This function applies IIR filter to ptrInput.

• BScale: B scale factor.
• AScale: A scale factor.
• ptrB: pointer to B coefficients (in program memory).
• ptrA: pointer to A coefficients (in program memory).
• FilterOrder: order of the filter + 1.
• ptrInput: address of input samples.
• InputLen: number of samples.
• ptrOutput: pointer to output samples. Output length is equal to Input length.
• Index: index of current sample.

Function returns value of the Index-th sample of the filtered signal :

Nothing.

// Filter setup:
//     Filter kind: IIR
//     Filter type: Lowpass filter
//     Filter order: 2
//     Design method: Butterworth

const unsigned int
  FILTER_ORDER  = 2;

const unsigned int
  COEFF_B[FILTER_ORDER+1] = {0x344D, 0x689A, 0x344D};
const unsigned int
  COEFF_A[FILTER_ORDER+1] = {0x4000, 0xA003, 0x2687};

const unsigned int
  SCALE_B       = 4;
const unsigned int
  SCALE_A       = -1;

int inputSamples[3] = {0x4000, 0x2000, 0x1000};
int outputSamples[10];
int i;

void main() {

 for(i = 0; i < 7; i++)
   outputSamples[i] = IIR_Radix(SCALE_B, SCALE_A, COEFF_B, COEFF_A, FILTER_ORDER+1, inputSamples, 3,outputSamples, i);
   // outputSamples[0] = 1/(2^SCALE_B)*COEFF_B[0]*inputSamples[0]
   // outputSamples[1] = 1/(2^SCALE_B) * (COEFF_B[0]*inputSamples[1] + COEFF_B[1]*inputSamples[0]) - 1/(2^SCALE_A)*(COEFF_A*outputSamples[0])
   // .
   // .
   // .
}

None.