source: rtems/c/src/libchip/shmdr/getlq.c @ 08311cc3

4.104.114.84.95
Last change on this file since 08311cc3 was 08311cc3, checked in by Joel Sherrill <joel.sherrill@…>, on Nov 17, 1999 at 5:51:34 PM

Updated copyright notice.

  • Property mode set to 100644
File size: 1.2 KB
Line 
1/*  Shm_Envelope_control *Shm_Locked_queue_Get( lq_cb )
2 *
3 *  This routine returns an envelope control block from a shared
4 *  memory queue.
5 *
6 *  Input parameters:
7 *    lq_cb - pointer to a locked queue control block
8 *
9 *  Output parameters:
10 *    returns - pointer to an envelope control block
11 *            - NULL if no envelopes on specified queue
12 *
13 *  COPYRIGHT (c) 1989-1999.
14 *  On-Line Applications Research Corporation (OAR).
15 *
16 *  The license and distribution terms for this file may be
17 *  found in the file LICENSE in this distribution or at
18 *  http://www.OARcorp.com/rtems/license.html.
19 *
20 *  $Id$
21 */
22
23#include <rtems.h>
24#include <shm.h>
25
26Shm_Envelope_control *Shm_Locked_queue_Get(
27  Shm_Locked_queue_Control *lq_cb
28)
29{
30  Shm_Envelope_control *tmp_ecb;
31  rtems_unsigned32 tmpfront;
32
33  tmp_ecb = NULL;
34  Shm_Lock( lq_cb );
35
36    tmpfront = Shm_Convert(lq_cb->front);
37    if ( tmpfront != Shm_Locked_queue_End_of_list ) {
38      tmp_ecb = &Shm_Envelopes[ tmpfront ];
39      lq_cb->front = tmp_ecb->next;
40      if ( tmp_ecb->next == Shm_Locked_queue_End_of_list )
41        lq_cb->rear = Shm_Locked_queue_End_of_list;
42      tmp_ecb->next = Shm_Locked_queue_Not_on_list;
43    }
44
45  Shm_Unlock( lq_cb );
46  return( tmp_ecb );
47}
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