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# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
"""Serial Number Arthimetic from RFC 1982"""
class Serial:
def __init__(self, value, bits=32):
self.value = value % 2 ** bits
self.bits = bits
def __repr__(self):
return f'dns.serial.Serial({self.value}, {self.bits})'
def __eq__(self, other):
if isinstance(other, int):
other = Serial(other, self.bits)
elif not isinstance(other, Serial) or other.bits != self.bits:
return NotImplemented
return self.value == other.value
def __ne__(self, other):
if isinstance(other, int):
other = Serial(other, self.bits)
elif not isinstance(other, Serial) or other.bits != self.bits:
return NotImplemented
return self.value != other.value
def __lt__(self, other):
if isinstance(other, int):
other = Serial(other, self.bits)
elif not isinstance(other, Serial) or other.bits != self.bits:
return NotImplemented
if self.value < other.value and \
other.value - self.value < 2 ** (self.bits - 1):
return True
elif self.value > other.value and \
self.value - other.value > 2 ** (self.bits - 1):
return True
else:
return False
def __le__(self, other):
return self == other or self < other
def __gt__(self, other):
if isinstance(other, int):
other = Serial(other, self.bits)
elif not isinstance(other, Serial) or other.bits != self.bits:
return NotImplemented
if self.value < other.value and \
other.value - self.value > 2 ** (self.bits - 1):
return True
elif self.value > other.value and \
self.value - other.value < 2 ** (self.bits - 1):
return True
else:
return False
def __ge__(self, other):
return self == other or self > other
def __add__(self, other):
v = self.value
if isinstance(other, Serial):
delta = other.value
elif isinstance(other, int):
delta = other
else:
raise ValueError
if abs(delta) > (2 ** (self.bits - 1) - 1):
raise ValueError
v += delta
v = v % 2 ** self.bits
return Serial(v, self.bits)
def __iadd__(self, other):
v = self.value
if isinstance(other, Serial):
delta = other.value
elif isinstance(other, int):
delta = other
else:
raise ValueError
if abs(delta) > (2 ** (self.bits - 1) - 1):
raise ValueError
v += delta
v = v % 2 ** self.bits
self.value = v
return self
def __sub__(self, other):
v = self.value
if isinstance(other, Serial):
delta = other.value
elif isinstance(other, int):
delta = other
else:
raise ValueError
if abs(delta) > (2 ** (self.bits - 1) - 1):
raise ValueError
v -= delta
v = v % 2 ** self.bits
return Serial(v, self.bits)
def __isub__(self, other):
v = self.value
if isinstance(other, Serial):
delta = other.value
elif isinstance(other, int):
delta = other
else:
raise ValueError
if abs(delta) > (2 ** (self.bits - 1) - 1):
raise ValueError
v -= delta
v = v % 2 ** self.bits
self.value = v
return self
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