<para>
<function>snd_printdd()</function> is compiled in only when
- <constant>CONFIG_SND_DEBUG_DETECT</constant> is set. Please note
- that <constant>DEBUG_DETECT</constant> is not set as default
+ <constant>CONFIG_SND_DEBUG_VERBOSE</constant> is set. Please note
+ that <constant>CONFIG_SND_DEBUG_VERBOSE</constant> is not set as default
even if you configure the alsa-driver with
<option>--with-debug=full</option> option. You need to give
explicitly <option>--with-debug=detect</option> option instead.
When no debug flag is set, this macro is ignored.
</para>
</section>
+
+ <section id="useful-functions-snd-bug-on">
+ <title><function>snd_BUG_ON()</function></title>
+ <para>
+ <function>snd_BUG_ON()</function> macro is similar with
+ <function>WARN_ON()</function> macro. For example,
+
+ <informalexample>
+ <programlisting>
+<![CDATA[
+ snd_BUG_ON(!pointer);
+]]>
+ </programlisting>
+ </informalexample>
+
+ or it can be used as the condition,
+ <informalexample>
+ <programlisting>
+<![CDATA[
+ if (snd_BUG_ON(non_zero_is_bug))
+ return -EINVAL;
+]]>
+ </programlisting>
+ </informalexample>
+
+ </para>
+
+ <para>
+ The macro takes an conditional expression to evaluate.
+ When <constant>CONFIG_SND_DEBUG</constant>, is set, the
+ expression is actually evaluated. If it's non-zero, it shows
+ the warning message such as
+ <computeroutput>BUG? (xxx)</computeroutput>
+ normally followed by stack trace. It returns the evaluated
+ value.
+ When no <constant>CONFIG_SND_DEBUG</constant> is set, this
+ macro always returns zero.
+ </para>
+
+ </section>
+
</chapter>