pcm_hw.c File Reference

PCM HW Plugin Interface. More...

Macros
#define	hw_param_mask(params, var)

Enumerations
enum	{ CHMAP_CTL_QUERY , CHMAP_CTL_GET , CHMAP_CTL_SET }

Functions
snd_pcm_chmap_query_t **	snd_pcm_query_chmaps_from_hw (int card, int dev, int subdev, snd_pcm_stream_t stream)
int	snd_pcm_hw_open_fd (snd_pcm_t **pcmp, const char *name, int fd, int sync_ptr_ioctl)
	Creates a new hw PCM.
int	snd_pcm_hw_open (snd_pcm_t **pcmp, const char *name, int card, int device, int subdevice, snd_pcm_stream_t stream, int mode, int mmap_emulation, int sync_ptr_ioctl)
	Creates a new hw PCM.
int	_snd_pcm_hw_open (snd_pcm_t **pcmp, const char *name, snd_config_t *root, snd_config_t *conf, snd_pcm_stream_t stream, int mode)
	Creates a new hw PCM.

Detailed Description

PCM HW Plugin Interface.

Author

Abramo Bagnara abram.nosp@m.o@al.nosp@m.sa-pr.nosp@m.ojec.nosp@m.t.org

Jaroslav Kysela perex.nosp@m.@per.nosp@m.ex.cz

Date

2000-2001

Macro Definition Documentation

hw_param_mask

#define hw_param_mask	(		params,
			var )

Value:

    &((params)->masks[(var) - SND_PCM_HW_PARAM_FIRST_MASK])

Function Documentation

_snd_pcm_hw_open()

int _snd_pcm_hw_open	(	snd_pcm_t **	pcmp,
		const char *	name,
		snd_config_t *	root,
		snd_config_t *	conf,
		snd_pcm_stream_t	stream,
		int	mode )

Creates a new hw PCM.

Parameters

pcmp	Returns created PCM handle
name	Name of PCM
root	Root configuration node
conf	Configuration node with hw PCM description
stream	PCM Stream
mode	PCM Mode

Warning

Using of this function might be dangerous in the sense of compatibility reasons. The prototype might be freely changed in future.

snd_pcm_hw_open()

int snd_pcm_hw_open	(	snd_pcm_t **	pcmp,
		const char *	name,
		int	card,
		int	device,
		int	subdevice,
		snd_pcm_stream_t	stream,
		int	mode,
		int	mmap_emulation,
		int	sync_ptr_ioctl )

Creates a new hw PCM.

Parameters

pcmp	Returns created PCM handle
name	Name of PCM
card	Number of card
device	Number of device
subdevice	Number of subdevice
stream	PCM Stream
mode	PCM Mode
mmap_emulation	Obsoleted parameter
sync_ptr_ioctl	Use SYNC_PTR ioctl rather than mmap for control structures

Return values

zero	on success otherwise a negative error code

Warning

Using of this function might be dangerous in the sense of compatibility reasons. The prototype might be freely changed in future.

snd_pcm_hw_open_fd()

int snd_pcm_hw_open_fd	(	snd_pcm_t **	pcmp,
		const char *	name,
		int	fd,
		int	sync_ptr_ioctl )

Creates a new hw PCM.

Parameters

pcmp	Returns created PCM handle
name	Name of PCM
fd	File descriptor
sync_ptr_ioctl	Boolean flag for sync_ptr ioctl

Return values

zero	on success otherwise a negative error code

Warning

Using of this function might be dangerous in the sense of compatibility reasons. The prototype might be freely changed in future.

snd_pcm_query_chmaps_from_hw()

snd_pcm_chmap_query_t ** snd_pcm_query_chmaps_from_hw	(	int	card,
		int	dev,
		int	subdev,
		snd_pcm_stream_t	stream )

!brief Query the available channel maps

Parameters

card	the card number
dev	the PCM device number
subdev	the PCM substream index
stream	the direction of PCM stream

Returns

the NULL-terminated array of integer pointers, or NULL at error.

This function works like snd_pcm_query_chmaps() but it takes the card, device, substream and stream numbers instead of the already opened snd_pcm_t instance, so that you can query available channel maps of a PCM before actually opening it.

As the parameters stand, the query is performed only to the hw PCM devices, not the abstracted PCM object in alsa-lib.