How to test if a function is already defined in the IAR? (W)

Hello,

I'm making a library that should be easily portable to other programs. So I tried to do the following:

01 #ifndef delay_ms
02 #define delay_ms(X)              OSTimeDlyHMSM(0u, 0u, 0u, (X), OS_OPT_TIME_HMSM_STRICT, &err)
03 #endif

However, whether or not the function 'delay_ms ()' is set, the code in line 02 will be set. Is there a way to do this test?

Thankful,