax_new_b, CCmax_new;
    opus_int   CBimax, CBimax_new, lag, start_lag, end_lag, lag_new;
    opus_int   cbk_size;
    silk_float lag_log2, prevLag_log2, delta_lag_log2_sqr;
    silk_float energies_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ];
    silk_float cross_corr_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ];
    opus_int   lag_counter;
    opus_int   frame_length, frame_length_8kHz, frame_length_4kHz;
    opus_int   sf_length, sf_length_8kHz, sf_length_4kHz;
    opus_int   min_lag, min_lag_8kHz, min_lag_4kHz;
    opus_int   max_lag, max_lag_8kHz, max_lag_4kHz;
    opus_int   nb_cbk_search;
    const opus_int8 *Lag_CB_ptr;

    /* Check for valid sampling frequency */
    celt_assert( Fs_kHz == 8 || Fs_kHz == 12 || Fs_kHz == 16 );

    /* Check for valid complexity setting */
    celt_assert( complexity >= SILK_PE_MIN_COMPLEX );
    celt_assert( complexity <= SILK_PE_MAX_COMPLEX );

    silk_assert( search_thres1 >= 0.0f && search_thres1 <= 1.0f );
    silk_assert( search_thres2 >= 0.0f && search_thres2 <= 1.0f );

    /* Set up frame lengths max / min lag for the sampling frequency */
    frame_length      = ( PE_LTP_MEM_LENGTH_MS + nb_subfr * PE_SUBFR_LENGTH_MS ) * Fs_kHz;
    frame_length_4kHz = ( PE_LTP_MEM_LENGTH_MS + nb_subfr * PE_SUBFR_LENGTH_MS ) * 4;
    frame_length_8kHz = ( PE_LTP_MEM_LENGTH_MS + nb_subfr * PE_SUBFR_LENGTH_MS ) * 8;
    sf_length         = PE_SUBFR_LENGTH_MS * Fs_kHz;
    sf_length_4kHz    = PE_SUBFR_LENGTH_MS * 4;
    sf_length_8kHz    = PE_SUBFR_LENGTH_MS * 8;
    min_lag           = PE_MIN_LAG_MS * Fs_kHz;
    min_lag_4kHz      = PE_MIN_LAG_MS * 4;
    min_lag_8kHz      = PE_MIN_LAG_MS * 8;
    max_lag           = PE_MAX_LAG_MS * Fs_kHz - 1;
    max_lag_4kHz      = PE_MAX_LAG_MS * 4;
    max_lag_8kHz      = PE_MAX_LAG_MS * 8 - 1;

    /* Resample from input sampled at Fs_kHz to 8 kHz */
    if( Fs_kHz == 16 ) {
        /* Resample to 16 -> 8 khz */
        opus_int16 frame_16_FIX[ 16 * PE_MAX_FRAME_LENGTH_MS ];
        silk_float2short_array( frame_16_FIX, frame, frame_length );
        silk_memset( filt_state, 0, 2 * sizeof( opus_int32 ) );
        silk_resampler_down2( filt_state, frame_8_FIX, frame_16_FIX, frame_length );
        silk_short2float_array( frame_8kHz, frame_8_FIX, frame_length_8kHz );
    } else if( Fs_kHz == 12 ) {
        /* Resample to 12 -> 8 khz */
        opus_int16 frame_12_FIX[ 12 * PE_MAX_FRAME_LENGTH_MS ];
        silk_float2short_array( frame_12_FIX, frame, frame_length );
        silk_memset( filt_state, 0, 6 * sizeof( opus_int32 ) );
        silk_resampler_down2_3( filt_state, frame_8_FIX, frame_12_FIX, frame_length );
        silk_short2float_array( frame_8kHz, frame_8_FIX, frame_length_8kHz );
    } else {
        celt_assert( Fs_kHz == 8 );
        silk_float2short_array( frame_8_FIX, frame, frame_length_8kHz );
    }

    /* Decimate again to 4 kHz */
    silk_memset( filt_state, 0, 2 * sizeof( opus_int32 ) );
    silk_resampler_down2( filt_state, frame_4_FIX, frame_8_FIX, frame_length_8kHz );
    silk_short2float_array( frame_4kHz, frame_4_FIX, frame_length_4kHz );

    /* Low-pass filter */
    for( i = frame_length_4kHz - 1; i > 0; i-- ) {
        frame_4kHz[ i ] = silk_ADD_SAT16( frame_4kHz[ i ], frame_4kHz[ i - 1 ] );
    }

    /******************************************************************************
    * FIRST STAGE, operating in 4 khz
    ******************************************************************************/
    silk_memset(C, 0, sizeof(silk_float) * nb_subfr * ((PE_MAX_LAG >> 1) + 5));
    target_ptr = &frame_4kHz[ silk_LSHIFT( sf_length_4kHz, 2 ) ];
    for( k = 0; k < nb_subfr >> 1; k++ ) {
        /* Check that we are within range of the array */
        celt_assert( target_ptr >= frame_4kHz );
        celt_assert( target_ptr + sf_length_8kHz <= frame_4kHz + frame_length_4kHz );

        basis_ptr = target_ptr - min_lag_4kHz;

        /* Check that we are within range of the array */
        celt_assert( basis_ptr >= frame_4kHz );
        celt_assert( basis_ptr + sf_length_8kHz <= frame_4kHz + frame_length_4kHz );

        celt_pitch_xcorr( target_ptr, target_ptr-max_lag_4kHz, xcorr, sf_length_8kHz, max_lag_4kHz - min_lag_4kHz + 1, arch );

        /* Calculate first vector products before loop */
        cross_corr = xcorr[ max_lag_4kHz - min_lag_4kHz ];
        normalizer = silk_energy_FLP( target_ptr, sf_length_8kHz ) +
                     silk_energy_FLP( basis_ptr,  sf_length_8kHz ) +
                     sf_length_8kHz * 4000.0f;

        C[ 0 ][ min_lag_4kHz ] += (silk_float)( 2 * cross_corr / normalizer );

        /* From now on normalizer is computed recursively */
        for( d = min_lag_4kHz + 1; d <= max_lag_4kHz; d++ ) {
            basis_ptr--;

            /* Check that we are within range of the array */
            silk_assert( basis_ptr >= frame_4kHz );
            silk_assert( basis_ptr + sf_length_8kHz <= frame_4kHz + frame_length_4kHz );

            cross_corr = xcorr[ max_lag_4kHz - d ];

            /* Add contribution of new sample and remove contribution from oldest sample */
            normalizer +=
                basis_ptr[ 0 ] * (double)basis_ptr[ 0 ] -
                basis_ptr[ sf_length_8kHz ] * (double)basis_ptr[ sf_length_8kHz ];
            C[ 0 ][ d ] += (silk_float)( 2 * cross_corr / normalizer );
        }
        /* Update target pointer */
        target_ptr += sf_length_8kHz;
    }

    /* Apply short-lag bias */
    for( i = max_lag_4kHz; i >= min_lag_4kHz; i-- ) {
        C[ 0 ][ i ] -= C[ 0 ][ i ] * i / 4096.0f;
    }

    /* Sort */
    length_d_srch = 4 + 2 * complexity;
    celt_assert( 3 * length_d_srch <= PE_D_SRCH_LENGTH );
    silk_insertion_sort_decreasing_FLP( &C[ 0 ][ min_lag_4kHz ], d_srch, max_lag_4kHz - min_lag_4kHz + 1, length_d_srch );

    /* Escape if correlation is very low already here */
    Cmax = C[ 0 ][ min_lag_4kHz ];
    if( Cmax < 0.2f ) {
        silk_memset( pitch_out, 0, nb_subfr * sizeof( opus_int ) );
        *LTPCorr      = 0.0f;
        *lagIndex     = 0;
        *contourIndex = 0;
        return 1;
    }

    threshold = search_thres1 * Cmax;
    for( i = 0; i < length_d_srch; i++ ) {
        /* Convert to 8 kHz indices for the sorted correlation that exceeds the threshold */
        if( C[ 0 ][ min_lag_4kHz + i ] > threshold ) {
            d_srch[ i ] = silk_LSHIFT( d_srch[ i ] + min_lag_4kHz, 1 );
        } else {
            length_d_srch = i;
            break;
        }
    }
    celt_assert( length_d_srch > 0 );

    for( i = min_lag_8kHz - 5; i < max_lag_8kHz + 5; i++ ) {
        d_comp[ i ] = 0;
    }
    for( i = 0; i < length_d_srch; i++ ) {
        d_comp[ d_srch[ i ] ] = 1;
    }

    /* Convolution */
    for( i = max_lag_8kHz + 3; i >= min_lag_8kHz; i-- ) {
        d_comp[ i ] += d_comp[ i - 1 ] + d_comp[ i - 2 ];
    }

    length_d_srch = 0;
    for( i = min_lag_8kHz; i < max_lag_8kHz + 1; i++ ) {
        if( d_comp[ i + 1 ] > 0 ) {
            d_srch[ length_d_srch ] = i;
            length_d_srch++;
        }
    }

    /* Convolution */
    for( i = max_lag_8kHz + 3; i >= min_lag_8kHz; i-- ) {
        d_comp[ i ] += d_comp[ i - 1 ] + d_comp[ i - 2 ] + d_comp[ i - 3 ];
    }

    length_d_comp = 0;
    for( i = min_lag_8kHz; i < max_lag_8kHz + 4; i++ ) {
        if( d_comp[ i ] > 0 ) {
            d_comp[ length_d_comp ] = (opus_int16)( i - 2 );
            length_d_comp++;
        }
    }

    /**********************************************************************************
    ** SECOND STAGE, operating at 8 kHz, on lag sections with high correlation
    *************************************************************************************/
    /*********************************************************************************
    * Find energy of each subframe projected onto its history, for a range of delays
    *********************************************************************************/
    silk_memset( C, 0, PE_MAX_NB_SUBFR*((PE_MAX_LAG >> 1) + 5) * sizeof(silk_float));

    if( Fs_kHz == 8 ) {
        target_ptr = &frame[ PE_LTP_MEM_LENGTH_MS * 8 ];
    } else {
        target_ptr = &frame_8kHz[ PE_LTP_MEM_LENGTH_MS * 8 ];
    }
    for( k = 0; k < nb_subfr; k++ ) {
        energy_tmp = silk_energy_FLP( target_ptr, sf_length_8kHz ) + 1.0;
        for( j = 0; j < length_d_comp; j++ ) {
            d = d_comp[ j ];
            basis_ptr = target_ptr - d;
            cross_corr = silk_inner_product_FLP( basis_ptr, target_ptr, sf_length_8kHz );
            if( cross_corr > 0.0f ) {
                energy = silk_energy_FLP( basis_ptr, sf_length_8kHz );
                C[ k ][ d ] = (silk_float)( 2 * cross_corr / ( energy + energy_tmp ) );
            } else {
                C[ k ][ d ] = 0.0f;
            }
        }
        target_ptr += sf_length_8kHz;
    }

    /* search over lag range and lags codebook */
    /* scale factor for lag codebook, as a function of center lag */

    CCmax   = 0.0f; /* This value doesn't matter */
    CCmax_b = -1000.0f;

    CBimax = 0; /* To avoid returning undefined lag values */
    lag = -1;   /* To check if lag with strong enough correlation has been found */

    if( prevLag > 0 ) {
        if( Fs_kHz == 12 ) {
            prevLag = silk_LSHIFT( prevLag, 1 ) / 3;
        } else if( Fs_kHz == 16 ) {
            prevLag = silk_RSHIFT( prevLag, 1 );
        }
        prevLag_log2 = silk_log2( (silk_float)prevLag );
    } else {
        prevLag_log2 = 0;
    }

    /* Set up stage 2 codebook based on number of subframes */
    if( nb_subfr == PE_MAX_NB_SUBFR ) {
        cbk_size   = PE_NB_CBKS_STAGE2_EXT;
        Lag_CB_ptr = &silk_CB_lags_stage2[ 0 ][ 0 ];
        if( Fs_kHz == 8 && complexity > SILK_PE_MIN_COMPLEX ) {
            /* If input is 8 khz use a larger codebook here because it is last stage */
            nb_cbk_search = PE_NB_CBKS_STAGE2_EXT;
        } else {
            nb_cbk_search = PE_NB_CBKS_STAGE2;
        }
    } else {
        cbk_size       = PE_NB_CBKS_STAGE2_10MS;
        Lag_CB_ptr     = &silk_CB_lags_stage2_10_ms[ 0 ][ 0 ];
        nb_cbk_search  = PE_NB_CBKS_STAGE2_10MS;
    }

    for( k = 0; k < length_d_srch; k++ ) {
        d = d_srch[ k ];
        for( j = 0; j < nb_cbk_search; j++ ) {
            CC[j] = 0.0f;
            for( i = 0; i < nb_subfr; i++ ) {
                /* Try all codebooks */
                CC[ j ] += C[ i ][ d + matrix_ptr( Lag_CB_ptr, i, j, cbk_size )];
            }
        }
        /* Find best codebook */
        CCmax_new  = -1000.0f;
        CBimax_new = 0;
        for( i = 0; i < nb_cbk_search; i++ ) {
            if( CC[ i ] > CCmax_new ) {
                CCmax_new = CC[ i ];
                CBimax_new = i;
            }
        }

        /* Bias towards shorter lags */
        lag_log2 = silk_log2( (silk_float)d );
        CCmax_new_b = CCmax_new - PE_SHORTLAG_BIAS * nb_subfr * lag_log2;

        /* Bias towards previous lag */
        if( prevLag > 0 ) {
            delta_lag_log2_sqr = lag_log2 - prevLag_log2;
            delta_lag_log2_sqr *= delta_lag_log2_sqr;
            CCmax_new_b -= PE_PREVLAG_BIAS * nb_subfr * (*LTPCorr) * delta_lag_log2_sqr / ( delta_lag_log2_sqr + 0.5f );
        }

        if( CCmax_new_b > CCmax_b &&                /* Find maximum biased correlation                  */
            CCmax_new > nb_subfr * search_thres2    /* Correlation needs to be high enough to be voiced */
        ) {
            CCmax_b = CCmax_new_b;
            CCmax   = CCmax_new;
            lag     = d;
            CBimax  = CBimax_new;
        }
    }

    if( lag == -1 ) {
        /* No suitable candidate found */
        silk_memset( pitch_out, 0, PE_MAX_NB_SUBFR * sizeof(opus_int) );
        *LTPCorr      = 0.0f;
        *lagIndex     = 0;
        *contourIndex = 0;
        return 1;
    }

    /* Output normalized correlation */
    *LTPCorr = (silk_float)( CCmax / nb_subfr );
    silk_assert( *LTPCorr >= 0.0f );

    if( Fs_kHz > 8 ) {
        /* Search in original signal */

        /* Compensate for decimation */
        silk_assert( lag == silk_SAT16( lag ) );
        if( Fs_kHz == 12 ) {
            lag = silk_RSHIFT_ROUND( silk_SMULBB( lag, 3 ), 1 );
        } else { /* Fs_kHz == 16 */
            lag = silk_LSHIFT( lag, 1 );
        }

        lag = silk_LIMIT_int( lag, min_lag, max_lag );
        start_lag = silk_max_int( lag - 2, min_lag );
        end_lag   = silk_min_int( lag + 2, max_lag );
        lag_new   = lag;                                    /* to avoid undefined lag */
        CBimax    = 0;                                      /* to avoid undefined lag */

        CCmax = -1000.0f;

        /* Calculate the correlations and energies needed in stage 3 */
        silk_P_Ana_calc_corr_st3( cross_corr_st3, frame, start_lag, sf_length, nb_subfr, complexity, arch );
        silk_P_Ana_calc_energy_st3( energies_st3, frame, start_lag, sf_length, nb_subfr, complexity );

        lag_counter = 0;
        silk_assert( lag == silk_SAT16( lag ) );
        contour_bias = PE_FLATCONTOUR_BIAS / lag;

        /* Set up cbk parameters according to complexity setting and frame length */
        if( nb_subfr == PE_MAX_NB_SUBFR ) {
            nb_cbk_search = (opus_int)silk_nb_cbk_searchs_stage3[ complexity ];
            cbk_size      = PE_NB_CBKS_STAGE3_MAX;
            Lag_CB_ptr    = &silk_CB_lags_stage3[ 0 ][ 0 ];
        } else {
            nb_cbk_search = PE_NB_CBKS_STAGE3_10MS;
            cbk_size      = PE_NB_CBKS_STAGE3_10MS;
            Lag_CB_ptr    = &silk_CB_lags_stage3_10_ms[ 0 ][ 0 ];
        }

        target_ptr = &frame[ PE_LTP_MEM_LENGTH_MS * Fs_kHz ];
        energy_tmp = silk_energy_FLP( target_ptr, nb_subfr * sf_length ) + 1.0;
        for( d = start_lag; d <= end_lag; d++ ) {
            for( j = 0; j < nb_cbk_search; j++ ) {
                cross_corr = 0.0;
                energy = energy_tmp;
                for( k = 0; k < nb_subfr; k++ ) {
                    cross_corr += cross_corr_st3[ k ][ j ][ lag_counter ];
                    energy     +=   energies_st3[ k ][ j ][ lag_counter ];
                }
                if( cross_corr > 0.0 ) {
                    CCmax_new = (silk_float)( 2 * cross_corr / energy );
                    /* Reduce depending on flatness of contour */
                    CCmax_new *= 1.0f - contour_bias * j;
                } else {
                    CCmax_new = 0.0f;
                }

                if( CCmax_new > CCmax && ( d + (opus_int)silk_CB_lags_stage3[ 0 ][ j ] ) <= max_lag ) {
                    CCmax   = CCmax_new;
                    lag_new = d;
                    CBimax  = j;
                }
            }
            lag_counter++;
        }

        for( k = 0; k < nb_subfr; k++ ) {
            pitch_out[ k ] = lag_new + matrix_ptr( Lag_CB_ptr, k, CBimax, cbk_size );
            pitch_out[ k ] = silk_LIMIT( pitch_out[ k ], min_lag, PE_MAX_LAG_MS * Fs_kHz );
        }
        *lagIndex = (opus_int16)( lag_new - min_lag );
        *contourIndex = (opus_int8)CBimax;
    } else {        /* Fs_kHz == 8 */
        /* Save Lags */
        for( k = 0; k < nb_subfr; k++ ) {
            pitch_out[ k ] = lag + matrix_ptr( Lag_CB_ptr, k, CBimax, cbk_size );
            pitch_out[ k ] = silk_LIMIT( pitch_out[ k ], min_lag_8kHz, PE_MAX_LAG_MS * 8 );
        }
        *lagIndex = (opus_int16)( lag - min_lag_8kHz );
        *contourIndex = (opus_int8)CBimax;
    }
    celt_assert( *lagIndex >= 0 );
    /* return as voiced */
    return 0;
}

/***********************************************************************
 * Calculates the correlations used in stage 3 search. In order to cover
 * the whole lag codebook for all the searched offset lags (lag +- 2),
 * the following correlations are needed in each sub frame:
 *
 * sf1: lag range [-8,...,7] total 16 correlations
 * sf2: lag range [-4,...,4] total 9 correlations
 * sf3: lag range [-3,....4] total 8 correltions
 * sf4: lag range [-6,....8] total 15 correlations
 *
 * In total 48 correlations. The direct implementation computed in worst
 * case 4*12*5 = 240 correlations, but more likely around 120.
 ***********************************************************************/
static void silk_P_Ana_calc_corr_st3(
    silk_float cross_corr_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ], /* O 3 DIM correlation array */
    const silk_float    frame[],            /* I vector to correlate                                            */
    opus_int            start_lag,          /* I start lag                                                      */
    opus_int            sf_length,          /* I sub frame length                                               */
    opus_int            nb_subfr,           /* I number of subframes                                            */
    opus_int            complexity,         /* I Complexity setting                                             */
    int                 arch                /* I Run-time architecture                                          */
)
{
    const silk_float *target_ptr;
    opus_int   i, j, k, lag_counter, lag_low, lag_high;
    opus_int   nb_cbk_search, delta, idx, cbk_size;
    silk_float scratch_mem[ SCRATCH_SIZE ];
    opus_val32 xcorr[ SCRATCH_SIZE ];
    const opus_int8 *Lag_range_ptr, *Lag_CB_ptr;

    celt_assert( complexity >= SILK_PE_MIN_COMPLEX );
    celt_assert( complexity <= SILK_PE_MAX_COMPLEX );

    if( nb_subfr == PE_MAX_NB_SUBFR ) {
        Lag_range_ptr = &silk_Lag_range_stage3[ complexity ][ 0 ][ 0 ];
        Lag_CB_ptr    = &silk_CB_lags_stage3[ 0 ][ 0 ];
        nb_cbk_search = silk_nb_cbk_searchs_stage3[ complexity ];
        cbk_size      = PE_NB_CBKS_STAGE3_MAX;
    } else {
        celt_assert( nb_subfr == PE_MAX_NB_SUBFR >> 1);
        Lag_range_ptr = &silk_Lag_range_stage3_10_ms[ 0 ][ 0 ];
        Lag_CB_ptr    = &silk_CB_lags_stage3_10_ms[ 0 ][ 0 ];
        nb_cbk_search = PE_NB_CBKS_STAGE3_10MS;
        cbk_size      = PE_NB_CBKS_STAGE3_10MS;
    }

    target_ptr = &frame[ silk_LSHIFT( sf_length, 2 ) ]; /* Pointer to middle of frame */
    for( k = 0; k < nb_subfr; k++ ) {
        lag_counter = 0;

        /* Calculate the correlations for each subframe */
        lag_low  = matrix_ptr( Lag_range_ptr, k, 0, 2 );
        lag_high = matrix_ptr( Lag_range_ptr, k, 1, 2 );
        silk_assert(lag_high-lag_low+1 <= SCRATCH_SIZE);
        celt_pitch_xcorr( target_ptr, target_ptr - start_lag - lag_high, xcorr, sf_length, lag_high - lag_low + 1, arch );
        for( j = lag_low; j <= lag_high; j++ ) {
            silk_assert( lag_counter < SCRATCH_SIZE );
            scratch_mem[ lag_counter ] = xcorr[ lag_high - j ];
            lag_counter++;
        }

        delta = matrix_ptr( Lag_range_ptr, k, 0, 2 );
        for( i = 0; i < nb_cbk_search; i++ ) {
            /* Fill out the 3 dim array that stores the correlations for */
            /* each code_book vector for each start lag */
            idx = matrix_ptr( Lag_CB_ptr, k, i, cbk_size ) - delta;
            for( j = 0; j < PE_NB_STAGE3_LAGS; j++ ) {
                silk_assert( idx + j < SCRATCH_SIZE );
                silk_assert( idx + j < lag_counter );
                cross_corr_st3[ k ][ i ][ j ] = scratch_mem[ idx + j ];
            }
        }
        target_ptr += sf_length;
    }
}

/********************************************************************/
/* Calculate the energies for first two subframes. The energies are */
/* calculated recursively.                                          */
/********************************************************************/
static void silk_P_Ana_calc_energy_st3(
    silk_float energies_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ], /* O 3 DIM correlation array */
    const silk_float    frame[],            /* I vector to correlate                                            */
    opus_int            start_lag,          /* I start lag                                                      */
    opus_int            sf_length,          /* I sub frame length                                               */
    opus_int            nb_subfr,           /* I number of subframes                                            */
    opus_int            complexity          /* I Complexity setting                                             */
)
{
    const silk_float *target_ptr, *basis_ptr;
    double    energy;
    opus_int   k, i, j, lag_counter;
    opus_int   nb_cbk_search, delta, idx, cbk_size, lag_diff;
    silk_float scratch_mem[ SCRATCH_SIZE ];
    const opus_int8 *Lag_range_ptr, *Lag_CB_ptr;

    celt_assert( complexity >= SILK_PE_MIN_COMPLEX );
    celt_assert( complexity <= SILK_PE_MAX_COMPLEX );

    if( nb_subfr == PE_MAX_NB_SUBFR ) {
        Lag_range_ptr = &silk_Lag_range_stage3[ complexity ][ 0 ][ 0 ];
        Lag_CB_ptr    = &silk_CB_lags_stage3[ 0 ][ 0 ];
        nb_cbk_search = silk_nb_cbk_searchs_stage3[ complexity ];
        cbk_size      = PE_NB_CBKS_STAGE3_MAX;
    } else {
        celt_assert( nb_subfr == PE_MAX_NB_SUBFR >> 1);
        Lag_range_ptr = &silk_Lag_range_stage3_10_ms[ 0 ][ 0 ];
        Lag_CB_ptr    = &silk_CB_lags_stage3_10_ms[ 0 ][ 0 ];
        nb_cbk_search = PE_NB_CBKS_STAGE3_10MS;
        cbk_size      = PE_NB_CBKS_STAGE3_10MS;
    }

    target_ptr = &frame[ silk_LSHIFT( sf_length, 2 ) ];
    for( k = 0; k < nb_subfr; k++ ) {
        lag_counter = 0;

        /* Calculate the energy for first lag */
        basis_ptr = target_ptr - ( start_lag + matrix_ptr( Lag_range_ptr, k, 0, 2 ) );
        energy = silk_energy_FLP( basis_ptr, sf_length ) + 1e-3;
        silk_assert( energy >= 0.0 );
        scratch_mem[lag_counter] = (silk_float)energy;
        lag_counter++;

        lag_diff = ( matrix_ptr( Lag_range_ptr, k, 1, 2 ) -  matrix_ptr( Lag_range_ptr, k, 0, 2 ) + 1 );
        for( i = 1; i < lag_diff; i++ ) {
            /* remove part outside new window */
            energy -= basis_ptr[sf_length - i] * (double)basis_ptr[sf_length - i];
            silk_assert( energy >= 0.0 );

            /* add part that comes into window */
            energy += basis_ptr[ -i ] * (double)basis_ptr[ -i ];
            silk_assert( energy >= 0.0 );
            silk_assert( lag_counter < SCRATCH_SIZE );
            scratch_mem[lag_counter] = (silk_float)energy;
            lag_counter++;
        }

        delta = matrix_ptr( Lag_range_ptr, k, 0, 2 );
        for( i = 0; i < nb_cbk_search; i++ ) {
            /* Fill out the 3 dim array that stores the correlations for    */
            /* each code_book vector for each start lag                     */
            idx = matrix_ptr( Lag_CB_ptr, k, i, cbk_size ) - delta;
            for( j = 0; j < PE_NB_STAGE3_LAGS; j++ ) {
                silk_assert( idx + j < SCRATCH_SIZE );
                silk_assert( idx + j < lag_counter );
                energies_st3[ k ][ i ][ j ] = scratch_mem[ idx + j ];
                silk_assert( energies_st3[ k ][ i ][ j ] >= 0.0f );
            }
        }
        target_ptr += sf_length;
    }
}