source: rtems/c/src/lib/libbsp/i960/cvme961/shmsupp/lock.c @ cbb5fc7

4.104.114.84.95
Last change on this file since cbb5fc7 was cbb5fc7, checked in by Joel Sherrill <joel.sherrill@…>, on 09/28/01 at 13:25:55

2001-09-27 Joel Sherrill <joel@…>

  • include/bsp.h: Renamed delay() to rtems_bsp_delay().
  • shmsupp/lock.c: Renamed delay() to rtems_bsp_delay().
  • Property mode set to 100644
File size: 1.6 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) 1989-1999.
10 *  On-Line Applications Research Corporation (OAR).
11 *
12 *  The license and distribution terms for this file may be
13 *  found in the file LICENSE in this distribution or at
14 *  http://www.OARcorp.com/rtems/license.html.
15 *
16 *  $Id$
17 */
18
19#include <rtems.h>
20#include <bsp.h>
21#include <shm_driver.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_UNLOCKED;
34}
35
36/*  void _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, oldlock;
48
49  rtems_interrupt_disable( isr_level );
50    Shm_isrstat = isr_level;
51    while ( 1 ) {
52      atomic_modify( SHM_LOCK_VALUE, &lq_cb->lock, oldlock );
53      if ( !(oldlock & SHM_LOCK_VALUE) )
54        return;
55      rtems_bsp_delay( 28 );        /* delay 28 microseconds */
56    }
57}
58
59/*
60 *  Shm_Unlock
61 *
62 *  Unlock the lock for the specified locked queue.
63 */
64
65void Shm_Unlock(
66  Shm_Locked_queue_Control *lq_cb
67)
68{
69  rtems_unsigned32 isr_level;
70
71  lq_cb->lock = SHM_UNLOCK_VALUE;
72  isr_level = Shm_isrstat;
73  rtems_interrupt_enable( isr_level );
74}
75
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