As you're doing it on an 8051, and not worried about portability, why not use a bit-addressable variable?
I don't know what you mean Andy, I have a serial stream of data and I keep shifting left till I get the frame sync signal right which is 32 bits.
Now I shift left another 32 bits for next message which is bitfields either code or data or idle cosdeword. I need the union of structure so that i test first for the frame sync DWORD then after shifting another 32 bits I check bitfields to extract address and data and stop when I have either idle codeword or new address.
My other question is I have 2 methods of shifting data in, since my baude rate is 512 BPS I can use the timer interrupt to start counting the pulses, or I can use edge interrupt, or I can combine the two together. Which method is better you think for noise immunity?
Mahmood