func (obj *Volume) FreePrivateData(refguid GUID) Error {
	ret, _, _ := syscall.Syscall(
		obj.vtbl.FreePrivateData,
		2,
		uintptr(unsafe.Pointer(obj)),
		uintptr(unsafe.Pointer(&refguid)),
		0,
	)
	return toErr(ret)
}
FreePrivateData frees the specified private data associated with this volume.
package d3d9
import (
	"syscall"
	"unsafe"
)
type Volume struct {
	vtbl *volumeVtbl
}
type volumeVtbl struct {
	QueryInterface uintptr
	AddRef         uintptr
	Release        uintptr
	GetDevice       uintptr
	SetPrivateData  uintptr
	GetPrivateData  uintptr
	FreePrivateData uintptr
	GetContainer    uintptr
	GetDesc         uintptr
	LockBox         uintptr
	UnlockBox       uintptr
}
func (obj *Volume) AddRef() uint32 {
	ret, _, _ := syscall.Syscall(
		obj.vtbl.AddRef,
		1,
		uintptr(unsafe.Pointer(obj)),
		0,
		0,
	)
	return uint32(ret)
}
func (obj *Volume) Release() uint32 {
	ret, _, _ := syscall.Syscall(
		obj.vtbl.Release,
		1,
		uintptr(unsafe.Pointer(obj)),
		0,
		0,
	)
	return uint32(ret)
}
func (obj *Volume) GetDevice() (device *Device, err Error) {
	ret, _, _ := syscall.Syscall(
		obj.vtbl.GetDevice,
		2,
		uintptr(unsafe.Pointer(obj)),
		uintptr(unsafe.Pointer(&device)),
		0,
	)
	err = toErr(ret)
	return
}
func (obj *Volume) SetPrivateData(
	refguid GUID,
	data uintptr,
	sizeOfData uint32,
	flags uint32,
) Error {
	ret, _, _ := syscall.Syscall6(
		obj.vtbl.SetPrivateData,
		5,
		uintptr(unsafe.Pointer(obj)),
		uintptr(unsafe.Pointer(&refguid)),
		data,
		uintptr(sizeOfData),
		uintptr(flags),
		0,
	)
	return toErr(ret)
}
func (obj Volume) SetPrivateDataInBytes(
	refguid GUID,
	data []byte,
	flags uint32,
) Error {
	return obj.SetPrivateData(
		refguid,
		uintptr(unsafe.Pointer(&data[0])),
		uint32(len(data)),
		flags,
	)
}
func (obj *Volume) GetPrivateData(refguid GUID) (data []byte, err Error) {
	var sizeInBytes uint
	ret, _, _ := syscall.Syscall6(
		obj.vtbl.GetPrivateData,
		4,
		uintptr(unsafe.Pointer(obj)),
		uintptr(unsafe.Pointer(&refguid)),
		0,
		uintptr(unsafe.Pointer(&sizeInBytes)),
		0,
		0,
	)
	if err := toErr(ret); err != nil {
		return nil, err
	}
	data = make([]byte, sizeInBytes)
	ret, _, _ = syscall.Syscall6(
		obj.vtbl.GetPrivateData,
		4,
		uintptr(unsafe.Pointer(obj)),
		uintptr(unsafe.Pointer(&refguid)),
		uintptr(unsafe.Pointer(&data[0])),
		uintptr(unsafe.Pointer(&sizeInBytes)),
		0,
		0,
	)
	err = toErr(ret)
	return
}