File syn_filter_design.c¶

FileList > dsp > syn_filter_design.c

Dynamic runtime IIR Biquad filter coefficient generator implementation.

#include "syn_filter_design.h"
#include <string.h>

Public Functions¶

Type	Name
SYN_Status	syn_filter_design_apply_to_biquad (const SYN_BiquadCoeffs * coeffs, SYN_FilterBiquad * biquad) Apply calculated coefficients to a SYN_FilterBiquad instance.
SYN_Status	syn_filter_design_bandpass (q16_t fc_hz, q16_t fs_hz, q16_t Q, SYN_BiquadCoeffs * out) Calculate Bandpass filter coefficients (constant skirt gain).
SYN_Status	syn_filter_design_highpass (q16_t fc_hz, q16_t fs_hz, q16_t Q, SYN_BiquadCoeffs * out) Calculate Butterworth Highpass filter coefficients.
SYN_Status	syn_filter_design_lowpass (q16_t fc_hz, q16_t fs_hz, q16_t Q, SYN_BiquadCoeffs * out) Calculate Butterworth Lowpass filter coefficients.
SYN_Status	syn_filter_design_notch (q16_t fc_hz, q16_t fs_hz, q16_t Q, SYN_BiquadCoeffs * out) Calculate Notch / Bandstop filter coefficients.

Public Static Functions¶

Type	Name
SYN_Status	compute_intermediate_vars (q16_t fc_hz, q16_t fs_hz, q16_t Q, q16_t * cos_w0, q16_t * sin_w0, q16_t * alpha, q16_t * a0_inv) Helper to pre-warp frequency and compute intermediate bilinear transform constants.

Public Functions Documentation¶

function syn_filter_design_apply_to_biquad¶

Apply calculated coefficients to a SYN_FilterBiquad instance.

SYN_Status syn_filter_design_apply_to_biquad (
    const SYN_BiquadCoeffs * coeffs,
    SYN_FilterBiquad * biquad
)

Parameters:

coeffs Calculated biquad coefficients.
biquad Target biquad filter instance.

Returns:

SYN_OK on success, SYN_INVALID_PARAM if NULL.

function syn_filter_design_bandpass¶

Calculate Bandpass filter coefficients (constant skirt gain).

SYN_Status syn_filter_design_bandpass (
    q16_t fc_hz,
    q16_t fs_hz,
    q16_t Q,
    SYN_BiquadCoeffs * out
)

Parameters:

fc_hz Center frequency in Hz (Q16.16).
fs_hz Sampling frequency in Hz (Q16.16).
Q Quality factor / bandwidth selectivity (Q16.16, e.g., Q16_FROM_FLOAT(2.0)).
out Pointer to output coefficient structure.

Returns:

SYN_OK on success, SYN_INVALID_PARAM if invalid.

function syn_filter_design_highpass¶

Calculate Butterworth Highpass filter coefficients.

SYN_Status syn_filter_design_highpass (
    q16_t fc_hz,
    q16_t fs_hz,
    q16_t Q,
    SYN_BiquadCoeffs * out
)

Parameters:

fc_hz Cutoff frequency in Hz (Q16.16).
fs_hz Sampling frequency in Hz (Q16.16).
Q Quality factor (Q16.16, e.g., Q16_FROM_FLOAT(0.7071) for Butterworth).
out Pointer to output coefficient structure.

Returns:

SYN_OK on success, SYN_INVALID_PARAM if invalid.

function syn_filter_design_lowpass¶

Calculate Butterworth Lowpass filter coefficients.

SYN_Status syn_filter_design_lowpass (
    q16_t fc_hz,
    q16_t fs_hz,
    q16_t Q,
    SYN_BiquadCoeffs * out
)

Parameters:

fc_hz Cutoff frequency in Hz (Q16.16).
fs_hz Sampling frequency in Hz (Q16.16).
Q Quality factor (Q16.16, e.g., Q16_FROM_FLOAT(0.7071) for Butterworth).
out Pointer to output coefficient structure.

Returns:

SYN_OK on success, SYN_INVALID_PARAM if invalid.

function syn_filter_design_notch¶

Calculate Notch / Bandstop filter coefficients.

SYN_Status syn_filter_design_notch (
    q16_t fc_hz,
    q16_t fs_hz,
    q16_t Q,
    SYN_BiquadCoeffs * out
)

Parameters:

fc_hz Rejection frequency in Hz (Q16.16).
fs_hz Sampling frequency in Hz (Q16.16).
Q Quality factor / notch depth selectivity (Q16.16, e.g., Q16_FROM_FLOAT(5.0)).
out Pointer to output coefficient structure.

Returns:

SYN_OK on success, SYN_INVALID_PARAM if invalid.

Public Static Functions Documentation¶

function compute_intermediate_vars¶

Helper to pre-warp frequency and compute intermediate bilinear transform constants.

static SYN_Status compute_intermediate_vars (
    q16_t fc_hz,
    q16_t fs_hz,
    q16_t Q,
    q16_t * cos_w0,
    q16_t * sin_w0,
    q16_t * alpha,
    q16_t * a0_inv
)

Parameters:

fc_hz Cutoff frequency in Hz.
fs_hz Sampling frequency in Hz.
Q Quality factor.
cos_w0 Output cos(w0).
sin_w0 Output sin(w0).
alpha Output alpha.
a0_inv Output 1/a0 scale factor.

Returns:

SYN_OK on success, SYN_INVALID_PARAM if invalid limits.

The documentation for this class was generated from the following file src/syntropic/dsp/syn_filter_design.c