215 lines
6.7 KiB
C
215 lines
6.7 KiB
C
/****************************************************************************
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* include/nuttx/mutex.h
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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#ifndef __INCLUDE_NUTTX_MUTEX_H
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#define __INCLUDE_NUTTX_MUTEX_H
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <stdbool.h>
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#include <errno.h>
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#include <assert.h>
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#include <nuttx/semaphore.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define MUTEX_INITIALIZER SEM_INITIALIZER(1);
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/****************************************************************************
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* Public Type Definitions
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****************************************************************************/
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typedef sem_t mutex_t;
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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#ifndef __ASSEMBLY__
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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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* Name: nxmutex_init
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*
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* Description:
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* This function initializes the UNNAMED mutex. Following a
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* successful call to nxmutex_init(), the mutex may be used in subsequent
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* calls to nxmutex_lock(), nxmutex_unlock(), and nxmutex_trylock(). The
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* mutex remains usable until it is destroyed.
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*
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* Parameters:
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* mutex - Semaphore to be initialized
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*
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* Return Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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*
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****************************************************************************/
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static inline int nxmutex_init(FAR mutex_t *mutex)
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{
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return nxsem_init(mutex, 0, 1);
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}
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/****************************************************************************
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* Name: nxmutex_destroy
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*
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* Description:
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* This function initializes the UNNAMED mutex. Following a
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* successful call to nxmutex_init(), the mutex may be used in subsequent
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* calls to nxmutex_lock(), nxmutex_unlock(), and nxmutex_trylock(). The
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* mutex remains usable until it is destroyed.
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*
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* Parameters:
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* mutex - Semaphore to be destroyed
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*
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* Return Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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*
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****************************************************************************/
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static inline int nxmutex_destroy(FAR mutex_t *mutex)
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{
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return nxsem_destroy(mutex);
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}
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/****************************************************************************
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* Name: nxmutex_lock
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*
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* Description:
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* This function attempts to lock the mutex referenced by 'mutex'. The
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* mutex is implemented with a semaphore, so if the semaphore value is
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* (<=) zero, then the calling task will not return until it successfully
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* acquires the lock.
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*
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* Parameters:
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* mutex - mutex descriptor.
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*
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* Return Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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* Possible returned errors:
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*
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****************************************************************************/
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static inline int nxmutex_lock(FAR mutex_t *mutex)
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{
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return nxsem_wait_uninterruptible(mutex);
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}
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/****************************************************************************
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* Name: nxmutex_trylock
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*
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* Description:
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* This function locks the mutex only if the mutex is currently not locked.
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* If the mutex has been locked already, the call returns without blocking.
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*
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* Parameters:
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* mutex - mutex descriptor.
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*
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* Return Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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* Possible returned errors:
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*
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* -EINVAL - Invalid attempt to lock the mutex
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* -EAGAIN - The mutex is not available.
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*
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****************************************************************************/
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static inline int nxmutex_trylock(FAR mutex_t *mutex)
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{
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return nxsem_trywait(mutex);
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}
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/****************************************************************************
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* Name: nxmutex_is_locked
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*
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* Description:
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* This function get the lock state the mutex referenced by 'mutex'.
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*
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* Parameters:
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* mutex - mutex descriptor.
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*
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* Return Value:
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*
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****************************************************************************/
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static inline bool nxmutex_is_locked(FAR mutex_t *mutex)
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{
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int cnt;
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int ret;
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ret = nxsem_get_value(mutex, &cnt);
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DEBUGASSERT(ret == OK);
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return cnt < 1;
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}
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/****************************************************************************
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* Name: nxmutex_unlock
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*
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* Description:
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* This function attempts to unlock the mutex referenced by 'mutex'.
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*
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* Parameters:
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* mutex - mutex descriptor.
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*
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* Return Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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* Possible returned errors:
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*
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* Assumptions:
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* This function may be called from an interrupt handler.
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*
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****************************************************************************/
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static inline int nxmutex_unlock(FAR mutex_t *mutex)
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{
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return nxsem_post(mutex);
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}
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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 /* __ASSEMBLY__ */
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#endif /* __INCLUDE_NUTTX_MUTEX_H */
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