Real-Time Digital Signal Processing from MATLAB® to C with the TMS320C6x DSPs, Second Edition, 2nd Edition

80 CHAPTER 4. IIR DIGITAL FILTERS

Listing 4.2: Brute-force IIR filter declarations.

#d e f i n e N1 // filter order

2

float B [ N +1] = {1.0 , −1.0}; // numerator filter coefficients

4 float A [ N +1] = {1.0 , −0.9}; // denominator filter coefficients

float x [ N +1]; // input values

6 float y [ N +1]; // output values

The code shown below performs the actual filtering operation. The four main steps

involved in this operation will be discussed following the code listing.

Listing 4.3: Brute-force IIR filtering for real-time.

/* I added my routine here */

2 x [0] = CodecDataIn . Channel [ LEFT ]; // current input value

4 y [0] = −A [1]∗ y [1] + B [0]∗ x [0]