178 lines
9.8 KiB
HTML
178 lines
9.8 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
<html xmlns="http://www.w3.org/1999/xhtml">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
|
|
<meta http-equiv="X-UA-Compatible" content="IE=9"/>
|
|
<meta name="generator" content="Doxygen 1.8.20"/>
|
|
<meta name="viewport" content="width=device-width, initial-scale=1"/>
|
|
<title>Labor04: xMessageBufferSendFromISR</title>
|
|
<link href="tabs.css" rel="stylesheet" type="text/css"/>
|
|
<script type="text/javascript" src="jquery.js"></script>
|
|
<script type="text/javascript" src="dynsections.js"></script>
|
|
<link href="navtree.css" rel="stylesheet" type="text/css"/>
|
|
<script type="text/javascript" src="resize.js"></script>
|
|
<script type="text/javascript" src="navtreedata.js"></script>
|
|
<script type="text/javascript" src="navtree.js"></script>
|
|
<link href="search/search.css" rel="stylesheet" type="text/css"/>
|
|
<script type="text/javascript" src="search/searchdata.js"></script>
|
|
<script type="text/javascript" src="search/search.js"></script>
|
|
<link href="doxygen.css" rel="stylesheet" type="text/css" />
|
|
</head>
|
|
<body>
|
|
<div id="top"><!-- do not remove this div, it is closed by doxygen! -->
|
|
<div id="titlearea">
|
|
<table cellspacing="0" cellpadding="0">
|
|
<tbody>
|
|
<tr style="height: 56px;">
|
|
<td id="projectalign" style="padding-left: 0.5em;">
|
|
<div id="projectname">Labor04
|
|
</div>
|
|
</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
<!-- end header part -->
|
|
<!-- Generated by Doxygen 1.8.20 -->
|
|
<script type="text/javascript">
|
|
/* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */
|
|
var searchBox = new SearchBox("searchBox", "search",false,'Search');
|
|
/* @license-end */
|
|
</script>
|
|
<script type="text/javascript" src="menudata.js"></script>
|
|
<script type="text/javascript" src="menu.js"></script>
|
|
<script type="text/javascript">
|
|
/* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */
|
|
$(function() {
|
|
initMenu('',true,false,'search.php','Search');
|
|
$(document).ready(function() { init_search(); });
|
|
});
|
|
/* @license-end */</script>
|
|
<div id="main-nav"></div>
|
|
</div><!-- top -->
|
|
<div id="side-nav" class="ui-resizable side-nav-resizable">
|
|
<div id="nav-tree">
|
|
<div id="nav-tree-contents">
|
|
<div id="nav-sync" class="sync"></div>
|
|
</div>
|
|
</div>
|
|
<div id="splitbar" style="-moz-user-select:none;"
|
|
class="ui-resizable-handle">
|
|
</div>
|
|
</div>
|
|
<script type="text/javascript">
|
|
/* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */
|
|
$(document).ready(function(){initNavTree('group__x_message_buffer_send_from_i_s_r.html',''); initResizable(); });
|
|
/* @license-end */
|
|
</script>
|
|
<div id="doc-content">
|
|
<!-- window showing the filter options -->
|
|
<div id="MSearchSelectWindow"
|
|
onmouseover="return searchBox.OnSearchSelectShow()"
|
|
onmouseout="return searchBox.OnSearchSelectHide()"
|
|
onkeydown="return searchBox.OnSearchSelectKey(event)">
|
|
</div>
|
|
|
|
<!-- iframe showing the search results (closed by default) -->
|
|
<div id="MSearchResultsWindow">
|
|
<iframe src="javascript:void(0)" frameborder="0"
|
|
name="MSearchResults" id="MSearchResults">
|
|
</iframe>
|
|
</div>
|
|
|
|
<div class="header">
|
|
<div class="headertitle">
|
|
<div class="title">xMessageBufferSendFromISR</div> </div>
|
|
</div><!--header-->
|
|
<div class="contents">
|
|
<p><a class="el" href="message__buffer_8h.html">message_buffer.h</a></p>
|
|
<pre>
|
|
size_t xMessageBufferSendFromISR( MessageBufferHandle_t xMessageBuffer,
|
|
const void *pvTxData,
|
|
size_t xDataLengthBytes,
|
|
BaseType_t *pxHigherPriorityTaskWoken );
|
|
<pre></pre></pre><pre><pre> Interrupt safe version of the API function that sends a discrete message to
|
|
the message buffer. The message can be any length that fits within the
|
|
buffer's free space, and is copied into the buffer.</pre></pre><pre><pre> ***NOTE***: Uniquely among FreeRTOS objects, the stream buffer
|
|
implementation (so also the message buffer implementation, as message buffers
|
|
are built on top of stream buffers) assumes there is only one task or
|
|
interrupt that will write to the buffer (the writer), and only one task or
|
|
interrupt that will read from the buffer (the reader). It is safe for the
|
|
writer and reader to be different tasks or interrupts, but, unlike other
|
|
FreeRTOS objects, it is not safe to have multiple different writers or
|
|
multiple different readers. If there are to be multiple different writers
|
|
then the application writer must place each call to a writing API function
|
|
(such as <a class="el" href="message__buffer_8h.html#a858f6da6fe24a226c45caf1634ea1605">xMessageBufferSend()</a>) inside a critical section and set the send
|
|
block time to 0. Likewise, if there are to be multiple different readers
|
|
then the application writer must place each call to a reading API function
|
|
(such as xMessageBufferRead()) inside a critical section and set the receive
|
|
block time to 0.</pre></pre><pre><pre> Use <a class="el" href="message__buffer_8h.html#a858f6da6fe24a226c45caf1634ea1605">xMessageBufferSend()</a> to write to a message buffer from a task. Use
|
|
<a class="el" href="message__buffer_8h.html#aeef5b0c4f8c2db6ca2230a8874813e79">xMessageBufferSendFromISR()</a> to write to a message buffer from an interrupt
|
|
service routine (ISR).</pre></pre><pre><pre><dl class="params"><dt>Parameters</dt><dd>
|
|
<table class="params">
|
|
<tr><td class="paramname">xMessageBuffer</td><td>The handle of the message buffer to which a message is
|
|
being sent.</td></tr>
|
|
<tr><td class="paramname">pvTxData</td><td>A pointer to the message that is to be copied into the
|
|
message buffer.</td></tr>
|
|
<tr><td class="paramname">xDataLengthBytes</td><td>The length of the message. That is, the number of
|
|
bytes to copy from pvTxData into the message buffer. When a message is
|
|
written to the message buffer an additional sizeof( size_t ) bytes are also
|
|
written to store the message's length. sizeof( size_t ) is typically 4 bytes
|
|
on a 32-bit architecture, so on most 32-bit architecture setting
|
|
xDataLengthBytes to 20 will reduce the free space in the message buffer by 24
|
|
bytes (20 bytes of message data and 4 bytes to hold the message length).</td></tr>
|
|
<tr><td class="paramname">pxHigherPriorityTaskWoken</td><td>It is possible that a message buffer will
|
|
have a task blocked on it waiting for data. Calling
|
|
<a class="el" href="message__buffer_8h.html#aeef5b0c4f8c2db6ca2230a8874813e79">xMessageBufferSendFromISR()</a> can make data available, and so cause a task that
|
|
was waiting for data to leave the Blocked state. If calling
|
|
<a class="el" href="message__buffer_8h.html#aeef5b0c4f8c2db6ca2230a8874813e79">xMessageBufferSendFromISR()</a> causes a task to leave the Blocked state, and the
|
|
unblocked task has a priority higher than the currently executing task (the
|
|
task that was interrupted), then, internally, <a class="el" href="message__buffer_8h.html#aeef5b0c4f8c2db6ca2230a8874813e79">xMessageBufferSendFromISR()</a>
|
|
will set *pxHigherPriorityTaskWoken to pdTRUE. If
|
|
<a class="el" href="message__buffer_8h.html#aeef5b0c4f8c2db6ca2230a8874813e79">xMessageBufferSendFromISR()</a> sets this value to pdTRUE, then normally a
|
|
context switch should be performed before the interrupt is exited. This will
|
|
ensure that the interrupt returns directly to the highest priority Ready
|
|
state task. *pxHigherPriorityTaskWoken should be set to pdFALSE before it
|
|
is passed into the function. See the code example below for an example.</td></tr>
|
|
</table>
|
|
</dd>
|
|
</dl>
|
|
<dl class="section return"><dt>Returns</dt><dd>The number of bytes actually written to the message buffer. If the
|
|
message buffer didn't have enough free space for the message to be stored
|
|
then 0 is returned, otherwise xDataLengthBytes is returned.</dd></dl>
|
|
Example use:
|
|
<pre>
|
|
// A message buffer that has already been created.
|
|
MessageBufferHandle_t xMessageBuffer;</pre></pre></pre><pre><pre><pre>void vAnInterruptServiceRoutine( void )
|
|
{
|
|
size_t xBytesSent;
|
|
char *pcStringToSend = "String to send";
|
|
BaseType_t xHigherPriorityTaskWoken = pdFALSE; // Initialised to pdFALSE.</pre></pre></pre><pre><pre><pre> // Attempt to send the string to the message buffer.
|
|
xBytesSent = xMessageBufferSendFromISR( xMessageBuffer,
|
|
( void * ) pcStringToSend,
|
|
strlen( pcStringToSend ),
|
|
&xHigherPriorityTaskWoken );</pre></pre></pre><pre><pre><pre> if( xBytesSent != strlen( pcStringToSend ) )
|
|
{
|
|
// The string could not be added to the message buffer because there was
|
|
// not enough free space in the buffer.
|
|
}</pre></pre></pre><pre><pre><pre> // If xHigherPriorityTaskWoken was set to pdTRUE inside
|
|
// <a class="el" href="message__buffer_8h.html#aeef5b0c4f8c2db6ca2230a8874813e79">xMessageBufferSendFromISR()</a> then a task that has a priority above the
|
|
// priority of the currently executing task was unblocked and a context
|
|
// switch should be performed to ensure the ISR returns to the unblocked
|
|
// task. In most FreeRTOS ports this is done by simply passing
|
|
// xHigherPriorityTaskWoken into taskYIELD_FROM_ISR(), which will test the
|
|
// variables value, and perform the context switch if necessary. Check the
|
|
// documentation for the port in use for port specific instructions.
|
|
taskYIELD_FROM_ISR( xHigherPriorityTaskWoken );
|
|
}
|
|
</pre> </pre></pre></div><!-- contents -->
|
|
</div><!-- doc-content -->
|
|
<!-- start footer part -->
|
|
<div id="nav-path" class="navpath"><!-- id is needed for treeview function! -->
|
|
<ul>
|
|
<li class="footer">Generated by <a href="http://www.doxygen.org/index.html"><img class="footer" src="doxygen.svg" width="104" height="31" alt="doxygen"/></a> 1.8.20 </li>
|
|
</ul>
|
|
</div>
|
|
</body>
|
|
</html>
|