a treelang question about printf.

[Der-Johng Sun]

Hi,
 
I try to implement a litter front end with the gcc. But I am confused, about
the printf().
How to implement the code?
 
test()
{
    write("Hello World!!\n");   -- I want to call printf.
}
 
I had found the informations such as BUILT_IN_PRINTF, expand_builtin_fprintf
etc...
But I still don't known how to implement it.
 
I'm novice. I'm sorry if it is a stupid question.
 
Best regards,
        Der-Johng Sun
-----
derjohng2@yahoo.com