I'm sad to say I've seen code where the answer is sprintf hex output into a temp string and some string functions to see if the last single char substring eq and/or neq certain values at the string level correlating with the 3rd bit being set (so ends in hex 2, well that means bit 3 can't be set... ends in hex 4 ding ding ding we have a winner) Only a slight upgrade in readability on a chain of mystifying if/then/else is a case statement with 16 possibilities. Only a slight upgrade on that is "optimizing" for speed by squirting out octal so your lookup stable is half the size of a hex one.
