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26***********************************************************************/
27
28#ifdef HAVE_CONFIG_H
29#include "config.h"
30#endif
31
32#include "main_FIX.h"
33
34void silk_LTP_analysis_filter_FIX(
35    opus_int16                      *LTP_res,                               /* O    LTP residual signal of length MAX_NB_SUBFR * ( pre_length + subfr_length )  */
36    const opus_int16                *x,                                     /* I    Pointer to input signal with at least max( pitchL ) preceding samples       */
37    const opus_int16                LTPCoef_Q14[ LTP_ORDER * MAX_NB_SUBFR ],/* I    LTP_ORDER LTP coefficients for each MAX_NB_SUBFR subframe                   */
38    const opus_int                  pitchL[ MAX_NB_SUBFR ],                 /* I    Pitch lag, one for each subframe                                            */
39    const opus_int32                invGains_Q16[ MAX_NB_SUBFR ],           /* I    Inverse quantization gains, one for each subframe                           */
40    const opus_int                  subfr_length,                           /* I    Length of each subframe                                                     */
41    const opus_int                  nb_subfr,                               /* I    Number of subframes                                                         */
42    const opus_int                  pre_length                              /* I    Length of the preceding samples starting at &x[0] for each subframe         */
43)
44{
45    const opus_int16 *x_ptr, *x_lag_ptr;
46    opus_int16   Btmp_Q14[ LTP_ORDER ];
47    opus_int16   *LTP_res_ptr;
48    opus_int     k, i, j;
49    opus_int32   LTP_est;
50
51    x_ptr = x;
52    LTP_res_ptr = LTP_res;
53    for( k = 0; k < nb_subfr; k++ ) {
54
55        x_lag_ptr = x_ptr - pitchL[ k ];
56        for( i = 0; i < LTP_ORDER; i++ ) {
57            Btmp_Q14[ i ] = LTPCoef_Q14[ k * LTP_ORDER + i ];
58        }
59
60        /* LTP analysis FIR filter */
61        for( i = 0; i < subfr_length + pre_length; i++ ) {
62            LTP_res_ptr[ i ] = x_ptr[ i ];
63
64            /* Long-term prediction */
65            LTP_est = silk_SMULBB( x_lag_ptr[ LTP_ORDER / 2 ], Btmp_Q14[ 0 ] );
66            for( j = 1; j < LTP_ORDER; j++ ) {
67                LTP_est = silk_SMLABB_ovflw( LTP_est, x_lag_ptr[ LTP_ORDER / 2 - j ], Btmp_Q14[ j ] );
68            }
69            LTP_est = silk_RSHIFT_ROUND( LTP_est, 14 ); /* round and -> Q0*/
70
71            /* Subtract long-term prediction */
72            LTP_res_ptr[ i ] = (opus_int16)silk_SAT16( (opus_int32)x_ptr[ i ] - LTP_est );
73
74            /* Scale residual */
75            LTP_res_ptr[ i ] = silk_SMULWB( invGains_Q16[ k ], LTP_res_ptr[ i ] );
76
77            x_lag_ptr++;
78        }
79
80        /* Update pointers */
81        LTP_res_ptr += subfr_length + pre_length;
82        x_ptr       += subfr_length;
83    }
84}
85
86