How to convert a ubyte to a byte without losing information?

[Adam D. Ruppe via Digitalmars-d-learn]

On Sunday, 16 August 2015 at 11:43:24 UTC, CharmingChocolate 
wrote:
> I can cast a ubyte to a byte, but as far as I know I'd only get 
> positive values out of that conversion.

ubyte b = 255;
byte b2 = cast(byte) b;
assert(b2 == -1);


No information is lost by that cast, all the bits remain exactly 
the same.