C-like structures in Python

bytes转Structure

def convert_bytes_to_structure(st: object, byte: bytes):
    assert  ctypes.sizeof(st) ==len(byte),'size error! need:%d,give:%d'%(ctypes.sizeof(st),len(byte))
    # ctypes.memmove(ctypes.pointer(st), byte, ctypes.sizeof(st))
    ctypes.memmove(ctypes.addressof(st), byte, ctypes.sizeof(st))

使用ctypes Structure来转换c中的结构体

class TYPE_BASE(ctypes.LittleEndianStructure):
    _pack_: int = 1
    def __init__(self, data: Union[bytes, list, tuple, set]) -> None:
        if isinstance(data, bytes):
            convert_bytes_to_structure(self, data)
        elif isinstance(data, (list, tuple, set)):
            convert_bytes_to_structure(self, bytes(data))
        elif isinstance(data, io.IOBase):
            data.readinto(self)
'''
struct MyClass{
    int val1;
    int val2;
    char buf[10];
};
'''
class MyClass(TYPE_BASE):
    # _pack_: int = 1
    _fields_: list = [
        ("val1", ctypes.c_int32),
        ("val2", ctypes.c_int32),
        ("buf", ctypes.c_byte * 10),
    ]
    # def __init__(self, data: Union[bytes, list, tuple, set]) -> None:
    #     super().__init__(data)

    def __str__(self) -> str:
        info=''
        info+='val1:%s\n'%self.val1
        info+='val2:%s\n'%self.val2
        info+='buf:%s\n'%bytes(self.buf)
        return info
def test_ty():
    # data=[1,0,0,0,2,0,0,0]+list(b'a'*10)
    data=int.to_bytes(1,4,'little')+int.to_bytes(2,4,'little')+b'a'*10
    obj=MyClass(data)
    print('bytes(obj):',bytes(obj))
    print(obj)
    
    data2=[10,0,0,0,20,0,0,0]+list(b'b'*10)
    #do not call __init__; use from_buffer_copy
    obj2=MyClass.from_buffer_copy(bytes(data2))
    print('bytes(obj2):',bytes(obj2))
    print(obj2)

输出：

bytes(obj): b'\x01\x00\x00\x00\x02\x00\x00\x00aaaaaaaaaa'
val1:1
val2:2
buf:b'aaaaaaaaaa'

bytes(obj2): b'\n\x00\x00\x00\x14\x00\x00\x00bbbbbbbbbb'
val1:10
val2:20
buf:b'bbbbbbbbbb'