/* semaphore.h
*
* This include file contains all the constants and structures associated
* with the Semaphore Manager. This manager utilizes standard Dijkstra
* counting semaphores to provide synchronization and mutual exclusion
* capabilities.
*
* Directives provided are:
*
* + create a semaphore
* + get an ID of a semaphore
* + delete a semaphore
* + acquire a semaphore
* + release a semaphore
*
* COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994.
* On-Line Applications Research Corporation (OAR).
* All rights assigned to U.S. Government, 1994.
*
* This material may be reproduced by or for the U.S. Government pursuant
* to the copyright license under the clause at DFARS 252.227-7013. This
* notice must appear in all copies of this file and its derivatives.
*
* $Id$
*/
#ifndef __RTEMS_SEMAPHORE_h
#define __RTEMS_SEMAPHORE_h
#ifdef __cplusplus
extern "C" {
#endif
#include <rtems/attr.h>
#include <rtems/object.h>
#include <rtems/threadq.h>
/*
* The following defines the control block used to manage each semaphore.
*/
typedef struct {
Objects_Control Object;
Thread_queue_Control Wait_queue;
rtems_attribute attribute_set;
unsigned32 count;
unsigned32 nest_count;
Thread_Control *holder;
Objects_Id holder_id;
} Semaphore_Control;
/*
* The following defines the information control block used to manage
* this class of objects.
*/
EXTERN Objects_Information _Semaphore_Information;
/*
* _Semaphore_Manager_initialization
*
* DESCRIPTION:
*
* This routine performs the initialization necessary for this manager.
*/
void _Semaphore_Manager_initialization(
unsigned32 maximum_semaphores
);
/*
* rtems_semaphore_create
*
* DESCRIPTION:
*
* This routine implements the rtems_semaphore_create directive. The
* semaphore will have the name name. The starting count for
* the semaphore is count. The attribute_set determines if
* the semaphore is global or local and the thread queue
* discipline. It returns the id of the created semaphore in ID.
*/
rtems_status_code rtems_semaphore_create(
Objects_Name name,
unsigned32 count,
rtems_attribute attribute_set,
Objects_Id *id
);
/*
* rtems_semaphore_ident
*
* DESCRIPTION:
*
* This routine implements the rtems_semaphore_ident directive.
* This directive returns the semaphore ID associated with name.
* If more than one semaphore is named name, then the semaphore
* to which the ID belongs is arbitrary. node indicates the
* extent of the search for the ID of the semaphore named name.
* The search can be limited to a particular node or allowed to
* encompass all nodes.
*/
rtems_status_code rtems_semaphore_ident(
Objects_Name name,
unsigned32 node,
Objects_Id *id
);
/*
* rtems_semaphore_delete
*
* DESCRIPTION:
*
* This routine implements the rtems_semaphore_delete directive. The
* semaphore indicated by ID is deleted.
*/
rtems_status_code rtems_semaphore_delete(
Objects_Id id
);
/*
* rtems_semaphore_obtain
*
* DESCRIPTION:
*
* This routine implements the rtems_semaphore_obtain directive. It
* attempts to obtain a unit from the semaphore associated with ID.
* If a unit can be allocated, the calling task will return immediately.
* If no unit is available, then the task may return immediately or
* block waiting for a unit with an optional timeout of timeout
* clock ticks. Whether the task blocks or returns immediately
* is based on the RTEMS_NO_WAIT option in the option_set.
*/
rtems_status_code rtems_semaphore_obtain(
Objects_Id id,
unsigned32 option_set,
rtems_interval timeout
);
/*
* rtems_semaphore_release
*
* DESCRIPTION:
*
* This routine implements the rtems_semaphore_release directive. It
* frees a unit to the semaphore associated with ID. If a task was
* blocked waiting for a unit from this semaphore, then that task will
* be readied and the unit given to that task. Otherwise, the unit
* will be returned to the semaphore.
*/
rtems_status_code rtems_semaphore_release(
Objects_Id id
);
/*
* _Semaphore_Seize
*
* DESCRIPTION:
*
* This routine attempts to receive a unit from the_semaphore.
* If a unit is available or if the RTEMS_NO_WAIT option is enabled in
* option_set, then the routine returns. Otherwise, the calling task
* is blocked until a unit becomes available.
*/
boolean _Semaphore_Seize(
Semaphore_Control *the_semaphore,
unsigned32 option_set
);
/*
* _Semaphore_Allocate
*
* DESCRIPTION:
*
* This function allocates a semaphore control block from
* the inactive chain of free semaphore control blocks.
*/
STATIC INLINE Semaphore_Control *_Semaphore_Allocate( void );
/*
* _Semaphore_Free
*
* DESCRIPTION:
*
* This routine frees a semaphore control block to the
* inactive chain of free semaphore control blocks.
*/
STATIC INLINE void _Semaphore_Free (
Semaphore_Control *the_semaphore
);
/*
* _Semaphore_Get
*
* DESCRIPTION:
*
* This function maps semaphore IDs to semaphore control blocks.
* If ID corresponds to a local semaphore, then it returns
* the_semaphore control pointer which maps to ID and location
* is set to OBJECTS_LOCAL. if the semaphore ID is global and
* resides on a remote node, then location is set to OBJECTS_REMOTE,
* and the_semaphore is undefined. Otherwise, location is set
* to OBJECTS_ERROR and the_semaphore is undefined.
*/
STATIC INLINE Semaphore_Control *_Semaphore_Get (
Objects_Id id,
Objects_Locations *location
);
/*
* _Semaphore_Is_null
*
* DESCRIPTION:
*
* This function returns TRUE if the_semaphore is NULL and FALSE otherwise.
*/
STATIC INLINE boolean _Semaphore_Is_null (
Semaphore_Control *the_semaphore
);
#include <rtems/sem.inl>
#include <rtems/semmp.h>
#ifdef __cplusplus
}
#endif
#endif
/* end of include file */
