Reading and converting binary file 2 bits at a time

[Andrew Brown via Digitalmars-d-learn]

Thanks very much for all the help, your advice worked a treat. 
One final question, originally I was defining the struct inside 
the main loop and it was using 4 bytes per field rather than 2 
bits, e.g.:

import std.bitmanip;
import std.stdio;

struct Crumb1
{
   mixin(bitfields!(
		   ubyte, "one", 2,
		   ubyte, "two", 2,
		   ubyte, "three", 2,
		   ubyte, "four", 2));
}

void main()
{
   struct Crumb2
   {
     mixin(bitfields!(
		     ubyte, "one", 2,
		     ubyte, "two", 2,
		     ubyte, "three", 2,
		     ubyte, "four", 2));
   }

   writeln(Crumb1.sizeof, " ", Crumb2.sizeof);

}

outputs:

1 16

Is this correect behaviour?

Andrew