Why a condition like If (~Input) changes to a complex condition with ternary operator ?

When I am trying to generate C code with Embedded Coder, the following condition

if (~Input)

is converted to the following ugly condition

if ((boolean_T)((int32_T)((Input ? ((int32_T)1) : ((int32_T)0)) ^ 1))) {

Is there any option to change in the setting to avoid this type of code being generated?

Is there a reason why this code would be generated instead of a simpler alternative?

The same code is generated if I change the condition to:

if (false == Input)

[Les Beckham]

Yikes. That is ugly. Just curious, what is the type (class) of Input? Double? Logical?

Also, are you sure there isn't a typo? Correct me if I'm wrong, but isn't this going to be 1: ((int32_T)0)) ^ 1))

[Miguel]

The class of variable "Input" is "boolean_T".

As I see, after the ^ operator, the result should be 1 if the Input is 0. The condition is performed correctly, but it is strange how it is written and not sure the advantage.

[Walter Roberson]

Bleh, that code is equivalent to

xor(1, Input ~= 0)

which is pretty ugly.

What happens if you change the condition to

if (Input == 0)

?

[Miguel]

I tried this different condition and the generated code was the same.

Answer 1

[Miguel]

Thanks everybody to take the time to review the question.

After reviewing all the possible options in the Code Generator and comparing one configuration that generated the ugly code vs a new one that didn't generate it, It was found that the parameter responsible for the ugly code is:

The ugly code is generated when it is set to "Bitwise operator"

[Les Beckham]

You are quite welcome. I'm glad you found a solution.

Answer 2

[Les Beckham]

So, the original condition if (~Input) is C code and not Matlab code? If so, you should use the logical not operator which is ! in C instead of ~ (as it is in Matlab).

~false in C will be 0xFFFFFFFE (or similar) and the ugly ternary expression coerces that back to a 1.

BTW - please post comments as comments rather than answers.

[Walter Roberson]

No, the original is MATLAB code, but Embedded Coder is generating the ugly version.

[Les Beckham]

I thought that too until OP said "The class of variable "Input" is "boolean_T". Perhaps he meant in the generated code. I meant in the original Matlab code when I asked that. Probably a misunderstanding.

@Miguel - can you tell us the class of Input in the Matlab code instead of in the generated C code?

[Miguel]

The original code was Matlab code. The "Input" variable type was inherited from simulink and it was of type boolean. The code is in a Matlab function inside of a simulink model.

In the generated C code, the "Input" variable was of type "boolean_T".