source: rtems/c/src/lib/libbsp/unix/posix/shmsupp/lock.c @ 98e4ebf5

4.104.114.84.95
Last change on this file since 98e4ebf5 was 98e4ebf5, checked in by Joel Sherrill <joel.sherrill@…>, on 10/08/97 at 15:45:54

Fixed typo in the pointer to the license terms.

  • Property mode set to 100644
File size: 1.5 KB
Line 
1/*  Shared Memory Lock Routines
2 *
3 *  This shared memory locked queue support routine need to be
4 *  able to lock the specified locked queue.  Interrupts are
5 *  disabled while the queue is locked to prevent preemption
6 *  and deadlock when two tasks poll for the same lock.
7 *  previous level.
8 *
9 *  COPYRIGHT (c) 1989-1997.
10 *  On-Line Applications Research Corporation (OAR).
11 *  Copyright assigned to U.S. Government, 1994.
12 *
13 *  The license and distribution terms for this file may be
14 *  found in the file LICENSE in this distribution or at
15 *  http://www.OARcorp.com/rtems/license.html.
16 *
17 *  $Id$
18 */
19
20#include <bsp.h>
21#include <shm.h>
22
23/*
24 *  Shm_Initialize_lock
25 *
26 *  Initialize the lock for the specified locked queue.
27 */
28
29void Shm_Initialize_lock(
30  Shm_Locked_queue_Control *lq_cb
31)
32{
33  lq_cb->lock = lq_cb - Shm_Locked_queues;
34}
35
36/*  Shm_Lock( &lq_cb )
37 *
38 *  This shared memory locked queue support routine locks the
39 *  specified locked queue.  It disables interrupts to prevent
40 *  a deadlock condition.
41 */
42
43void Shm_Lock(
44  Shm_Locked_queue_Control *lq_cb
45)
46{
47  rtems_unsigned32   isr_level;
48
49  rtems_interrupt_disable( isr_level );
50
51  Shm_isrstat = isr_level;
52
53  _CPU_SHM_Lock( lq_cb->lock );
54}
55
56/*
57 *  Shm_Unlock
58 *
59 *  Unlock the lock for the specified locked queue.
60 */
61
62void Shm_Unlock(
63  Shm_Locked_queue_Control *lq_cb
64)
65{
66  rtems_unsigned32   isr_level;
67
68  _CPU_SHM_Unlock( lq_cb->lock );
69
70  isr_level = Shm_isrstat;
71  rtems_interrupt_enable( isr_level );
72}
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