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/* Shm_Envelope_control *Shm_Locked_queue_Get( lq_cb )
*
* This routine returns an envelope control block from a shared
* memory queue.
*
* Input parameters:
* lq_cb - pointer to a locked queue control block
*
* Output parameters:
* returns - pointer to an envelope control block
* - NULL if no envelopes on specified queue
*
* COPYRIGHT (c) 1989-1999.
* 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.OARcorp.com/rtems/license.html.
*
* $Id$
*/
#include <rtems.h>
#include <shm_driver.h>
Shm_Envelope_control *Shm_Locked_queue_Get(
Shm_Locked_queue_Control *lq_cb
)
{
Shm_Envelope_control *tmp_ecb;
rtems_unsigned32 tmpfront;
tmp_ecb = NULL;
Shm_Lock( lq_cb );
tmpfront = Shm_Convert(lq_cb->front);
if ( tmpfront != Shm_Locked_queue_End_of_list ) {
tmp_ecb = &Shm_Envelopes[ tmpfront ];
lq_cb->front = tmp_ecb->next;
if ( tmp_ecb->next == Shm_Locked_queue_End_of_list )
lq_cb->rear = Shm_Locked_queue_End_of_list;
tmp_ecb->next = Shm_Locked_queue_Not_on_list;
}
Shm_Unlock( lq_cb );
return( tmp_ecb );
}
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