Question

I have a c++ application which writes blocks of unsigned char data. So I would be writing unsigned char data[8].

Now, I am using python (read ctypes functionality in python), to read and buffer it in my tool for further processing.

Problem
When I read the data from file and break it down into chunks of 8, all the resultant data is in string format.I have the following structure

class MyData(Union):
     _fields_=[ ("data",8 * c_ubytes), ("overlap", SelfStructure) ]

Now, I am trying to pass the data as follows

  dataObj = MyData(str[0:8])  

It throws an error, expected c_ubyte_Array_8 instance, got str. I think I need to convert string to array of size 8 of c_ubyte. Tried with bytearray but did not succeed. Please let me know how to do.

Answer 1

Try this:

(ctypes.c_ubyte * 8)(*[ctypes.c_ubyte(ord(c)) for c in str[:8]])