BITS_PER_OBJ
#define OBJS_PER_BYTE (BITS_PER_BYTE / BITS_PER_OBJ)
#define OBJ_MASK ((1 << BITS_PER_OBJ) - 1)
*shift = (OBJS_PER_BYTE - off - 1) * BITS_PER_OBJ;
object_map_bytes = DIV_ROUND_UP_ULL(num_objects * BITS_PER_OBJ,