External I/O plugin SDK [External PCM plugin SDK]

Data Structures
struct	snd_pcm_ioplug_t
struct	snd_pcm_ioplug_callback_t
Defines
#define	SND_PCM_IOPLUG_FLAG_LISTED   (1<<0)
#define	SND_PCM_IOPLUG_FLAG_MONOTONIC   (1<<1)
#define	SND_PCM_IOPLUG_VERSION_MAJOR   1
#define	SND_PCM_IOPLUG_VERSION_MINOR   0
#define	SND_PCM_IOPLUG_VERSION_TINY   1
#define	SND_PCM_IOPLUG_VERSION
Enumerations
enum	{   SND_PCM_IOPLUG_HW_ACCESS = 0, SND_PCM_IOPLUG_HW_FORMAT, SND_PCM_IOPLUG_HW_CHANNELS, SND_PCM_IOPLUG_HW_RATE,   SND_PCM_IOPLUG_HW_PERIOD_BYTES, SND_PCM_IOPLUG_HW_BUFFER_BYTES, SND_PCM_IOPLUG_HW_PERIODS, SND_PCM_IOPLUG_HW_PARAMS }
Functions
int	snd_pcm_ioplug_create (snd_pcm_ioplug_t *io, const char *name, snd_pcm_stream_t stream, int mode)
	Create an ioplug instance.
int	snd_pcm_ioplug_delete (snd_pcm_ioplug_t *io)
	Delete the ioplug instance.
int	snd_pcm_ioplug_reinit_status (snd_pcm_ioplug_t *ioplug)
	Reinitialize the poll and mmap status.
const snd_pcm_channel_area_t *	snd_pcm_ioplug_mmap_areas (snd_pcm_ioplug_t *ioplug)
	Get mmap area of ioplug.
void	snd_pcm_ioplug_params_reset (snd_pcm_ioplug_t *io)
	Reset ioplug parameters.
int	snd_pcm_ioplug_set_param_minmax (snd_pcm_ioplug_t *io, int type, unsigned int min, unsigned int max)
	Set parameter as the min/max values.
int	snd_pcm_ioplug_set_param_list (snd_pcm_ioplug_t *io, int type, unsigned int num_list, const unsigned int *list)
	Set parameter as the list.
int	snd_pcm_ioplug_set_state (snd_pcm_ioplug_t *ioplug, snd_pcm_state_t state)
	Change the ioplug PCM status.

---

Detailed Description

See the PCM (digital audio) interface page for more details.

---

Define Documentation

#define SND_PCM_IOPLUG_FLAG_LISTED   (1<<0)

list up this PCM

#define SND_PCM_IOPLUG_FLAG_MONOTONIC   (1<<1)

monotonic timestamps

#define SND_PCM_IOPLUG_VERSION

Value:

((SND_PCM_IOPLUG_VERSION_MAJOR<<16) |\
                                         (SND_PCM_IOPLUG_VERSION_MINOR<<8) |\
                                         (SND_PCM_IOPLUG_VERSION_TINY))

IO-plugin protocol version

#define SND_PCM_IOPLUG_VERSION_MAJOR   1

Protocol major version

#define SND_PCM_IOPLUG_VERSION_MINOR   0

Protocol minor version

#define SND_PCM_IOPLUG_VERSION_TINY   1

Protocol tiny version

---

Enumeration Type Documentation

anonymous enum

hw constraints for ioplug

Enumerator:

SND_PCM_IOPLUG_HW_ACCESS	access type
SND_PCM_IOPLUG_HW_FORMAT	format
SND_PCM_IOPLUG_HW_CHANNELS	channels
SND_PCM_IOPLUG_HW_RATE	rate
SND_PCM_IOPLUG_HW_PERIOD_BYTES	period bytes
SND_PCM_IOPLUG_HW_BUFFER_BYTES	buffer bytes
SND_PCM_IOPLUG_HW_PERIODS	number of periods
SND_PCM_IOPLUG_HW_PARAMS	max number of hw constraints

---

Function Documentation

int snd_pcm_ioplug_create	(	snd_pcm_ioplug_t *	ioplug,
		const char *	name,
		snd_pcm_stream_t	stream,
		int	mode
	)

Create an ioplug instance.

Parameters:

	ioplug	the ioplug handle
	name	name of PCM
	stream	stream direction
	mode	PCM open mode

Returns:

0 if successful, or a negative error code

Creates the ioplug instance.

The callback is the mandatory field of ioplug handle. At least, start, stop and pointer callbacks must be set before calling this function.

int snd_pcm_ioplug_delete

(

snd_pcm_ioplug_t *

ioplug

)

Delete the ioplug instance.

Parameters:

ioplug

the ioplug handle

Returns:

0 if successful, or a negative error code

const snd_pcm_channel_area_t* snd_pcm_ioplug_mmap_areas

(

snd_pcm_ioplug_t *

ioplug

)

Get mmap area of ioplug.

Parameters:

ioplug

the ioplug handle

Returns:

the mmap channel areas if available, or NULL

Returns the mmap channel areas if available. When mmap_rw field is not set, this function always returns NULL.

void snd_pcm_ioplug_params_reset

(

snd_pcm_ioplug_t *

ioplug

)

Reset ioplug parameters.

Parameters:

ioplug

the ioplug handle

Resets the all parameters for the given ioplug handle.

int snd_pcm_ioplug_reinit_status

(

snd_pcm_ioplug_t *

ioplug

)

Reinitialize the poll and mmap status.

Parameters:

ioplug

the ioplug handle

Returns:

0 if successful, or a negative error code

Reinitializes the poll and the mmap status of the PCM. Call this function to propagate the status change in the ioplug instance to its PCM internals.

int snd_pcm_ioplug_set_param_list	(	snd_pcm_ioplug_t *	ioplug,
		int	type,
		unsigned int	num_list,
		const unsigned int *	list
	)

Set parameter as the list.

Parameters:

	ioplug	the ioplug handle
	type	parameter type
	num_list	number of available values
	list	the list of available values

Returns:

0 if successful, or a negative error code

Sets the parameter as the list. The available values of the given parameter type is restricted to the ones of the given list.

int snd_pcm_ioplug_set_param_minmax	(	snd_pcm_ioplug_t *	ioplug,
		int	type,
		unsigned int	min,
		unsigned int	max
	)

Set parameter as the min/max values.

Parameters:

	ioplug	the ioplug handle
	type	parameter type
	min	the minimum value
	max	the maximum value

Returns:

0 if successful, or a negative error code

Sets the parameter as the min/max values. The available values of the given parameter type is restricted between the given minimum and maximum values.

int snd_pcm_ioplug_set_state	(	snd_pcm_ioplug_t *	ioplug,
		snd_pcm_state_t	state
	)

Change the ioplug PCM status.

Parameters:

	ioplug	the ioplug handle
	state	the PCM status

Returns:

zero if successful or a negative error code

Changes the PCM status of the ioplug to the given value. This function can be used for external plugins to notify the status change, e.g. XRUN.