codecs/ilbc/hpOutput.c

   1
   2 /******************************************************************
   3
   4     iLBC Speech Coder ANSI-C Source Code
   5
   6     hpOutput.c
   7
   8     Copyright (C) The Internet Society (2004).
   9     All Rights Reserved.
  10
  11
  12
  13 ******************************************************************/
  14
  15 #include "constants.h"
  16 #include "hpOutput.h"
  17 /*----------------------------------------------------------------*
  18  *  Output high-pass filter
  19  *---------------------------------------------------------------*/
  20
  21 void hpOutput(
  22     float *In,  /* (i) vector to filter */
  23     int len,/* (i) length of vector to filter */
  24     float *Out, /* (o) the resulting filtered vector */
  25     float *mem  /* (i/o) the filter state */
  26 ){
  27     int i;
  28     float *pi, *po;
  29
  30     /* all-zero section*/
  31
  32     pi = &In[0];
  33     po = &Out[0];
  34     for (i=0; i<len; i++) {
  35         *po = hpo_zero_coefsTbl[0] * (*pi);
  36         *po += hpo_zero_coefsTbl[1] * mem[0];
  37         *po += hpo_zero_coefsTbl[2] * mem[1];
  38
  39         mem[1] = mem[0];
  40         mem[0] = *pi;
  41         po++;
  42         pi++;
  43
  44     }
  45
  46     /* all-pole section*/
  47
  48     po = &Out[0];
  49     for (i=0; i<len; i++) {
  50         *po -= hpo_pole_coefsTbl[1] * mem[2];
  51         *po -= hpo_pole_coefsTbl[2] * mem[3];
  52
  53         mem[3] = mem[2];
  54         mem[2] = *po;
  55         po++;
  56     }
  57 }
  58
  59