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from functools import reduce
from os import urandom
from ufastrsa.util import get_bit_length
class Random:
def __init__(self, seed=None, rndsrc=None):
if rndsrc is None:
rndsrc = urandom
self.rndsrc = rndsrc
def getrandbits(self, k):
if not k >= 0:
raise ValueError("number of bits must be >= 0")
return reduce(
lambda x, y: x << 8 | y,
self.rndsrc(k >> 3),
int.from_bytes(self.rndsrc(1), "little") & ((1 << (k & 7)) - 1),
)
def randint(self, a, b):
if a > b:
raise ValueError("empty range for randint(): %d, %d" % (a, b))
c = 1 + b - a
k = get_bit_length(c - 1)
while True:
r = self.getrandbits(k)
if r <= c:
break
return a + r
def rndsrcnz(self, size):
rv = self.rndsrc(size).replace(b"\x00", b"")
mv = size - len(rv)
while mv > 0:
rv += self.rndsrc(mv).replace(b"\x00", b"")
mv = size - len(rv)
assert len(rv) == size
return rv
basernd = Random()
rndsrc = basernd.rndsrc
getrandbits = basernd.getrandbits
randint = basernd.randint
rndsrcnz = basernd.rndsrcnz
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