How can I use a macro from custom C code in code generated by MATLAB Coder R2022b?

I am writing MATLAB code intended for code generation with MATLAB Coder in MATLAB R2022b. I have a "uint8" macro "MYVAL" defined in a C header file “myHeader.h”.

I want to use my macro from "myHeader.h" in the code generated from MATLAB Coder. Is there a way to use my macro in the generated code?

Answer 1

[MathWorks Support Team]

One way to use a custom macro in generated code is with the "coder.opaque" function. Please see the documentation for this function below:

https://www.mathworks.com/help/releases/R2022b/coder/ref/coder.opaque.html

Using the "coder.opaque" function, you can use a C macro in the default value ("value") argument. For instance, the MATLAB function below sets a variable "x" equal to a macro "MYVAL" defined in a custom header file:

function x = myFunction() %#codegen
  x = coder.opaque('uint8', 'MYVAL', 'HeaderFile', '"myHeader.h"');
  x = uint8(x);
end

If you generate C code from the above function, the generated function returns “MYVAL”. Please see the generated C function below:

/* Function Definitions */
uint8_T myFunction(void)
{
  return (uint8_T)MYVAL;
}

Please see the attached file "MacroInGeneratedCode.zip" for the files to follow this example.