tlv.c File Reference

dB conversion functions from control TLV information More...

Functions
int	snd_tlv_parse_dB_info (unsigned int *tlv, unsigned int tlv_size, unsigned int **db_tlvp)
	Parse TLV stream and retrieve dB information.
int	snd_tlv_get_dB_range (unsigned int *tlv, long rangemin, long rangemax, long *min, long *max)
	Get the dB min/max values.
int	snd_tlv_convert_to_dB (unsigned int *tlv, long rangemin, long rangemax, long volume, long *db_gain)
	Convert the given raw volume value to a dB gain.
int	snd_tlv_convert_from_dB (unsigned int *tlv, long rangemin, long rangemax, long db_gain, long *value, int xdir)
	Convert from dB gain to the corresponding raw value.
int	snd_ctl_get_dB_range (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, long *min, long *max)
	Get the dB min/max values on the given control element.
int	snd_ctl_convert_to_dB (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, long volume, long *db_gain)
	Convert the volume value to dB on the given control element.
int	snd_ctl_convert_from_dB (snd_ctl_t *ctl, const snd_ctl_elem_id_t *id, long db_gain, long *value, int xdir)
	Convert from dB gain to the raw volume value on the given control element.

Detailed Description

dB conversion functions from control TLV information

Author

Takashi Iwai tiwai.nosp@m.@sus.nosp@m.e.de

Date

2007

Function Documentation

snd_ctl_convert_from_dB()

int snd_ctl_convert_from_dB	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		long	db_gain,
		long *	value,
		int	xdir )

Convert from dB gain to the raw volume value on the given control element.

Parameters

ctl	the control handler
id	the element id
db_gain	the dB gain to convert (in 0.01dB unit)
value	the pointer to store the converted raw volume value
xdir	the direction for round-up. The value is round up when this is positive.

Returns

0 if successful, or a negative error code

snd_ctl_convert_to_dB()

int snd_ctl_convert_to_dB	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		long	volume,
		long *	db_gain )

Convert the volume value to dB on the given control element.

Parameters

ctl	the control handler
id	the element id
volume	the raw volume value to convert
db_gain	the dB gain (in 0.01dB unit)

Returns

0 if successful, or a negative error code

snd_ctl_get_dB_range()

int snd_ctl_get_dB_range	(	snd_ctl_t *	ctl,
		const snd_ctl_elem_id_t *	id,
		long *	min,
		long *	max )

Get the dB min/max values on the given control element.

Parameters

ctl	the control handler
id	the element id
min	the pointer to store the minimum dB value (in 0.01dB unit)
max	the pointer to store the maximum dB value (in 0.01dB unit)

Returns

0 if successful, or a negative error code

snd_tlv_convert_from_dB()

int snd_tlv_convert_from_dB	(	unsigned int *	tlv,
		long	rangemin,
		long	rangemax,
		long	db_gain,
		long *	value,
		int	xdir )

Convert from dB gain to the corresponding raw value.

Parameters

tlv	the TLV source returned by snd_tlv_parse_dB_info()
rangemin	the minimum value of the raw volume
rangemax	the maximum value of the raw volume
db_gain	the dB gain to convert (in 0.01dB unit)
value	the pointer to store the converted raw volume value
xdir	the direction for round-up. The value is round up when this is positive. A negative value means round down. Zero means round-up to nearest.

Returns

0 if successful, or a negative error code

snd_tlv_convert_to_dB()

int snd_tlv_convert_to_dB	(	unsigned int *	tlv,
		long	rangemin,
		long	rangemax,
		long	volume,
		long *	db_gain )

Convert the given raw volume value to a dB gain.

Parameters

tlv	the TLV source returned by snd_tlv_parse_dB_info()
rangemin	the minimum value of the raw volume
rangemax	the maximum value of the raw volume
volume	the raw volume value to convert
db_gain	the dB gain (in 0.01dB unit)

Returns

0 if successful, or a negative error code

snd_tlv_get_dB_range()

int snd_tlv_get_dB_range	(	unsigned int *	tlv,
		long	rangemin,
		long	rangemax,
		long *	min,
		long *	max )

Get the dB min/max values.

Parameters

tlv	the TLV source returned by snd_tlv_parse_dB_info()
rangemin	the minimum value of the raw volume
rangemax	the maximum value of the raw volume
min	the pointer to store the minimum dB value (in 0.01dB unit)
max	the pointer to store the maximum dB value (in 0.01dB unit)

Returns

0 if successful, or a negative error code

snd_tlv_parse_dB_info()

int snd_tlv_parse_dB_info	(	unsigned int *	tlv,
		unsigned int	tlv_size,
		unsigned int **	db_tlvp )

Parse TLV stream and retrieve dB information.

Parameters

tlv	the TLV source
tlv_size	the byte size of TLV source
db_tlvp	the pointer stored the dB TLV information

Returns

The byte size of dB TLV information if found in the given TLV source, -ENOENT if not found, or a negative error code in case of an error.

This function parses the given TLV source and stores the TLV start point if the TLV information regarding dB conversion is found. The stored TLV pointer can be passed to the conversion functions snd_tlv_convert_to_dB(), snd_tlv_convert_from_dB() and snd_tlv_get_dB_range().