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26***********************************************************************/
27
28#ifdef HAVE_CONFIG_H
29#include "config.h"
30#endif
31
32#include "main.h"
33
34/* Predictive dequantizer for NLSF residuals */
35static OPUS_INLINE void silk_NLSF_residual_dequant(               /* O    Returns RD value in Q30                     */
36          opus_int16         x_Q10[],                        /* O    Output [ order ]                            */
37    const opus_int8          indices[],                      /* I    Quantization indices [ order ]              */
38    const opus_uint8         pred_coef_Q8[],                 /* I    Backward predictor coefs [ order ]          */
39    const opus_int           quant_step_size_Q16,            /* I    Quantization step size                      */
40    const opus_int16         order                           /* I    Number of input values                      */
41)
42{
43    opus_int     i, out_Q10, pred_Q10;
44
45    out_Q10 = 0;
46    for( i = order-1; i >= 0; i-- ) {
47        pred_Q10 = silk_RSHIFT( silk_SMULBB( out_Q10, (opus_int16)pred_coef_Q8[ i ] ), 8 );
48        out_Q10  = silk_LSHIFT( indices[ i ], 10 );
49        if( out_Q10 > 0 ) {
50            out_Q10 = silk_SUB16( out_Q10, SILK_FIX_CONST( NLSF_QUANT_LEVEL_ADJ, 10 ) );
51        } else if( out_Q10 < 0 ) {
52            out_Q10 = silk_ADD16( out_Q10, SILK_FIX_CONST( NLSF_QUANT_LEVEL_ADJ, 10 ) );
53        }
54        out_Q10  = silk_SMLAWB( pred_Q10, (opus_int32)out_Q10, quant_step_size_Q16 );
55        x_Q10[ i ] = out_Q10;
56    }
57}
58
59
60/***********************/
61/* NLSF vector decoder */
62/***********************/
63void silk_NLSF_decode(
64          opus_int16            *pNLSF_Q15,                     /* O    Quantized NLSF vector [ LPC_ORDER ]         */
65          opus_int8             *NLSFIndices,                   /* I    Codebook path vector [ LPC_ORDER + 1 ]      */
66    const silk_NLSF_CB_struct   *psNLSF_CB                      /* I    Codebook object                             */
67)
68{
69    opus_int         i;
70    opus_uint8       pred_Q8[  MAX_LPC_ORDER ];
71    opus_int16       ec_ix[    MAX_LPC_ORDER ];
72    opus_int16       res_Q10[  MAX_LPC_ORDER ];
73    opus_int16       W_tmp_QW[ MAX_LPC_ORDER ];
74    opus_int32       W_tmp_Q9, NLSF_Q15_tmp;
75    const opus_uint8 *pCB_element;
76
77    /* Decode first stage */
78    pCB_element = &psNLSF_CB->CB1_NLSF_Q8[ NLSFIndices[ 0 ] * psNLSF_CB->order ];
79    for( i = 0; i < psNLSF_CB->order; i++ ) {
80        pNLSF_Q15[ i ] = silk_LSHIFT( (opus_int16)pCB_element[ i ], 7 );
81    }
82
83    /* Unpack entropy table indices and predictor for current CB1 index */
84    silk_NLSF_unpack( ec_ix, pred_Q8, psNLSF_CB, NLSFIndices[ 0 ] );
85
86    /* Predictive residual dequantizer */
87    silk_NLSF_residual_dequant( res_Q10, &NLSFIndices[ 1 ], pred_Q8, psNLSF_CB->quantStepSize_Q16, psNLSF_CB->order );
88
89    /* Weights from codebook vector */
90    silk_NLSF_VQ_weights_laroia( W_tmp_QW, pNLSF_Q15, psNLSF_CB->order );
91
92    /* Apply inverse square-rooted weights and add to output */
93    for( i = 0; i < psNLSF_CB->order; i++ ) {
94        W_tmp_Q9 = silk_SQRT_APPROX( silk_LSHIFT( (opus_int32)W_tmp_QW[ i ], 18 - NLSF_W_Q ) );
95        NLSF_Q15_tmp = silk_ADD32( pNLSF_Q15[ i ], silk_DIV32_16( silk_LSHIFT( (opus_int32)res_Q10[ i ], 14 ), W_tmp_Q9 ) );
96        pNLSF_Q15[ i ] = (opus_int16)silk_LIMIT( NLSF_Q15_tmp, 0, 32767 );
97    }
98
99    /* NLSF stabilization */
100    silk_NLSF_stabilize( pNLSF_Q15, psNLSF_CB->deltaMin_Q15, psNLSF_CB->order );
101}
102