C language encapsulation

Hello, may I ask if this library supports encapsulating the C language? For example, how can the following code be packaged using fastffi?
```C
// func.h
extern "C" {
extern int func(int **matrix, int n);
};

// func.cpp
int func (int ** matrix, int n) {
// do xxx
return sum;
}
```

Review fastFFI's current support and documentation for C/C++ interoperability, using the func.h and func.cpp example as the starting point. Determine whether this pointer-based example is supported and identify the project entry points or tests that would need to define the expected behavior.

Written by the indexing model from the issue text.