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<h1><a class="anchor" id="conffunc">Runtime functions in configuration files </a></h1><p>The ALSA library can modify the configuration at runtime. Several built-in functions are available.</p>
<p>A function is defined with the id <code>@func</code> and the function name. All other values in the current compound are used as configuration for the function. If the compound func.<function_name> is defined in the root node, then the library and function from this compound configuration are used, otherwise 'snd_func_' is prefixed to the string and code from the ALSA library is used. The definition of a function looks like:</p>
<div class="fragment"><pre class="fragment">func.remove_first_char {
lib <span class="stringliteral">"/usr/lib/libasoundextend.so"</span>
func <span class="stringliteral">"extend_remove_first_char"</span>
}
</pre></div><h2><a class="anchor" id="conffunc_ref">
Function reference</a></h2>
<ul>
<li>
The getenv function - <a class="el" href="confmisc_8c.html#a033eab97ee6619aeb8c5eca585acf6c0" title="Returns an environment value.">snd_func_getenv()</a> - obtains an environment value. The result is a string. </li>
<li>
The igetenv function - <a class="el" href="confmisc_8c.html#a121864fba02478b9f605be44c97f5dc8" title="Returns an integer environment value.">snd_func_igetenv()</a> - obtains an environment value. The result is an integer. </li>
<li>
The concat function - <a class="el" href="confmisc_8c.html#a43a3685d5e397fdc0e46af6d7b121616" title="Merges the given strings.">snd_func_concat()</a> - merges all specified strings. The result is a string. </li>
<li>
The iadd function - <a class="el" href="confmisc_8c.html#a4e7acbc261ca8b6bf4602753ea5c17fe" title="Sum the given integers.">snd_func_iadd()</a> - sum all specified integers. The result is an integer. </li>
<li>
The imul function - <a class="el" href="confmisc_8c.html#a12f4b8b67e0976a260859edb929f4d36" title="Multiply the given integers.">snd_func_imul()</a> - multiply all specified integers. The result is an integer. </li>
<li>
The datadir function - <a class="el" href="confmisc_8c.html#aa24c85e86b4c1f6c4d2d440e4782d098" title="Returns the ALSA data directory.">snd_func_datadir()</a> - returns the ALSA data directory. The result is a string. </li>
<li>
The refer function - <a class="el" href="confmisc_8c.html#a8d91af8387a708c526bac3ee2c7ea10e" title="Copies the specified configuration node.">snd_func_refer()</a> - copies the referred configuration. The result has the same type as the referred node. </li>
<li>
The card_inum function - <a class="el" href="confmisc_8c.html#a023f9fd40df7c2c428a457b6ec7f8004" title="Returns the card number as integer.">snd_func_card_inum()</a> - returns a card number (integers). </li>
<li>
The card_driver function - <a class="el" href="confmisc_8c.html#a2d147e387821449a8927d60ef4f8ff16" title="Returns the driver identification for a card.">snd_func_card_driver()</a> - returns a driver identification. The result is a string. </li>
<li>
The card_id function - <a class="el" href="confmisc_8c.html#a9ccfc361f1bc1d81837335de02707ee8" title="Returns the identification of a card.">snd_func_card_id()</a> - returns a card identification. The result is a string. </li>
<li>
The card_name function - <a class="el" href="confmisc_8c.html#aba1ae0185e2d3e9b50291b40e7048181" title="Returns the name of a card.">snd_func_card_name()</a> - returns a card's name. The result is a string. </li>
<li>
The pcm_id function - snd_func_pcm_id() - returns a pcm identification. The result is a string. </li>
<li>
The private_string function - <a class="el" href="confmisc_8c.html#af14b528e2502f2037294301473389948" title="Returns the string from private_data.">snd_func_private_string()</a> - returns the string from the private_data node. </li>
<li>
The private_card_driver function - <a class="el" href="confmisc_8c.html#a7bc4fec8cb3499997934a00210d34fe7" title="Returns the driver identification from private_data.">snd_func_private_card_driver()</a> - returns the driver identification from the private_data node. The result is a string. </li>
<li>
The private_pcm_subdevice function - snd_func_private_pcm_subdevice() - returns the PCM subdevice number from the private_data node. The result is a string. </li>
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