def windowsRam(self):
        """
        Uses Windows API to check RAM
        """
        kernel32 = ctypes.windll.kernel32
        c_ulong = ctypes.c_ulong

        class MEMORYSTATUS(ctypes.Structure):
            _fields_ = [
                ("dwLength", c_ulong),
                ("dwMemoryLoad", c_ulong),
                ("dwTotalPhys", c_ulong),
                ("dwAvailPhys", c_ulong),
                ("dwTotalPageFile", c_ulong),
                ("dwAvailPageFile", c_ulong),
                ("dwTotalVirtual", c_ulong),
                ("dwAvailVirtual", c_ulong)
            ]

        memoryStatus = MEMORYSTATUS()
        memoryStatus.dwLength = ctypes.sizeof(MEMORYSTATUS)
        kernel32.GlobalMemoryStatus(ctypes.byref(memoryStatus))

        return int(memoryStatus.dwTotalPhys / 1024 ** 2) 

def _is_gui_available():
        UOI_FLAGS = 1
        WSF_VISIBLE = 0x0001
        class USEROBJECTFLAGS(ctypes.Structure):
            _fields_ = [("fInherit", ctypes.wintypes.BOOL),
                        ("fReserved", ctypes.wintypes.BOOL),
                        ("dwFlags", ctypes.wintypes.DWORD)]
        dll = ctypes.windll.user32
        h = dll.GetProcessWindowStation()
        if not h:
            raise ctypes.WinError()
        uof = USEROBJECTFLAGS()
        needed = ctypes.wintypes.DWORD()
        res = dll.GetUserObjectInformationW(h,
            UOI_FLAGS,
            ctypes.byref(uof),
            ctypes.sizeof(uof),
            ctypes.byref(needed))
        if not res:
            raise ctypes.WinError()
        return bool(uof.dwFlags & WSF_VISIBLE) 

def test_union_with_struct_packed(self):
        class Struct(ctypes.Structure):
            _pack_ = 1
            _fields_ = [
                ('one', ctypes.c_uint8),
                ('two', ctypes.c_uint32)
            ]

        class Union(ctypes.Union):
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16),
                ('c', ctypes.c_uint32),
                ('d', Struct),
            ]
        expected = np.dtype(dict(
            names=['a', 'b', 'c', 'd'],
            formats=['u1', np.uint16, np.uint32, [('one', 'u1'), ('two', np.uint32)]],
            offsets=[0, 0, 0, 0],
            itemsize=ctypes.sizeof(Union)
        ))
        self.check(Union, expected) 

def _is_gui_available():
        UOI_FLAGS = 1
        WSF_VISIBLE = 0x0001
        class USEROBJECTFLAGS(ctypes.Structure):
            _fields_ = [("fInherit", ctypes.wintypes.BOOL),
                        ("fReserved", ctypes.wintypes.BOOL),
                        ("dwFlags", ctypes.wintypes.DWORD)]
        dll = ctypes.windll.user32
        h = dll.GetProcessWindowStation()
        if not h:
            raise ctypes.WinError()
        uof = USEROBJECTFLAGS()
        needed = ctypes.wintypes.DWORD()
        res = dll.GetUserObjectInformationW(h,
            UOI_FLAGS,
            ctypes.byref(uof),
            ctypes.sizeof(uof),
            ctypes.byref(needed))
        if not res:
            raise ctypes.WinError()
        return bool(uof.dwFlags & WSF_VISIBLE) 

def test_union_packed(self):
        class Struct(ctypes.Structure):
            _fields_ = [
                ('one', ctypes.c_uint8),
                ('two', ctypes.c_uint32)
            ]
            _pack_ = 1
        class Union(ctypes.Union):
            _pack_ = 1
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16),
                ('c', ctypes.c_uint32),
                ('d', Struct),
            ]
        expected = np.dtype(dict(
            names=['a', 'b', 'c', 'd'],
            formats=['u1', np.uint16, np.uint32, [('one', 'u1'), ('two', np.uint32)]],
            offsets=[0, 0, 0, 0],
            itemsize=ctypes.sizeof(Union)
        ))
        self.check(Union, expected) 

def MessageClass(length=DMX_LENGTH):
    assert 0 <= length <= DMX_LENGTH
    assert length % 2 == 0, 'artnet only takes messages of even length'

    Char, Int8, Int16 = ctypes.c_char, ctypes.c_ubyte, ctypes.c_ushort

    class DMXMessage(ctypes.Structure):
        # http://artisticlicence.com/WebSiteMaster/User%20Guides/art-net.pdf p47
        _fields_ = [
            ('id', Char * 8),
            ('opCode', Int16),
            ('protVerHi', Int8),
            ('protVerLo', Int8),
            ('sequence', Int8),
            ('physical', Int8),
            ('subUni', Int8),
            ('net', Int8),
            ('lengthHi', Int8),
            ('length', Int8),
            ('data', Int8 * length),  # At position 18
        ]

    return DMXMessage 

def __init__(self, **kwargs):
        """
        Ctypes.Structure with integrated default values.
        https://stackoverflow.com/questions/7946519/default-values-in-a-ctypes-structure/25892189#25892189

        :param kwargs: values different to defaults
        :type kwargs: dict
        """

        # sanity checks
        defaults = type(self)._defaults_
        assert type(defaults) is types.DictionaryType

        # use defaults, but override with keyword arguments, if any
        values = defaults.copy()
        for (key, val) in kwargs.items():
            values[key] = val

        # appropriately initialize ctypes.Structure
        #super().__init__(**values)                     # Python 3 syntax
        return Structure.__init__(self, **values)       # Python 2 syntax

    # http://stackoverflow.com/questions/1825715/how-to-pack-and-unpack-using-ctypes-structure-str/1827666#1827666
    # https://wiki.python.org/moin/ctypes 

def create_remote_array(subtype, len):

    class RemoteArray(_ctypes.Array):
        _length_ = len
        _type_ = subtype

        def __init__(self, addr, target):
            self._base_addr = addr
            self.target = target

        def __getitem__(self, slice):
            if not isinstance(slice, (int, long)):
                raise NotImplementedError("RemoteArray slice __getitem__")
            if slice >= len:
                raise IndexError("Access to {0} for a RemoteArray of size {1}".format(slice, len))
            item_addr = self._base_addr + (ctypes.sizeof(subtype) * slice)

            # TODO: do better ?
            class TST(ctypes.Structure):
                _fields_ = [("TST", subtype)]
            return RemoteStructure.from_structure(TST)(item_addr, target=self.target).TST
    return RemoteArray


# 64bits pointers 

def _handle_field_getattr(self, ftype, fosset, fsize):
        s = self._target.read_memory(self._base_addr + fosset, fsize)
        if ftype in self._field_type_to_remote_type:
            return self._field_type_to_remote_type[ftype].from_buffer_with_target(bytearray(s), target=self._target).value
        if issubclass(ftype, _ctypes._Pointer):  # Pointer
            return RemoteStructurePointer.from_buffer_with_target_and_ptr_type(bytearray(s), target=self._target, ptr_type=ftype)
        if issubclass(ftype, RemotePtr64):  # Pointer to remote64 bits process
            return RemoteStructurePointer64.from_buffer_with_target_and_ptr_type(bytearray(s), target=self._target, ptr_type=ftype)
        if issubclass(ftype, RemoteStructureUnion):  # Structure|Union already transfomed in remote
            return ftype(self._base_addr + fosset, self._target)
        if issubclass(ftype, ctypes.Structure):  # Structure that must be transfomed
            return RemoteStructure.from_structure(ftype)(self._base_addr + fosset, self._target)
        if issubclass(ftype, ctypes.Union):  # Union that must be transfomed
            return RemoteUnion.from_structure(ftype)(self._base_addr + fosset, self._target)
        if issubclass(ftype, _ctypes.Array):  # Arrays
            return create_remote_array(ftype._type_, ftype._length_)(self._base_addr + fosset, self._target)
        # Normal types
        # Follow the ctypes usage: if it's not directly inherited from _SimpleCData
        # We do not apply the .value
        # Seems weird but it's mandatory AND useful :D (in pe_parse)
        if _SimpleCData not in ftype.__bases__:
            return ftype.from_buffer(bytearray(s))
        return ftype.from_buffer(bytearray(s)).value 

def write_virtual_memory(self, addr, data):
        """Write data to a given virtual address

           :param addr: The Symbol to write to
           :type addr: Symbol
           :param size: The Data to write
           :type size: str or ctypes.Structure
           :returns: the size written -- :class:`int`
        """
        try:
            # ctypes structure
            size = ctypes.sizeof(data)
            buffer = ctypes.byref(data)
        except TypeError:
            # buffer
            size = len(data)
            buffer = data
        written = ULONG(0)
        addr = self.resolve_symbol(addr)
        self.DebugDataSpaces.WriteVirtual(c_uint64(addr), buffer, size, byref(written))
        return written.value 

def write_physical_memory(self, addr, data):
        """Write data to a given physical address

           :param addr: The Symbol to write to
           :type addr: Symbol
           :param size: The Data to write
           :type size: str or ctypes.Structure
           :returns: the size written -- :class:`int`
        """
        try:
            # ctypes structure
            size = ctypes.sizeof(data)
            buffer = ctypes.byref(data)
        except TypeError:
            # buffer
            size = len(data)
            buffer = data
        written = ULONG(0)
        self.DebugDataSpaces.WritePhysical(c_uint64(addr), buffer, size, byref(written))
        return written.value 

def create_vtable(cls, **implem_overwrite):
        vtables_names = [x[0] for x in cls._funcs_]
        non_expected_args = [func_name for func_name in implem_overwrite if func_name not in vtables_names]
        if non_expected_args:
            raise ValueError("Non expected function : {0}".format(non_expected_args))

        implems = []
        for name, types, func_implem in cls._funcs_:
            func_implem = implem_overwrite.get(name, func_implem)
            if func_implem is None:
                raise ValueError("Missing implementation for function <{0}>".format(name))
            implems.append(create_c_callable(func_implem, types))

        class Vtable(ctypes.Structure):
            _fields_ = [(name, ctypes.c_void_p) for name in vtables_names]

        return Vtable(*implems) 

def test_union_with_struct_packed(self):
        class Struct(ctypes.Structure):
            _pack_ = 1
            _fields_ = [
                ('one', ctypes.c_uint8),
                ('two', ctypes.c_uint32)
            ]

        class Union(ctypes.Union):
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16),
                ('c', ctypes.c_uint32),
                ('d', Struct),
            ]
        expected = np.dtype(dict(
            names=['a', 'b', 'c', 'd'],
            formats=['u1', np.uint16, np.uint32, [('one', 'u1'), ('two', np.uint32)]],
            offsets=[0, 0, 0, 0],
            itemsize=ctypes.sizeof(Union)
        ))
        self.check(Union, expected) 

def test_union_packed(self):
        class Struct(ctypes.Structure):
            _fields_ = [
                ('one', ctypes.c_uint8),
                ('two', ctypes.c_uint32)
            ]
            _pack_ = 1
        class Union(ctypes.Union):
            _pack_ = 1
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16),
                ('c', ctypes.c_uint32),
                ('d', Struct),
            ]
        expected = np.dtype(dict(
            names=['a', 'b', 'c', 'd'],
            formats=['u1', np.uint16, np.uint32, [('one', 'u1'), ('two', np.uint32)]],
            offsets=[0, 0, 0, 0],
            itemsize=ctypes.sizeof(Union)
        ))
        self.check(Union, expected) 

def _is_gui_available():
        UOI_FLAGS = 1
        WSF_VISIBLE = 0x0001
        class USEROBJECTFLAGS(ctypes.Structure):
            _fields_ = [("fInherit", ctypes.wintypes.BOOL),
                        ("fReserved", ctypes.wintypes.BOOL),
                        ("dwFlags", ctypes.wintypes.DWORD)]
        dll = ctypes.windll.user32
        h = dll.GetProcessWindowStation()
        if not h:
            raise ctypes.WinError()
        uof = USEROBJECTFLAGS()
        needed = ctypes.wintypes.DWORD()
        res = dll.GetUserObjectInformationW(h,
            UOI_FLAGS,
            ctypes.byref(uof),
            ctypes.sizeof(uof),
            ctypes.byref(needed))
        if not res:
            raise ctypes.WinError()
        return bool(uof.dwFlags & WSF_VISIBLE) 

def compile(self, structure):
        source = self.gen_struct_class(structure)
        c = compile(source, '<compiled>', 'exec')

        env = {
            'OrderedDict': OrderedDict,
            'Structure': Structure,
            'Instance': Instance,
            'Expression': Expression,
            'EnumInstance': EnumInstance,
            'PointerInstance': PointerInstance,
            'BytesInteger': BytesInteger,
            'BitBuffer': BitBuffer,
            'struct': struct,
            'xrange': xrange,
        }

        exec(c, env)
        sc = env[structure.name](self.cstruct, structure, source)

        return sc 

def __init__(self, this):
        if not this:
            raise WindowsError('Could not construct {}'.format(self.__class__))
        self.this = ctypes.cast(this, ctypes.POINTER(self.__class__))
        ctypes.Structure.__init__(self) 

def getWindowsBuild():   
    class OSVersionInfo(ctypes.Structure):
        _fields_ = [
            ("dwOSVersionInfoSize" , ctypes.c_int),
            ("dwMajorVersion"      , ctypes.c_int),
            ("dwMinorVersion"      , ctypes.c_int),
            ("dwBuildNumber"       , ctypes.c_int),
            ("dwPlatformId"        , ctypes.c_int),
            ("szCSDVersion"        , ctypes.c_char*128)];
    GetVersionEx = getattr( ctypes.windll.kernel32 , "GetVersionExA")
    version  = OSVersionInfo()
    version.dwOSVersionInfoSize = ctypes.sizeof(OSVersionInfo)
    GetVersionEx( ctypes.byref(version) )    
    return version.dwBuildNumber 

def as_ctypes_type(dtype):
        """
        Convert a dtype into a ctypes type.

        Parameters
        ----------
        dtype : dtype
            The dtype to convert

        Returns
        -------
        ctypes
            A ctype scalar, union, array, or struct

        Raises
        ------
        NotImplementedError
            If the conversion is not possible

        Notes
        -----
        This function does not losslessly round-trip in either direction.

        ``np.dtype(as_ctypes_type(dt))`` will:
         - insert padding fields
         - reorder fields to be sorted by offset
         - discard field titles

        ``as_ctypes_type(np.dtype(ctype))`` will:
         - discard the class names of ``Structure``s and ``Union``s
         - convert single-element ``Union``s into single-element ``Structure``s
         - insert padding fields

        """
        return _ctype_from_dtype(_dtype(dtype)) 

def test_struct_array_pointer(self):
        from ctypes import c_int16, Structure, pointer

        class Struct(Structure):
            _fields_ = [('a', c_int16)]

        Struct3 = 3 * Struct

        c_array = (2 * Struct3)(
            Struct3(Struct(a=1), Struct(a=2), Struct(a=3)),
            Struct3(Struct(a=4), Struct(a=5), Struct(a=6))
        )

        expected = np.array([
            [(1,), (2,), (3,)],
            [(4,), (5,), (6,)],
        ], dtype=[('a', np.int16)])

        def check(x):
            assert_equal(x.dtype, expected.dtype)
            assert_equal(x, expected)

        # all of these should be equivalent
        check(as_array(c_array))
        check(as_array(pointer(c_array), shape=()))
        check(as_array(pointer(c_array[0]), shape=(2,)))
        check(as_array(pointer(c_array[0][0]), shape=(2, 3))) 

def test_structure(self):
        dt = np.dtype([
            ('a', np.uint16),
            ('b', np.uint32),
        ])

        ct = np.ctypeslib.as_ctypes_type(dt)
        assert_(issubclass(ct, ctypes.Structure))
        assert_equal(ctypes.sizeof(ct), dt.itemsize)
        assert_equal(ct._fields_, [
            ('a', ctypes.c_uint16),
            ('b', ctypes.c_uint32),
        ]) 

def test_structure_aligned(self):
        dt = np.dtype([
            ('a', np.uint16),
            ('b', np.uint32),
        ], align=True)

        ct = np.ctypeslib.as_ctypes_type(dt)
        assert_(issubclass(ct, ctypes.Structure))
        assert_equal(ctypes.sizeof(ct), dt.itemsize)
        assert_equal(ct._fields_, [
            ('a', ctypes.c_uint16),
            ('', ctypes.c_char * 2),  # padding
            ('b', ctypes.c_uint32),
        ]) 

def test_padded_structure(self):
        class PaddedStruct(ctypes.Structure):
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16)
            ]
        expected = np.dtype([
            ('a', np.uint8),
            ('b', np.uint16)
        ], align=True)
        self.check(PaddedStruct, expected) 

def test_bit_fields(self):
        class BitfieldStruct(ctypes.Structure):
            _fields_ = [
                ('a', ctypes.c_uint8, 7),
                ('b', ctypes.c_uint8, 1)
            ]
        assert_raises(TypeError, np.dtype, BitfieldStruct)
        assert_raises(TypeError, np.dtype, BitfieldStruct()) 

def test_packed_structure(self):
        class PackedStructure(ctypes.Structure):
            _pack_ = 1
            _fields_ = [
                ('a', ctypes.c_uint8),
                ('b', ctypes.c_uint16)
            ]
        expected = np.dtype([
            ('a', np.uint8),
            ('b', np.uint16)
        ])
        self.check(PackedStructure, expected) 

def struct_field( offset, ctype, name='field' ):
    @fix_ctypes_struct
    class Struct( ctypes.Structure ):
        _fields_ = [ ("", ubyte * offset), (name, ctype) ]
    return getattr( Struct, name ) 

def __init__(self, *args):
        """
        The initialization function may take an OGREnvelope structure, 4-element
        tuple or list, or 4 individual arguments.
        """

        if len(args) == 1:
            if isinstance(args[0], OGREnvelope):
                # OGREnvelope (a ctypes Structure) was passed in.
                self._envelope = args[0]
            elif isinstance(args[0], (tuple, list)):
                # A tuple was passed in.
                if len(args[0]) != 4:
                    raise GDALException('Incorrect number of tuple elements (%d).' % len(args[0]))
                else:
                    self._from_sequence(args[0])
            else:
                raise TypeError('Incorrect type of argument: %s' % str(type(args[0])))
        elif len(args) == 4:
            # Individual parameters passed in.
            #  Thanks to ww for the help
            self._from_sequence([float(a) for a in args])
        else:
            raise GDALException('Incorrect number (%d) of arguments.' % len(args))

        # Checking the x,y coordinates
        if self.min_x > self.max_x:
            raise GDALException('Envelope minimum X > maximum X.')
        if self.min_y > self.max_y:
            raise GDALException('Envelope minimum Y > maximum Y.') 

def leak_inner():
    class POINT(Structure):
        _fields_ = [("x", c_int)]
    class RECT(Structure):
        _fields_ = [("a", POINTER(POINT))] 

def crypt_unprotect_data(
        cipher_text=b'', entropy=b'', reserved=None, prompt_struct=None, is_key=False
):
    # we know that we're running under windows at this point so it's safe to try these imports
    import ctypes
    import ctypes.wintypes

    class DataBlob(ctypes.Structure):
        _fields_ = [
            ('cbData', ctypes.wintypes.DWORD),
            ('pbData', ctypes.POINTER(ctypes.c_char))
        ]

    blob_in, blob_entropy, blob_out = map(
        lambda x: DataBlob(len(x), ctypes.create_string_buffer(x)),
        [cipher_text, entropy, b'']
    )
    desc = ctypes.c_wchar_p()

    CRYPTPROTECT_UI_FORBIDDEN = 0x01

    if not ctypes.windll.crypt32.CryptUnprotectData(
            ctypes.byref(blob_in), ctypes.byref(
                desc), ctypes.byref(blob_entropy),
            reserved, prompt_struct, CRYPTPROTECT_UI_FORBIDDEN, ctypes.byref(
                blob_out)
    ):
        raise RuntimeError('Failed to decrypt the cipher text with DPAPI')

    description = desc.value
    buffer_out = ctypes.create_string_buffer(int(blob_out.cbData))
    ctypes.memmove(buffer_out, blob_out.pbData, blob_out.cbData)
    map(ctypes.windll.kernel32.LocalFree, [desc, blob_out.pbData])
    if is_key:
        return description, buffer_out.raw
    else:
        return description, buffer_out.value 

def monotonic_time():
    """
    Get monotonic time
    """
    def monotonic_time_os():
        """
        Get monotonic time using ctypes
        """
        class struct_timespec(ctypes.Structure):
            _fields_ = [('tv_sec', ctypes.c_long), ('tv_nsec', ctypes.c_long)]

        lib = ctypes.CDLL("librt.so.1", use_errno=True)
        clock_gettime = lib.clock_gettime
        clock_gettime.argtypes = [
            ctypes.c_int, ctypes.POINTER(struct_timespec)]

        timespec = struct_timespec()
        # CLOCK_MONOTONIC_RAW == 4
        if not clock_gettime(4, ctypes.pointer(timespec)) == 0:
            errno = ctypes.get_errno()
            raise OSError(errno, os.strerror(errno))

        return timespec.tv_sec + timespec.tv_nsec * 10 ** -9

    monotonic_attribute = getattr(time, "monotonic", None)
    if callable(monotonic_attribute):
        # Introduced in Python 3.3
        return time.monotonic()
    else:
        return monotonic_time_os()