function called from task, ISR or main?

Hi,
I'm running RL-RTX and I have a function that can be called either from a task, from an ISR or from main (at startup).

Is there is way to identify the calling routine so I can make the proper function call.
In my particular case, I want to write something like the example below:

myFunction( ) {

execute some code here;

if calling function is a task

os_dly_wait( ); //put the task to sleep

else

SysCtlDelay( ); //wait using CPU cycles

}

thanks.
Khaled.