I4_BITS
struct sw842_hlist_node4 node4[1 << I4_BITS];
ret = add_bits(p, p->index4[b >> 2], I4_BITS);
u64 n4 = (pos >> 2) % (1 << I4_BITS);
#define I4_FIFO_SIZE (4 * (1 << I4_BITS))
return __do_index(p, 4, I4_BITS, I4_FIFO_SIZE);