what is user_routines_fast.c?

When do we use user_routines_fast.c?
I don’t know what to put in…
Is this the file that I have to put Autonomous mode in? or some other file like
user_routines.c?
Our mentor is still out of country, so we really can’t ask anyone in the team…

user_routines_fast.c is used for code that runs on every loop (see main.c to find the loop). Autonomous code goes in User_Autonomous_Code() in user_routines_fast.c
The autonomous code is in user_routines_fast.c because it has a loop that repeats every processor cycle instead of every 26.2ms, as opposed to most other code, which is called from main() once every 26.2ms.

thanks