Configuration:

- changed snd_config_get_id function to follow semantic of other get functions
  - added snd_config_test_id
  - added runtime pointer type (not persistent)
    - added snd_config_make_pointer, snd_config_set_pointer, snd_config_get_pointer
  - added type/contents checking for callback functions
    - changed 'void *private_data' to 'snd_config_t *private_data'
  - renamed card_strtype functions to card_driver
Control:
  - fixed passing parameters to snd_ctl_async
Async handlers:
  - added public snd_async_handler_get_signo function
Documentation:
  - moved all documentation to source files

src/async.c

@@ -30,7 +30,8 @@
 
 #ifdef SND_ASYNC_RT_SIGNAL
 /** async signal number */
-int snd_async_signo;
+static int snd_async_signo;
+
 void snd_async_init(void) __attribute__ ((constructor));
 
 void snd_async_init(void)
@@ -43,7 +44,7 @@ void snd_async_init(void)
 }
 #else
 /** async signal number */
-int snd_async_signo = SIGIO;
+static int snd_async_signo = SIGIO;
 #endif
 
 static LIST_HEAD(snd_async_handlers);
@@ -68,12 +69,18 @@ static void snd_async_handler(int signo ATTRIBUTE_UNUSED, siginfo_t *siginfo, vo
  * \param callback - Async callback
  * \param private_data - Private data for async callback
  * \result zero if success, otherwise a negative error code
+ *
+ * The function create the async handler. The ALSA extension
+ * for the standard SIGIO signal contains the multiplexer
+ * for multiple asynchronous notifiers using one sigaction
+ * callback.
  */
 int snd_async_add_handler(snd_async_handler_t **handler, int fd, 
 			  snd_async_callback_t callback, void *private_data)
 {
 	snd_async_handler_t *h;
 	int was_empty;
+	assert(handler);
 	h = malloc(sizeof(*h));
 	if (!h)
 		return -ENOMEM;
@@ -107,6 +114,7 @@ int snd_async_add_handler(snd_async_handler_t **handler, int fd,
 int snd_async_del_handler(snd_async_handler_t *handler)
 {
 	int err = 0;
+	assert(handler);
 	list_del(&handler->glist);
 	if (list_empty(&snd_async_handlers)) {
 		struct sigaction act;
@@ -139,6 +147,17 @@ int snd_async_del_handler(snd_async_handler_t *handler)
 	return err;
 }
 
+/**
+ * \brief Get signal number assigned to async handler
+ * \param handler Async handler
+ * \result signal number if success, otherwise a negative error code
+ */
+int snd_async_handler_get_signo(snd_async_handler_t *handler)
+{
+	assert(handler);
+	return snd_async_signo;
+}
+
 /**
  * \brief Get file descriptor assigned to async handler
  * \param handler Async handler
@@ -146,6 +165,7 @@ int snd_async_del_handler(snd_async_handler_t *handler)
  */
 int snd_async_handler_get_fd(snd_async_handler_t *handler)
 {
+	assert(handler);
 	return handler->fd;
 }
 
@@ -156,6 +176,7 @@ int snd_async_handler_get_fd(snd_async_handler_t *handler)
  */
 void *snd_async_handler_get_callback_private(snd_async_handler_t *handler)
 {
+	assert(handler);
 	return handler->private_data;
 }