Documentation/DocBook/v4l/vidioc-dqevent.xml

   1 <refentry id="vidioc-dqevent">
   2   <refmeta>
   3     <refentrytitle>ioctl VIDIOC_DQEVENT</refentrytitle>
   4     &manvol;
   5   </refmeta>
   6
   7   <refnamediv>
   8     <refname>VIDIOC_DQEVENT</refname>
   9     <refpurpose>Dequeue event</refpurpose>
  10   </refnamediv>
  11
  12   <refsynopsisdiv>
  13     <funcsynopsis>
  14       <funcprototype>
  15         <funcdef>int <function>ioctl</function></funcdef>
  16         <paramdef>int <parameter>fd</parameter></paramdef>
  17         <paramdef>int <parameter>request</parameter></paramdef>
  18         <paramdef>struct v4l2_event
  19 *<parameter>argp</parameter></paramdef>
  20       </funcprototype>
  21     </funcsynopsis>
  22   </refsynopsisdiv>
  23
  24   <refsect1>
  25     <title>Arguments</title>
  26
  27     <variablelist>
  28       <varlistentry>
  29         <term><parameter>fd</parameter></term>
  30         <listitem>
  31           <para>&fd;</para>
  32         </listitem>
  33       </varlistentry>
  34       <varlistentry>
  35         <term><parameter>request</parameter></term>
  36         <listitem>
  37           <para>VIDIOC_DQEVENT</para>
  38         </listitem>
  39       </varlistentry>
  40       <varlistentry>
  41         <term><parameter>argp</parameter></term>
  42         <listitem>
  43           <para></para>
  44         </listitem>
  45       </varlistentry>
  46     </variablelist>
  47   </refsect1>
  48
  49   <refsect1>
  50     <title>Description</title>
  51
  52     <para>Dequeue an event from a video device. No input is required
  53     for this ioctl. All the fields of the &v4l2-event; structure are
  54     filled by the driver. The file handle will also receive exceptions
  55     which the application may get by e.g. using the select system
  56     call.</para>
  57
  58     <table frame="none" pgwide="1" id="v4l2-event">
  59       <title>struct <structname>v4l2_event</structname></title>
  60       <tgroup cols="4">
  61         &cs-str;
  62         <tbody valign="top">
  63           <row>
  64             <entry>__u32</entry>
  65             <entry><structfield>type</structfield></entry>
  66             <entry></entry>
  67             <entry>Type of the event.</entry>
  68           </row>
  69           <row>
  70             <entry>union</entry>
  71             <entry><structfield>u</structfield></entry>
  72             <entry></entry>
  73             <entry></entry>
  74           </row>
  75           <row>
  76             <entry></entry>
  77             <entry>__u8</entry>
  78             <entry><structfield>data</structfield>[64]</entry>
  79             <entry>Event data. Defined by the event type. The union
  80             should be used to define easily accessible type for
  81             events.</entry>
  82           </row>
  83           <row>
  84             <entry>__u32</entry>
  85             <entry><structfield>pending</structfield></entry>
  86             <entry></entry>
  87             <entry>Number of pending events excluding this one.</entry>
  88           </row>
  89           <row>
  90             <entry>__u32</entry>
  91             <entry><structfield>sequence</structfield></entry>
  92             <entry></entry>
  93             <entry>Event sequence number. The sequence number is
  94             incremented for every subscribed event that takes place.
  95             If sequence numbers are not contiguous it means that
  96             events have been lost.
  97             </entry>
  98           </row>
  99           <row>
 100             <entry>struct timeval</entry>
 101             <entry><structfield>timestamp</structfield></entry>
 102             <entry></entry>
 103             <entry>Event timestamp.</entry>
 104           </row>
 105           <row>
 106             <entry>__u32</entry>
 107             <entry><structfield>reserved</structfield>[9]</entry>
 108             <entry></entry>
 109             <entry>Reserved for future extensions. Drivers must set
 110             the array to zero.</entry>
 111           </row>
 112         </tbody>
 113       </tgroup>
 114     </table>
 115
 116   </refsect1>
 117 </refentry>
 118 <!--
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