/**

 * \file pcm/pcm_empty.c

 * \ingroup PCM_Plugins

 * \brief PCM Null Plugin Interface

 * \author Jaroslav Kysela <perex@perex.cz>

 * \date 2006

 */

/*

 *  PCM - Null plugin

 *  Copyright (c) 2006 by Jaroslav Kysela <perex@perex.cz>

 *

 *

 *   This library is free software; you can redistribute it and/or modify

 *   it under the terms of the GNU Lesser General Public License as

 *   published by the Free Software Foundation; either version 2.1 of

 *   the License, or (at your option) any later version.

 *

 *   This program is distributed in the hope that it will be useful,

 *   but WITHOUT ANY WARRANTY; without even the implied warranty of

 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *   GNU Lesser General Public License for more details.

 *

 *   You should have received a copy of the GNU Lesser General Public

 *   License along with this library; if not, write to the Free Software

 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 *

 */

#include "pcm_local.h"

#include "pcm_plugin.h"

#ifndef PIC

/* entry for static linking */

const char *_snd_module_pcm_empty = "";

#endif

/*! \page pcm_plugins

\section pcm_plugins_null Plugin: Null

This plugin discards contents of a PCM stream or creates a stream with zero

samples.

Note: This implementation uses devices /dev/null (playback, must be writable)

and /dev/full (capture, must be readable).

\code

pcm.name {

        type null               # Null PCM

}

\endcode

\subsection pcm_plugins_null_funcref Function reference

  
_snd_pcm_empty_open()

*/

/**

 * \brief Creates a new Empty PCM

 * \param pcmp Returns created PCM handle

 * \param name Name of PCM

 * \param root Root configuration node

 * \param conf Configuration node with empty 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_empty_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_t *slave = NULL, *sconf;

	snd_config_iterator_t i, next;

	int err;

	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, "slave") == 0) {

			slave = n;

			continue;

		}

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

		return -EINVAL;

	}

	if (!slave) {

		SNDERR("slave is not defined");

		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_empty_open, SND_PCM_DLSYM_VERSION);

#endif