##
##
## USB DESCRIPTORS
##
##

# Originally by Vojtech Horky.

# Block prefixed with a byte length
transform block = (in.data) <- struct {
	.bLength <- uint8;
	.data <- known_length(.bLength - 1);
};

# USB configuration descriptor
# This is not the full configuration descriptor (i.e. with interface
# and endpoint descriptors included) but only the header.
transform usb_configuration_descriptor_bare = struct {
	.wTotalLength <- uint16le;
	.bNumInterfaces <- uint8;
	.bConfigurationValue <- uint8;
	.iConfiguration <- uint8;
	.bmAttributes <- uint8;
	.MaxPower <- uint8;
};

# USB interface descriptor
transform usb_interface_descriptor = struct {
	.bInterfaceNumber <- uint8;
	.bAlternateSetting <- uint8;
	.bNumEndpoints <- uint8;
	.bInterfaceClass <- uint8;
	.bInterfaceSubClass <- uint8;
	.bInterfaceProtocol <- uint8;
	.iInterface <- uint8;
};

# USB endpoint descriptor
transform usb_endpoint_descriptor = struct {
	.bEndpointAddress  <- uint8;
	.bmAttributes <- uint8;
	.wMaxPacketSize <- uint16le;
	.bInterval <- uint8;
};

# USB HID descriptor
transform usb_hid_descriptor = struct {
	.bcdHID <- uint16le;
	.bCountryCode <- uint8;
	.bNumDescriptors <- uint8;
	<- repeat(.bNumDescriptors) { struct {
		.bDescriptorType <- uint8;
		.wDescriptorLength <- uint16le;
	} };
};

# USB descriptor
transform usb_descriptor = struct {
	.bDescriptorType <- uint8;
	<- switch (.bDescriptorType) {
		 2: usb_configuration_descriptor_bare;
		 4: usb_interface_descriptor;
		 5: usb_endpoint_descriptor;
		33: usb_hid_descriptor;
	};
} <- block;

transform main = repeat { usb_descriptor };