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Change BitSequence comparison to use int value & pad bytes in tobytes() #255

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a61350b
Change comparison to use int value
addinh Jul 5, 2021
a14b569
minor fix
addinh Jul 5, 2021
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55 changes: 32 additions & 23 deletions pyftdi/bits.py
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Original file line number Diff line number Diff line change
Expand Up @@ -128,8 +128,10 @@ def tobyte(self, msb: bool = False) -> int:
def tobytes(self, msb: bool = False, msby: bool = False) -> bytearray:
"""Convert the sequence into a sequence of byte values"""
blength = (len(self)+7) & (~0x7)
sequence = list(self._seq)
if not msb:
if msb:
sequence = list(bytes(blength - len(self)) + self._seq)
else:
sequence = list(self._seq + bytes(blength - len(self)))
sequence.reverse()
bytes_ = bytearray()
for pos in range(0, blength, 8):
Expand Down Expand Up @@ -238,26 +240,21 @@ def __ne__(self, other):
return not self == other

def __le__(self, other):
return not self._cmp(other) <= 0
return self._cmp(other) <= 0

def __lt__(self, other):
return not self._cmp(other) < 0
return self._cmp(other) < 0

def __ge__(self, other):
return not self._cmp(other) >= 0
return self._cmp(other) >= 0

def __gt__(self, other):
return not self._cmp(other) > 0
return self._cmp(other) > 0

def _cmp(self, other):
# the bit sequence should be of the same length
ld = len(self) - len(other)
if ld:
return ld
for n, (x, y) in enumerate(zip(self._seq, other.sequence()), start=1):
if xor(x, y):
return n
return 0
a = int(self)
b = int(other)
return (a > b) - (a < b)

def __repr__(self):
# cannot use bin() as it truncates the MSB zero bits
Expand Down Expand Up @@ -418,15 +415,27 @@ def __int__(self):
"an integral type")
return BitSequence.__int__(self)

def __cmp__(self, other):
# the bit sequence should be of the same length
ld = len(self) - len(other)
if ld:
return ld
for n, (x, y) in enumerate(zip(self._seq, other.sequence()), start=1):
if x is not y:
return n
return 0
def _pseudo_int(self):
# returns int value of sequence by treating it as ternary sequence
value = 0
bit_value = {
0: 0,
BitZSequence.Z: 1,
1: 2,
}
for b in reversed(self._seq):
value *= 3
value += bit_value[b]
return value

def _cmp(self, other):
try:
a = self._pseudo_int()
b = other._pseudo_int()
except AttributeError: # if other is not BitZSequence, compare both as normal BitSequence
a = int(self)
b = int(other)
return (a > b) - (a < b)

def __and__(self, other):
if not isinstance(self, BitSequence):
Expand Down
31 changes: 21 additions & 10 deletions pyftdi/tests/bits.py
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Original file line number Diff line number Diff line change
Expand Up @@ -55,8 +55,8 @@ def test_bitwise_ops(self):
self.assertEqual(repr(self.bzs4.invert()), '00Z0Z101ZZ1011')
self.assertLess(self.bs5, self.bs6)
self.assertLessEqual(self.bs5, self.bs6)
self.assertLess(self.bs6, self.bs5)
self.assertLessEqual(self.bs6, self.bs5)
self.assertGreater(self.bs6, self.bs5)
self.assertGreaterEqual(self.bs6, self.bs5)

def test_cmp(self):
self.assertTrue(self.bs1 == self.bs1)
Expand All @@ -66,12 +66,12 @@ def test_cmp(self):
self.assertTrue(self.bzs1 != self.bzs2)
self.assertTrue(self.bs1 == self.bzs1)
self.assertTrue(self.bzs1 == self.bs1)
self.assertTrue(self.bzs3 != self.bzs2)
self.assertTrue(self.bzs3 == self.bzs2)
self.assertNotEqual(self.bzs4, self.bzs5)
bzs = BitZSequence(self.bs7)
self.assertTrue(bzs == self.bs7)
bzs |= BitZSequence('00Z0Z000ZZ0Z00')
self.assertFalse(bzs == self.bs7)
self.assertFalse(bzs == BitZSequence(self.bs7))
self.assertTrue(bzs.matches(self.bs7))

def test_representation(self):
Expand Down Expand Up @@ -161,9 +161,9 @@ def test_misc(self):
bl = [ba, bb]
bl.sort(key=int)
self.assertEqual(str(bl), "[00110000000000, 0011000000000000]")
self.assertEqual(str(ba.tobytes()), "[48, 0]")
self.assertEqual(str(ba.tobytes(True)), "[0, 12]")
self.assertEqual(str(bb.tobytes(True)), "[0, 12]")
self.assertEqual(ba.tobytes(), bytearray([48, 0]))
self.assertEqual(ba.tobytes(True), bytearray([0, 12]))
self.assertEqual(bb.tobytes(True), bytearray([0, 12]))

b = BitSequence(length=254)
b[0:4] = '1111'
Expand All @@ -174,9 +174,9 @@ def test_misc(self):
'00000000 00000000 00000000 00000000 00000000 00000000 00000000 '
'00000000 00000000 00000000 00000000 00000000 00000000 00001111')
self.assertEqual(
str(b.tobytes()),
'[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, '
'0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15]')
b.tobytes(),
bytearray([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15]))

b = BitSequence(bytes_=[0xa0, '\x0f', 0x77], msb=False, msby=False)
self.assertEqual(str(['%02x' % x for x in b.tobytes(False)]),
Expand All @@ -203,6 +203,17 @@ def test_concat(self):
'1111101010100111Z1Z010ZZ0100')
self.assertEqual(repr(self.bs7+self.bzs4),
'11Z1Z010ZZ010011111010101001')

def test_int(self):
self.assertEqual(int(BitSequence(65535)), 65535)
self.assertEqual(int(BitSequence(65536)), 65536)
self.assertEqual(int(BitSequence(65537)), 65537)
self.assertEqual(int(BitSequence(65539)), 65539)
self.assertEqual(int.from_bytes(BitSequence(65535).tobytes(), byteorder='big'), 65535)
self.assertEqual(int.from_bytes(BitSequence(65536).tobytes(), byteorder='big'), 65536)
self.assertEqual(int.from_bytes(BitSequence(65537).tobytes(), byteorder='big'), 65537)
self.assertEqual(int.from_bytes(BitSequence(65539).tobytes(), byteorder='big'), 65539)
self.assertEqual(int.from_bytes(BitSequence(65539).tobytes(msby=True), byteorder='little'), 65539)


def suite():
Expand Down