HCTL Interface - High Level CTL. More...

Functions
int	snd_hctl_open (snd_hctl_t *hctlp, const char name, int mode)
	Opens an HCTL.

int	snd_hctl_open_ctl (snd_hctl_t *hctlp, snd_ctl_t ctl)
	Opens an HCTL.

int	snd_hctl_close (snd_hctl_t *hctl)
	close HCTL handle

const char *	snd_hctl_name (snd_hctl_t *hctl)
	get identifier of HCTL handle

int	snd_hctl_nonblock (snd_hctl_t *hctl, int nonblock)
	set nonblock mode

int	snd_hctl_async (snd_hctl_t *hctl, int sig, pid_t pid)
	set async mode

int	snd_hctl_poll_descriptors_count (snd_hctl_t *hctl)
	get count of poll descriptors for HCTL handle

int	snd_hctl_poll_descriptors (snd_hctl_t hctl, struct pollfd pfds, unsigned int space)
	get poll descriptors

int	snd_hctl_poll_descriptors_revents (snd_hctl_t hctl, struct pollfd pfds, unsigned int nfds, unsigned short *revents)
	get returned events from poll descriptors

int	snd_hctl_free (snd_hctl_t *hctl)
	free HCTL loaded elements

int	snd_hctl_set_compare (snd_hctl_t *hctl, snd_hctl_compare_t compare)
	Change HCTL compare function and reorder elements.

int	snd_hctl_compare_fast (const snd_hctl_elem_t c1, const snd_hctl_elem_t c2)
	A "don't care" fast compare functions that may be used with snd_hctl_set_compare.

snd_hctl_elem_t *	snd_hctl_first_elem (snd_hctl_t *hctl)
	get first element for an HCTL

snd_hctl_elem_t *	snd_hctl_last_elem (snd_hctl_t *hctl)
	get last element for an HCTL

snd_hctl_elem_t *	snd_hctl_elem_next (snd_hctl_elem_t *elem)
	get next HCTL element

snd_hctl_elem_t *	snd_hctl_elem_prev (snd_hctl_elem_t *elem)
	get previous HCTL element

snd_hctl_elem_t *	snd_hctl_find_elem (snd_hctl_t hctl, const snd_ctl_elem_id_t id)
	Search an HCTL element.

int	snd_hctl_load (snd_hctl_t *hctl)
	Load an HCTL with all elements and sort them.

void	snd_hctl_set_callback (snd_hctl_t *hctl, snd_hctl_callback_t callback)
	Set callback function for an HCTL.

void	snd_hctl_set_callback_private (snd_hctl_t hctl, void callback_private)
	Set callback private value for an HCTL.

void *	snd_hctl_get_callback_private (snd_hctl_t *hctl)
	Get callback private value for an HCTL.

unsigned int	snd_hctl_get_count (snd_hctl_t *hctl)
	Get number of loaded elements for an HCTL.

int	snd_hctl_wait (snd_hctl_t *hctl, int timeout)
	Wait for a HCTL to become ready (i.e. at least one event pending)

snd_ctl_t *	snd_hctl_ctl (snd_hctl_t *hctl)
	Get a ctl handle associated to the given hctl handle.

int	snd_hctl_handle_events (snd_hctl_t *hctl)
	Handle pending HCTL events invoking callbacks.

int	snd_hctl_elem_info (snd_hctl_elem_t elem, snd_ctl_elem_info_t info)
	Get information for an HCTL element.

int	snd_hctl_elem_read (snd_hctl_elem_t elem, snd_ctl_elem_value_t value)
	Get value for an HCTL element.

int	snd_hctl_elem_write (snd_hctl_elem_t elem, snd_ctl_elem_value_t value)
	Set value for an HCTL element.

int	snd_hctl_elem_tlv_read (snd_hctl_elem_t elem, unsigned int tlv, unsigned int tlv_size)
	Get TLV value for an HCTL element.

int	snd_hctl_elem_tlv_write (snd_hctl_elem_t elem, const unsigned int tlv)
	Set TLV value for an HCTL element.

int	snd_hctl_elem_tlv_command (snd_hctl_elem_t elem, const unsigned int tlv)
	Set TLV value for an HCTL element.

snd_hctl_t *	snd_hctl_elem_get_hctl (snd_hctl_elem_t *elem)
	Get HCTL handle for an HCTL element.

void	snd_hctl_elem_get_id (const snd_hctl_elem_t obj, snd_ctl_elem_id_t ptr)
	Get CTL element identifier of a CTL element id/value.

unsigned int	snd_hctl_elem_get_numid (const snd_hctl_elem_t *obj)
	Get element numeric identifier of a CTL element id/value.

snd_ctl_elem_iface_t	snd_hctl_elem_get_interface (const snd_hctl_elem_t *obj)
	Get interface part of CTL element identifier of a CTL element id/value.

unsigned int	snd_hctl_elem_get_device (const snd_hctl_elem_t *obj)
	Get device part of CTL element identifier of a CTL element id/value.

unsigned int	snd_hctl_elem_get_subdevice (const snd_hctl_elem_t *obj)
	Get subdevice part of CTL element identifier of a CTL element id/value.

const char *	snd_hctl_elem_get_name (const snd_hctl_elem_t *obj)
	Get name part of CTL element identifier of a CTL element id/value.

unsigned int	snd_hctl_elem_get_index (const snd_hctl_elem_t *obj)
	Get index part of CTL element identifier of a CTL element id/value.

void	snd_hctl_elem_set_callback (snd_hctl_elem_t *obj, snd_hctl_elem_callback_t val)
	Set callback function for an HCTL element.

void	snd_hctl_elem_set_callback_private (snd_hctl_elem_t obj, void val)
	Set callback private value for an HCTL element.

void *	snd_hctl_elem_get_callback_private (const snd_hctl_elem_t *obj)
	Get callback private value for an HCTL element.

Detailed Description

HCTL Interface - High Level CTL.

Author: Jaroslav Kysela perex.nosp@m.@per.nosp@m.ex.cz; Abramo Bagnara abram.nosp@m.o@al.nosp@m.sa-pr.nosp@m.ojec.nosp@m.t.org

Date: 2000

HCTL interface is designed to access preloaded and sorted primitive controls. Callbacks may be used for event handling. See High level control interface page for more details.

Function Documentation

◆ snd_hctl_async()

int snd_hctl_async	(	snd_hctl_t *	hctl,
		int	sig,
		pid_t	pid )

set async mode

Parameters

hctl	HCTL handle
sig	Signal to raise: < 0 disable, 0 default (SIGIO)
pid	Process ID to signal: 0 current

Returns: 0 on success otherwise a negative error code

A signal is raised when a change happens.

◆ snd_hctl_close()

int snd_hctl_close ( snd_hctl_t * hctl )

close HCTL handle

Parameters

hctl	HCTL handle

Returns: 0 on success otherwise a negative error code

Closes the specified HCTL handle and frees all associated resources.

◆ snd_hctl_compare_fast()

int snd_hctl_compare_fast	(	const snd_hctl_elem_t *	c1,
		const snd_hctl_elem_t *	c2 )

A "don't care" fast compare functions that may be used with snd_hctl_set_compare.

Parameters

c1	First HCTL element
c2	Second HCTL element

Returns: -1 if c1 < c2, 0 if c1 == c2, 1 if c1 > c2

◆ snd_hctl_ctl()

snd_ctl_t * snd_hctl_ctl ( snd_hctl_t * hctl )

Get a ctl handle associated to the given hctl handle.

Parameters

hctl	HCTL handle

Returns: a ctl handle otherwise NULL

◆ snd_hctl_elem_get_callback_private()

void * snd_hctl_elem_get_callback_private ( const snd_hctl_elem_t * obj )

Get callback private value for an HCTL element.

Parameters

obj	HCTL element

Returns: callback private value

◆ snd_hctl_elem_get_device()

unsigned int snd_hctl_elem_get_device ( const snd_hctl_elem_t * obj )

Get device part of CTL element identifier of a CTL element id/value.

Parameters

obj	CTL element id/value

Returns: device part of element identifier

◆ snd_hctl_elem_get_hctl()

snd_hctl_t * snd_hctl_elem_get_hctl ( snd_hctl_elem_t * elem )

Get HCTL handle for an HCTL element.

Parameters

elem	HCTL element

Returns: HCTL handle

◆ snd_hctl_elem_get_id()

void snd_hctl_elem_get_id	(	const snd_hctl_elem_t *	obj,
		snd_ctl_elem_id_t *	ptr )

Get CTL element identifier of a CTL element id/value.

Parameters

obj	CTL element id/value
ptr	Pointer to returned CTL element identifier

◆ snd_hctl_elem_get_index()

unsigned int snd_hctl_elem_get_index ( const snd_hctl_elem_t * obj )

Get index part of CTL element identifier of a CTL element id/value.

Parameters

obj	CTL element id/value

Returns: index part of element identifier

◆ snd_hctl_elem_get_interface()

snd_ctl_elem_iface_t snd_hctl_elem_get_interface ( const snd_hctl_elem_t * obj )

Get interface part of CTL element identifier of a CTL element id/value.

Parameters

obj	CTL element id/value

Returns: interface part of element identifier

◆ snd_hctl_elem_get_name()

const char * snd_hctl_elem_get_name ( const snd_hctl_elem_t * obj )

Get name part of CTL element identifier of a CTL element id/value.

Parameters

obj	CTL element id/value

Returns: name part of element identifier

◆ snd_hctl_elem_get_numid()

unsigned int snd_hctl_elem_get_numid ( const snd_hctl_elem_t * obj )

Get element numeric identifier of a CTL element id/value.

Parameters

obj	CTL element id/value

Returns: element numeric identifier

◆ snd_hctl_elem_get_subdevice()

unsigned int snd_hctl_elem_get_subdevice ( const snd_hctl_elem_t * obj )

Get subdevice part of CTL element identifier of a CTL element id/value.

Parameters

obj	CTL element id/value

Returns: subdevice part of element identifier

◆ snd_hctl_elem_info()

int snd_hctl_elem_info	(	snd_hctl_elem_t *	elem,
		snd_ctl_elem_info_t *	info )

Get information for an HCTL element.

Parameters

elem	HCTL element
info	HCTL element information

Returns: 0 otherwise a negative error code on failure

◆ snd_hctl_elem_next()

snd_hctl_elem_t * snd_hctl_elem_next ( snd_hctl_elem_t * elem )

get next HCTL element

Parameters

elem	HCTL element

Returns: pointer to next element

◆ snd_hctl_elem_prev()

snd_hctl_elem_t * snd_hctl_elem_prev ( snd_hctl_elem_t * elem )

get previous HCTL element

Parameters

elem	HCTL element

Returns: pointer to previous element

◆ snd_hctl_elem_read()

int snd_hctl_elem_read	(	snd_hctl_elem_t *	elem,
		snd_ctl_elem_value_t *	value )

Get value for an HCTL element.

Parameters

elem	HCTL element
value	HCTL element value

Returns: 0 otherwise a negative error code on failure

◆ snd_hctl_elem_set_callback()

void snd_hctl_elem_set_callback	(	snd_hctl_elem_t *	obj,
		snd_hctl_elem_callback_t	val )

Set callback function for an HCTL element.

Parameters

obj	HCTL element
val	callback function

◆ snd_hctl_elem_set_callback_private()

void snd_hctl_elem_set_callback_private	(	snd_hctl_elem_t *	obj,
		void *	val )

Set callback private value for an HCTL element.

Parameters

obj	HCTL element
val	callback private value

◆ snd_hctl_elem_tlv_command()

int snd_hctl_elem_tlv_command	(	snd_hctl_elem_t *	elem,
		const unsigned int *	tlv )

Set TLV value for an HCTL element.

Parameters

elem	HCTL element
tlv	TLV array for value

Return values

0	on success
>1	on success when value was changed
<0	a negative error code on failure

◆ snd_hctl_elem_tlv_read()

int snd_hctl_elem_tlv_read	(	snd_hctl_elem_t *	elem,
		unsigned int *	tlv,
		unsigned int	tlv_size )

Get TLV value for an HCTL element.

Parameters

elem	HCTL element
tlv	TLV array for value
tlv_size	size of TLV array in bytes

Returns: 0 otherwise a negative error code on failure

◆ snd_hctl_elem_tlv_write()

int snd_hctl_elem_tlv_write	(	snd_hctl_elem_t *	elem,
		const unsigned int *	tlv )

Set TLV value for an HCTL element.

Parameters

elem	HCTL element
tlv	TLV array for value

Return values

0	on success
>1	on success when value was changed
<0	a negative error code on failure

◆ snd_hctl_elem_write()

int snd_hctl_elem_write	(	snd_hctl_elem_t *	elem,
		snd_ctl_elem_value_t *	value )

Set value for an HCTL element.

Parameters

elem	HCTL element
value	HCTL element value

Return values

0	on success
>1	on success when value was changed
<0	a negative error code on failure

◆ snd_hctl_find_elem()

snd_hctl_elem_t * snd_hctl_find_elem	(	snd_hctl_t *	hctl,
		const snd_ctl_elem_id_t *	id )

Search an HCTL element.

Parameters

hctl	HCTL handle
id	Element identifier

Returns: pointer to found HCTL element or NULL if it does not exists

◆ snd_hctl_first_elem()

snd_hctl_elem_t * snd_hctl_first_elem ( snd_hctl_t * hctl )

get first element for an HCTL

Parameters

hctl	HCTL handle

Returns: pointer to first element

◆ snd_hctl_free()

int snd_hctl_free ( snd_hctl_t * hctl )

free HCTL loaded elements

Parameters

hctl	HCTL handle

Returns: 0 on success otherwise a negative error code

◆ snd_hctl_get_callback_private()

void * snd_hctl_get_callback_private ( snd_hctl_t * hctl )

Get callback private value for an HCTL.

Parameters

hctl	HCTL handle

Returns: callback private value

◆ snd_hctl_get_count()

unsigned int snd_hctl_get_count ( snd_hctl_t * hctl )

Get number of loaded elements for an HCTL.

Parameters

hctl	HCTL handle

Returns: elements count

◆ snd_hctl_handle_events()

int snd_hctl_handle_events ( snd_hctl_t * hctl )

Handle pending HCTL events invoking callbacks.

Parameters

hctl	HCTL handle

Returns: 0 otherwise a negative error code on failure

◆ snd_hctl_last_elem()

snd_hctl_elem_t * snd_hctl_last_elem ( snd_hctl_t * hctl )

get last element for an HCTL

Parameters

hctl	HCTL handle

Returns: pointer to last element

◆ snd_hctl_load()

int snd_hctl_load ( snd_hctl_t * hctl )

Load an HCTL with all elements and sort them.

Parameters

hctl	HCTL handle

Returns: 0 on success otherwise a negative error code

◆ snd_hctl_name()

const char * snd_hctl_name ( snd_hctl_t * hctl )

get identifier of HCTL handle

Parameters

hctl	HCTL handle

Returns: ascii identifier of HCTL handle

Returns the ASCII identifier of given HCTL handle. It's the same identifier specified in snd_hctl_open().

◆ snd_hctl_nonblock()

int snd_hctl_nonblock	(	snd_hctl_t *	hctl,
		int	nonblock )

set nonblock mode

Parameters

hctl	HCTL handle
nonblock	0 = block, 1 = nonblock mode

Returns: 0 on success otherwise a negative error code

◆ snd_hctl_open()

int snd_hctl_open	(	snd_hctl_t **	hctlp,
		const char *	name,
		int	mode )

Opens an HCTL.

Parameters

hctlp	Returned HCTL handle
name	ASCII identifier of the underlying CTL handle
mode	Open mode (see #SND_CTL_NONBLOCK, #SND_CTL_ASYNC)

Returns: 0 on success otherwise a negative error code

◆ snd_hctl_open_ctl()

int snd_hctl_open_ctl	(	snd_hctl_t **	hctlp,
		snd_ctl_t *	ctl )

Opens an HCTL.

Parameters

hctlp	Returned HCTL handle
ctl	underlying CTL handle

Returns: 0 on success otherwise a negative error code

◆ snd_hctl_poll_descriptors()

int snd_hctl_poll_descriptors	(	snd_hctl_t *	hctl,
		struct pollfd *	pfds,
		unsigned int	space )

get poll descriptors

Parameters

hctl	HCTL handle
pfds	array of poll descriptors
space	space in the poll descriptor array

Returns: count of filled descriptors

◆ snd_hctl_poll_descriptors_count()

int snd_hctl_poll_descriptors_count ( snd_hctl_t * hctl )

get count of poll descriptors for HCTL handle

Parameters

hctl	HCTL handle

Returns: count of poll descriptors

◆ snd_hctl_poll_descriptors_revents()

int snd_hctl_poll_descriptors_revents	(	snd_hctl_t *	hctl,
		struct pollfd *	pfds,
		unsigned int	nfds,
		unsigned short *	revents )

get returned events from poll descriptors

Parameters

hctl	HCTL handle
pfds	array of poll descriptors
nfds	count of poll descriptors
revents	returned events

Returns: zero if success, otherwise a negative error code

◆ snd_hctl_set_callback()

void snd_hctl_set_callback	(	snd_hctl_t *	hctl,
		snd_hctl_callback_t	callback )

Set callback function for an HCTL.

Parameters

hctl	HCTL handle
callback	callback function

◆ snd_hctl_set_callback_private()

void snd_hctl_set_callback_private	(	snd_hctl_t *	hctl,
		void *	callback_private )

Set callback private value for an HCTL.

Parameters

hctl	HCTL handle
callback_private	callback private value

◆ snd_hctl_set_compare()

int snd_hctl_set_compare	(	snd_hctl_t *	hctl,
		snd_hctl_compare_t	compare )

Change HCTL compare function and reorder elements.

Parameters

hctl	HCTL handle
compare	Element compare function

Returns: 0 on success otherwise a negative error code

◆ snd_hctl_wait()

int snd_hctl_wait	(	snd_hctl_t *	hctl,
		int	timeout )

Wait for a HCTL to become ready (i.e. at least one event pending)

Parameters

hctl	HCTL handle
timeout	maximum time in milliseconds to wait

Returns: a positive value on success otherwise a negative error code

Return values

0	timeout occurred
1	an event is pending

Functions

Detailed Description

Function Documentation

◆ snd_hctl_async()

◆ snd_hctl_close()

◆ snd_hctl_compare_fast()

◆ snd_hctl_ctl()

◆ snd_hctl_elem_get_callback_private()

◆ snd_hctl_elem_get_device()

◆ snd_hctl_elem_get_hctl()

◆ snd_hctl_elem_get_id()

◆ snd_hctl_elem_get_index()

◆ snd_hctl_elem_get_interface()

◆ snd_hctl_elem_get_name()

◆ snd_hctl_elem_get_numid()

◆ snd_hctl_elem_get_subdevice()

◆ snd_hctl_elem_info()

◆ snd_hctl_elem_next()

◆ snd_hctl_elem_prev()

◆ snd_hctl_elem_read()

◆ snd_hctl_elem_set_callback()

◆ snd_hctl_elem_set_callback_private()

◆ snd_hctl_elem_tlv_command()

◆ snd_hctl_elem_tlv_read()

◆ snd_hctl_elem_tlv_write()

◆ snd_hctl_elem_write()

◆ snd_hctl_find_elem()

◆ snd_hctl_first_elem()

◆ snd_hctl_free()

◆ snd_hctl_get_callback_private()

◆ snd_hctl_get_count()

◆ snd_hctl_handle_events()

◆ snd_hctl_last_elem()

◆ snd_hctl_load()

◆ snd_hctl_name()

◆ snd_hctl_nonblock()

◆ snd_hctl_open()

◆ snd_hctl_open_ctl()

◆ snd_hctl_poll_descriptors()

◆ snd_hctl_poll_descriptors_count()

◆ snd_hctl_poll_descriptors_revents()

◆ snd_hctl_set_callback()

◆ snd_hctl_set_callback_private()

◆ snd_hctl_set_compare()

◆ snd_hctl_wait()