This is doing extra work for all miscregs when only the SPSR is affected. This should be a function just for picking the right SPSR index and only called when the SPSR is accessed, basically just exporting the switch statement in the original code into a function.

Changed this to only call flattenMiscIndex if SPSR, however I imagine it's a wash since this is being inlined in the function and the first thing in does is the check.