[mattbee]

ARM was my start with assembler too. But you appear to a have forgotten there are 5 more registers you can use for that blit ;-)

[stusmith1977]

I can't remember how tight I made it... but I would think you need a couple spare: one for the number of iterations, and another for the screen stride. But yes, spilling registers like SP and LR is a useful trick if you need it.