/****************************************************************** 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++; } }