/*
* CORE Semaphore Handler
*
* DESCRIPTION:
*
* This package is the implementation of the CORE Semaphore Handler.
* This core object utilizes standard Dijkstra counting semaphores to provide
* synchronization and mutual exclusion capabilities.
*
* 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.
*
* $Id$
*/
#include <rtems/system.h>
#include <rtems/score/isr.h>
#include <rtems/score/coresem.h>
#include <rtems/score/states.h>
#include <rtems/score/thread.h>
#include <rtems/score/threadq.h>
#include <rtems/score/mpci.h>
/*PAGE
*
* CORE_semaphore_Initialize
*
* This function initialize a semaphore and sets the initial value based
* on the given count.
*
* Input parameters:
* the_semaphore - the semaphore control block to initialize
* the_class - the API class of the object
* the_semaphore_attributes - the attributes specified at create time
* initial_value - semaphore's initial value
* proxy_extract_callout - MP specific extract callout
*
* Output parameters: NONE
*/
void _CORE_semaphore_Initialize(
CORE_semaphore_Control *the_semaphore,
Objects_Classes the_class,
CORE_semaphore_Attributes *the_semaphore_attributes,
unsigned32 initial_value,
Thread_queue_Extract_callout proxy_extract_callout
)
{
the_semaphore->Attributes = *the_semaphore_attributes;
the_semaphore->count = initial_value;
_Thread_queue_Initialize(
&the_semaphore->Wait_queue,
the_class,
_CORE_semaphore_Is_priority( the_semaphore_attributes ) ?
THREAD_QUEUE_DISCIPLINE_PRIORITY : THREAD_QUEUE_DISCIPLINE_FIFO,
STATES_WAITING_FOR_SEMAPHORE,
proxy_extract_callout,
CORE_SEMAPHORE_TIMEOUT
);
}
/*PAGE
*
* _CORE_semaphore_Surrender
*
* Input parameters:
* the_semaphore - the semaphore to be flushed
* id - id of parent semaphore
* api_semaphore_mp_support - api dependent MP support actions
*
* Output parameters:
* CORE_SEMAPHORE_STATUS_SUCCESSFUL - if successful
* core error code - if unsuccessful
*
* Output parameters:
*/
CORE_semaphore_Status _CORE_semaphore_Surrender(
CORE_semaphore_Control *the_semaphore,
Objects_Id id,
CORE_semaphore_API_mp_support_callout api_semaphore_mp_support
)
{
Thread_Control *the_thread;
if ( (the_thread = _Thread_queue_Dequeue(&the_semaphore->Wait_queue)) ) {
if ( !_Objects_Is_local_id( the_thread->Object.id ) )
(*api_semaphore_mp_support) ( the_thread, id );
} else
the_semaphore->count += 1;
return( CORE_SEMAPHORE_STATUS_SUCCESSFUL );
}
/*PAGE
*
* _CORE_semaphore_Seize
*
* This routine attempts to allocate a core semaphore to the calling thread.
*
* Input parameters:
* the_semaphore - pointer to semaphore control block
* id - id of object to wait on
* wait - TRUE if wait is allowed, FALSE otherwise
* timeout - number of ticks to wait (0 means forever)
*
* Output parameters: NONE
*
* INTERRUPT LATENCY:
* available
* wait
*/
void _CORE_semaphore_Seize(
CORE_semaphore_Control *the_semaphore,
Objects_Id id,
boolean wait,
Watchdog_Interval timeout
)
{
Thread_Control *executing;
ISR_Level level;
executing = _Thread_Executing;
executing->Wait.return_code = CORE_SEMAPHORE_STATUS_SUCCESSFUL;
_ISR_Disable( level );
if ( the_semaphore->count != 0 ) {
the_semaphore->count -= 1;
executing->resource_count++;
_ISR_Enable( level );
return;
}
if ( !wait ) {
_ISR_Enable( level );
executing->Wait.return_code = CORE_SEMAPHORE_STATUS_UNSATISFIED_NOWAIT;
return;
}
_Thread_queue_Enter_critical_section( &the_semaphore->Wait_queue );
executing->Wait.queue = &the_semaphore->Wait_queue;
executing->Wait.id = id;
_ISR_Enable( level );
_Thread_queue_Enqueue( &the_semaphore->Wait_queue, timeout );
}
/*PAGE
*
* _CORE_semaphore_Flush
*
* This function a flushes the semaphore's task wait queue.
*
* Input parameters:
* the_semaphore - the semaphore to be flushed
* remote_extract_callout - function to invoke remotely
* status - status to pass to thread
*
* Output parameters: NONE
*/
void _CORE_semaphore_Flush(
CORE_semaphore_Control *the_semaphore,
Thread_queue_Flush_callout remote_extract_callout,
unsigned32 status
)
{
_Thread_queue_Flush(
&the_semaphore->Wait_queue,
remote_extract_callout,
status
);
}
