NuttX RTOS

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 170 insertions, 0 deletions

diff --git a/nuttx/sched/mq_notify.c b/nuttx/sched/mq_notify.c
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+/************************************************************
+ * mq_notify.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <sys/types.h>      /* uint32, etc. */
+#include <mqueue.h>
+#include <sched.h>
+#include "os_internal.h"
+#include "mq_internal.h"
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/************************************************************
+ * Private Type Declarations
+ ************************************************************/
+
+/************************************************************
+ * Global Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Functions
+ ************************************************************/
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Function:  mq_notify
+ *
+ * Description:
+ *   If "notification" is not NULL, this function connects
+ *   the task with the message queue such that the specified
+ *   signal will be sent to the task whenever the message
+ *   changes from empty to non-empty.  One one notification
+ *   can be attached to a message queue.
+ *
+ *   If "notification" is NULL, the attached notification is
+ *   detached (if it was held by the calling task) and the
+ *   queue is available to attach another notification.
+ *
+ *   When the notification is sent to the registered process,
+ *   its registration will be removed.  The message queue
+ *   will then be available for registration.
+ *
+ * Parameters:
+ *   mqdes - Message queue descriptor
+ *   notification - Real-time signal structure containing:
+ *      sigev_notify - Should be SIGEV_SIGNAL (but actually ignored)
+ *      sigev_signo - The signo to use for the notification
+ *      sigev_value - Value associated with the signal
+ *
+ * Return Value:
+ *   None
+ *
+ * Assumptions:
+ *
+ * POSIX Compatibility:
+ *   int mq_notify(mqd_t mqdes, const struct sigevent *notification);
+ *
+ *   The notification will be sent to the registered task even if another
+ *   task is waiting for the message queue to become non-empty.  This is
+ *   inconsistent with the POSIX specification which says, "If a process
+ *   has registered for notification of message a arrival at a message
+ *   queue and some process is blocked in mq_receive() waiting to receive
+ *   a message when a message arrives at the queue, the arriving message
+ *   message shall satisfy mq_receive()... The resulting behavior is as if
+ *   the message queue remains empty, and no notification shall be sent."
+ *
+ ************************************************************/
+
+int mq_notify(mqd_t mqdes, const struct sigevent *notification)
+{
+  _TCB   *rtcb;
+  msgq_t *msgq;
+  int     ret = ERROR;
+
+  if (mqdes)
+    {
+      sched_lock();
+
+      /* Get a pointer to the message queue */
+
+      msgq = mqdes->msgq;
+
+      /* Get the current process ID */
+
+      rtcb = (_TCB*)g_readytorun.head;
+
+      /* Is there already a notification attached */
+
+      if (!msgq->ntmqdes)
+        {
+          /* No... Have we been asked to establish one?  Make
+           * sure a good signal number has been provided
+           */
+
+          if (notification && GOOD_SIGNO(notification->sigev_signo))
+            {
+              /* Yes... Assign it to the current task. */
+
+              msgq->ntvalue = notification->sigev_value;
+              msgq->ntsigno = notification->sigev_signo;
+              msgq->ntpid   = rtcb->pid;
+              msgq->ntmqdes = mqdes;
+              ret           = OK;
+            }
+        }
+
+      /* Yes... a notification is attached.  Does this task own it?
+       * Is it trying to remove it?
+       */
+
+      else if ((msgq->ntpid == rtcb->pid) && (!notification))
+        {
+          /* Yes... Detach the notification */
+
+          msgq->ntpid             = INVALID_PROCESS_ID;
+          msgq->ntsigno           = 0;
+          msgq->ntvalue.sival_int = 0;
+          msgq->ntmqdes           = NULL;
+          ret                     = OK;
+        }
+      sched_unlock();
+    }
+
+  return ret;
+}