An implementation of runtime host API selection (see ticket #10). See the changes to portaudio.h for documentation for the API. Note that unlike other proposals, this version of the interface allows the client to specify the order of host API initialization. The API is excercised by patest_select_hostapis.c. To reviewers: please verify that the implementation of Pa_SelectHostApis, Pa_GetSelectedHostApis and Pa_GetAvailableHostApis in pa_front.c matches the documentation in portaudio.h

include/portaudio.h

@@ -274,6 +274,64 @@ typedef enum PaHostApiTypeId
 } PaHostApiTypeId;
 
 
+/** Select host APIs and their initialization order.
+
+ The selected host APIs take effect the next time that Pa_Initialize() is
+ invoked.
+
+ @param hostApiTypes An array of host API identifiers belonging to the
+ PaHostApiTypeId enumeration.
+
+ @param count The number of elements in the hostApiTypes array. A count of
+ zero causes the default host API selection to be restored.
+
+ @return A PaErrorCode indicating whether the call succeeded or failed.
+
+ The paHostApiNotFound error code indicates that a host API specified by the
+ hostApiTypeIds parameter is not available.
+
+ The paInvalidHostApi error indicates that there was a problem with the
+ hostApiTypes array. E.g. it contained duplicate entries.
+
+ @note The host API initialization order determines default devices.
+
+ @see PaHostApiTypeId
+*/
+PaError Pa_SelectHostApis( const PaHostApiTypeId *hostApiTypes, int count );
+
+/** Returns the type ids of the selected host APIs in initialization order.
+
+ @param hostApiTypes (IN/OUT) An array that will be filled with
+ host API identifiers belonging to the PaHostApiTypeId enumeration.
+
+ @param count (OUT) The number of selected host APIs, returned even on error.
+
+ @param countAvailable The number of available elements in the hostApiTypes array.
+
+ @return A PaErrorCode indicating whether the call succeeded or failed.
+
+ The paInsufficientMemory error indicates that countAvailable was not large enough
+ to accommodate the list of selected host APIs. In this case, the needed
+ count is returned in the count parameter.
+
+ @see Pa_SelectHostApis
+*/
+PaError Pa_GetSelectedHostApis( PaHostApiTypeId *hostApiTypes, int countAvailable, int *count );
+
+/** Returns the type ids of all available host APIs in initialization order.
+
+ @param hostApiTypes (IN/OUT) An array that will be filled with
+ host API identifiers belonging to the PaHostApiTypeId enumeration.
+
+ @param count (OUT) The number of host APIs, returned even on error.
+
+ @param countAvailable The number of available elements in the hostApiTypes array.
+
+ @see Pa_SelectHostApis
+*/
+PaError Pa_GetAvailableHostApis( PaHostApiTypeId *hostApiTypes, int countAvailable, int *count );
+
+
 /** A structure containing information about a particular host API. */
 
 typedef struct PaHostApiInfo