Reading constants and variables from external header files in Matlab Coder

If I have the C header file external_vars.h containing:

const int ext_var = 5;

How do I use it in a Matlab Coder generated C function? The following code doesn't work, as ext_var is not defined in the Matlab code.

function external_test() %#codegen

coder.cinclude('external_vars.h')
a = ext_var;
end

Answer 1

[Denis Gurchenkov]

If you have an Embedded Coder license, you can use coder.storageclass to bind an extern C variable to a variable in MATLAB function: https://www.mathworks.com/help/ecoder/ref/coder.storageclass.html?s_tid=doc_ta

Without Embedded Coder, one possible workaround is to have a C function that reads/writes to this variable, and call that C function using coder.ceval.

[Philip Bergander]

Thanks for the response! I considered the workaround earlier too, and it might be enough for my use. I'll realise if the use of ecoder is necessary, in that case my employer will have to get a license.