Implement own Pragma ?

[Che]

Hi,

 I am unsure of this message should be posted here. If not please let
me know the appropriate group.

 I was wondering how i could implement my own pragma in g++/gcc.
 Say #pragma to_asm_code {function_name}
 {function_name} is an assembly routine. I believe some compilers
provide this feature by mechanism of "FastCall". I don't want anything
complicated. All I wish to do is the language must recognize this as a
pragma, push the return address and transfer control to the assembly
routine.

Thanks,
Che