How do I link extern variables and stateflow input when using custom c code?

I am trying to use a custom C code function in my stateflow chart. The C file looks like

extern float A1;
extern float A2;
extern float A3;

float do_something(void) {
    return cos(A1)*sin(A2)*cos(A3);
}

I also have three stateflow inputs of the same name? When I run the simulink model, I get undefined reference errors for A1, A2 and A3. How can link the inputs with the extern variables so that the inputs to the stateflow chart can be used in the C code function?

Also please don't tell me to do:

float do_something(float A1, float A2, float A3) {
    return cos(A1)*sin(A2)*cos(A3);
}

Since, I know that this works. I need the inputs to be assigned to the extern variables.

Thanks

Answer 1

[Fangjun Jiang]

follow this demo model

Including Custom C Code Functions and Structures

[Alexander Dingwall]

This example isn't the same as what I want.

I can't upload my model and C code if you want?