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#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

/*

 * Matrix of resampling methods used:

 *                                 Fs_out (kHz)

 *                        8      12     16     24     48

 *

 *               8        C      UF     U      UF     UF

 *              12        AF     C      UF     U      UF

 * Fs_in (kHz)  16        D      AF     C      UF     UF

 *              24        AF     D      AF     C      U

 *              48        AF     AF     AF     D      C

 *

 * C   -> Copy (no resampling)

 * D   -> Allpass-based 2x downsampling

 * U   -> Allpass-based 2x upsampling

 * UF  -> Allpass-based 2x upsampling followed by FIR interpolation

 * AF  -> AR2 filter followed by FIR interpolation

 */

#include "resampler_private.h"

/* Tables with delay compensation values to equalize total delay for different modes */

static const opus_int8 delay_matrix_enc[ 5 ][ 3 ] = {

/* in  \ out  8  12  16 */

/*  8 */   {  6,  0,  3 },

/* 12 */   {  0,  7,  3 },

/* 16 */   {  0,  1, 10 },

/* 24 */   {  0,  2,  6 },

/* 48 */   { 18, 10, 12 }

};

static const opus_int8 delay_matrix_dec[ 3 ][ 5 ] = {

/* in  \ out  8  12  16  24  48 */

/*  8 */   {  4,  0,  2,  0,  0 },

/* 12 */   {  0,  9,  4,  7,  4 },

/* 16 */   {  0,  3, 12,  7,  7 }

};

/* Simple way to make [8000, 12000, 16000, 24000, 48000] to [0, 1, 2, 3, 4] */

#define rateID(R) ( ( ( ((R)>>12) - ((R)>16000) ) >> ((R)>24000) ) - 1 )

#define USE_silk_resampler_copy                     (0)

#define USE_silk_resampler_private_up2_HQ_wrapper   (1)

#define USE_silk_resampler_private_IIR_FIR          (2)

#define USE_silk_resampler_private_down_FIR         (3)

/* Initialize/reset the resampler state for a given pair of input/output sampling rates */

opus_int silk_resampler_init(

    silk_resampler_state_struct *S,                 /* I/O  Resampler state                                             */

    opus_int32                  Fs_Hz_in,           /* I    Input sampling rate (Hz)                                    */

    opus_int32                  Fs_Hz_out,          /* I    Output sampling rate (Hz)                                   */

    opus_int                    forEnc              /* I    If 1: encoder; if 0: decoder                                */

)

{

    opus_int up2x;

    /* Clear state */

    silk_memset( S, 0, sizeof( silk_resampler_state_struct ) );

    /* Input checking */

    if( forEnc ) {

        if( ( Fs_Hz_in  != 8000 && Fs_Hz_in  != 12000 && Fs_Hz_in  != 16000 && Fs_Hz_in  != 24000 && Fs_Hz_in  != 48000 ) ||

            ( Fs_Hz_out != 8000 && Fs_Hz_out != 12000 && Fs_Hz_out != 16000 ) ) {

            celt_assert( 0 );

            return -1;

        }

        S->inputDelay = delay_matrix_enc[ rateID( Fs_Hz_in ) ][ rateID( Fs_Hz_out ) ];

    } else {

        if( ( Fs_Hz_in  != 8000 && Fs_Hz_in  != 12000 && Fs_Hz_in  != 16000 ) ||

            ( Fs_Hz_out != 8000 && Fs_Hz_out != 12000 && Fs_Hz_out != 16000 && Fs_Hz_out != 24000 && Fs_Hz_out != 48000 ) ) {

            celt_assert( 0 );

            return -1;

        }

        S->inputDelay = delay_matrix_dec[ rateID( Fs_Hz_in ) ][ rateID( Fs_Hz_out ) ];

    }

    S->Fs_in_kHz  = silk_DIV32_16( Fs_Hz_in,  1000 );

    S->Fs_out_kHz = silk_DIV32_16( Fs_Hz_out, 1000 );

    /* Number of samples processed per batch */

    S->batchSize = S->Fs_in_kHz * RESAMPLER_MAX_BATCH_SIZE_MS;

    /* Find resampler with the right sampling ratio */

    up2x = 0;

    if( Fs_Hz_out > Fs_Hz_in ) {

        /* Upsample */

        if( Fs_Hz_out == silk_MUL( Fs_Hz_in, 2 ) ) {                            /* Fs_out : Fs_in = 2 : 1 */

            /* Special case: directly use 2x upsampler */

            S->resampler_function = USE_silk_resampler_private_up2_HQ_wrapper;

        } else {

            /* Default resampler */

            S->resampler_function = USE_silk_resampler_private_IIR_FIR;

            up2x = 1;

        }

    } else if ( Fs_Hz_out < Fs_Hz_in ) {

        /* Downsample */

         S->resampler_function = USE_silk_resampler_private_down_FIR;

        if( silk_MUL( Fs_Hz_out, 4 ) == silk_MUL( Fs_Hz_in, 3 ) ) {             /* Fs_out : Fs_in = 3 : 4 */

            S->FIR_Fracs = 3;

            S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR0;

            S->Coefs = silk_Resampler_3_4_COEFS;

        } else if( silk_MUL( Fs_Hz_out, 3 ) == silk_MUL( Fs_Hz_in, 2 ) ) {      /* Fs_out : Fs_in = 2 : 3 */

            S->FIR_Fracs = 2;

            S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR0;

            S->Coefs = silk_Resampler_2_3_COEFS;

        } else if( silk_MUL( Fs_Hz_out, 2 ) == Fs_Hz_in ) {                     /* Fs_out : Fs_in = 1 : 2 */

            S->FIR_Fracs = 1;

            S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR1;

            S->Coefs = silk_Resampler_1_2_COEFS;

        } else if( silk_MUL( Fs_Hz_out, 3 ) == Fs_Hz_in ) {                     /* Fs_out : Fs_in = 1 : 3 */

            S->FIR_Fracs = 1;

            S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR2;

            S->Coefs = silk_Resampler_1_3_COEFS;

        } else if( silk_MUL( Fs_Hz_out, 4 ) == Fs_Hz_in ) {                     /* Fs_out : Fs_in = 1 : 4 */

            S->FIR_Fracs = 1;

            S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR2;

            S->Coefs = silk_Resampler_1_4_COEFS;

        } else if( silk_MUL( Fs_Hz_out, 6 ) == Fs_Hz_in ) {                     /* Fs_out : Fs_in = 1 : 6 */

            S->FIR_Fracs = 1;

            S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR2;

            S->Coefs = silk_Resampler_1_6_COEFS;

        } else {

            /* None available */

            celt_assert( 0 );

            return -1;

        }

    } else {

        /* Input and output sampling rates are equal: copy */

        S->resampler_function = USE_silk_resampler_copy;

    }

    /* Ratio of input/output samples */

    S->invRatio_Q16 = silk_LSHIFT32( silk_DIV32( silk_LSHIFT32( Fs_Hz_in, 14 + up2x ), Fs_Hz_out ), 2 );

    /* Make sure the ratio is rounded up */

    while( silk_SMULWW( S->invRatio_Q16, Fs_Hz_out ) < silk_LSHIFT32( Fs_Hz_in, up2x ) ) {

        S->invRatio_Q16++;

    }

    return 0;

}

/* Resampler: convert from one sampling rate to another */

/* Input and output sampling rate are at most 48000 Hz  */

opus_int silk_resampler(

    silk_resampler_state_struct *S,                 /* I/O  Resampler state                                             */

    opus_int16                  out[],              /* O    Output signal                                               */

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

    opus_int32                  inLen               /* I    Number of input samples                                     */

)

{

    opus_int nSamples;

    /* Need at least 1 ms of input data */

    celt_assert( inLen >= S->Fs_in_kHz );

    /* Delay can't exceed the 1 ms of buffering */

    celt_assert( S->inputDelay <= S->Fs_in_kHz );

    nSamples = S->Fs_in_kHz - S->inputDelay;

    /* Copy to delay buffer */

    silk_memcpy( &S->delayBuf[ S->inputDelay ], in, nSamples * sizeof( opus_int16 ) );

    switch( S->resampler_function ) {

        case USE_silk_resampler_private_up2_HQ_wrapper:

            silk_resampler_private_up2_HQ_wrapper( S, out, S->delayBuf, S->Fs_in_kHz );

            silk_resampler_private_up2_HQ_wrapper( S, &out[ S->Fs_out_kHz ], &in[ nSamples ], inLen - S->Fs_in_kHz );

            break;

        case USE_silk_resampler_private_IIR_FIR:

            silk_resampler_private_IIR_FIR( S, out, S->delayBuf, S->Fs_in_kHz );

            silk_resampler_private_IIR_FIR( S, &out[ S->Fs_out_kHz ], &in[ nSamples ], inLen - S->Fs_in_kHz );

            break;

        case USE_silk_resampler_private_down_FIR:

            silk_resampler_private_down_FIR( S, out, S->delayBuf, S->Fs_in_kHz );

            silk_resampler_private_down_FIR( S, &out[ S->Fs_out_kHz ], &in[ nSamples ], inLen - S->Fs_in_kHz );

            break;

        default:

            silk_memcpy( out, S->delayBuf, S->Fs_in_kHz * sizeof( opus_int16 ) );

            silk_memcpy( &out[ S->Fs_out_kHz ], &in[ nSamples ], ( inLen - S->Fs_in_kHz ) * sizeof( opus_int16 ) );

    }

    /* Copy to delay buffer */

    silk_memcpy( S->delayBuf, &in[ inLen - S->inputDelay ], S->inputDelay * sizeof( opus_int16 ) );

    return 0;

}