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<HTML><HEAD> <TITLE>RTAI 1.0 documentation - Mailbox</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_mbx_init"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_init - initialize mailbox</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_init (MBX*</B> <I>mbx</I><b>, int </b><i>size</i><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_mbx_init</b> initializes a mailbox of size <i>size</i>. <i>mbx</i>have to point to a statically allocated structure.<p>Using mailboxes is a flexible method of task-to-task communication.Tasks are allowed to send arbitrary size messages by using any mailboxbuffer size.Clearly you should use a buffer sized at least as the largest message youenvisage. However if youexpect a message larger than the average message size very rarely you can usea smaller buffer without much loss of efficiency. In such a way you can set upyour own mailbox usage protocol, e.g. using fix size messages with a bufferthat is an integer multiple of such a size guarantees that each message issent/received atomically to/from the mailbox. Multiple senders and receiversare allowed and each will get the service it requires in turn, according to itspriority.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success 0 is returned.On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> Space could not be allocated for the mailbox buffer. </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_mbx_delete"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_delete - delete mailbox</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_delete (MBX*</B> <I>mbx</I><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_mbx_delete</b> removes a mailbox previously createdwith <b>rt_mbox_init</b>. <i>mbx</i> points to the structure used in thecorresponding call to <b>rt_mbox_init</b>.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success 0 is returned. On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> <i>mbx</i> points to not a valid mailbox. </dd><dt> -EFAULT </dt><dd> ??? <i>Paolo, fill this line please.</i> </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_mbx_send"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_send - send message unconditionally</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_send (MBX*</B> <I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_mbx_send</b> sends a message <I>msg</I> of <I>msg_size</I> bytesto the mailbox <I>mbx</I>. The caller will be blocked untilthe whole message is enqueued or an error occurs.</font></dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, the number of unsent bytes is returned.On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> <i>mbx</i> points to not a valid mailbox. </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_mbx_send_wp"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_send_wp - send bytes as many as possible</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_send_wp (MBX*</B> <I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_mbx_send_wp</b> sends as many as possible of bytes of message<i>msg</i> to mailbox <i>mbx</i>then returns immediately. The message length is <i>msg_size</i>.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, the number of unsent bytes is returned.On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> <i>mbx</i> points to not a valid mailbox. </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_mbx_send_if"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_send_if - send a message if possible</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_send_if (MBX*</B> <I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><B>rt_mbx_send_if</b> tries to enqueue a message <i>msg</i> of<i>msg_size</i> bytes to the mailbox <i>mbx</i>.It returns immediately, the caller is never blocked.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, the number of unsent bytes (0 or <i>msg_size</i>)is returned.On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> <i>mbx</i> points to not a valid mailbox. </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_mbx_send_until"></A><A NAME="rt_mbx_send_timed"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_send_until, rt_mbx_send_timed - send a message with timeout</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_send_until (MBX* </B><I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>, RTIME </b><i>time</i><b>);</b><p><B>int rt_mbx_send_timed (MBX* </B><I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>, RTIME </b><i>delay</i><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_mbx_send_until</b> and <b>rt_mbx_send_timed</b>send a message <I>msg</I> of <I>msg_size</I> bytesto the mailbox <I>mbx</I>. The caller will be blocked untilall bytes of message is enqueued, timeout expires or an error occurs.<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, the number of unsent bytes is returned.On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> <i>mbx</i> points to not a valid mailbox. </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_mbx_receive"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_receive - receive message unconditionally</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_receive (MBX*</B> <I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_mbx_receive</b> receives a message of <I>msg_size</I> bytesfrom the mailbox <I>mbx</I>. The caller will be blocked untilall bytes of the message arrive or an error occurs.</font><br><i>msg</i> points to a buffer provided by the caller.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, the number of received bytes is returned.On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> <i>mbx</i> points to not a valid mailbox. </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_mbx_receive_wp"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_receive_wp - receive bytes as many as possible</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_receive_wp (MBX*</B> <I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_mbx_receive_wp</b>receives at most <i>msg_size</i> of bytes of message from mailbox <i>mbx</i>then returns immediately.<br><i>msg</i> points to a buffer provided by the caller.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, the number of received bytes is returned.On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> <i>mbx</i> points to not a valid mailbox. </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_mbx_receive_if"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_receive_if - receive a message if available</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_receive_if (MBX*</B> <I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_mbx_receive_if</b>receives a message from the mailbox <i>mbx</i> if the whole messageof <i>msg_size</i> bytes is available immediately.<br><i>msg</i> points to a buffer provided by the caller.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, the number of received bytes (0 or <i>msg_size</i>)is returned.On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> <i>mbx</i> points to not a valid mailbox. </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p><HR ALIGN=LEFT SIZE=1 NOSHADE WIDTH="100%"><!-- -------------------------------------------------------- --><A NAME="rt_mbx_receive_until"></A><A NAME="rt_mbx_receive_timed"></A><dl><dt><H3>NAME</H3></dt><dd>rt_mbx_receive_until, rt_mbx_receive_timed - receive a message with timeout</dd></dl><dl><dt><H3>SYNOPSIS</H3></dt><dd>#include "rtai_sched.h"<p><B>int rt_mbx_receive_until (MBX* </B><I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>, RTIME </b><i>time</i><b>);</b><p><B>int rt_mbx_receive_timed (MBX* </B><I>mbx</I><b>, void* </b><I>msg</I><b>, int </b><i>msg_size</i><b>, RTIME </b><i>delay</i><b>);</b></dd></dl><dl><dt><H3>DESCRIPTION</H3></dt><dd><b>rt_mbx_receive_until</b> and <b>rt_mbx_receive_timed</b>receive a message of <I>msg_size</I> bytesfrom the mailbox <I>mbx</I>. The caller will be blocked untilall bytes of the message arrive, timeout expires or an error occurs.<br><i>time</i> is an absolute value.<i>delay</i> is relative to the current time.<br><i>msg</i> points to a buffer provided by the caller.</dd></dl><dl><dt><H3>RETURN VALUE</H3></dt><dd>On success, the number of received bytes is returned.On failure a negative value is returned as described below.</dd></dl><dl><dt><H3>ERRORS</H3></dt><dd> <dl><dt> -EINVAL </dt><dd> <i>mbx</i> points to not a valid mailbox. </dd></dl></dd></dl><p align=right><A HREF="manual.html#mbox">[return to index]</A></p></BODY></HTML>⌨️ 快捷键说明
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