wasapi: Enumerate only active devices when matching BT output device.

Potentially significantly shrinks the list of devices to search when
matching BT output device with specified BT input device.  On my local
machine, this shrinks the list from 25 to 7, and reduces the initial
enumerate time from ~67ms to ~32ms (and a subsequent call from ~14ms to
~12ms).

src/cubeb_wasapi.cpp

@@ -240,8 +240,9 @@ wasapi_create_device(cubeb * ctx, cubeb_device_info & ret,
 void
 wasapi_destroy_device(cubeb_device_info * device_info);
 static int
-wasapi_enumerate_devices(cubeb * context, cubeb_device_type type,
-                         cubeb_device_collection * out);
+wasapi_enumerate_devices_internal(cubeb * context, cubeb_device_type type,
+                                  cubeb_device_collection * out,
+                                  DWORD state_mask);
 static int
 wasapi_device_collection_destroy(cubeb * ctx,
                                  cubeb_device_collection * collection);
@@ -2393,10 +2394,10 @@ wasapi_find_bt_handsfree_output_device(cubeb_stream * stm)
     return nullptr;
   }
 
-  int rv = wasapi_enumerate_devices(
+  int rv = wasapi_enumerate_devices_internal(
       stm->context,
       (cubeb_device_type)(CUBEB_DEVICE_TYPE_INPUT | CUBEB_DEVICE_TYPE_OUTPUT),
-      &collection);
+      &collection, DEVICE_STATE_ACTIVE);
   if (rv != CUBEB_OK) {
     return nullptr;
   }
@@ -3330,8 +3331,9 @@ wasapi_destroy_device(cubeb_device_info * device)
 }
 
 static int
-wasapi_enumerate_devices(cubeb * context, cubeb_device_type type,
-                         cubeb_device_collection * out)
+wasapi_enumerate_devices_internal(cubeb * context, cubeb_device_type type,
+                                  cubeb_device_collection * out,
+                                  DWORD state_mask)
 {
   com_ptr<IMMDeviceEnumerator> enumerator;
   com_ptr<IMMDeviceCollection> collection;
@@ -3359,10 +3361,7 @@ wasapi_enumerate_devices(cubeb * context, cubeb_device_type type,
     return CUBEB_ERROR;
   }
 
-  hr = enumerator->EnumAudioEndpoints(
-      flow,
-      DEVICE_STATE_ACTIVE | DEVICE_STATE_DISABLED | DEVICE_STATE_UNPLUGGED,
-      collection.receive());
+  hr = enumerator->EnumAudioEndpoints(flow, state_mask, collection.receive());
   if (FAILED(hr)) {
     LOG("Could not enumerate audio endpoints: %lx", hr);
     return CUBEB_ERROR;
@@ -3396,6 +3395,15 @@ wasapi_enumerate_devices(cubeb * context, cubeb_device_type type,
   return CUBEB_OK;
 }
 
+static int
+wasapi_enumerate_devices(cubeb * context, cubeb_device_type type,
+                         cubeb_device_collection * out)
+{
+  return wasapi_enumerate_devices_internal(
+      context, type, out,
+      DEVICE_STATE_ACTIVE | DEVICE_STATE_DISABLED | DEVICE_STATE_UNPLUGGED);
+}
+
 static int
 wasapi_device_collection_destroy(cubeb * /*ctx*/,
                                  cubeb_device_collection * collection)