godot/drivers/opus/silk/resampler_private_IIR_FIR.c

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#ifdef OPUS_HAVE_CONFIG_H
#include "opus/opus_config.h"
#endif

#include "opus/silk/SigProc_FIX.h"
#include "opus/silk/resampler_private.h"
#include "opus/celt/stack_alloc.h"

static OPUS_INLINE opus_int16 *silk_resampler_private_IIR_FIR_INTERPOL(
    opus_int16  *out,
    opus_int16  *buf,
    opus_int32  max_index_Q16,
    opus_int32  index_increment_Q16
)
{
    opus_int32 index_Q16, res_Q15;
    opus_int16 *buf_ptr;
    opus_int32 table_index;

    /* Interpolate upsampled signal and store in output array */
    for( index_Q16 = 0; index_Q16 < max_index_Q16; index_Q16 += index_increment_Q16 ) {
        table_index = silk_SMULWB( index_Q16 & 0xFFFF, 12 );
        buf_ptr = &buf[ index_Q16 >> 16 ];

        res_Q15 = silk_SMULBB(          buf_ptr[ 0 ], silk_resampler_frac_FIR_12[      table_index ][ 0 ] );
        res_Q15 = silk_SMLABB( res_Q15, buf_ptr[ 1 ], silk_resampler_frac_FIR_12[      table_index ][ 1 ] );
        res_Q15 = silk_SMLABB( res_Q15, buf_ptr[ 2 ], silk_resampler_frac_FIR_12[      table_index ][ 2 ] );
        res_Q15 = silk_SMLABB( res_Q15, buf_ptr[ 3 ], silk_resampler_frac_FIR_12[      table_index ][ 3 ] );
        res_Q15 = silk_SMLABB( res_Q15, buf_ptr[ 4 ], silk_resampler_frac_FIR_12[ 11 - table_index ][ 3 ] );
        res_Q15 = silk_SMLABB( res_Q15, buf_ptr[ 5 ], silk_resampler_frac_FIR_12[ 11 - table_index ][ 2 ] );
        res_Q15 = silk_SMLABB( res_Q15, buf_ptr[ 6 ], silk_resampler_frac_FIR_12[ 11 - table_index ][ 1 ] );
        res_Q15 = silk_SMLABB( res_Q15, buf_ptr[ 7 ], silk_resampler_frac_FIR_12[ 11 - table_index ][ 0 ] );
        *out++ = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( res_Q15, 15 ) );
    }
    return out;
}
/* Upsample using a combination of allpass-based 2x upsampling and FIR interpolation */
void silk_resampler_private_IIR_FIR(
    void                            *SS,            /* 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     */
)
{
    silk_resampler_state_struct *S = (silk_resampler_state_struct *)SS;
    opus_int32 nSamplesIn;
    opus_int32 max_index_Q16, index_increment_Q16;
    VARDECL( opus_int16, buf );
    SAVE_STACK;

    ALLOC( buf, 2 * S->batchSize + RESAMPLER_ORDER_FIR_12, opus_int16 );

    /* Copy buffered samples to start of buffer */
    silk_memcpy( buf, S->sFIR.i16, RESAMPLER_ORDER_FIR_12 * sizeof( opus_int16 ) );

    /* Iterate over blocks of frameSizeIn input samples */
    index_increment_Q16 = S->invRatio_Q16;
    while( 1 ) {
        nSamplesIn = silk_min( inLen, S->batchSize );

        /* Upsample 2x */
        silk_resampler_private_up2_HQ( S->sIIR, &buf[ RESAMPLER_ORDER_FIR_12 ], in, nSamplesIn );

        max_index_Q16 = silk_LSHIFT32( nSamplesIn, 16 + 1 );         /* + 1 because 2x upsampling */
        out = silk_resampler_private_IIR_FIR_INTERPOL( out, buf, max_index_Q16, index_increment_Q16 );
        in += nSamplesIn;
        inLen -= nSamplesIn;

        if( inLen > 0 ) {
            /* More iterations to do; copy last part of filtered signal to beginning of buffer */
            silk_memcpy( buf, &buf[ nSamplesIn << 1 ], RESAMPLER_ORDER_FIR_12 * sizeof( opus_int16 ) );
        } else {
            break;
        }
    }

    /* Copy last part of filtered signal to the state for the next call */
    silk_memcpy( S->sFIR.i16, &buf[ nSamplesIn << 1 ], RESAMPLER_ORDER_FIR_12 * sizeof( opus_int16 ) );
    RESTORE_STACK;
}