NB_BITS_PER_LONG
#define BITS_TO_LONGS(x) howmany(x, NB_BITS_PER_LONG)
#define __bit_word(b) ((b) / NB_BITS_PER_LONG)
#define __bit_mask(b) (1UL << (b) % NB_BITS_PER_LONG)
KASSERT(max % NB_BITS_PER_LONG == 0, ("invalid bitmap size %lu", max));
for (i = 0; i < max / NB_BITS_PER_LONG; i++) {
return (i * NB_BITS_PER_LONG + ffsl(n) - 1);