BIT_MASK
mask = (*addr) & BIT_MASK(size);
mask = ~(*addr) & BIT_MASK(size);
mask = (*addr) & BIT_MASK(offs);
mask = (*addr) & ~BIT_MASK(offs);
mask = (*addr) & BIT_MASK(size);
mask = ~(*addr) & ~BIT_MASK(offs);
mask = ~(*addr) & BIT_MASK(size);
addr[size / BITS_PER_LONG] = BIT_MASK(tail);
mask = BIT_MASK(tail);
mask = BIT_MASK(tail);
maxbits &= BIT_MASK;
zs->zs_maxbits &= BIT_MASK;