xref: /aosp_15_r20/external/libopus/silk/shell_coder.c (revision a58d3d2adb790c104798cd88c8a3aff4fa8b82cc)

/***********************************************************************
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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***********************************************************************/

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

#include "main.h"

/* shell coder; pulse-subframe length is hardcoded */

static OPUS_INLINE void combine_pulses(
    opus_int         *out,   /* O    combined pulses vector [len] */
    const opus_int   *in,    /* I    input vector       [2 * len] */
    const opus_int   len     /* I    number of OUTPUT samples     */
)
{
    opus_int k;
    for( k = 0; k < len; k++ ) {
        out[ k ] = in[ 2 * k ] + in[ 2 * k + 1 ];
    }
}

static OPUS_INLINE void encode_split(
    ec_enc                      *psRangeEnc,    /* I/O  compressor data structure                   */
    const opus_int              p_child1,       /* I    pulse amplitude of first child subframe     */
    const opus_int              p,              /* I    pulse amplitude of current subframe         */
    const opus_uint8            *shell_table    /* I    table of shell cdfs                         */
)
{
    if( p > 0 ) {
        ec_enc_icdf( psRangeEnc, p_child1, &shell_table[ silk_shell_code_table_offsets[ p ] ], 8 );
    }
}

static OPUS_INLINE void decode_split(
    opus_int16                  *p_child1,      /* O    pulse amplitude of first child subframe     */
    opus_int16                  *p_child2,      /* O    pulse amplitude of second child subframe    */
    ec_dec                      *psRangeDec,    /* I/O  Compressor data structure                   */
    const opus_int              p,              /* I    pulse amplitude of current subframe         */
    const opus_uint8            *shell_table    /* I    table of shell cdfs                         */
)
{
    if( p > 0 ) {
        p_child1[ 0 ] = ec_dec_icdf( psRangeDec, &shell_table[ silk_shell_code_table_offsets[ p ] ], 8 );
        p_child2[ 0 ] = p - p_child1[ 0 ];
    } else {
        p_child1[ 0 ] = 0;
        p_child2[ 0 ] = 0;
    }
}

/* Shell encoder, operates on one shell code frame of 16 pulses */
void silk_shell_encoder(
    ec_enc                      *psRangeEnc,                    /* I/O  compressor data structure                   */
    const opus_int              *pulses0                        /* I    data: nonnegative pulse amplitudes          */
)
{
    opus_int pulses1[ 8 ], pulses2[ 4 ], pulses3[ 2 ], pulses4[ 1 ];

    /* this function operates on one shell code frame of 16 pulses */
    silk_assert( SHELL_CODEC_FRAME_LENGTH == 16 );

    /* tree representation per pulse-subframe */
    combine_pulses( pulses1, pulses0, 8 );
    combine_pulses( pulses2, pulses1, 4 );
    combine_pulses( pulses3, pulses2, 2 );
    combine_pulses( pulses4, pulses3, 1 );

    encode_split( psRangeEnc, pulses3[  0 ], pulses4[ 0 ], silk_shell_code_table3 );

    encode_split( psRangeEnc, pulses2[  0 ], pulses3[ 0 ], silk_shell_code_table2 );

    encode_split( psRangeEnc, pulses1[  0 ], pulses2[ 0 ], silk_shell_code_table1 );
    encode_split( psRangeEnc, pulses0[  0 ], pulses1[ 0 ], silk_shell_code_table0 );
    encode_split( psRangeEnc, pulses0[  2 ], pulses1[ 1 ], silk_shell_code_table0 );

    encode_split( psRangeEnc, pulses1[  2 ], pulses2[ 1 ], silk_shell_code_table1 );
    encode_split( psRangeEnc, pulses0[  4 ], pulses1[ 2 ], silk_shell_code_table0 );
    encode_split( psRangeEnc, pulses0[  6 ], pulses1[ 3 ], silk_shell_code_table0 );

    encode_split( psRangeEnc, pulses2[  2 ], pulses3[ 1 ], silk_shell_code_table2 );

    encode_split( psRangeEnc, pulses1[  4 ], pulses2[ 2 ], silk_shell_code_table1 );
    encode_split( psRangeEnc, pulses0[  8 ], pulses1[ 4 ], silk_shell_code_table0 );
    encode_split( psRangeEnc, pulses0[ 10 ], pulses1[ 5 ], silk_shell_code_table0 );

    encode_split( psRangeEnc, pulses1[  6 ], pulses2[ 3 ], silk_shell_code_table1 );
    encode_split( psRangeEnc, pulses0[ 12 ], pulses1[ 6 ], silk_shell_code_table0 );
    encode_split( psRangeEnc, pulses0[ 14 ], pulses1[ 7 ], silk_shell_code_table0 );
}


/* Shell decoder, operates on one shell code frame of 16 pulses */
void silk_shell_decoder(
    opus_int16                  *pulses0,                       /* O    data: nonnegative pulse amplitudes          */
    ec_dec                      *psRangeDec,                    /* I/O  Compressor data structure                   */
    const opus_int              pulses4                         /* I    number of pulses per pulse-subframe         */
)
{
    opus_int16 pulses3[ 2 ], pulses2[ 4 ], pulses1[ 8 ];

    /* this function operates on one shell code frame of 16 pulses */
    silk_assert( SHELL_CODEC_FRAME_LENGTH == 16 );

    decode_split( &pulses3[  0 ], &pulses3[  1 ], psRangeDec, pulses4,      silk_shell_code_table3 );

    decode_split( &pulses2[  0 ], &pulses2[  1 ], psRangeDec, pulses3[ 0 ], silk_shell_code_table2 );

    decode_split( &pulses1[  0 ], &pulses1[  1 ], psRangeDec, pulses2[ 0 ], silk_shell_code_table1 );
    decode_split( &pulses0[  0 ], &pulses0[  1 ], psRangeDec, pulses1[ 0 ], silk_shell_code_table0 );
    decode_split( &pulses0[  2 ], &pulses0[  3 ], psRangeDec, pulses1[ 1 ], silk_shell_code_table0 );

    decode_split( &pulses1[  2 ], &pulses1[  3 ], psRangeDec, pulses2[ 1 ], silk_shell_code_table1 );
    decode_split( &pulses0[  4 ], &pulses0[  5 ], psRangeDec, pulses1[ 2 ], silk_shell_code_table0 );
    decode_split( &pulses0[  6 ], &pulses0[  7 ], psRangeDec, pulses1[ 3 ], silk_shell_code_table0 );

    decode_split( &pulses2[  2 ], &pulses2[  3 ], psRangeDec, pulses3[ 1 ], silk_shell_code_table2 );

    decode_split( &pulses1[  4 ], &pulses1[  5 ], psRangeDec, pulses2[ 2 ], silk_shell_code_table1 );
    decode_split( &pulses0[  8 ], &pulses0[  9 ], psRangeDec, pulses1[ 4 ], silk_shell_code_table0 );
    decode_split( &pulses0[ 10 ], &pulses0[ 11 ], psRangeDec, pulses1[ 5 ], silk_shell_code_table0 );

    decode_split( &pulses1[  6 ], &pulses1[  7 ], psRangeDec, pulses2[ 3 ], silk_shell_code_table1 );
    decode_split( &pulses0[ 12 ], &pulses0[ 13 ], psRangeDec, pulses1[ 6 ], silk_shell_code_table0 );
    decode_split( &pulses0[ 14 ], &pulses0[ 15 ], psRangeDec, pulses1[ 7 ], silk_shell_code_table0 );
}