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