source: rtems/c/src/libchip/shmdr/getlq.c @ ac7d5ef0

4.104.114.84.95
Last change on this file since ac7d5ef0 was ac7d5ef0, checked in by Joel Sherrill <joel.sherrill@…>, on May 11, 1995 at 5:39:37 PM

Initial revision

  • Property mode set to 100644
File size: 1.3 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, 1990, 1991, 1992, 1993, 1994.
14 *  On-Line Applications Research Corporation (OAR).
15 *  All rights assigned to U.S. Government, 1994.
16 *
17 *  This material may be reproduced by or for the U.S. Government pursuant
18 *  to the copyright license under the clause at DFARS 252.227-7013.  This
19 *  notice must appear in all copies of this file and its derivatives.
20 *
21 *  $Id$
22 */
23
24#include <rtems.h>
25#include "shm.h"
26
27Shm_Envelope_control *Shm_Locked_queue_Get(
28  Shm_Locked_queue_Control *lq_cb
29)
30{
31  Shm_Envelope_control *tmp_ecb;
32  rtems_unsigned32 tmpfront;
33
34  tmp_ecb = NULL;
35  Shm_Lock( lq_cb );
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  Shm_Unlock( lq_cb );
45  return( tmp_ecb );
46}
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