/*! \page conffunc Configuration - runtime functions

<P>The ALSA library accepts the runtime modification of configuration.
The several build-in functions are available.</P>

<P>The function is refered using id @func and function name. All other
values in the current compound are used as configuration for the function.
If compound func.<function_name> is defined in the root leafs, then library
and function from this compound configuration is used, otherwise the prefix
'snd_func_' is added to string and the code from the ALSA library is used.
The definition of function looks like:</P> 

\code
func.remove_first_char {
	lib "/usr/lib/libasoundextend.so"
	func "extend_remove_first_char"
}
\endcode

\section conffunc_getenv The getenv function

The getenv function allows to get an environment value. The vars values
(array) defined the order and names for the environment values. When the
first environment value is found, then the function replaces the whole
compound by this result. If no value is found, then the default value is
used, if defined.

\code
	card {
		@func getenv
		vars [ MY_CARD CARD C ]
		default 0
	}
\endcode

\section conffunc_igetenv The igetenv function

This function is same as getenv function, but the result value is converted
to integer.

\section conffunc_concat The concat function

The concat function merges all given string in the array named string into
one.

\code
	filename {
		@func concat
		strings [
			"/usr/share"
			"/sound"
			"/a.wav"
		]
	}
\endcode

\section conffunc_datadir The datadir function

This function return the configuration data directory (usually /usr/share/alsa)
as string as result. This function requires no other values.


\section conffunc_refer The refer function

This function substitutes the current compound with the compound named (key
name, value string) and filename (key file - optional, value string).

\code
	{
		@func refer
		file /etc/my-alsa.conf
		name pcm.lastone
	}
\endcode

\section conffunc_card_strtype The card_strtype function

This function converts the given card number (key card, value integer) to card type
(string).

\section conffunc_card_id The card_id function

This function returns the card id string for the given card number (key card, value
integer).

\section conffunc_pcm_id The pcm_id function

This function returns the pcm id string for the given PCM device (key card,
value integer; key device, value integer; key subdevice (optional), value
integer).

\section conffunc_private_string The private_string function

This function returns the private data as string as result.

\section conffunc_private_card_strtype The private_card_strtype function

This function converts the private data (int) with card number to card type
(string).

\section conffunc_private_pcm_subdevice The private_pcm_subdevice function

This functions returns the subdevice number for the pcm handle specified by
the private data.

*/