156 lines
5.4 KiB
C
156 lines
5.4 KiB
C
/****************************************************************************
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* include/semaphore.h
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*
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* Copyright (C) 2007-2009, 2012-2013 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 __INCLUDE_SEMAPHORE_H
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#define __INCLUDE_SEMAPHORE_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 <stdint.h>
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#include <limits.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* Bit definitions for the struct sem_s flags field */
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#define PRIOINHERIT_FLAGS_DISABLE (1 << 0) /* Bit 0: Priority inheritance
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* is disabled for this semaphore. */
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/****************************************************************************
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* Public Type Declarations
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****************************************************************************/
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/* This structure contains information about the holder of a semaphore */
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#ifdef CONFIG_PRIORITY_INHERITANCE
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struct tcb_s; /* Forward reference */
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struct semholder_s
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{
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#if CONFIG_SEM_PREALLOCHOLDERS > 0
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struct semholder_s *flink; /* Implements singly linked list */
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#endif
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FAR struct tcb_s *htcb; /* Holder TCB */
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int16_t counts; /* Number of counts owned by this holder */
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};
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#if CONFIG_SEM_PREALLOCHOLDERS > 0
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# define SEMHOLDER_INITIALIZER {NULL, NULL, 0}
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#else
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# define SEMHOLDER_INITIALIZER {NULL, 0}
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#endif
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#endif /* CONFIG_PRIORITY_INHERITANCE */
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/* This is the generic semaphore structure. */
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struct sem_s
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{
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volatile int16_t semcount; /* >0 -> Num counts available */
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/* <0 -> Num tasks waiting for semaphore */
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/* If priority inheritance is enabled, then we have to keep track of which
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* tasks hold references to the semaphore.
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*/
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#ifdef CONFIG_PRIORITY_INHERITANCE
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uint8_t flags; /* See PRIOINHERIT_FLAGS_* definitions */
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# if CONFIG_SEM_PREALLOCHOLDERS > 0
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FAR struct semholder_s *hhead; /* List of holders of semaphore counts */
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# else
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struct semholder_s holder; /* Single holder */
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# endif
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#endif
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};
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typedef struct sem_s sem_t;
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/* Initializers */
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#ifdef CONFIG_PRIORITY_INHERITANCE
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# if CONFIG_SEM_PREALLOCHOLDERS > 0
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# define SEM_INITIALIZER(c) {(c), 0, NULL} /* semcount, flags, hhead */
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# else
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# define SEM_INITIALIZER(c) {(c), 0, SEMHOLDER_INITIALIZER} /* semcount, flags, holder */
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# endif
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#else
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# define SEM_INITIALIZER(c) {(c)} /* semcount */
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#endif
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/****************************************************************************
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* Public Data
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****************************************************************************/
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#ifdef __cplusplus
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#define EXTERN extern "C"
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extern "C"
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{
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#else
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#define EXTERN extern
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#endif
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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/* Forward references needed by some prototypes */
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struct timespec; /* Defined in time.h */
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/* Counting Semaphore Interfaces (based on POSIX APIs) */
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int sem_init(FAR sem_t *sem, int pshared, unsigned int value);
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int sem_destroy(FAR sem_t *sem);
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int sem_wait(FAR sem_t *sem);
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int sem_timedwait(FAR sem_t *sem, FAR const struct timespec *abstime);
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int sem_trywait(FAR sem_t *sem);
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int sem_post(FAR sem_t *sem);
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int sem_getvalue(FAR sem_t *sem, FAR int *sval);
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#ifdef CONFIG_FS_NAMED_SEMAPHORES
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FAR sem_t *sem_open(FAR const char *name, int oflag, ...);
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int sem_close(FAR sem_t *sem);
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int sem_unlink(FAR const char *name);
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#endif
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#undef EXTERN
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#ifdef __cplusplus
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}
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#endif
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#endif /* __INCLUDE_SEMAPHORE_H */
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