正点原子sys.c出现错误

edasky

*** Using Compiler 'V5.05 update 1 (build 106)', folder: 'C:\Keil_v5\ARM\ARMCC\Bin'
Rebuild target 'CAR'
compiling test.c...
compiling delay.c...
assembling STM32F10x.s...
compiling led.c...
compiling sys.c...
..\SYSTEM\sys\sys.c(94): error:  #20: identifier "f" is undefined
  

zuozhongkai

直接编译的例程？