Help Calling PHP_FUNCTION's from C ( inside PHP extension's function)

Hi, Consider two PHP extension A and B.

 Extension A exports a PHP_FUNCTION to userspace.. Let s call it

Afunc().
Extension B exports a PHP_FUNCTION to userspace.. Let s call it
Bfunc().

Now, Is there any way to use Afunc1() inside the body of Bfunc()?

I don't want to call back to userspace. I want to call the PHP_FUNCTION
of one extension in some other extension's C function.
PHP_FUNCTION internally expands by a macro to C prototype. Am not getting
a proper idea in calling them by passing arguments
and getting values returned.

I have been trying hard in this regard. Please help me in this.