<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://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 1.8.7"/> <title>ALSA project - the C library reference: Timer interface</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="search/search.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="search/search.js"></script> <script type="text/javascript"> $(document).ready(function() { searchBox.OnSelectItem(0); }); </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 style="padding-left: 0.5em;"> <div id="projectname">ALSA project - the C library reference </div> </td> </tr> </tbody> </table> </div> <!-- end header part --> <!-- Generated by Doxygen 1.8.7 --> <script type="text/javascript"> var searchBox = new SearchBox("searchBox", "search",false,'Search'); </script> <div id="navrow1" class="tabs"> <ul class="tablist"> <li><a href="index.html"><span>Main Page</span></a></li> <li class="current"><a href="pages.html"><span>Related Pages</span></a></li> <li><a href="modules.html"><span>Modules</span></a></li> <li><a href="annotated.html"><span>Data Structures</span></a></li> <li><a href="files.html"><span>Files</span></a></li> <li><a href="examples.html"><span>Examples</span></a></li> <li> <div id="MSearchBox" class="MSearchBoxInactive"> <span class="left"> <img id="MSearchSelect" src="search/mag_sel.png" onmouseover="return searchBox.OnSearchSelectShow()" onmouseout="return searchBox.OnSearchSelectHide()" alt=""/> <input type="text" id="MSearchField" value="Search" accesskey="S" onfocus="searchBox.OnSearchFieldFocus(true)" onblur="searchBox.OnSearchFieldFocus(false)" onkeyup="searchBox.OnSearchFieldChange(event)"/> </span><span class="right"> <a id="MSearchClose" href="javascript:searchBox.CloseResultsWindow()"><img id="MSearchCloseImg" border="0" src="search/close.png" alt=""/></a> </span> </div> </li> </ul> </div> <!-- window showing the filter options --> <div id="MSearchSelectWindow" onmouseover="return searchBox.OnSearchSelectShow()" onmouseout="return searchBox.OnSearchSelectHide()" onkeydown="return searchBox.OnSearchSelectKey(event)"> <a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(0)"><span class="SelectionMark"> </span>All</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(1)"><span class="SelectionMark"> </span>Data Structures</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(2)"><span class="SelectionMark"> </span>Files</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(3)"><span class="SelectionMark"> </span>Functions</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(4)"><span class="SelectionMark"> </span>Variables</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(5)"><span class="SelectionMark"> </span>Typedefs</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(6)"><span class="SelectionMark"> </span>Enumerations</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(7)"><span class="SelectionMark"> </span>Enumerator</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(8)"><span class="SelectionMark"> </span>Macros</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(9)"><span class="SelectionMark"> </span>Groups</a><a class="SelectItem" href="javascript:void(0)" onclick="searchBox.OnSelectItem(10)"><span class="SelectionMark"> </span>Pages</a></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><!-- top --> <div class="header"> <div class="headertitle"> <div class="title">Timer interface </div> </div> </div><!--header--> <div class="contents"> <div class="textblock"><p>Timer interface is designed to use internal timers in sound hardware, but it can be driven with any timer.</p> <h1><a class="anchor" id="timer_general_overview"></a> General overview</h1> <p>The timer implementation uses ring buffer to store information about timing events. In this buffer is recorded count of ticks and current tick resolution in nanoseconds.</p> <h1><a class="anchor" id="timer_open"></a> Opening</h1> <p>Timer devices can be opened in two ways. When <a class="el" href="group___timer.html#gac2c50bf6045560bc13aab81f25b2b740">SND_TIMER_OPEN_NONBLOCK</a> flag is used, then the open functions return immediately with -EBUSY error code when resources are occupied with another application. When <a class="el" href="group___timer.html#gac2c50bf6045560bc13aab81f25b2b740">SND_TIMER_OPEN_NONBLOCK</a> is not used (by default) the open functions block the application requesting device until resources are not free.</p> <h1><a class="anchor" id="timer_events"></a> Events</h1> <p>Events are read via <a class="el" href="group___timer.html#ga724ada94d0bc3564ad77973c0a084682" title="read bytes using timer handle ">snd_timer_read()</a> function.</p> <h1><a class="anchor" id="timer_examples"></a> Examples</h1> <p>The full featured examples with cross-links:</p> <dl class="section user"><dt>Simple timer test program</dt><dd><a class="el" href="/home/iurt/rpmbuild/BUILD/alsa-lib-1.0.28/src/timer/timer.c.html#example_test_timer">example code</a> </dd></dl> <dl class="section user"><dt></dt><dd>This example shows opening a timer device and reading of timer events. </dd></dl> </div></div><!-- contents --> <!-- start footer part --> <hr class="footer"/><address class="footer"><small> Generated on Wed Jun 18 2014 05:47:49 for ALSA project - the C library reference by  <a href="http://www.doxygen.org/index.html"> <img class="footer" src="doxygen.png" alt="doxygen"/> </a> 1.8.7 </small></address> </body> </html>