function arguments are passed in registers

[Zheng Da]

Hello,

I need to do something like this:
in one program, the arguments of one specific function are passed in
the registers, and others are passed in the stack.
I know I can do it by using some inline assembly, but is there any better way?
I was looking for it in the internet. FUNCTION_ARG seems to work. But
I don't understand its explanation, and don't know how to use it.
So can anyone help me?

Best,
Zheng Da