def throw_random_bits(lengths, mask, allow_overlap=False):
rval = BitSet(mask.size)
throw_random_gap_list(lengths, mask, lambda s, e: rval.set_range(s, e - s),
allow_overlap)
if not allow_overlap:
assert rval.count_range(0, rval.size) == sum(lengths)
return rval
def count_overlap(bits1, bits2):
"""
Count the number of bits that overlap between two sets
"""
b = BitSet(bits1.size)
b |= bits1
b &= bits2
return b.count_range(0, b.size)