Cheating via Lookup Table

One of the assignments in college was to write a binary-to-decimal converter in MIPS assembly, of all things. The goal was, given a 32-bit unsigned number like 0xdecafbad, print out “three seven three seven eight four four six five three”. Or “six four” for 0x40.

So the professor got 150 submissions like

print_digit:
  cmp #0
  beq print_zero
... nine more digits ...
print_zero:
  (load address of "zero" string)
  (call library function to actually print)
  rts
... nine more digits ...

I almost coded mine the same way, but I asked myself, “I don't want to write the same code for ten cases. How would a real hacker solve this?” So I made a lookup table of pointers to each string, and my function was more like:

print_digit:
  (load value from "string_addrs + digit")
  (call library function to actually print)
  rts

Of course, I’m just showing snippets of the core function; everyone had to write their own complete program.

The prof had apparently never seen my approach, because he asked if I had even run it to see if it worked. In shock, I said something like, “Yeah, why? Didn’t it work for you?” and he replied, “Um well yes. I just thought you maybe cheated.”

Haha, no. I’m just awesome.