Betrayed by a bitfield

in that case I have to agree with the other poster who said that if the compiler considers it Ok to write over any arbitrary memory locations, as long as what it's writing matches what the compiler thinks is already there, then that compiler is unsuitable for use with any memory mapped I/O as it will feel free to clobber the new data that is waiting to be read.

since this sort of thing has been part of C's traditional strength, this doesn't seem like a sane interpretation to me.