hpInput.c

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 /******************************************************************

 iLBC Speech Coder ANSI-C Source Code





 hpInput.c

 Copyright (C) The Internet Society (2004).
 All Rights Reserved.

 ******************************************************************/

 #include "constants.h"

 /*----------------------------------------------------------------*
 * Input high-pass filter
 *---------------------------------------------------------------*/

 void hpInput(
 float *In, /* (i) vector to filter */
 int len, /* (i) length of vector to filter */
 float *Out, /* (o) the resulting filtered vector */
 float *mem /* (i/o) the filter state */
 ){
 int i;
 float *pi, *po;

 /* all-zero section*/

 pi = &In[0];
 po = &Out[0];
 for (i=0; i<len; i++) {
 *po = hpi_zero_coefsTbl[0] * (*pi);
 *po += hpi_zero_coefsTbl[1] * mem[0];
 *po += hpi_zero_coefsTbl[2] * mem[1];

 mem[1] = mem[0];
 mem[0] = *pi;
 po++;
 pi++;

 }

 /* all-pole section*/

 po = &Out[0];
 for (i=0; i<len; i++) {
 *po -= hpi_pole_coefsTbl[1] * mem[2];
 *po -= hpi_pole_coefsTbl[2] * mem[3];

 mem[3] = mem[2];
 mem[2] = *po;
 po++;





 }
 }