I don't like it personally, as alot of people will preach I keep my definitions in my source files and let my header file be a window into the public areas of the source file. Your header file would be much cleaner if all the #ifdef's and #endif's (except the double inclusion protection at the top) were removed. Why put all the clutter in header file? Only put what you want the outside world to be able to access here and it is much easier to look at.

Also, I'm not crazy about putting all my memory mapped variables in one header file either. Putting all variable definitions/declarations in their respective source/header files makes the code more modular.