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/**
* @file rtems/score/corerwlock.h
*
* This include file contains all the constants and structures associated
* with the RWLock Handler.
*/
/*
* COPYRIGHT (c) 1989-2008.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
#ifndef _RTEMS_SCORE_CORERWLOCK_H
#define _RTEMS_SCORE_CORERWLOCK_H
/**
* @defgroup ScoreRWLock RWLock Handler
*
* @ingroup Score
*
* This handler encapsulates functionality which provides the foundation
* RWLock services used in all of the APIs supported by RTEMS.
*/
/**@{*/
#ifdef __cplusplus
extern "C" {
#endif
#include <rtems/score/thread.h>
#include <rtems/score/threadq.h>
#include <rtems/score/priority.h>
#include <rtems/score/watchdog.h>
/**
* The following type defines the callout which the API provides
* to support global/multiprocessor operations on RWLocks.
*/
typedef void ( *CORE_RWLock_API_mp_support_callout )(
Thread_Control *,
Objects_Id
);
/**
* RWLock State.
*/
typedef enum {
/** This indicates the the RWLock is not currently locked.
*/
CORE_RWLOCK_UNLOCKED,
/** This indicates the the RWLock is currently locked for reading.
*/
CORE_RWLOCK_LOCKED_FOR_READING,
/** This indicates the the RWLock is currently locked for reading.
*/
CORE_RWLOCK_LOCKED_FOR_WRITING
} CORE_RWLock_States;
/**
* Core RWLock handler return statuses.
*/
typedef enum {
/** This status indicates that the operation completed successfully. */
CORE_RWLOCK_SUCCESSFUL,
/** This status indicates that the thread was blocked waiting for an */
CORE_RWLOCK_WAS_DELETED,
/** This status indicates that the rwlock was not immediately available. */
CORE_RWLOCK_UNAVAILABLE,
/** This status indicates that the calling task was willing to block
* but the operation was unable to complete within the time allotted
* because the resource never became available.
*/
CORE_RWLOCK_TIMEOUT
} CORE_RWLock_Status;
/** This is the last status value.
*/
#define CORE_RWLOCK_STATUS_LAST CORE_RWLOCK_TIMEOUT
/**
* This is used to denote that a thread is blocking waiting for
* read-only access to the RWLock.
*/
#define CORE_RWLOCK_THREAD_WAITING_FOR_READ 0
/**
* This is used to denote that a thread is blocking waiting for
* write-exclusive access to the RWLock.
*/
#define CORE_RWLOCK_THREAD_WAITING_FOR_WRITE 1
/**
* The following defines the control block used to manage the
* attributes of each RWLock.
*/
typedef struct {
/** This field indicates XXX.
*/
int XXX;
} CORE_RWLock_Attributes;
/**
* The following defines the control block used to manage each
* RWLock.
*/
typedef struct {
/** This field is the Waiting Queue used to manage the set of tasks
* which are blocked waiting for the RWLock to be released.
*/
Thread_queue_Control Wait_queue;
/** This element is the set of attributes which define this instance's
* behavior.
*/
CORE_RWLock_Attributes Attributes;
/** This element is the current state of the RWLock.
*/
CORE_RWLock_States current_state;
/** This element contains the current number of thread waiting for this
* RWLock to be released. */
uint32_t number_of_readers;
} CORE_RWLock_Control;
/**
* This routine initializes the RWLock based on the parameters passed.
*
* @param[in] the_rwlock is the RWLock to initialize
* @param[in] the_rwlock_attributes define the behavior of this instance
*/
void _CORE_RWLock_Initialize(
CORE_RWLock_Control *the_rwlock,
CORE_RWLock_Attributes *the_rwlock_attributes
);
/**
* This routine attempts to obtain the RWLock for read access.
*
* @param[in] the_rwlock is the RWLock to wait for
* @param[in] id is the id of the object being waited upon
* @param[in] wait is true if the calling thread is willing to wait
* @param[in] timeout is the number of ticks the calling thread is willing
* to wait if @a wait is true.
* @param[in] api_rwlock_mp_support is the routine to invoke if the
* thread unblocked is remote
*
* @note Status is returned via the thread control block.
*/
void _CORE_RWLock_Obtain_for_reading(
CORE_RWLock_Control *the_rwlock,
Objects_Id id,
bool wait,
Watchdog_Interval timeout,
CORE_RWLock_API_mp_support_callout api_rwlock_mp_support
);
/**
* This routine attempts to obtain the RWLock for write exclusive access.
*
* @param[in] the_rwlock is the RWLock to wait for
* @param[in] id is the id of the object being waited upon
* @param[in] wait is true if the calling thread is willing to wait
* @param[in] timeout is the number of ticks the calling thread is willing
* to wait if @a wait is true.
* @param[in] api_rwlock_mp_support is the routine to invoke if the
* thread unblocked is remote
*
* @note Status is returned via the thread control block.
*/
void _CORE_RWLock_Obtain_for_writing(
CORE_RWLock_Control *the_rwlock,
Objects_Id id,
bool wait,
Watchdog_Interval timeout,
CORE_RWLock_API_mp_support_callout api_rwlock_mp_support
);
/**
* This routine manually releases the RWLock. All of the threads waiting
* for the RWLock will be readied.
*
* @param[in] the_rwlock is the RWLock to surrender
*
* @return Status is returned to indicate successful or failure.
*/
CORE_RWLock_Status _CORE_RWLock_Release(
CORE_RWLock_Control *the_rwlock
);
/**
* This routine assists in the deletion of a RWLock by flushing the
* associated wait queue.
*
* @param[in] _the_rwlock is the RWLock to flush
* @param[in] _remote_extract_callout is the routine to invoke if the
* thread unblocked is remote
* @param[in] _status is the status to be returned to the unblocked thread
*/
#define _CORE_RWLock_Flush( _the_rwlock, _remote_extract_callout, _status) \
_Thread_queue_Flush( \
&((_the_rwlock)->Wait_queue), \
(_remote_extract_callout), \
(_status) \
)
/**
* @brief RWLock Specific Thread Queue Timeout
*
* This routine processes a thread which timeouts while waiting on
* an RWLock's thread queue. It is called by the watchdog handler.
*
* @param[in] id is the Id of thread to timeout
* @param[in] ignored is an unused pointer to a caller defined area
*/
void _CORE_RWLock_Timeout(
Objects_Id id,
void *ignored
);
#ifndef __RTEMS_APPLICATION__
#include <rtems/score/corerwlock.inl>
#endif
#ifdef __cplusplus
}
#endif
/**@}*/
#endif
/* end of include file */
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