filter APIs

filter API More...

Data Structures
struct	iir_filter_single_pole_s16
	Signed 16-bit IIR single-pole filter with fraction saving. More...
struct	iir_filter_single_pole_s32
	Signed 32-bit IIR single-pole filter with fraction saving. More...
struct	iir_filter_single_pole_f32
	Floating point IIR single-pole filter. More...

Functions
static uint32_t	iir_filter_alpha_init (float alpha)
	Convert a filter alpha to a form compatible with IIR filters.
static void	iir_filter_single_pole_s16_init (struct iir_filter_single_pole_s16 *filter, uint32_t alpha, int16_t initial)
	Initialise the integer IIR single-pole filter.
static int16_t	iir_filter_single_pole_s16_step (struct iir_filter_single_pole_s16 *filter, int16_t x)
	Run the filter for one step.
static void	iir_filter_single_pole_s32_init (struct iir_filter_single_pole_s32 *filter, uint32_t alpha, int32_t initial)
	Initialise the integer IIR single-pole filter.
static int32_t	iir_filter_single_pole_s32_step (struct iir_filter_single_pole_s32 *filter, int32_t x)
	Run the filter for one step.
static void	iir_filter_single_pole_f32_init (struct iir_filter_single_pole_f32 *filter, float alpha, float initial)
	Initialise the float IIR single-pole filter.
static float	iir_filter_single_pole_f32_step (struct iir_filter_single_pole_f32 *filter, float x)
	Run the filter for one step.

Detailed Description

filter API

Function Documentation

iir_filter_alpha_init()

static uint32_t iir_filter_alpha_init ( float alpha )

inlinestatic

#include <infuse/math/filter.h>

Convert a filter alpha to a form compatible with IIR filters.

Parameters

alpha

Filter alpha value, between 0.0f and 1.0f exclusive.

Returns

uint32_t alpha value suitable for IIR filters

iir_filter_single_pole_f32_init()

static void iir_filter_single_pole_f32_init ( struct iir_filter_single_pole_f32 * filter, float alpha, float initial )

inlinestatic

#include <infuse/math/filter.h>

Initialise the float IIR single-pole filter.

Parameters

filter	Filter state
alpha	Filter time constant
initial	Initial value for filter output

iir_filter_single_pole_f32_step()

static float iir_filter_single_pole_f32_step ( struct iir_filter_single_pole_f32 * filter, float x )

inlinestatic

#include <infuse/math/filter.h>

Run the filter for one step.

Parameters

filter	Filter state
x	Filter input value

Returns

float Output value of the filter

iir_filter_single_pole_s16_init()

static void iir_filter_single_pole_s16_init ( struct iir_filter_single_pole_s16 * filter, uint32_t alpha, int16_t initial )

inlinestatic

#include <infuse/math/filter.h>

Initialise the integer IIR single-pole filter.

Note

Use iir_filter_alpha_init to initialise alpha from a float

Parameters

filter	Filter state
alpha	Filter time constant (α=1−e^(−Δt/RC)), 0-1 scaled by (1 << 32)
initial	Initial value for filter output

iir_filter_single_pole_s16_step()

static int16_t iir_filter_single_pole_s16_step ( struct iir_filter_single_pole_s16 * filter, int16_t x )

inlinestatic

#include <infuse/math/filter.h>

Run the filter for one step.

Parameters

filter	Filter state
x	Filter input value

Returns

int32_t Output value of the filter

iir_filter_single_pole_s32_init()

static void iir_filter_single_pole_s32_init ( struct iir_filter_single_pole_s32 * filter, uint32_t alpha, int32_t initial )

inlinestatic

#include <infuse/math/filter.h>

Initialise the integer IIR single-pole filter.

Note

Use iir_filter_alpha_init to initialise alpha from a float

Parameters

filter	Filter state
alpha	Filter time constant (α=1−e^(−Δt/RC)), 0-1 scaled by (1 << 32)
initial	Initial value for filter output

iir_filter_single_pole_s32_step()

static int32_t iir_filter_single_pole_s32_step ( struct iir_filter_single_pole_s32 * filter, int32_t x )

inlinestatic

#include <infuse/math/filter.h>

Run the filter for one step.

Parameters

filter	Filter state
x	Filter input value

Returns

int32_t Output value of the filter