Checking register values

[Stubbz]

I have some code that runs in a loop until a button is pushed. At this point it is meant to branch into a different sub-routine.

I am attempting this by using the button to set off an interrupt, which then sets a value of a register (e.g. r16). I've then been told to use "TST" command, which is meant to set the zero, overflow flags. How do I use this to branch to another routine if the register has changed to a known number.

[Darkwraith]

Do you mean the TEST instruction?