/**

 * \file pcm/pcm_asym.c

 * \ingroup PCM_Plugins

 * \brief PCM Asymmetrical Plugin Interface

 * \author Takashi Iwai <tiwai@suse.de>

 * \date 2003

 */

#include "pcm_local.h"

#ifndef PIC

/* entry for static linking */

const char *_snd_module_pcm_asym = "";

#endif

/*! \page pcm_plugins

\section pcm_plugins_asym Plugin: asym

This plugin is a combination of playback and capture PCM streams.

Slave PCMs can be defined asymmetrically for both directions.

\code

pcm.name {

        type asym               # Asym PCM

        playback STR            # Playback slave name

        # or

        playback {              # Playback slave definition

                pcm STR         # Slave PCM name

                # or

                pcm { }         # Slave PCM definition

        }

        capture STR             # Capture slave name

        # or

        capture {               # Capture slave definition

                pcm STR         # Slave PCM name

                # or

                pcm { }         # Slave PCM definition

        }

}

\endcode

For example, you can combine a dmix plugin and a dsnoop plugin as

as a single PCM for playback and capture directions, respectively.

\code

pcm.duplex {

	type asym

	playback.pcm "dmix"

	capture.pcm "dsnoop"

}

\endcode

By defining only a single direction, the resultant PCM becomes

half-duplex.

\subsection pcm_plugins_asym_funcref Function reference

  
_snd_pcm_asym_open()

*/

/**

 * \brief Creates a new asym stream PCM

 * \param pcmp Returns created PCM handle

 * \param name Name of PCM

 * \param root Root configuration node

 * \param conf Configuration node with copy PCM description

 * \param stream Stream type

 * \param mode Stream mode

 * \retval 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.

 */

int _snd_pcm_asym_open(snd_pcm_t **pcmp, const char *name ATTRIBUTE_UNUSED,

			 snd_config_t *root, snd_config_t *conf,

			 snd_pcm_stream_t stream, int mode)

{

	snd_config_iterator_t i, next;

	int err;

	snd_config_t *slave = NULL, *sconf;

	snd_config_for_each(i, next, conf) {

		snd_config_t *n = snd_config_iterator_entry(i);

		const char *id;

		if (snd_config_get_id(n, &id) < 0)

			continue;

		if (snd_pcm_conf_generic_id(id))

			continue;

		if (strcmp(id, "playback") == 0) {

			if (stream == SND_PCM_STREAM_PLAYBACK)

				slave = n;

			continue;

		}

		if (strcmp(id, "capture") == 0) {

			if (stream == SND_PCM_STREAM_CAPTURE)

				slave = n;

			continue;

		}

		SNDERR("Unknown field %s", id);

		return -EINVAL;

	}

	if (! slave) {

		SNDERR("%s slave is not defined",

		       stream == SND_PCM_STREAM_PLAYBACK ? "playback" : "capture");

		return -EINVAL;

	}

	err = snd_pcm_slave_conf(root, slave, &sconf, 0);

	if (err < 0)

		return err;

	err = snd_pcm_open_named_slave(pcmp, name, root, sconf, stream,

				       mode, conf);

	snd_config_delete(sconf);

	return err;

}

#ifndef DOC_HIDDEN

SND_DLSYM_BUILD_VERSION(_snd_pcm_asym_open, SND_PCM_DLSYM_VERSION);

#endif