TABLE OF CONTENTS In the main file of the FILTER program on the CD, we called Calc_Filter_Coefs (as shown in Listing D.1) in order to calculate the necessary filter coefficients for the user-specified design. That function in turn called one of three other functions named Calc_Analog_Coefs, Calc_DigFIR_Coefs, or Calc_DigIIR_Coefs.
/*==================================================== Calc_Filter_Coefs() - determines implementation and calls appropriate calculation function Prototype: int Calc_Filter_Coefs(Filt_Params *FP); Return: error value Arguments: FP - ptr to struct holding filter params ====================================================*/int Calc_Filter_Coefs(Filt_Params *FP){ int Error; /* error value */ /* Call correct calc function for analog, digital FIR or IIR filters. */ switch(FP->implem) { case 'A': Error = Calc_Analog_Coefs(FP); if(Error) { return 10*Error+1;} break; case 'F': Error = Calc_DigFIR_Coefs(FP); if(Error) { return 10*Error+2;) break; case 'I': Error = Calc_DigIIR_Coefs(FP); if(Error) { return 10*Error+3;} break; default: return ERR_FILTER; } return ERR_NONE;} The implementation type for the filter is stored in the FP->implem
