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ref: 5c3d155188366f02a1dd7ecdcb055ef7df4f20c0
dir: /silk/float/silk_pitch_analysis_core_FLP.c/

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/***********************************************************************
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are permitted provided that the following conditions are met:
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NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
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COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
***********************************************************************/

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

/*****************************************************************************
*
* Pitch analyser function
*
******************************************************************************/
#include "silk_SigProc_FLP.h"
#include "silk_SigProc_FIX.h"
#include "silk_pitch_est_defines.h"

#define SCRATCH_SIZE    22

/************************************************************/
/* Definitions                                              */
/************************************************************/
#define eps                     1.192092896e-07f

/************************************************************/
/* Internally used functions                                */
/************************************************************/
static void silk_P_Ana_calc_corr_st3(
    SKP_float cross_corr_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ], /* O 3 DIM correlation array */
    const SKP_float signal[],           /* 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                                             */
);

static void silk_P_Ana_calc_energy_st3(
    SKP_float energies_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ], /* O 3 DIM correlation array */
    const SKP_float signal[],           /* 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 SKP_float *signal,            /* I signal of length PE_FRAME_LENGTH_MS*Fs_kHz                     */
    opus_int         *pitch_out,         /* O 4 pitch lag values                                             */
    opus_int16        *lagIndex,         /* O lag Index                                                      */
    opus_int8        *contourIndex,      /* O pitch contour Index                                            */
    SKP_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 SKP_float search_thres1,      /* I first stage threshold for lag candidates 0 - 1                 */
    const SKP_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                                    */
)
{
    opus_int   i, k, d, j;
    SKP_float signal_8kHz[  PE_MAX_FRAME_LENGTH_MS * 8 ];
    SKP_float signal_4kHz[  PE_MAX_FRAME_LENGTH_MS * 4 ];
    opus_int16 signal_8_FIX[ PE_MAX_FRAME_LENGTH_MS * 8 ];
    opus_int16 signal_4_FIX[ PE_MAX_FRAME_LENGTH_MS * 4 ];
    opus_int32 filt_state[ 6 ];
    SKP_float threshold, contour_bias;
    SKP_float C[ PE_MAX_NB_SUBFR][ (PE_MAX_LAG >> 1) + 5 ];
    SKP_float CC[ PE_NB_CBKS_STAGE2_EXT ];
    const SKP_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;
    SKP_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;
    SKP_float lag_log2, prevLag_log2, delta_lag_log2_sqr;
    SKP_float energies_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ];
    SKP_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 */
    SKP_assert( Fs_kHz == 8 || Fs_kHz == 12 || Fs_kHz == 16 );

    /* Check for valid complexity setting */
    SKP_assert( complexity >= SigProc_PE_MIN_COMPLEX );
    SKP_assert( complexity <= SigProc_PE_MAX_COMPLEX );

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

    /* Setup 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;

    SKP_memset(C, 0, sizeof(SKP_float) * nb_subfr * ((PE_MAX_LAG >> 1) + 5));

    /* Resample from input sampled at Fs_kHz to 8 kHz */
    if( Fs_kHz == 16 ) {
        /* Resample to 16 -> 8 khz */
        opus_int16 signal_16_FIX[ 16 * PE_MAX_FRAME_LENGTH_MS ];
        SKP_float2short_array( signal_16_FIX, signal, frame_length );
        SKP_memset( filt_state, 0, 2 * sizeof( opus_int32 ) );
        silk_resampler_down2( filt_state, signal_8_FIX, signal_16_FIX, frame_length );
        SKP_short2float_array( signal_8kHz, signal_8_FIX, frame_length_8kHz );
    } else if( Fs_kHz == 12 ) {
        /* Resample to 12 -> 8 khz */
        opus_int16 signal_12_FIX[ 12 * PE_MAX_FRAME_LENGTH_MS ];
        SKP_float2short_array( signal_12_FIX, signal, frame_length );
        SKP_memset( filt_state, 0, 6 * sizeof( opus_int32 ) );
        silk_resampler_down2_3( filt_state, signal_8_FIX, signal_12_FIX, frame_length );
        SKP_short2float_array( signal_8kHz, signal_8_FIX, frame_length_8kHz );
    } else {
        SKP_assert( Fs_kHz == 8 );
        SKP_float2short_array( signal_8_FIX, signal, frame_length_8kHz );
    }

    /* Decimate again to 4 kHz */
    SKP_memset( filt_state, 0, 2 * sizeof( opus_int32 ) );
    silk_resampler_down2( filt_state, signal_4_FIX, signal_8_FIX, frame_length_8kHz );
    SKP_short2float_array( signal_4kHz, signal_4_FIX, frame_length_4kHz );

    /* Low-pass filter */
    for( i = frame_length_4kHz - 1; i > 0; i-- ) {
        signal_4kHz[ i ] += signal_4kHz[ i - 1 ];
    }

    /******************************************************************************
    * FIRST STAGE, operating in 4 khz
    ******************************************************************************/
    target_ptr = &signal_4kHz[ SKP_LSHIFT( sf_length_4kHz, 2 ) ];
    for( k = 0; k < nb_subfr >> 1; k++ ) {
        /* Check that we are within range of the array */
        SKP_assert( target_ptr >= signal_4kHz );
        SKP_assert( target_ptr + sf_length_8kHz <= signal_4kHz + frame_length_4kHz );

        basis_ptr = target_ptr - min_lag_4kHz;

        /* Check that we are within range of the array */
        SKP_assert( basis_ptr >= signal_4kHz );
        SKP_assert( basis_ptr + sf_length_8kHz <= signal_4kHz + frame_length_4kHz );

        /* Calculate first vector products before loop */
        cross_corr = silk_inner_product_FLP( target_ptr, basis_ptr, sf_length_8kHz );
        normalizer = silk_energy_FLP( basis_ptr, sf_length_8kHz ) + sf_length_8kHz * 4000.0f;

        C[ 0 ][ min_lag_4kHz ] += (SKP_float)(cross_corr / sqrt(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 */
            SKP_assert( basis_ptr >= signal_4kHz );
            SKP_assert( basis_ptr + sf_length_8kHz <= signal_4kHz + frame_length_4kHz );

            cross_corr = silk_inner_product_FLP(target_ptr, basis_ptr, sf_length_8kHz);

            /* Add contribution of new sample and remove contribution from oldest sample */
            normalizer +=
                basis_ptr[ 0 ] * basis_ptr[ 0 ] -
                basis_ptr[ sf_length_8kHz ] * basis_ptr[ sf_length_8kHz ];
            C[ 0 ][ d ] += (SKP_float)(cross_corr / sqrt( 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;
    SKP_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 ];
    target_ptr = &signal_4kHz[ SKP_SMULBB( sf_length_4kHz, nb_subfr ) ];
    energy = 1000.0f;
    for( i = 0; i < SKP_LSHIFT( sf_length_4kHz, 2 ); i++ ) {
        energy += target_ptr[i] * target_ptr[i];
    }
    threshold = Cmax * Cmax;
    if( energy / 16.0f > threshold ) {
        SKP_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 ] = SKP_LSHIFT( d_srch[ i ] + min_lag_4kHz, 1 );
        } else {
            length_d_srch = i;
            break;
        }
    }
    SKP_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
    *********************************************************************************/
    SKP_memset( C, 0, PE_MAX_NB_SUBFR*((PE_MAX_LAG >> 1) + 5) * sizeof(SKP_float)); // Is this needed?

    if( Fs_kHz == 8 ) {
        target_ptr = &signal[ PE_LTP_MEM_LENGTH_MS * 8 ];
    } else {
        target_ptr = &signal_8kHz[ PE_LTP_MEM_LENGTH_MS * 8 ];
    }
    for( k = 0; k < nb_subfr; k++ ) {
        energy_tmp = silk_energy_FLP( target_ptr, sf_length_8kHz );
        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 );
            energy     = silk_energy_FLP( basis_ptr, sf_length_8kHz );
            if (cross_corr > 0.0f) {
                C[ k ][ d ] = (SKP_float)(cross_corr * cross_corr / (energy * energy_tmp + eps));
            } 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 = SKP_LSHIFT( prevLag, 1 ) / 3;
        } else if( Fs_kHz == 16 ) {
            prevLag = SKP_RSHIFT( prevLag, 1 );
        }
        prevLag_log2 = silk_log2((SKP_float)prevLag);
    } else {
        prevLag_log2 = 0;
    }

    /* Setup 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 > SigProc_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;
            }
        }
        CCmax_new = SKP_max_float(CCmax_new, 0.0f); /* To avoid taking square root of negative number later */
        CCmax_new_b = CCmax_new;

        /* Bias towards shorter lags */
        lag_log2 = silk_log2((SKP_float)d);
        CCmax_new_b -= 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 * search_thres2       && /* Correlation needs to be high enough to be voiced */
             silk_CB_lags_stage2[ 0 ][ CBimax_new ] <= min_lag_8kHz    /* Lag must be in range                             */
            ) {
            CCmax_b = CCmax_new_b;
            CCmax   = CCmax_new;
            lag     = d;
            CBimax  = CBimax_new;
        }
    }

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

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

        /* Compensate for decimation */
        SKP_assert( lag == SKP_SAT16( lag ) );
        if( Fs_kHz == 12 ) {
            lag = SKP_RSHIFT_ROUND( SKP_SMULBB( lag, 3 ), 1 );
        } else if( Fs_kHz == 16 ) {
            lag = SKP_LSHIFT( lag, 1 );
        } else {
            lag = SKP_SMULBB( lag, 3 );
        }

        lag = SKP_LIMIT_int( lag, min_lag, max_lag );
        start_lag = SKP_max_int( lag - 2, min_lag );
        end_lag   = SKP_min_int( lag + 2, max_lag );
        lag_new   = lag;                                    /* to avoid undefined lag */
        CBimax    = 0;                                      /* to avoid undefined lag */
        SKP_assert( CCmax >= 0.0f );
        *LTPCorr = (SKP_float)sqrt( CCmax / nb_subfr );     /* Output normalized correlation */

        CCmax = -1000.0f;

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

        lag_counter = 0;
        SKP_assert( lag == SKP_SAT16( lag ) );
        contour_bias = PE_FLATCONTOUR_BIAS / lag;

        /* Setup cbk parameters acording 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 ];
        }

        for( d = start_lag; d <= end_lag; d++ ) {
            for( j = 0; j < nb_cbk_search; j++ ) {
                cross_corr = 0.0;
                energy = eps;
                for( k = 0; k < nb_subfr; k++ ) {
                    energy     +=   energies_st3[ k ][ j ][ lag_counter ];
                    cross_corr += cross_corr_st3[ k ][ j ][ lag_counter ];
                }
                if( cross_corr > 0.0 ) {
                    CCmax_new = (SKP_float)(cross_corr * 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 );
        }
        *lagIndex = (opus_int16)( lag_new - min_lag );
        *contourIndex = (opus_int8)CBimax;
    } else {
        /* Save Lags and correlation */
        SKP_assert( CCmax >= 0.0f );
        *LTPCorr = (SKP_float)sqrt( CCmax / nb_subfr ); /* Output normalized correlation */
        for( k = 0; k < nb_subfr; k++ ) {
            pitch_out[ k ] = lag + matrix_ptr( Lag_CB_ptr, k, CBimax, cbk_size );
        }
        *lagIndex = (opus_int16)( lag - min_lag );
        *contourIndex = (opus_int8)CBimax;
    }
    SKP_assert( *lagIndex >= 0 );
    /* return as voiced */
    return 0;
}

static void silk_P_Ana_calc_corr_st3(
    SKP_float cross_corr_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ], /* O 3 DIM correlation array */
    const SKP_float signal[],           /* 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                                             */
)
    /***********************************************************************
     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.
     **********************************************************************/
{
    const SKP_float *target_ptr, *basis_ptr;
    opus_int   i, j, k, lag_counter, lag_low, lag_high;
    opus_int   nb_cbk_search, delta, idx, cbk_size;
    SKP_float scratch_mem[ SCRATCH_SIZE ];
    const opus_int8 *Lag_range_ptr, *Lag_CB_ptr;

    SKP_assert( complexity >= SigProc_PE_MIN_COMPLEX );
    SKP_assert( complexity <= SigProc_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 {
        SKP_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 = &signal[ SKP_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 );
        for( j = lag_low; j <= lag_high; j++ ) {
            basis_ptr = target_ptr - ( start_lag + j );
            SKP_assert( lag_counter < SCRATCH_SIZE );
            scratch_mem[ lag_counter ] = (SKP_float)silk_inner_product_FLP( target_ptr, basis_ptr, sf_length );
            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++ ) {
                SKP_assert( idx + j < SCRATCH_SIZE );
                SKP_assert( idx + j < lag_counter );
                cross_corr_st3[ k ][ i ][ j ] = scratch_mem[ idx + j ];
            }
        }
        target_ptr += sf_length;
    }
}

static void silk_P_Ana_calc_energy_st3(
    SKP_float energies_st3[ PE_MAX_NB_SUBFR ][ PE_NB_CBKS_STAGE3_MAX ][ PE_NB_STAGE3_LAGS ], /* O 3 DIM correlation array */
    const SKP_float signal[],           /* 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                                             */
)
/****************************************************************
Calculate the energies for first two subframes. The energies are
calculated recursively.
****************************************************************/
{
    const SKP_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;
    SKP_float scratch_mem[ SCRATCH_SIZE ];
    const opus_int8 *Lag_range_ptr, *Lag_CB_ptr;

    SKP_assert( complexity >= SigProc_PE_MIN_COMPLEX );
    SKP_assert( complexity <= SigProc_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 {
        SKP_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 = &signal[ SKP_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;
        SKP_assert( energy >= 0.0 );
        scratch_mem[lag_counter] = (SKP_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] * basis_ptr[sf_length - i];
            SKP_assert( energy >= 0.0 );

            /* add part that comes into window */
            energy += basis_ptr[ -i ] * basis_ptr[ -i ];
            SKP_assert( energy >= 0.0 );
            SKP_assert( lag_counter < SCRATCH_SIZE );
            scratch_mem[lag_counter] = (SKP_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++ ) {
                SKP_assert( idx + j < SCRATCH_SIZE );
                SKP_assert( idx + j < lag_counter );
                energies_st3[ k ][ i ][ j ] = scratch_mem[ idx + j ];
                SKP_assert( energies_st3[ k ][ i ][ j ] >= 0.0f );
            }
        }
        target_ptr += sf_length;
    }
}