Mixer Interface

Modules
	Simple Mixer Interface
Defines
#define	snd_mixer_class_alloca(ptr)
	allocate an invalid snd_mixer_class_t using standard alloca
Typedefs
typedef _snd_mixer	snd_mixer_t
typedef _snd_mixer_class	snd_mixer_class_t
typedef _snd_mixer_elem	snd_mixer_elem_t
typedef int(*	snd_mixer_callback_t )(snd_mixer_t *ctl, unsigned int mask, snd_mixer_elem_t *elem)
	Mixer callback function.
typedef int(*	snd_mixer_elem_callback_t )(snd_mixer_elem_t *elem, unsigned int mask)
	Mixer element callback function.
typedef int(*	snd_mixer_compare_t )(const snd_mixer_elem_t *e1, const snd_mixer_elem_t *e2)
	Compare function for sorting mixer elements.
typedef int(*	snd_mixer_event_t )(snd_mixer_class_t *class_, unsigned int mask, snd_hctl_elem_t *helem, snd_mixer_elem_t *melem)
	Event callback for the mixer class.
typedef enum _snd_mixer_elem_type	snd_mixer_elem_type_t
Enumerations
enum	_snd_mixer_elem_type { SND_MIXER_ELEM_SIMPLE, SND_MIXER_ELEM_LAST = SND_MIXER_ELEM_SIMPLE }
Functions
int	snd_mixer_open (snd_mixer_t **mixer, int mode)
	Opens an empty mixer.
int	snd_mixer_close (snd_mixer_t *mixer)
	Close a mixer and free all related resources.
snd_mixer_elem_t *	snd_mixer_first_elem (snd_mixer_t *mixer)
	get first element for a mixer
snd_mixer_elem_t *	snd_mixer_last_elem (snd_mixer_t *mixer)
	get last element for a mixer
int	snd_mixer_handle_events (snd_mixer_t *mixer)
	Handle pending mixer events invoking callbacks.
int	snd_mixer_attach (snd_mixer_t *mixer, const char *name)
	Attach an HCTL specified with the CTL device name to an opened mixer.
int	snd_mixer_attach_hctl (snd_mixer_t *mixer, snd_hctl_t *hctl)
	Attach an HCTL to an opened mixer.
int	snd_mixer_detach (snd_mixer_t *mixer, const char *name)
	Detach a previously attached HCTL to an opened mixer freeing all related resources.
int	snd_mixer_detach_hctl (snd_mixer_t *mixer, snd_hctl_t *hctl)
	Detach a previously attached HCTL to an opened mixer freeing all related resources.
int	snd_mixer_get_hctl (snd_mixer_t *mixer, const char *name, snd_hctl_t **hctl)
	Obtain a HCTL pointer associated to given name.
int	snd_mixer_poll_descriptors_count (snd_mixer_t *mixer)
	get count of poll descriptors for mixer handle
int	snd_mixer_poll_descriptors (snd_mixer_t *mixer, struct pollfd *pfds, unsigned int space)
	get poll descriptors
int	snd_mixer_poll_descriptors_revents (snd_mixer_t *mixer, struct pollfd *pfds, unsigned int nfds, unsigned short *revents)
	get returned events from poll descriptors
int	snd_mixer_load (snd_mixer_t *mixer)
	Load a mixer elements.
void	snd_mixer_free (snd_mixer_t *mixer)
	Unload all mixer elements and free all related resources.
int	snd_mixer_wait (snd_mixer_t *mixer, int timeout)
	Wait for a mixer to become ready (i.e. at least one event pending).
int	snd_mixer_set_compare (snd_mixer_t *mixer, snd_mixer_compare_t msort)
	Change mixer compare function and reorder elements.
void	snd_mixer_set_callback (snd_mixer_t *obj, snd_mixer_callback_t val)
	Set callback function for a mixer.
void *	snd_mixer_get_callback_private (const snd_mixer_t *obj)
	Get callback private value for a mixer.
void	snd_mixer_set_callback_private (snd_mixer_t *obj, void *val)
	Set callback private value for a mixer.
unsigned int	snd_mixer_get_count (const snd_mixer_t *obj)
	Get elements count for a mixer.
int	snd_mixer_class_unregister (snd_mixer_class_t *clss)
	Unregister mixer element class and remove all its elements.
snd_mixer_elem_t *	snd_mixer_elem_next (snd_mixer_elem_t *elem)
	get next mixer element
snd_mixer_elem_t *	snd_mixer_elem_prev (snd_mixer_elem_t *elem)
	get previous mixer element
void	snd_mixer_elem_set_callback (snd_mixer_elem_t *obj, snd_mixer_elem_callback_t val)
	Set callback function for a mixer element.
void *	snd_mixer_elem_get_callback_private (const snd_mixer_elem_t *obj)
	Get callback private value for a mixer element.
void	snd_mixer_elem_set_callback_private (snd_mixer_elem_t *obj, void *val)
	Set callback private value for a mixer element.
snd_mixer_elem_type_t	snd_mixer_elem_get_type (const snd_mixer_elem_t *obj)
	Get type for a mixer element.
int	snd_mixer_class_register (snd_mixer_class_t *class_, snd_mixer_t *mixer)
	Register mixer element class.
int	snd_mixer_add_elem (snd_mixer_t *mixer, snd_mixer_elem_t *elem)
int	snd_mixer_remove_elem (snd_mixer_t *mixer, snd_mixer_elem_t *elem)
int	snd_mixer_elem_new (snd_mixer_elem_t **elem, snd_mixer_elem_type_t type, int compare_weight, void *private_data, void(*private_free)(snd_mixer_elem_t *elem))
	Allocate a new mixer element.
int	snd_mixer_elem_add (snd_mixer_elem_t *elem, snd_mixer_class_t *class_)
	Add an element for a registered mixer element class.
int	snd_mixer_elem_remove (snd_mixer_elem_t *elem)
	Remove a mixer element.
void	snd_mixer_elem_free (snd_mixer_elem_t *elem)
	Free a mixer element.
int	snd_mixer_elem_info (snd_mixer_elem_t *elem)
	Mixer element informations are changed.
int	snd_mixer_elem_value (snd_mixer_elem_t *elem)
	Mixer element values is changed.
int	snd_mixer_elem_attach (snd_mixer_elem_t *melem, snd_hctl_elem_t *helem)
	Attach an HCTL element to a mixer element.
int	snd_mixer_elem_detach (snd_mixer_elem_t *melem, snd_hctl_elem_t *helem)
	Detach an HCTL element from a mixer element.
int	snd_mixer_elem_empty (snd_mixer_elem_t *melem)
	Return true if a mixer element does not contain any HCTL elements.
void *	snd_mixer_elem_get_private (const snd_mixer_elem_t *melem)
	Get private data associated to give mixer element.
size_t	snd_mixer_class_sizeof (void)
	get size of snd_mixer_class_t
int	snd_mixer_class_malloc (snd_mixer_class_t **ptr)
	allocate an invalid snd_mixer_class_t using standard malloc
void	snd_mixer_class_free (snd_mixer_class_t *obj)
	frees a previously allocated snd_mixer_class_t
void	snd_mixer_class_copy (snd_mixer_class_t *dst, const snd_mixer_class_t *src)
	copy one snd_mixer_class_t to another
snd_mixer_t *	snd_mixer_class_get_mixer (const snd_mixer_class_t *class_)
	Get a mixer associated to given mixer class.
snd_mixer_event_t	snd_mixer_class_get_event (const snd_mixer_class_t *class_)
	Get mixer event callback associated to given mixer class.
void *	snd_mixer_class_get_private (const snd_mixer_class_t *class_)
	Get mixer private data associated to given mixer class.
snd_mixer_compare_t	snd_mixer_class_get_compare (const snd_mixer_class_t *class_)
	Get mixer compare callback associated to given mixer class.
int	snd_mixer_class_set_event (snd_mixer_class_t *class_, snd_mixer_event_t event)
	Set mixer event callback to given mixer class.
int	snd_mixer_class_set_private (snd_mixer_class_t *class_, void *private_data)
	Set mixer private data to given mixer class.
int	snd_mixer_class_set_private_free (snd_mixer_class_t *class_, void(*private_free)(snd_mixer_class_t *class_))
int	snd_mixer_class_set_compare (snd_mixer_class_t *class_, snd_mixer_compare_t compare)
	Set mixer compare callback to given mixer class.

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Detailed Description

The mixer interface.

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Define Documentation

#define snd_mixer_class_alloca (  ptr   )

allocate an invalid snd_mixer_class_t using standard alloca Parameters: ptr  returned pointer

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Typedef Documentation

typedef int(* snd_mixer_callback_t)(snd_mixer_t *ctl, unsigned int mask, snd_mixer_elem_t *elem)

Mixer callback function. Parameters: mixer  Mixer handle mask  event mask elem  related mixer element (if any) Returns: 0 on success otherwise a negative error code

typedef struct _snd_mixer_class snd_mixer_class_t

Mixer elements class handle

typedef int(* snd_mixer_compare_t)(const snd_mixer_elem_t *e1, const snd_mixer_elem_t *e2)

Compare function for sorting mixer elements. Parameters: e1  First element e2  Second element Returns: -1 if e1 < e2, 0 if e1 == e2, 1 if e1 > e2

typedef int(* snd_mixer_elem_callback_t)(snd_mixer_elem_t *elem, unsigned int mask)

Mixer element callback function. Parameters: elem  Mixer element mask  event mask Returns: 0 on success otherwise a negative error code

typedef struct _snd_mixer_elem snd_mixer_elem_t

Mixer element handle

typedef enum _snd_mixer_elem_type snd_mixer_elem_type_t

Mixer element type

typedef int(* snd_mixer_event_t)(snd_mixer_class_t *class_, unsigned int mask, snd_hctl_elem_t *helem, snd_mixer_elem_t *melem)

Event callback for the mixer class. Parameters: class_  Mixer class mask  Event mask (SND_CTL_EVENT_*) helem  HCTL element which invoked the event melem  Mixer element associated to HCTL element Returns: zero if success, otherwise a negative error value

typedef struct _snd_mixer snd_mixer_t

Mixer handle

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Enumeration Type Documentation

enum _snd_mixer_elem_type

Mixer element type

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Function Documentation

int snd_mixer_attach (  snd_mixer_t *  mixer, const char *  name )

Attach an HCTL specified with the CTL device name to an opened mixer. Parameters: mixer  Mixer handle name  HCTL name (see snd_hctl_open) Returns: 0 on success otherwise a negative error code

int snd_mixer_attach_hctl (  snd_mixer_t *  mixer, snd_hctl_t *  hctl )

Attach an HCTL to an opened mixer. Parameters: mixer  Mixer handle hctl  the HCTL to be attached Returns: 0 on success otherwise a negative error code

void snd_mixer_class_copy (  snd_mixer_class_t *  dst, const snd_mixer_class_t *  src )

copy one snd_mixer_class_t to another Parameters: dst  pointer to destination src  pointer to source

void snd_mixer_class_free (  snd_mixer_class_t *  obj  )

frees a previously allocated snd_mixer_class_t Parameters: obj  pointer to object to free

snd_mixer_compare_t snd_mixer_class_get_compare (  const snd_mixer_class_t *  obj  )

Get mixer compare callback associated to given mixer class. Parameters: obj  Mixer simple class identifier Returns: event callback pointer

snd_mixer_event_t snd_mixer_class_get_event (  const snd_mixer_class_t *  obj  )

Get mixer event callback associated to given mixer class. Parameters: obj  Mixer simple class identifier Returns: event callback pointer

snd_mixer_t* snd_mixer_class_get_mixer (  const snd_mixer_class_t *  obj  )

Get a mixer associated to given mixer class. Parameters: obj  Mixer simple class identifier Returns: mixer pointer

void* snd_mixer_class_get_private (  const snd_mixer_class_t *  obj  )

Get mixer private data associated to given mixer class. Parameters: obj  Mixer simple class identifier Returns: event callback pointer

int snd_mixer_class_malloc (  snd_mixer_class_t **  ptr  )

allocate an invalid snd_mixer_class_t using standard malloc Parameters: ptr  returned pointer Returns: 0 on success otherwise negative error code

int snd_mixer_class_register (  snd_mixer_class_t *  class, snd_mixer_t *  mixer )

Register mixer element class. Parameters: class  Mixer element class mixer  Mixer handle Returns: 0 on success otherwise a negative error code For use by mixer element class specific code.

int snd_mixer_class_set_compare (  snd_mixer_class_t *  obj, snd_mixer_compare_t  compare )

Set mixer compare callback to given mixer class. Parameters: obj  Mixer simple class identifier compare  the compare callback to be used Returns: zero if success, otherwise a negative error code

int snd_mixer_class_set_event (  snd_mixer_class_t *  obj, snd_mixer_event_t  event )

Set mixer event callback to given mixer class. Parameters: obj  Mixer simple class identifier event  Event callback Returns: zero if success, otherwise a negative error code

int snd_mixer_class_set_private (  snd_mixer_class_t *  obj, void *  private_data )

Set mixer private data to given mixer class. Parameters: obj  Mixer simple class identifier private_data  class private data Returns: zero if success, otherwise a negative error code

size_t snd_mixer_class_sizeof (  void   )

get size of snd_mixer_class_t Returns: size in bytes

int snd_mixer_class_unregister (  snd_mixer_class_t *  class  )

Unregister mixer element class and remove all its elements. Parameters: class  Mixer element class Returns: 0 on success otherwise a negative error code Note that the class structure is also deallocated!

int snd_mixer_close (  snd_mixer_t *  mixer  )

Close a mixer and free all related resources. Parameters: mixer  Mixer handle Returns: 0 on success otherwise a negative error code

int snd_mixer_detach (  snd_mixer_t *  mixer, const char *  name )

Detach a previously attached HCTL to an opened mixer freeing all related resources. Parameters: mixer  Mixer handle name  HCTL previously attached Returns: 0 on success otherwise a negative error code

int snd_mixer_detach_hctl (  snd_mixer_t *  mixer, snd_hctl_t *  hctl )

Detach a previously attached HCTL to an opened mixer freeing all related resources. Parameters: mixer  Mixer handle hctl  HCTL previously attached Returns: 0 on success otherwise a negative error code Note: The hctl handle is not closed!

int snd_mixer_elem_add (  snd_mixer_elem_t *  elem, snd_mixer_class_t *  class )

Add an element for a registered mixer element class. Parameters: elem  Mixer element class  Mixer element class Returns: 0 on success otherwise a negative error code For use by mixer element class specific code.

int snd_mixer_elem_attach (  snd_mixer_elem_t *  melem, snd_hctl_elem_t *  helem )

Attach an HCTL element to a mixer element. Parameters: melem  Mixer element helem  HCTL element Returns: 0 on success otherwise a negative error code For use by mixer element class specific code.

int snd_mixer_elem_detach (  snd_mixer_elem_t *  melem, snd_hctl_elem_t *  helem )

Detach an HCTL element from a mixer element. Parameters: melem  Mixer element helem  HCTL element Returns: 0 on success otherwise a negative error code For use by mixer element class specific code.

int snd_mixer_elem_empty (  snd_mixer_elem_t *  melem  )

Return true if a mixer element does not contain any HCTL elements. Parameters: melem  Mixer element Returns: 0 if not empty, 1 if empty For use by mixer element class specific code.

void snd_mixer_elem_free (  snd_mixer_elem_t *  elem  )

Free a mixer element. Parameters: elem  Mixer element Returns: 0 on success otherwise a negative error code For use by mixer element class specific code.

void* snd_mixer_elem_get_callback_private (  const snd_mixer_elem_t *  mixer  )

Get callback private value for a mixer element. Parameters: mixer  mixer element Returns: callback private value

void* snd_mixer_elem_get_private (  const snd_mixer_elem_t *  elem  )

Get private data associated to give mixer element. Parameters: elem  Mixer element Returns: private data For use by mixer element class specific code.

snd_mixer_elem_type_t snd_mixer_elem_get_type (  const snd_mixer_elem_t *  mixer  )

Get type for a mixer element. Parameters: mixer  mixer element Returns: mixer element type

int snd_mixer_elem_info (  snd_mixer_elem_t *  elem  )

Mixer element informations are changed. Parameters: elem  Mixer element Returns: 0 on success otherwise a negative error code For use by mixer element class specific code.

int snd_mixer_elem_new (  snd_mixer_elem_t **  elem, snd_mixer_elem_type_t  type, int  compare_weight, void *  private_data, void(*)(snd_mixer_elem_t *elem)  private_free )

Allocate a new mixer element. Parameters: elem  Returned mixer element type  Mixer element type compare_weight  Mixer element compare weight private_data  Private data private_free  Private data free callback Returns: 0 on success otherwise a negative error code For use by mixer element class specific code.

snd_mixer_elem_t* snd_mixer_elem_next (  snd_mixer_elem_t *  elem  )

get next mixer element Parameters: elem  mixer element Returns: pointer to next element

snd_mixer_elem_t* snd_mixer_elem_prev (  snd_mixer_elem_t *  elem  )

get previous mixer element Parameters: elem  mixer element Returns: pointer to previous element

int snd_mixer_elem_remove (  snd_mixer_elem_t *  elem  )

Remove a mixer element. Parameters: elem  Mixer element Returns: 0 on success otherwise a negative error code For use by mixer element class specific code.

void snd_mixer_elem_set_callback (  snd_mixer_elem_t *  mixer, snd_mixer_elem_callback_t  val )

Set callback function for a mixer element. Parameters: mixer  mixer element val  callback function

void snd_mixer_elem_set_callback_private (  snd_mixer_elem_t *  mixer, void *  val )

Set callback private value for a mixer element. Parameters: mixer  mixer element val  callback private value

int snd_mixer_elem_value (  snd_mixer_elem_t *  elem  )

Mixer element values is changed. Parameters: elem  Mixer element Returns: 0 on success otherwise a negative error code For use by mixer element class specific code.

snd_mixer_elem_t* snd_mixer_first_elem (  snd_mixer_t *  mixer  )

get first element for a mixer Parameters: mixer  Mixer handle Returns: pointer to first element

void snd_mixer_free (  snd_mixer_t *  mixer  )

Unload all mixer elements and free all related resources. Parameters: mixer  Mixer handle

void* snd_mixer_get_callback_private (  const snd_mixer_t *  mixer  )

Get callback private value for a mixer. Parameters: mixer  mixer handle Returns: callback private value

unsigned int snd_mixer_get_count (  const snd_mixer_t *  mixer  )

Get elements count for a mixer. Parameters: mixer  mixer handle Returns: elements count

int snd_mixer_get_hctl (  snd_mixer_t *  mixer, const char *  name, snd_hctl_t **  hctl )

Obtain a HCTL pointer associated to given name. Parameters: mixer  Mixer handle name  HCTL previously attached hctl  HCTL pointer Returns: 0 on success otherwise a negative error code

int snd_mixer_handle_events (  snd_mixer_t *  mixer  )

Handle pending mixer events invoking callbacks. Parameters: mixer  Mixer handle Returns: Number of events that occured on success, otherwise a negative error code on failure

snd_mixer_elem_t* snd_mixer_last_elem (  snd_mixer_t *  mixer  )

get last element for a mixer Parameters: mixer  Mixer handle Returns: pointer to last element

int snd_mixer_load (  snd_mixer_t *  mixer  )

Load a mixer elements. Parameters: mixer  Mixer handle Returns: 0 on success otherwise a negative error code

int snd_mixer_open (  snd_mixer_t **  mixerp, int  mode )

Opens an empty mixer. Parameters: mixerp  Returned mixer handle mode  Open mode Returns: 0 on success otherwise a negative error code

int snd_mixer_poll_descriptors (  snd_mixer_t *  mixer, struct pollfd *  pfds, unsigned int  space )

get poll descriptors Parameters: mixer  Mixer handle pfds  array of poll descriptors space  space in the poll descriptor array Returns: count of filled descriptors

int snd_mixer_poll_descriptors_count (  snd_mixer_t *  mixer  )

get count of poll descriptors for mixer handle Parameters: mixer  Mixer handle Returns: count of poll descriptors

int snd_mixer_poll_descriptors_revents (  snd_mixer_t *  mixer, struct pollfd *  pfds, unsigned int  nfds, unsigned short *  revents )

get returned events from poll descriptors Parameters: mixer  Mixer handle pfds  array of poll descriptors nfds  count of poll descriptors revents  returned events Returns: zero if success, otherwise a negative error code

void snd_mixer_set_callback (  snd_mixer_t *  obj, snd_mixer_callback_t  val )

Set callback function for a mixer. Parameters: obj  mixer handle val  callback function

void snd_mixer_set_callback_private (  snd_mixer_t *  mixer, void *  val )

Set callback private value for a mixer. Parameters: mixer  mixer handle val  callback private value

int snd_mixer_set_compare (  snd_mixer_t *  mixer, snd_mixer_compare_t  compare )

Change mixer compare function and reorder elements. Parameters: mixer  Mixer handle compare  Element compare function Returns: 0 on success otherwise a negative error code

int snd_mixer_wait (  snd_mixer_t *  mixer, int  timeout )

Wait for a mixer to become ready (i.e. at least one event pending). Parameters: mixer  Mixer handle timeout  maximum time in milliseconds to wait Returns: 0 otherwise a negative error code on failure

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