| # bits1 = # bits1 ⊦ bits2 + bits1 = [], bits0 = [], lastn(# bits1, fillsgn(# bits1, bitsand(bits1, bits0))) = lastn(# bits1, fillsgn(# bits1, bitsand(bits2 + bits1, bits0))) |
⊦ bits2 + bits1 = [], bits0 = [], lastn(# bits1, fillsgn(# bits1, bitsand(bits1, bits0))) = lastn(# bits1, fillsgn(# bits1, bitsand(bits2 + bits1, bits0)))