DPI C++ Exported functions

[zhon1231]

Hi all,

I've been practicing with the DPI calls and was able to take full advantage of the DPI Import call. However, the DPI export does not seem to work for me. My code essentially looks like this:

// in SV

package my_dpi_pkg;

task get_value(input int idx, output longint data);

data = a[idx];

endtask : get_value

export "DPI-C" task get_value;

...

endpackage

// in C++, my_model.h

extern void get_value(int idx, long long *data)

....

// in C++, my_model.cc

void my_model::do_something() {

...

get_value(0, data);

}

However, when the C++ files compile to .o files, I get the error message, "undefined reference to get_value(..."

Any ideas on why I am seeing this error?

Thanks!!!

Billy

[dave_59]

For C++, you need to do

extern "C" get_value(
    int idx,
    int64_t* data);

If you you are using Questa, you should generate this header file from your SV code directly using the switch -dpiheader file.h. That way you can be sure at compile time that your arguments across the DPI match up.

One other tip about using DPI exports, make sure you use only SV tasks when your call might consume time, otherwise use stick with SV functions. There is some extra work to deal with process control if your process gets terminated.