This function applies IIR filter to ptrInput.

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

Nothing.

const BUFFER_SIZE = 8
const FILTER_ORDER = 6
const COEFF_B as word[FILTER_ORDER+1] = (0x0548, 0x1FAE, 0x4F34, 0x699B, 0x4F34, 0x1FAE, 0x0548)
const COEFF_A as word[FILTER_ORDER+1] = (0x4000, 0xB3FE, 0x5389, 0xD4D8, 0x10DD, 0xFCB0, 0x0052)
const SCALE_B = 2  
const SCALE_A = -1  
dim inext as word                      ' Input buffer index
    input as word[BUFFER_SIZE] ydata   ' Input buffer
    output as word[BUFFER_SIZE] ydata  ' Output buffer
...
dim CurrentValue as word
CurrentValue = IIR_Radix(SCALE_B,         
                         SCALE_A,         
                         word(@COEFF_B),  ' b coefficients of the filter
                         word(@COEFF_A),  ' a coefficients of the filter
                         FILTER_ORDER+1,  ' Filter order + 1
                         word(@input),    ' Input buffer
                         BUFFER_SIZE,     ' Input buffer length
                         word(@output),   ' Input buffer
                         inext)           ' Current sample

Input and output samples must be in Y data space.