Shadow Register Problem

[Adam Y.]

That said, I'm unclear as to why you are unable to operate directly on the registers with your structures. If the compiler is generating code that utilizes bit set/clear instructions, those should be read/modify/write type of operations and should perform no differently than you manually read/modify/writing the registers as you seem to propose.

Well. Reading the manual it makes it pretty clear that if Im going to do any operations to certain registers that I either have to do it to all 32-bits or risk corrupting the register which would actually mean your example code wouldn't work unless you added a few extra zeros. Don't ask me why because its not applicable for any of their other peripherals that I have used. Only the CAN bus is like this.

I realize that some CPU vendor's header files promote this approach, and for CPU specific hardware registers, portablity isn't a big concern. Where I've seen problems like this create a mess is many years later, when you want to impliment a new compiler, from a new vendor.

Im not too worried about this happening because there is probably only going to be one compiler for this device for as long as I live.