def test_untemper_right_invert_tempering_without_and_mask(self):
expected = 172233979
tempered = 172234346 # y ^ (y >> l)
untempered = _untemper_right(tempered, 18,
(1 << get_numbits(tempered)) - 1)
self.assertEqual(expected, untempered)
def test_untemper_right_shift_half_bitsize(self):
bits = 0xE
shift = 2
mask = 0x1
tempered = self.temper_right(bits, shift, mask)
untempered = _untemper_right(tempered, shift, mask)
self.assertEqual(bits, untempered)
def test_untemper_right_smaller_than_bitshift(self):
bits = 12
shift = 4
mask = 7
tempered = self.temper_right(bits, shift, mask)
untempered = _untemper_right(tempered, shift, mask)
self.assertEqual(bits, untempered)
def test_untemper_right_last_shift_results_in_smaller_block(self):
bits = 0x1D
shift = 2
mask = 0x1
tempered = self.temper_right(bits, shift, mask)
untempered = _untemper_right(tempered, shift, mask)
self.assertEqual(bits, untempered)
def test_untemper_right_negative_shift_raises(self):
with self.assertRaises(ValueError):
_untemper_right(12, -1, 7)