1 113_btdll.c:12: at f_1: hello from f_1() / 113_btdll.c:12
2 113_btdll.c:37: by main
3 113_btdll.c:20: at f_2: hello from f_2() / 113_btdll.c:20
4 113_btdll.c:38: by main
5 113_btdll.c:31: at f_main: hello from f_main() / 113_btdll.c:31
6 113_btdll.c:39: by main
