Reading and converting binary file 2 bits at a time

[Rikki Cattermole via Digitalmars-d-learn]

On 27/08/15 9:00 PM, Andrew Brown wrote:
> Hi,
>
> I need to read a binary file, and then process it two bits at a time.
> But I'm a little stuck on the first step. So far I have:
>
> import std.file;
> import std.stdio;
>
> void main(){
>    auto f = std.file.read("binaryfile");
>    auto g = cast(bool[])    f;
>    writeln(g);
> }
>
> but all the values of g then are just true, could you tell me what I'm
> doing wrong? I've also looked at the bitmanip module, I couldn't get it
> to help, but is that the direction I should be looking?
>
> Thanks very much
>
> Andrew

You do not use the std.file to prefix call read.
The bool type is one byte in size. A value of 0 is false, anything else 
is true. But commonly defined as 1.

So if you want to read only one bit you will need to use e.g. bit shifts 
and bitwise and operator.

I believe bitsSet may help you.
http://dlang.org/phobos/std_bitmanip.html#.bitsSet