src/third_party/opus/silk/NLSF_unpack.c

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

#include "main.h"

/* Unpack predictor values and indices for entropy coding tables */
void silk_NLSF_unpack(
          opus_int16            ec_ix[],                        /* O    Indices to entropy tables [ LPC_ORDER ]     */
          opus_uint8            pred_Q8[],                      /* O    LSF predictor [ LPC_ORDER ]                 */
    const silk_NLSF_CB_struct   *psNLSF_CB,                     /* I    Codebook object                             */
    const opus_int              CB1_index                       /* I    Index of vector in first LSF codebook       */
)
{
    opus_int   i;
    opus_uint8 entry;
    const opus_uint8 *ec_sel_ptr;

    ec_sel_ptr = &psNLSF_CB->ec_sel[ CB1_index * psNLSF_CB->order / 2 ];
    for( i = 0; i < psNLSF_CB->order; i += 2 ) {
        entry = *ec_sel_ptr++;
        ec_ix  [ i     ] = silk_SMULBB( silk_RSHIFT( entry, 1 ) & 7, 2 * NLSF_QUANT_MAX_AMPLITUDE + 1 );
        pred_Q8[ i     ] = psNLSF_CB->pred_Q8[ i + ( entry & 1 ) * ( psNLSF_CB->order - 1 ) ];
        ec_ix  [ i + 1 ] = silk_SMULBB( silk_RSHIFT( entry, 5 ) & 7, 2 * NLSF_QUANT_MAX_AMPLITUDE + 1 );
        pred_Q8[ i + 1 ] = psNLSF_CB->pred_Q8[ i + ( silk_RSHIFT( entry, 4 ) & 1 ) * ( psNLSF_CB->order - 1 ) + 1 ];
    }
}