GUD initialization

#define NUM_INTERFACES (2)
#define NUM_ENDPOINTS (3)

GUD_InterfaceInitTypeDef interfaces[NUM_INTERFACES];
GUD_EndpointInitTypeDef endpoints[NUM_ENDPOINTS];

static GUD_GenericUsbDriverTypeDef hgud;
static GUD_CallbacksTypeDef callbacks = { GetStringDescriptor };
static char serial[25];

uint8_t* GetStringDescriptor(uint8_t index);

GUD_GenericUsbDriverTypeDef* potatoscope_usb_init() {
	sprintf(serial, "%08X%08X%08X", STM32_UUID[0], STM32_UUID[1], STM32_UUID[2]);
	serial[24] = '\0';

	hgud.init.vendor_id = 0x0483;
	hgud.init.product_id = 0x5740;
	hgud.init.device_revision = 0x0100; // 1.0
	hgud.init.num_configurations = 1; // Total number of configurations
	hgud.init.num_interfaces = 0; // Total number of interfaces
	hgud.init.num_endpoints = 0; // Total number of endpoints
	hgud.init.functional_configuration_length = 0;
	hgud.init.speed = USB_SPEED_HIGH;

#ifdef USE_USB_CDC
	gud_setup_cdc(&hgud, interfaces, endpoints);
#endif
	hgud.callbacks = &callbacks; // Callbacks
	GUD_Init(&hpcd_USB_OTG_HS, &hgud);

	// Init configuration #1
	GUD_ConfigurationInitTypeDef conf;
	conf.max_power = 50; // = 100mA/2
	conf.self_powered = 0;
	conf.remote_wakeup = 0;
	conf.num_interfaces = NUM_INTERFACES;
	conf.interfaces = interfaces;
	// Register configuration
	GUD_RegisterConfiguration(&conf);
	GUD_Start();

	return &hgud;
}

uint8_t* GetStringDescriptor(uint8_t index) {
	switch(index) {
	case GUD_MANUFACTURER_STRING_INDEX :
		return (uint8_t*) "IBR";
	case GUD_PRODUCT_STRING_INDEX :
		return (uint8_t*) "PotatoScope";
	case GUD_SERIAL_STRING_INDEX :
		return (uint8_t*) serial;
	default :
		//printf("Unknown index: %d\r\n", index);
		return (uint8_t*) "Unknown";
	}
}