/*

 *  IPC SHM area manager

 *  Copyright (c) 2003 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 "config.h"

/* These funcs are only used by pcm_mmap when sys/shm.h is available. */

#ifdef HAVE_SYS_SHM_H

#include <stdio.h>

#include <malloc.h>

#include <string.h>

#include <errno.h>

#include <poll.h>

#include <sys/mman.h>

#include <sys/shm.h>

#include "list.h"

#ifndef DOC_HIDDEN

struct snd_shm_area {

	struct list_head list;

	int shmid;

	void *ptr;

	int share;

};

#endif

static LIST_HEAD(shm_areas);

/**

 * \brief Create a shm area record

 * \param shmid IPC SHM ID

 * \param ptr the shared area pointer

 * \return The allocated shm area record, NULL if fail

 *

 * Allocates a shared area record with the given SHM ID and pointer.

 * The record has a reference counter, which is initialized to 1 by this function.

 */

struct snd_shm_area *snd_shm_area_create(int shmid, void *ptr)

{

	struct snd_shm_area *area = malloc(sizeof(*area));

	if (area) {

		area->shmid = shmid;

		area->ptr = ptr;

		area->share = 1;

		list_add_tail(&area->list, &shm_areas);

	}

	return area;

}

/**

 * \brief Increase the reference counter of shm area record

 * \param area shm area record

 * \return the shm area record (identical with the argument)

 *

 * Increases the reference counter of the given shared area record.

 */

struct snd_shm_area *snd_shm_area_share(struct snd_shm_area *area)

{

	if (area == NULL)

		return NULL;

	area->share++;

	return area;

}

/**

 * \brief Release the shared area record

 * \param area the shared are record

 * \return 0 if successful, or a negative error code

 *

 * Decreases the reference counter of the given shared area record, and

 * releases the resources automaticall if it reaches to 0.

 */

int snd_shm_area_destroy(struct snd_shm_area *area)

{

	if (area == NULL)

		return -ENOENT;

	if (--area->share)

		return 0;

	list_del(&area->list);

	shmdt(area->ptr);

	free(area);

	return 0;

}

void snd_shm_area_destructor(void) __attribute__ ((destructor));

void snd_shm_area_destructor(void)

{

	struct list_head *pos;

	struct snd_shm_area *area;

	list_for_each(pos, &shm_areas) {

		area = list_entry(pos, struct snd_shm_area, list);

		shmdt(area->ptr);

	}

}

#endif