import sys
from struct import unpack

# unpack way
def getCRC(filename):
    with open(filename, "rb") as f:
        crc = 0
        data =f.read(4)
        while data != b"":
            word, = unpack("I", data)
            crc ^= word
            data = f.read(4)
        print 'crc: {0:X}'.format(crc)

# array way
def getCRC1(filename):
    import os
    from array import array
    with open(filename, "rb") as f:
        data = array('I')
        data.fromfile(f, os.stat(filename).st_size / 4)
        crc = reduce(lambda x,y: x^y, data.tolist(), 0)
        print 'crc: {0:X}'.format(crc)

if __name__ == '__main__':
    if not len(sys.argv) == 2:
        print "Usage: python crc.py ELF_FILE"
    else:
        getCRC1(sys.argv[1])