How to fix 'ctypes.ArgumentError: argument 2: <type 'exceptions.TypeError'>: wrong type' error in RaspberryPi

Question

我想创建一个 C++ 库 (.so) 并在 Python 中使用它。 但正如您所见，C++ 函数参数是固定大小的数组。 如下所示创建 python 源时， lib.ShiftRows.argypes=types.c_void_p, ?] 我应该在“？”中输入什么类型的数据？部分？

而在实际使用上述class时，Python如何声明一个数组，以便声明与c++相同的数组变量？

AES.cpp:

void AESS::ShiftRows( char state[0x04][0x04]) {
int i, j, k, tmp;

for (i = 0; i<4; i++) {
    for (j = 4 - i; j<4; j++) {
        tmp = state[i][0];
        for (k = 0; k<4 - 1; k++) {
            state[i][k] = state[i][k + 1];
        }
        state[i][3] = tmp;
    }
  }
}

extern "C"
{
    AESS* AESS_new(){return new AESS();}
    void ShiftRows(AESS* aes,  char state[0x04][0x04]) {aes->ShiftRows(state);}
}

AESClass.py:

import ctypes

lib = ctypes.cdll.LoadLibrary('./libAESS.so')

class AESS():
    def __init__(self):
        lib.AESS_new.argtypes = []
        lib.AESS_new.restype = ctypes.c_void_p        

        lib.ShiftRows.argtypes=[ctypes.c_void_p , ?]
        lib.ShiftRows.restype= ctypes.c_void_p

        self.obj=lib.AESS_new()

    def ShiftRows(self, state):
        lib.ShiftRows(self.obj, state)

AES.py:

import numpy as np
from AESClass import AESS

state = np.zeros((4,4))

aes = AESS()

aes.ShiftRows(state)

Answer 1

选中 [Python 3.Docs]: ctypes - A foreign function library for Python（数组 部分）。

你可以这样做：

• AESClass.py:

  CharArr4 = ctypes.c_char * 4
  CharArr4Arr4 = CharArr4 * 4
  
  class AESS():
  
  # ...
  
          lib.ShiftRows.argtypes = [ctypes.c_void_p , CharArr4Arr4]
  

• AES.py（使用[SciPy]: numpy.ctypeslib.as_array(obj, shape=None)）：

  import numpy as np
  from AESClass import AESS, CharArr4Arr4
  
  
  state_arr = CharArr4Arr4()  # Initialize the 4 X 4 array to 0
  aes = AESS()
  aes.ShiftRows(state_arr)
  
  state = np.ctypeslib.as_array(state_arr)
  

  或反过来：

  # ...
  state = np.zeros((4, 4), dtype=np.int8)
  # ...
  aes.ShiftRows(np.ctypeslib.as_ctypes(state))