Thank you guys so much for the extensive help. PaulS, that was really nice of you to go so far.
It seems C doesn't quite like passing structs around by reference, but I know it's perfectly sensible in C++. I wonder: If a function accepts a struct where the argument should be a struct pointer, does this mean that structs are actually just pointers (like arrays?), and member access is just shorthand for pointer arithmetic?
I don't have the hardware either, it's still in the mail. But getting it compiled takes a huge worry off my shoulders. Thanks so much.