1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>Constructor</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Writing an ALSA Driver"><link rel="up" href="control-interface.html" title="Chapter&#160;6.&#160;Control Interface"><link rel="prev" href="control-interface-callbacks.html" title="Callbacks"><link rel="next" href="control-interface-change-notification.html" title="Change Notification"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Constructor</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="control-interface-callbacks.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;6.&#160;Control Interface</th><td width="20%" align="right">&#160;<a accesskey="n" href="control-interface-change-notification.html">Next</a></td></tr></table><hr></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="control-interface-constructor"></a>Constructor</h2></div></div></div><p>
2        When everything is ready, finally we can create a new
3      control. To create a control, there are two functions to be
4      called, <code class="function">snd_ctl_new1()</code> and
5      <code class="function">snd_ctl_add()</code>. 
6      </p><p>
7        In the simplest way, you can do like this:
8
9        </p><div class="informalexample"><pre class="programlisting">
10
11  err = snd_ctl_add(card, snd_ctl_new1(&amp;my_control, chip));
12  if (err &lt; 0)
13          return err;
14
15          </pre></div><p>
16
17        where <em class="parameter"><code>my_control</code></em> is the
18      struct <span class="structname">snd_kcontrol_new</span> object defined above, and chip
19      is the object pointer to be passed to
20      kcontrol-&gt;private_data 
21      which can be referred to in callbacks. 
22      </p><p>
23        <code class="function">snd_ctl_new1()</code> allocates a new
24      <span class="structname">snd_kcontrol</span> instance,
25      and <code class="function">snd_ctl_add</code> assigns the given
26      control component to the card. 
27      </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="control-interface-callbacks.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="control-interface.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="control-interface-change-notification.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Callbacks&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;Change Notification</td></tr></table></div></body></html>
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