src/iLBC/hpOutput.c

   1
   2    /******************************************************************
   3
   4        iLBC Speech Coder ANSI-C Source Code
   5
   6        hpOutput.c
   7
   8        Copyright (c) 2001,
   9        Global IP Sound AB.
  10        All rights reserved.
  11
  12    ******************************************************************/
  13
  14    #include "constants.h"
  15
  16    /*----------------------------------------------------------------*
  17     *  Output high-pass filter
  18     *---------------------------------------------------------------*/
  19
  20    void hpOutput(
  21        float *In,  /* (i) vector to filter */
  22        int len,/* (i) length of vector to filter */
  23        float *Out, /* (o) the resulting filtered vector */
  24        float *mem  /* (i/o) the filter state */
  25    ){
  26        int i;
  27        float *pi, *po;
  28
  29        /* all-zero section*/
  30
  31        pi = &In[0];
  32        po = &Out[0];
  33        for (i=0; i<len; i++) {
  34            *po = hpo_zero_coefsTbl[0] * (*pi);
  35            *po += hpo_zero_coefsTbl[1] * mem[0];
  36            *po += hpo_zero_coefsTbl[2] * mem[1];
  37
  38            mem[1] = mem[0];
  39            mem[0] = *pi;
  40            po++;
  41            pi++;
  42
  43        }
  44
  45        /* all-pole section*/
  46
  47     \f
  48
  49
  50        po = &Out[0];
  51        for (i=0; i<len; i++) {
  52            *po -= hpo_pole_coefsTbl[1] * mem[2];
  53            *po -= hpo_pole_coefsTbl[2] * mem[3];
  54
  55            mem[3] = mem[2];
  56            mem[2] = *po;
  57            po++;
  58        }
  59    }
  60
  61