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/****************************************************************************
* mm/shm/shm.h
*
* Copyright (C) 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
#ifndef __MM_SHM_SHM_H
#define __MM_SHM_SHM_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdint.h>
#include <semaphore.h>
#include <nuttx/addrenv.h>
#ifdef CONFIG_MM_SHM
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Bit definitions for the struct shm_region_s sr_flags field */
#define SRFLAG_AVAILABLE 0 /* Available if no flag bits set */
#define SRFLAG_INUSE (1 << 0) /* Bit 0: Region is in use */
#define SRFLAG_UNLINKED (1 << 1) /* Bit 1: Region perists while references */
/****************************************************************************
* Public Types
****************************************************************************/
/* This structure represents the state of one shared memory region
* allocation. Cast compatible with struct shmid_ds.
*/
struct shm_region_s
{
struct shmid_ds sr_ds; /* Region info */
bool sr_flags; /* See SRFLAGS_* definitions */
key_t sr_key; /* Lookup key */
sem_t sr_sem; /* Manages exclusive access to this region */
/* List of physical pages allocated for this memory region */
uintptr_t sr_pages[CONFIG_ARCH_SHM_NPAGES];
};
/* This structure represents the set of all shared memory regions.
* Access to the region
*/
struct shm_info_s
{
sem_t si_sem; /* Manages exclusive access to the region list */
struct shm_region_s si_region[CONFIG_ARCH_SHM_MAXREGIONS];
};
/****************************************************************************
* Public Data
****************************************************************************/
/* State of the all shared memory */
extern struct shm_info_s g_shminfo;
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
/****************************************************************************
* Name: shm_destroy
*
* Description:
* Destroy a memory region. This function is called:
*
* - On certain conditions when shmget() is not successful in instantiating
* the full memory region and we need to clean up and free a table entry.
* - When shmctl() is called with cmd == IPC_RMID and there are no
* processes attached to the memory region.
* - When shmdt() is called after the last process detaches from memory
* region after it was previously marked for deletion by shmctl().
*
* Input Parameters:
* shmid - Shared memory identifier
*
* Returned Value:
* None
*
* Assumption:
* The caller holds either the region table semaphore or else the
* semaphore on the particular entry being deleted.
*
****************************************************************************/
void shm_destroy(int shmid);
#endif /* CONFIG_MM_SHM */
#endif /* __MM_SHM_SHM_H */
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