def minimum_size(format):
    """
    Return the minimum possible size of the given packed data format.
    """
    if not format[:1] in b"@=<>!":
        format = b"!" + format

    return _calcsize(format.replace(b"$", b""))

    def unpack(self, format_text):
        """Unpack bytes using struct modules format

        :param format_text: struct's module format
        :type  format_text: :class:`str`
        :return data: result from :func:`struct.unpack_from`
        :rtype: :class:`tuple`
        """
        data = _unpack_from(format_text, self.data, self.offset)
        self.offset += _calcsize(format_text)
        return data

def initial_size(format):
    """
    Return the size of the given packed data format up to the first
    variable-length string.
    """
    if format[:1] in b"@=<>!":
        byte_order = format[:1]
        format = format[1:]
    else:
        byte_order = b"!"

    index = format.find(b"$")
    if not index:
        return 0
    elif index > 0:
        if b"$$" in format:
            raise error("invalid sequence in netstruct format")
        format = format[:index]
    return _calcsize(byte_order + format)

    _type_ = "h"
_check_size(c_short)

class c_ushort(_SimpleCData):
    _type_ = "H"
_check_size(c_ushort)

class c_long(_SimpleCData):
    _type_ = "l"
_check_size(c_long)

class c_ulong(_SimpleCData):
    _type_ = "L"
_check_size(c_ulong)

if _calcsize("i") == _calcsize("l"):
    # if int and long have the same size, make c_int an alias for c_long
    c_int = c_long
    c_uint = c_ulong
else:
    class c_int(_SimpleCData):
        _type_ = "i"
    _check_size(c_int)

    class c_uint(_SimpleCData):
        _type_ = "I"
    _check_size(c_uint)

class c_float(_SimpleCData):
    _type_ = "f"
_check_size(c_float)

_check_size(c_ushort)

class c_long(_SimpleCData):
    _type_ = 'l'


_check_size(c_long)

class c_ulong(_SimpleCData):
    _type_ = 'L'


_check_size(c_ulong)
if _calcsize('i') == _calcsize('l'):
    c_int = c_long
    c_uint = c_ulong
else:

    class c_int(_SimpleCData):
        _type_ = 'i'


    _check_size(c_int)

    class c_uint(_SimpleCData):
        _type_ = 'I'


    _check_size(c_uint)