lock.c

来自「RTEMS (Real-Time Executive for Multiproc」· C语言 代码 · 共 69 行

/*  Shared Memory Lock Routines
 *
 *  This shared memory locked queue support routine need to be
 *  able to lock the specified locked queue.  Interrupts are
 *  disabled while the queue is locked to prevent preemption
 *  and deadlock when two tasks poll for the same lock.
 *  previous level.
 *
 *  COPYRIGHT (c) 1989-1997.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may in
 *  the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 *
 *  $Id: lock.c,v 1.3.4.1 2003/09/04 18:45:12 joel Exp $
 */

#include <rtems.h>
#include <bsp.h>
#include <shm_driver.h>

typedef volatile unsigned int volint;

/*
 *  Shm_Initialize_lock
 *
 *  Initialize the lock for the specified locked queue.
 */

void Shm_Initialize_lock(
  Shm_Locked_queue_Control *lq_cb
)
{
  /* nothing required -- done implicitly by device tree */
}

/*  void _Shm_Lock( &lq_cb )
 *
 *  This shared memory locked queue support routine locks the
 *  specified locked queue.  It disables interrupts to prevent
 *  a deadlock condition.
 */

void Shm_Lock(
  Shm_Locked_queue_Control *lq_cb
)
{
  volint *p = (volint *)0xc0010000;

  (void) p[1];
}

/*
 *  Shm_Unlock
 *
 *  Unlock the lock for the specified locked queue.
 */

void Shm_Unlock(
  Shm_Locked_queue_Control *lq_cb
)
{
  volint *p = (volint *)0xc0010000;

  (void) p[2];
}