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<HTML><HEAD>   <TITLE>RTAI 1.0 documentation - Messages</TITLE>   <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">   <META NAME="Generator" CONTENT="VIM - Vi IMproved 5.3"></HEAD><BODY><A NAME="rt_send"></A><dl><dt><H3>NAME</H3></dt><dd>rt_send - send a message</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>RT_TASK* rt_send (RT_TASK* </B><I>task</I><B>,	unsigned int </B><I>msg</I><B>);</B></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_send</b> sends the message <I>msg</I> to the task <I>task</I>.If the receiver task is ready to get the message <b>rt_send</b> returnsimmediately. Otherwise the caller task is blocked and queued up.(Queueing may happen in priority order or on FIFO base.This is determined by compile time option MSG_PRIORD.)</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, <i>task</i> (the pointer to the task that received the message)is returned.If the caller is unblocked but message has not been sent (e.g. thetask <I>task</I> was killed before receiving the message) 0 is returned.On other failure, a special value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd>        <dl><dt>        <code>0</code>        </dt><dd>        The receiver task was killed before receiving the message.        </dd></dl>        <dl><dt>        <code>0xffff</code>        </dt><dd>        <I>task</I> does not refer to a valid task.        </dd></dl></dd></dl><dl><dt><H3>BUGS</H3></dt><dd>There is no guarantee, that the value of pointer <i>task</i> cannot be<code>0xffff</code>. In this theoretical case the caller cannot figureout if the operation was succesful or not.</dd></dl><p align=right><A HREF="manual.html#message">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_send_if"></A><dl><dt><H3>NAME</H3></dt><dd>rt_send_if - send a message if possible</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>RT_TASK* rt_send_if (RT_TASK* </B><I>task</I><B>,	unsigned int </B><I>msg</I><B>);</B></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_send_if</b> tries to send the message <I>msg</I> to the task <I>task</I>.The caller task is never blocked.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, <i>task</i> (the pointer to the task that received the message)is returned.If message has not been sent, 0 is returned.On other failure, a special value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd>        <dl><dt>        <code>0</code>        </dt><dd>	The task <i>task</i> was not ready to receive the message.        </dd></dl>        <dl><dt>        <code>0xffff</code>        </dt><dd>        <I>task</I> does not refer to a valid task.        </dd></dl></dd></dl><dl><dt><H3>BUGS</H3></dt><dd>There is no guarantee, that the value of pointer <i>task</i> cannot be<code>0xffff</code>. In this theoretical case the caller cannot figureout if the operation was succesful or not.</dd></dl><p align=right><A HREF="manual.html#message">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_send_until"></A><A NAME="rt_send_timed"></A><dl><dt><H3>NAME</H3></dt><dd>rt_send_until, rt_send_timed - send a message with timeout</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>RT_TASK* rt_send_until (RT_TASK* </B><I>task</I><B>,	unsigned int </B><I>msg</I><B>, RTIME </b><i>time</i><b>);</B><p><B>RT_TASK* rt_send_timed (RT_TASK* </B><I>task</I><B>,	unsigned int </B><I>msg</I><B>, RTIME </b><i>delay</i><b>);</B></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_send_until</b> and <b>rt_send_timed</b> send the message <I>msg</I>to the task <I>task</I>.If the receiver task is ready to get the message these functions returnimmediately. Otherwise the caller task is blocked and queued up.(Queueing may happen in priority order or on FIFO base.This is determined by compile time option MSG_PRIORD.)In this case these functions return if<ul><li> The caller task is in the first place of the waiting queue and        the receiver gets the message;<li> Timeout occurs;<li> An error occurs (e.g. the receiver task is killed);</ul><i>time</i> is an absolute value.<i>delay</i> is relative to the current time.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, <i>task</i> (the pointer to the task that received the message)is returned.If message has not been sent, 0 is returned.On other failure, a special value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd>        <dl><dt>        <code>0</code>        </dt><dd>	Operation timed out, message was not delivered.        </dd></dl>        <dl><dt>        <code>0xffff</code>        </dt><dd>        <I>task</I> does not refer to a valid task.        </dd></dl></dd></dl><dl><dt><H3>BUGS</H3></dt><dd>There is no guarantee, that the value of pointer <i>task</i> cannot be<code>0xffff</code>. In this theoretical case the caller cannot figureout if the operation was succesful or not.</dd></dl><p align=right><A HREF="manual.html#message">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_receive"></A><dl><dt><H3>NAME</H3></dt><dd>rt_receive - receive a message</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>RT_TASK* rt_receive (RT_TASK* </B><I>task</I><B>,	unsigned int *</B><I>msg</I><B>);</B></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_receive</b> gets a message from the task specified by<I>task</I>. If <I>task</I> is equal to 0, the caller accepts messagefrom any task.If there is a pending message, <b>rt_receive</b> returnsimmediately. Otherwise the caller task is blocked and queued up.(Queueing may happen in priority order or on FIFO base.This is determined by compile time option MSG_PRIORD.)<br><i>msg</i> points to a buffer provided by the caller.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, a pointer to the sender task is returned.If the caller is unblocked but no message has been received (e.g. thetask <I>task</I> was killed before sending the message) 0 is returned.On other failure, a special value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd>        <dl><dt>        <code>0</code>        </dt><dd>        The sender task was killed before sending the message.        </dd></dl>        <dl><dt>        <code>0xffff</code>        </dt><dd>        <I>task</I> does not refer to a valid task.        </dd></dl></dd></dl><dl><dt><H3>BUGS</H3></dt><dd>There is no guarantee, that the value of returned task pointer cannot be<code>0xffff</code>. In this theoretical case the caller cannot figureout if the operation was succesful or not.</dd></dl><p align=right><A HREF="manual.html#message">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_receive_if"></A><dl><dt><H3>NAME</H3></dt><dd>rt_receive_if - receive a message if possible</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>RT_TASK* rt_receive_if (RT_TASK* </B><I>task</I><B>,	unsigned int *</B><I>msg</I><B>);</B></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_receive_if</b> tries to get a message from the task specified by<I>task</I>. If <I>task</I> is equal to 0, the caller accepts messagefrom any task.The caller task is never blocked.<br><i>msg</i> points to a buffer provided by the caller.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, a pointer to the sender task is returned.If no message has been received, 0 is returned.On other failure, a special value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd>        <dl><dt>        <code>0</code>        </dt><dd>	There was no message to receive.        </dd></dl>        <dl><dt>        <code>0xffff</code>        </dt><dd>        <I>task</I> does not refer to a valid task.        </dd></dl></dd></dl><dl><dt><H3>BUGS</H3></dt><dd>There is no guarantee, that the value of returned task pointer cannot be<code>0xffff</code>. In this theoretical case the caller cannot figureout if the operation was succesful or not.</dd></dl><p align=right><A HREF="manual.html#message">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_receive_until"></A><A NAME="rt_receive_timed"></A><dl><dt><H3>NAME</H3></dt><dd>rt_receive_until, rt_receive_timed - receive a message with timeout</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>RT_TASK* rt_receive_until (RT_TASK* </B><I>task</I><B>,	unsigned int *</B><I>msg</I><B>, RTIME </b><i>time</i><b>);</B><p><B>RT_TASK* rt_receive_timed (RT_TASK* </B><I>task</I><B>,	unsigned int *</B><I>msg</I><B>, RTIME </b><i>delay</i><b>);</B></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_receive_until</b> and <b>rt_receive_timed</b> receive a messagefrom the task specified by <I>task</I>. If <I>task</I> is equal to 0,the caller accepts message from any task.If there is a pending message, these functions returnimmediately. Otherwise the caller task is blocked and queued up.(Queueing may happen in priority order or on FIFO base.This is determined by compile time option MSG_PRIORD.)In this case these functions return if<ul><li> The caller task is in the first place of the waiting queue and        the sender sends a message;<li> Timeout occurs;<li> An error occurs (e.g. the sender task is killed);</ul><i>msg</i> points to a buffer provided by the caller.<br><i>time</i> is an absolute value.<i>delay</i> is relative to the current time.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, a pointer to the sender task is returned.If no message has been received, 0 is returned.On other failure, a special value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd>        <dl><dt>        <code>0</code>        </dt><dd>	Operation timed out, no message was received.        </dd></dl>        <dl><dt>        <code>0xffff</code>        </dt><dd>        <I>task</I> does not refer to a valid task.        </dd></dl></dd></dl><dl><dt><H3>BUGS</H3></dt><dd>There is no guarantee, that the value of returned task pointer cannot be<code>0xffff</code>. In this theoretical case the caller cannot figureout if the operation was succesful or not.</dd></dl><p align=right><A HREF="manual.html#message">[return to index]</A></p></BODY></HTML>
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