Thread: How do I force my compiler to access HW registers as 32 bit instead of bytes?

Originally Posted by tabstop

Unionizing the bitfields requires 32 bits of space. A register variable and using bitmasks requires 32 bits of space (unless you want to store the values separately from the register-as-a-whole, then that would take 64 bits).

I have never used "union" before. What will union do to the struct?

Originally Posted by samdomville

I have never used "union" before. What will union do to the struct?

Nothing.

union just overlays two variables into the same memory location (broadly speaking). So you would have a union with an int and your struct, and each of them would use the same 32 bits of memory. (But reading/writing the int would force the compiler to read all 32 bits, instead of just 8 sometimes.)