Had the same question. This is the minimal implementation of the error, so there is no clue what was the original purpose. I think as it is, it indexes a table

Had the same question. This is the minimal implementation of the error, so there is no clue what was the original purpose. I think as it is, it indexes a table where the first positions return tab[0], the next ffff/1ff will return tab[1] and so on. If I see such a code at work I would reject it in less than 1ms