hpinput.c

PA1688网络电话机全部源程序

    
   /****************************************************************** 
    
       iLBC Speech Coder ANSI-C Source Code 
    
       hpInput.c  
    
       Copyright (c) 2001, 
       Global IP Sound AB. 
       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++; 
       } 
   }