CopyConfigurationDescriptorWithValue
Returns the configuration descriptor with the specified configuration value.
Declaration
virtual const IOUSBConfigurationDescriptor * CopyConfigurationDescriptorWithValue(uint8_t bConfigurationValue);Parameters
- bConfigurationValue:
The value assigned to the Bconfigurationvalue field of the descriptor.
Return Value
A pointer to the configuration descriptor if found, or NULL if the device isn’t configured. It’s your responsibility to free the returned descriptor.
Discussion
This method searches the descriptor cache for the specified descriptor. If the descriptor isn’t in the cache, the method retrieves it from the device using a GET_DESCRIPTOR control request (USB 2.0, section 9.4.3) and adds it to the cache. When making a GET_DESCRIPTOR control request, this method acquires the service’s workloop lock and may call commandSleep.