bwexpander_32.c 2.5 KB

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