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27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 #include "SigProc_FIX.h"
33
34 /* Chirp (bandwidth expand) LP AR filter.
35 This logic is reused in _celt_lpc(). Any bug fixes should also be applied there. */
silk_bwexpander_32(opus_int32 * ar,const opus_int d,opus_int32 chirp_Q16)36 void silk_bwexpander_32(
37 opus_int32 *ar, /* I/O AR filter to be expanded (without leading 1) */
38 const opus_int d, /* I Length of ar */
39 opus_int32 chirp_Q16 /* I Chirp factor in Q16 */
40 )
41 {
42 opus_int i;
43 opus_int32 chirp_minus_one_Q16 = chirp_Q16 - 65536;
44
45 for( i = 0; i < d - 1; i++ ) {
46 ar[ i ] = silk_SMULWW( chirp_Q16, ar[ i ] );
47 chirp_Q16 += silk_RSHIFT_ROUND( silk_MUL( chirp_Q16, chirp_minus_one_Q16 ), 16 );
48 }
49 ar[ d - 1 ] = silk_SMULWW( chirp_Q16, ar[ d - 1 ] );
50 }
51
52