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/**
* @file rtems/score/corespinlock.h
*
* This include file contains all the constants and structures associated
* with the Spinlock Handler.
*/
/*
* COPYRIGHT (c) 1989-2006.
* 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_CORESPINLOCK_H
#define _RTEMS_SCORE_CORESPINLOCK_H
/**
* @defgroup ScoreSpinlock Spinlock Handler
*
* @ingroup Score
*
* This handler encapsulates functionality which provides the foundation
* Spinlock services used in all of the APIs supported by RTEMS.
*/
/**@{*/
#ifdef __cplusplus
extern "C" {
#endif
#include <rtems/score/thread.h>
#include <rtems/score/priority.h>
/**
* Core Spinlock handler return statuses.
*/
typedef enum {
/** This status indicates that the operation completed successfully. */
CORE_SPINLOCK_SUCCESSFUL,
/** This status indicates that the current thread already holds the spinlock.
* An attempt to relock it will result in deadlock.
*/
CORE_SPINLOCK_HOLDER_RELOCKING,
/** This status indicates that the current thread is attempting to unlock a
* spinlock that is held by another thread.
*/
CORE_SPINLOCK_NOT_HOLDER,
/** This status indicates that a thread reached the limit of time it
* was willing to wait on the spin lock.
*/
CORE_SPINLOCK_TIMEOUT,
/** This status indicates that a thread is currently waiting for this
* spin lock.
*/
CORE_SPINLOCK_IS_BUSY,
/** This status indicates that the spinlock is currently locked and thus
* unavailable.
*/
CORE_SPINLOCK_UNAVAILABLE,
/** This status indicates that the spinlock is not currently locked and thus
* should not be released.
*/
CORE_SPINLOCK_NOT_LOCKED
} CORE_spinlock_Status;
/** This is a shorthand for the last status code. */
#define CORE_SPINLOCK_STATUS_LAST CORE_SPINLOCK_NOT_LOCKED
/** This indicates the lock is available. */
#define CORE_SPINLOCK_UNLOCKED 0
/** This indicates the lock is unavailable. */
#define CORE_SPINLOCK_LOCKED 1
/**
* The following defines the control block used to manage the
* attributes of each spinlock.
*/
typedef struct {
/** This element indicates XXX
*/
uint32_t XXX;
} CORE_spinlock_Attributes;
/**
* The following defines the control block used to manage each
* spinlock.
*/
typedef struct {
/** XXX may not be needed */
CORE_spinlock_Attributes Attributes;
/** This field is the lock.
*/
volatile uint32_t lock;
/** This field is a count of the current number of threads using
* this spinlock. It includes the thread holding the lock as well
* as those waiting.
*/
volatile uint32_t users;
/** This field is the Id of the thread holding the lock. It may or may
* not be the thread which acquired it.
*/
volatile Objects_Id holder;
} CORE_spinlock_Control;
/**
* This routine initializes the spinlock based on the parameters passed.
*
* @param[in] the_spinlock is the spinlock to initialize
* @param[in] the_spinlock_attributes define the behavior of this instance
*/
void _CORE_spinlock_Initialize(
CORE_spinlock_Control *the_spinlock,
CORE_spinlock_Attributes *the_spinlock_attributes
);
/**
* This routine wait for the spinlock to be released. If the spinlock
* is set to automatic and this is the appropriate thread, then it returns
* immediately. Otherwise, the calling thread is blocked until the spinlock
* is released.
*
* @param[in] the_spinlock is the spinlock to wait for
* @param[in] wait is true if willing to wait
* @param[in] timeout is the maximum number of ticks to spin (0 is forever)
*
* @return A status is returned which indicates the success or failure of
* this operation.
*/
CORE_spinlock_Status _CORE_spinlock_Wait(
CORE_spinlock_Control *the_spinlock,
bool wait,
Watchdog_Interval timeout
);
/**
* This routine manually releases the spinlock. All of the threads waiting
* for the spinlock will be readied.
*
* @param[in] the_spinlock is the spinlock to surrender
*/
CORE_spinlock_Status _CORE_spinlock_Release(
CORE_spinlock_Control *the_spinlock
);
#ifndef __RTEMS_APPLICATION__
#include <rtems/score/corespinlock.inl>
#endif
#ifdef __cplusplus
}
#endif
/**@}*/
#endif
/* end of include file */
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