Does Simulink offer any block that can tell me if the input is signed or unsigned ?

Hello,

I am using Simulink/Embedded Coder and I was implementing a subsytem that needs to know if one of its inputs is signed or unsigned.

is there a block/function that can tell if an input is signed or unsinged? For example if the type of the input is Uint8, Uint16,Uint32 then the output of the block will be 0, and if the type is Int8, Int16, Int32 the block will be 1, let's say.

Thank you

Diaa

[Paul]

I don't think, but could be wrong, that there is a block that does what you ask. But, with more information about what the subsystem would do based on the signed-ness of the input, maybe there is an alternative approach.

[Diaa Younes]

Hi Paul,

The alternative approach will be that the user of the subsytem will tell that subsystem via an additional port whether the data type is signed or unsigned, but a block/function that determines this will make it less error prone.

Thanks

Diaa

[Paul]

Does the subsystem in question behave fundamentally differently for a signed input compared to an unsigned input?

[Diaa Younes]

yes and that's why I needed it

Answer 1

[Benjamin Thompson]

There is a block in the Math Operations library called "Sign".

[Diaa Younes]

Thanks for your answer.

The sign block detects if the value of the input is positive or negative.

But I am looking for a block that detects the data type, not the value.

So For unsigned integer type we get say 0 and for signed integer type (regarless if it's positive or negative) we get say 1.

Thanks

Diaa

[Benjamin Thompson]

The Signal Attributes library in Simulink has blocks similar to what you are asking for, such as data type inheritance, data type propagation. Or you could use a MATLAB Function block and use the "isa" functions to check on the type of the incoming inputs: isinteger, isnumeric.

isa(uint32(3), 'uint32')

ans =

logical

1

[Diaa Younes]

Your suggsetion of having a function block and the "isa" seems to be the solution. I tried it, it works; at least in simulation. I am yet to try to see if embeded coder will be fine with.

function y = fcn(u)

y = isa(u, 'uint8') || isa(u, 'uint16') || isa(u, 'uint32') || isa(u, 'uint64') ;

The Simulink signal attribute block didn't seem to help.

Thank for your answer.

Diaa