ASSOC_ARRAY_LEVEL_STEP
#define ASSOC_ARRAY_LEVEL_STEP_MASK (ASSOC_ARRAY_LEVEL_STEP - 1)
level += ASSOC_ARRAY_LEVEL_STEP;
sc_level = level + ASSOC_ARRAY_LEVEL_STEP;
BUG_ON(diff < level + ASSOC_ARRAY_LEVEL_STEP);
level += ASSOC_ARRAY_LEVEL_STEP;
level = diff + ASSOC_ARRAY_LEVEL_STEP;
const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP;