Feature request: Calling convention for interrupt functions which take arguments and return values

[KyleCardoza]

This is a bit of an odd one; what I want to do is use the COP interrupt as a kernel API entry point, taking arguments in C, X, and Y, and use that to call a kernel function, returning values in any or all of C, X, and Y as appropriate to the call. I can always manipulate the stack with inline asm, or just handle it with a trampoline in an external asm file, but it would be wonderful if there were a way for the compiler to handle this for me.