#python 3.7

from ctypes import *

class TestCaseA(Union):
    _fields_ = [("a", c_uint32, 16), ("b", c_uint16, 8)]

class TestCaseB(Union):
    _fields_ = [("a", c_uint32, 16), ("b", c_uint16, 16)]
    
class TestCaseC(Union):
    _fields_ = [("a", c_uint32, 16), ("b", c_uint16)]
    
def test_union(test_case):
    buff = bytearray(4)
    bitfield_union = test_case.from_buffer(buff)
    bitfield_union.a = 1
    bitfield_union.b = 2
    print("a is {}".format(bitfield_union.a))
    print("b is {}".format(bitfield_union.b))
    print("Buffer: {}\n".format(buff))

print("Test Case A")
test_union(TestCaseA)
print("Test Case B")
test_union(TestCaseB)
print("Test Case C")
test_union(TestCaseC)