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is inserted into the message queue at the position indicated by the 
<i>msgPrio</i> argument.  A message with a higher numeric value for <i>msgPrio</i>
is inserted before messages with a lower value.  The value
of <i>msgPrio</i> must be less than or equal to 31.
<p>
If the specified message queue is full and <b>O_NONBLOCK</b> is not set in the
message queue's, <b><a href="./mqPxLib.html#mq_send">mq_send</a>(&nbsp;)</b> will block until space becomes available to
queue the message, or until it is interrupted by a signal.  The priority
scheduling option is supported in the event that there is more than one
task waiting on space becoming available.  If the message queue is full
and <b>O_NONBLOCK</b> is set in the message queue's description, the message is
not queued, and <b><a href="./mqPxLib.html#mq_send">mq_send</a>(&nbsp;)</b> returns an error.
<p>
</blockquote><h4>USE BY INTERRUPT SERVICE ROUTINES</h4><blockquote><p>
This routine can be called by interrupt service routines as well as
by tasks.  This is one of the primary means of communication
between an interrupt service routine and a task.  If <b><a href="./mqPxLib.html#mq_send">mq_send</a>(&nbsp;)</b>
is called from an interrupt service routine, it will behave as if
the <b>O_NONBLOCK</b> flag were set.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
0 (OK), otherwise -1 (ERROR).
<p>
</blockquote><h4>ERRNO</h4><blockquote><p>
EAGAIN, EBADF, EINTR, EINVAL, EMSGSIZE
<p>
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./mqPxLib.html#top">mqPxLib</a></b>, <b><a href="./mqPxLib.html#mq_receive">mq_receive</a>(&nbsp;)</b>

<hr>
<a name="mq_close"></a>
<p align=right>
<a href="rtnIndex.htm"><i>OS Libraries :  Routines</i></a></p>

</blockquote><h1>mq_close(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong>mq_close(&nbsp;)</strong> - close a message queue (POSIX)</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>int mq_close
    (
    mqd_t mqdes               /* message queue descriptor */
    )
</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
This routine is used to indicate that the calling task is finished
with the specified message queue <i>mqdes</i>.  
The <b><a href="./mqPxLib.html#mq_close">mq_close</a>(&nbsp;)</b> call deallocates any system resources allocated 
by the system for use by this task for its message queue.
The behavior of a task that is blocked on either a <b><a href="./mqPxLib.html#mq_send">mq_send</a>(&nbsp;)</b> or
<b><a href="./mqPxLib.html#mq_receive">mq_receive</a>(&nbsp;)</b> is undefined when <b><a href="./mqPxLib.html#mq_close">mq_close</a>(&nbsp;)</b> is called.
The <i>mqdes</i> parameter will no longer be a valid message queue ID.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
0 (OK) if the message queue is closed successfully,
otherwise -1 (ERROR).
<p>
</blockquote><h4>ERRNO</h4><blockquote><p>
EBADF
<p>
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./mqPxLib.html#top">mqPxLib</a></b>, <b><a href="./mqPxLib.html#mq_open">mq_open</a>(&nbsp;)</b>

<hr>
<a name="mq_unlink"></a>
<p align=right>
<a href="rtnIndex.htm"><i>OS Libraries :  Routines</i></a></p>

</blockquote><h1>mq_unlink(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong>mq_unlink(&nbsp;)</strong> - remove a message queue (POSIX)</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>int mq_unlink
    (
    const char * mqName       /* name of message queue */
    )
</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
This routine removes the message queue named by the pathname <i>mqName</i>.
After a successful call to <b><a href="./mqPxLib.html#mq_unlink">mq_unlink</a>(&nbsp;)</b>, a call to <b><a href="./mqPxLib.html#mq_open">mq_open</a>(&nbsp;)</b> on the same
message queue will fail if the flag <b>O_CREAT</b> is not set.  If one or more
tasks have the message queue open when <b><a href="./mqPxLib.html#mq_unlink">mq_unlink</a>(&nbsp;)</b> is called, removal of
the message queue is postponed until all references to the message queue
have been closed.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
0 (OK) if the message queue is unlinked successfully,
otherwise -1 (ERROR).
<p>
</blockquote><h4>ERRNO</h4><blockquote><p>
ENOENT
<p>
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./mqPxLib.html#top">mqPxLib</a></b>, <b><a href="./mqPxLib.html#mq_close">mq_close</a>(&nbsp;)</b>, <b><a href="./mqPxLib.html#mq_open">mq_open</a>(&nbsp;)</b>

<hr>
<a name="mq_notify"></a>
<p align=right>
<a href="rtnIndex.htm"><i>OS Libraries :  Routines</i></a></p>

</blockquote><h1>mq_notify(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong>mq_notify(&nbsp;)</strong> - notify a task that a message is available on a queue (POSIX)</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>int mq_notify
    (
    mqd_t                   mqdes,        /* message queue descriptor */
    const struct sigevent * pNotification /* real-time signal */
    )
</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
If <i>pNotification</i> is not NULL, this routine attaches the specified
<i>pNotification</i> request by the calling task to the specified message queue
<i>mqdes</i> associated with the calling task.  The real-time signal specified
by <i>pNotification</i> will be sent to the task when the message queue changes
from empty to non-empty.  If a task has already attached a notification
request to the message queue, all subsequent attempts to attach a
notification to the message queue will fail.  A task is able to attach a
single notification to each <i>mqdes</i> it has unless another task has already
attached one.
<p>
If <i>pNotification</i> is NULL and the task has previously attached a
notification request to the message queue, the attached notification
request is detached and the queue is available for another task to attach
a notification request.
<p>
If a notification request is attached to a message queue and any task
is blocked in <b><a href="./mqPxLib.html#mq_receive">mq_receive</a>(&nbsp;)</b> waiting to receive a message when a message
arrives at the queue, then the appropriate <b><a href="./mqPxLib.html#mq_receive">mq_receive</a>(&nbsp;)</b> will be completed
and the notification request remains pending.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
0 (OK) if successful, otherwise -1 (ERROR).
<p>
</blockquote><h4>ERRNO</h4><blockquote><p>
EBADF, EBUSY, EINVAL
<p>
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./mqPxLib.html#top">mqPxLib</a></b>, <b><a href="./mqPxLib.html#mq_open">mq_open</a>(&nbsp;)</b>, <b><a href="./mqPxLib.html#mq_send">mq_send</a>(&nbsp;)</b>

<hr>
<a name="mq_setattr"></a>
<p align=right>
<a href="rtnIndex.htm"><i>OS Libraries :  Routines</i></a></p>

</blockquote><h1>mq_setattr(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong>mq_setattr(&nbsp;)</strong> - set message queue attributes (POSIX)</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>int mq_setattr
    (
    mqd_t                  mqdes,     /* message queue descriptor */
    const struct mq_attr * pMqStat,   /* new attributes */
    struct mq_attr *       pOldMqStat /* old attributes */
    )
</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
This routine sets attributes associated with the specified message
queue <i>mqdes</i>.
<p>
The message queue attributes corresponding to the following members
defined in the <b>mq_attr</b> structure are set to the specified values upon
successful completion of the call:
<dl>
<dt>
<b>mq_flags</b>
<dd>
The value the <b>O_NONBLOCK</b> flag.
</dl>

<p>
If <i>pOldMqStat</i> is non-NULL, <b><a href="./mqPxLib.html#mq_setattr">mq_setattr</a>(&nbsp;)</b> will store, in the
location referenced by <i>pOldMqStat</i>, the previous message queue attributes
and the current queue status.  These values are the same as would be returned
by a call to <b><a href="./mqPxLib.html#mq_getattr">mq_getattr</a>(&nbsp;)</b> at that point.
<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
0 (OK) if attributes are set successfully, otherwise -1 (ERROR).
<p>
</blockquote><h4>ERRNO</h4><blockquote><p>
EBADF
<p>
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./mqPxLib.html#top">mqPxLib</a></b>, <b><a href="./mqPxLib.html#mq_open">mq_open</a>(&nbsp;)</b>, <b><a href="./mqPxLib.html#mq_send">mq_send</a>(&nbsp;)</b>, <b><a href="./mqPxLib.html#mq_getattr">mq_getattr</a>(&nbsp;)</b>

<hr>
<a name="mq_getattr"></a>
<p align=right>
<a href="rtnIndex.htm"><i>OS Libraries :  Routines</i></a></p>

</blockquote><h1>mq_getattr(&nbsp;)</h1> <blockquote></a></blockquote><h4>NAME</h4><blockquote>  
<p><strong>mq_getattr(&nbsp;)</strong> - get message queue attributes (POSIX)</p>

</blockquote><h4>SYNOPSIS</h4><blockquote><p>
<pre>int mq_getattr
    (
    mqd_t            mqdes,   /* message queue descriptor */
    struct mq_attr * pMqStat  /* buffer in which to return attributes */
    )
</pre>

</blockquote><h4>DESCRIPTION</h4><blockquote><p>
This routine gets status information and attributes associated with a
specified message queue <i>mqdes</i>.  Upon return, the following members of
the <b>mq_attr</b> structure referenced by <i>pMqStat</i> will contain the values
set when the message queue was created but with modifications made by
subsequent calls to <b><a href="./mqPxLib.html#mq_setattr">mq_setattr</a>(&nbsp;)</b>:
<dl>
<dt>
<b>mq_flags</b>
<dd>
May be modified by <b><a href="./mqPxLib.html#mq_setattr">mq_setattr</a>(&nbsp;)</b>.
</dl>

<p>
The following were set at message queue creation:
<dl>
<dt>
<b>mq_maxmsg</b>
<dd>
Maximum number of messages.
<dt>
<b>mq_msgsize</b>
<dd>
Maximum message size.
</dl>

<p>
<dl>
<dt>
<b>mq_curmsgs</b>
<dd>
The number of messages currently in the queue.
</dl>

<p>
</blockquote><h4>RETURNS</h4><blockquote><p>
0 (OK) if message attributes can be determined, otherwise -1 (ERROR).
<p>
</blockquote><h4>ERRNO</h4><blockquote><p>
EBADF
<p>
</blockquote><h4>SEE ALSO</h4><blockquote><p>
<b><a href="./mqPxLib.html#top">mqPxLib</a></b>, <b><a href="./mqPxLib.html#mq_open">mq_open</a>(&nbsp;)</b>, <b><a href="./mqPxLib.html#mq_send">mq_send</a>(&nbsp;)</b>, <b><a href="./mqPxLib.html#mq_setattr">mq_setattr</a>(&nbsp;)</b>

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