Issue while using ctypes in python

[GiggsB]

I have the below python script which I am using to collect data from a microcontroller using SPI communication. That part is working fine, however, now I am trying to implement CRC function from a c file.

import ctypes
lib = ctypes.CDLL('/home/pi/serial_communication/crc.so')
lib.crc32Word.argtypes = ctypes.c_uint32, ctypes.c_void_p, ctypes.c_uint32
lib.crc32Word.restype = ctypes.c_uint32

INTERRUPT_GPIO=12
pi.set_mode(INTERRUPT_GPIO, pigpio.INPUT)
C=0
 
def output_file_path(): return os.path.join(os.path.dirname(__file__), datetime.datetime.now().strftime("%dT%H.%M.%S") + ".csv")
 
def spi_process(gpio,level,tick):
    data = [0]*1024
    spi.xfer([0x02])
    with open(output_file_path(), 'w') as f:
        for x in range(1):
            spi.xfer2(data)
            values = struct.unpack("<" +"I"*256, bytes(data))
            C = lib.crc32Word(0xffffffff,data,len(data))
            f.write("\n")
            f.write("\n".join([str(x) for x in values]))
        print(C)

cb1=pi.callback(INTERRUPT_GPIO, pigpio.RISING_EDGE, spi_process)

while True:
    time.sleep(1)

The C function that I am trying to invoke from the python script is

crc32Word(uint32_t crc, const void *buffer, uint32_t size)

But when I run the above script, I receive error as:

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python3.7/threading.py", line 917, in _bootstrap_innerself.run()
  File "/usr/lib/python3/dist-packages/pigpio.py", line 1213, in run cb.func(cb.gpio, newLevel, tick)
  File "2crc_spi.py", line 50, in spi_process
    C=lib.crc32Word(0xffffffff,data,len(data))
ctypes.ArgumentError: argument 2: <class 'TypeError'>: wrong type

One way to solve this is to use data = bytes([0]*1024). But if I use this method, the file stores 0s even if I am actually receiving data correctly (checked using logic analyzer).

Can someone please help? Thanks.