diff options
Diffstat (limited to 'rfc1982_serial_number.py')
| -rw-r--r-- | rfc1982_serial_number.py | 23 |
1 files changed, 10 insertions, 13 deletions
diff --git a/rfc1982_serial_number.py b/rfc1982_serial_number.py index 5344b91..9cb1a09 100644 --- a/rfc1982_serial_number.py +++ b/rfc1982_serial_number.py @@ -4,25 +4,22 @@ class Serial: modulus = 2 ** 32 - @property - def bitmask(self): - return self.modulus - 1 - - @property - def signbit(self): - return self.modulus >> 1 - def __init__(self, val): - self._val = int(val) & self.bitmask + self._val = int(val) + if self._val < 0 or self._val >= self.modulus: + raise ValueError def __add__(self, val): - return type(self)(self._val + int(val)) + val = int(val) + if val < 0 or val > (self.modulus - 1) >> 1: + raise ValueError + return type(self)((self._val + val) & (self.modulus - 1)) def __le__(self, other): - return (self.modulus - int(self) + int(other)) & self.signbit == 0 + return (self.modulus - int(self) + int(other)) & (self.modulus >> 1) == 0 def __ge__(self, other): - return (self.modulus + int(self) - int(other)) & self.signbit == 0 + return (self.modulus + int(self) - int(other)) & (self.modulus >> 1) == 0 def __eq__(self, other): return int(self) == int(other) @@ -53,7 +50,7 @@ def step(start, finish): if __name__ == "__main__": from random import randint - for test in range(100): + for test in range(10000): i1 = Serial(randint(0, Serial.modulus - 1)) i2 = Serial(randint(0, Serial.modulus - 1)) |