| /**************************************************************************** |
| * include/semaphore.h |
| * |
| * Copyright (C) 2007-2009, 2012-2013 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 __INCLUDE_SEMAPHORE_H |
| #define __INCLUDE_SEMAPHORE_H |
| |
| /**************************************************************************** |
| * Included Files |
| ****************************************************************************/ |
| |
| #include <nuttx/config.h> |
| |
| #include <stdint.h> |
| #include <limits.h> |
| |
| /**************************************************************************** |
| * Pre-processor Definitions |
| ****************************************************************************/ |
| |
| /* Value returned by sem_open() in the event of a failure. */ |
| |
| #define SEM_FAILED ((FAR sem_t *)NULL) |
| |
| /* Bit definitions for the struct sem_s flags field */ |
| |
| #define PRIOINHERIT_FLAGS_DISABLE (1 << 0) /* Bit 0: Priority inheritance |
| * is disabled for this semaphore. */ |
| |
| /**************************************************************************** |
| * Public Type Declarations |
| ****************************************************************************/ |
| |
| /* This structure contains information about the holder of a semaphore */ |
| |
| #ifdef CONFIG_PRIORITY_INHERITANCE |
| struct tcb_s; /* Forward reference */ |
| struct semholder_s |
| { |
| #if CONFIG_SEM_PREALLOCHOLDERS > 0 |
| struct semholder_s *flink; /* Implements singly linked list */ |
| #endif |
| FAR struct tcb_s *htcb; /* Holder TCB */ |
| int16_t counts; /* Number of counts owned by this holder */ |
| }; |
| |
| #if CONFIG_SEM_PREALLOCHOLDERS > 0 |
| # define SEMHOLDER_INITIALIZER {NULL, NULL, 0} |
| #else |
| # define SEMHOLDER_INITIALIZER {NULL, 0} |
| #endif |
| #endif /* CONFIG_PRIORITY_INHERITANCE */ |
| |
| /* This is the generic semaphore structure. */ |
| |
| struct sem_s |
| { |
| volatile int16_t semcount; /* >0 -> Num counts available */ |
| /* <0 -> Num tasks waiting for semaphore */ |
| /* If priority inheritance is enabled, then we have to keep track of which |
| * tasks hold references to the semaphore. |
| */ |
| |
| #ifdef CONFIG_PRIORITY_INHERITANCE |
| uint8_t flags; /* See PRIOINHERIT_FLAGS_* definitions */ |
| # if CONFIG_SEM_PREALLOCHOLDERS > 0 |
| FAR struct semholder_s *hhead; /* List of holders of semaphore counts */ |
| # else |
| struct semholder_s holder[2]; /* Slot for old and new holder */ |
| # endif |
| #endif |
| }; |
| |
| typedef struct sem_s sem_t; |
| |
| /* Initializers */ |
| |
| #ifdef CONFIG_PRIORITY_INHERITANCE |
| # if CONFIG_SEM_PREALLOCHOLDERS > 0 |
| # define SEM_INITIALIZER(c) \ |
| {(c), 0, NULL} /* semcount, flags, hhead */ |
| # else |
| # define SEM_INITIALIZER(c) \ |
| {(c), 0, {SEMHOLDER_INITIALIZER, SEMHOLDER_INITIALIZER}} /* semcount, flags, holder[2] */ |
| # endif |
| #else |
| # define SEM_INITIALIZER(c) \ |
| {(c)} /* semcount */ |
| #endif |
| |
| /**************************************************************************** |
| * Public Data |
| ****************************************************************************/ |
| |
| #ifdef __cplusplus |
| #define EXTERN extern "C" |
| extern "C" |
| { |
| #else |
| #define EXTERN extern |
| #endif |
| |
| /**************************************************************************** |
| * Public Function Prototypes |
| ****************************************************************************/ |
| /* Forward references needed by some prototypes */ |
| |
| struct timespec; /* Defined in time.h */ |
| |
| /* Counting Semaphore Interfaces (based on POSIX APIs) */ |
| |
| int sem_init(FAR sem_t *sem, int pshared, unsigned int value); |
| int sem_destroy(FAR sem_t *sem); |
| int sem_wait(FAR sem_t *sem); |
| int sem_timedwait(FAR sem_t *sem, FAR const struct timespec *abstime); |
| int sem_trywait(FAR sem_t *sem); |
| int sem_post(FAR sem_t *sem); |
| int sem_getvalue(FAR sem_t *sem, FAR int *sval); |
| |
| #ifdef CONFIG_FS_NAMED_SEMAPHORES |
| FAR sem_t *sem_open(FAR const char *name, int oflag, ...); |
| int sem_close(FAR sem_t *sem); |
| int sem_unlink(FAR const char *name); |
| #endif |
| |
| #undef EXTERN |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| #endif /* __INCLUDE_SEMAPHORE_H */ |