How can I use bit operation functions like bitconcat with both fi and built-in integer types without branching on isfi?

I'm working with bit operation functions (e.g., bitconcat) that only accept fi objects as input. My code sometimes deals with built-in integer types (like uint8, int16, etc.), so I currently check with isfi(var) and branch accordingly to convert to fi only when needed.

Is there a cleaner or more efficient way to ensure compatibility with bitconcat and similar functions, without manual branching on input type?

If I write:

a = uint8(2)

bitconcat(a)

I got error like: Input arguments must be fi objects.

Current workaround

if isfi(var)

% Already fi

else

var = fi(var, ...);

end

Answer 1

[MathWorks Fixed Point Team]

Use castIntToFi to handle both fi and integer types.

If you want your code to work with both built-in integer types and fi objects, you can use the castIntToFi utility. This function converts integer types to equivalent fi objects, and passes through fi objects unchanged—eliminating the need for explicit branching.

x = uint8(15); % Built-in integer type

y = fi(3, 0, 8, 0); % fi object

% Use castIntToFi to ensure both are fi objects

x_fi = castIntToFi(x);

y_fi = castIntToFi(y);

result = bitconcat(x_fi, y_fi); % Now works regardless of original type

• If the input is already a fi object, castIntToFi returns it unchanged.
• If the input is an integer type, it creates a fi object with the same value and numerictype.