/****************************************************************************
* include/semaphore.h
*
* Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 __SEMAPHORE_H
#define __SEMAPHORE_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <sys/types.h>
#include <limits.h>
#ifdef __cplusplus
#define EXTERN extern "C"
extern "C" {
#else
#define EXTERN extern
#endif
/****************************************************************************
* Definitions
****************************************************************************/
/****************************************************************************
* Public Type Declarations
****************************************************************************/
/* This structure contains the holder of a semaphore */
#ifdef CONFIG_PRIORITY_INHERITANCE
struct semholder_s
{
#if !defined(CONFIG_SEM_PREALLOCHOLDERS) || CONFIG_SEM_PREALLOCHOLDERS > 0
struct semholder_s *flink; /* Implements singly linked list */
#endif
void *holder; /* Holder TCB (actual type is _TCB) */
sint16 counts; /* Number of counts owned by this holder */
};
#endif
/* This is the generic semaphore structure. */
struct sem_s
{
sint16 semcount; /* >0 -> Num counts available */
/* <0 -> Num tasks waiting for semaphore */
#ifdef CONFIG_PRIORITY_INHERITANCE
struct semholder_s hlist; /* List of holders of semaphore counts */
#endif
};
typedef struct sem_s sem_t;
/****************************************************************************
* Public Variables
****************************************************************************/
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
/* Counting Semaphore Interfaces (based on POSIX APIs) */
EXTERN int sem_init(FAR sem_t *sem, int pshared, unsigned int value);
EXTERN int sem_destroy(FAR sem_t *sem);
EXTERN FAR sem_t *sem_open(FAR const char *name, int oflag, ...);
EXTERN int sem_close(FAR sem_t *sem);
EXTERN int sem_unlink(FAR const char *name);
EXTERN int sem_wait(FAR sem_t *sem);
EXTERN int sem_trywait(FAR sem_t *sem);
EXTERN int sem_post(FAR sem_t *sem);
EXTERN int sem_getvalue(FAR sem_t *sem, FAR int *sval);
#undef EXTERN
#ifdef __cplusplus
}
#endif
#endif /* __SEMAPHORE_H */
