iir_df1.h File Reference

Infinite Impulse Response Direct Form I (DF1) filter definitions. More...

Include dependency graph for iir_df1.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	iir_state_df1

Macros
#define	IIR_DF1_NUM_STATE   4
#define	SOF_IIR_DF1_4TH_NUM_BIQUADS   2

Functions
int	iir_init_coef_df1 (struct iir_state_df1 *iir, struct sof_eq_iir_header *config)
	Initialize IIR Direct Form 1 coefficients from configuration header.
int	iir_delay_size_df1 (struct sof_eq_iir_header *config)
	Calculate required delay line buffer size in bytes for a DF1 configuration.
void	iir_init_delay_df1 (struct iir_state_df1 *iir, int32_t **state)
	Assign and initialize delay line state memory for DF1 filter.
void	iir_reset_df1 (struct iir_state_df1 *iir)
	Clear delay history of a Direct Form 1 IIR filter.
int32_t	iir_df1 (struct iir_state_df1 *iir, int32_t x)
	Calculate IIR filter consisting of biquads.
int32_t	iir_df1_4th (struct iir_state_df1 *iir, int32_t x)
	Calculate IIR filter consisting of biquads, special simplified version for 4th order filter with two biquads in series.

Detailed Description

Infinite Impulse Response Direct Form I (DF1) filter definitions.

Macro Definition Documentation

IIR_DF1_NUM_STATE

#define IIR_DF1_NUM_STATE   4

SOF_IIR_DF1_4TH_NUM_BIQUADS

#define SOF_IIR_DF1_4TH_NUM_BIQUADS   2

Function Documentation

iir_delay_size_df1()

int iir_delay_size_df1

(

struct sof_eq_iir_header *

config

)

Calculate required delay line buffer size in bytes for a DF1 configuration.

Parameters

config

Pointer to IIR equalizer configuration header.

Returns

Required delay buffer size in bytes.

iir_df1()

int32_t iir_df1	(	struct iir_state_df1 *	iir,
		int32_t	x
	)

Calculate IIR filter consisting of biquads.

Parameters

iir	IIR state with configured biquad coefficients and delay lines data
x	Single s32 Q1.31 format input sample

Returns

Single s32 Q1.31 format output samples

iir_df1_4th()

int32_t iir_df1_4th	(	struct iir_state_df1 *	iir,
		int32_t	x
	)

Calculate IIR filter consisting of biquads, special simplified version for 4th order filter with two biquads in series.

Note: There are no checks for iir struct members.

Parameters

iir	IIR state with configured biquad coefficients and delay lines data
x	Single s32 Q1.31 format input sample

Returns

Single s32 Q1.31 format output samples

iir_init_coef_df1()

int iir_init_coef_df1	(	struct iir_state_df1 *	iir,
		struct sof_eq_iir_header *	config
	)

Initialize IIR Direct Form 1 coefficients from configuration header.

Parameters

iir	Pointer to DF1 filter state structure.
config	Pointer to IIR equalizer configuration header.

Returns

0 on success, negative error code on failure.

iir_init_delay_df1()

void iir_init_delay_df1	(	struct iir_state_df1 *	iir,
		int32_t **	state
	)

Assign and initialize delay line state memory for DF1 filter.

Parameters

iir	Pointer to DF1 filter state structure.
state	Double pointer to delay state buffer (updated with new buffer offset).

iir_reset_df1()

void iir_reset_df1

(

struct iir_state_df1 *

iir

)

Clear delay history of a Direct Form 1 IIR filter.

Parameters

iir	Pointer to DF1 filter state structure.