Can I expose input fixed point data type parameters to mask variables in Simulink?

I have experimented with Data Type Propagation in Simulink 2013b, and it can do some of what I want, but ideally I'd like to have mask variables that would know the incoming sign, word and fraction lengths of inputs to the mask, and then I can use those variables to modify the mask contents (e.g. change a value of a constant block in the mask). Is this possible? If not, are there any other tricks to know besides the Data Propagation block which can control output data type relative to input (e.g. add a constant number of bits and move the binary point)

Thanks, Dara

[Dara Parsavand]

Another example is a bit reverse block. It's easy to make a hardcoded (in terms of input bitwidth) block that reverses bits, but if your mask doesn't know the input bitwidth, it seems hard to make a parmeterizable block.

(There may be other ways to do bit reverse, but I was just slicing into indiviual bits, and then concatenating in reverse order. Obviously no matter what way you do it, this block costs nothing in hardware).