No pbr in extern call?

[newbieg]

I'm trying to do a pass by reference in an extern function call.

extern void getCpuid(int &a, int &b, int &c, int &d);

kernel.c:4:26: error: expected ‘;’, ‘,’ or ‘)’ before ‘&’ token
4 | extern void getCpuid(int &a, int &b, int &c, int &d);

I'm going to read the systemV abi pdf found here: https://uclibc.org/docs/psABI-x86_64.pdf
I don't know if I'll find an answer there, so I'm hoping someone with more experience in calling assembly from C/C++ might get me a quicker answer.

Is it possible to do pass by reference from an external function that's defined in assembly?
Should I instead pass the pointers of those integers?

[Ganado]

kernel.c

You're trying to compile C++ syntax as C.

Should I instead pass the pointers of those integers?

If you need to modify the ints, and you're compiling as C, then yes you have to use pointers.