key没有赋初值

int Main(int argc, char **argv)
{
    int i;
    U8 key;
    U32 mpll_val=0;
    int data;
  
    mpll_val = (92<<12)|(1<<4)|(1);
    
    //init FCLK=400M, so change MPLL first
    ChangeMPllValue((mpll_val>>12)&0xff, (mpll_val>>4)&0x3f, mpll_val&3);
    ChangeClockDivider(key, 12);    


//以上程序摘自官方LED工程,为什么key没有赋初值,而程序没有问题?

这是ChangeClockDivider()函数的源代码，当传入的参数有错误时，函数并不一定会出错。硬件帮了一把？

复制代码 void ChangeClockDivider(int hdivn_val,int pdivn_val) {     int hdivn=2, pdivn=0;           // hdivn_val (FCLK:HCLK)ratio hdivn      // 11           1:1       (0)      // 12           1:2       (1)      // 13           1:3       (3)      // 14           1:4       (2)      // pdivn_val (HCLK:PCLK)ratio pdivn      // 11           1:1       (0)      // 12           1:2       (1)     switch(hdivn_val) {         case 11: hdivn=0; break;         case 12: hdivn=1; break;         case 13:         case 16: hdivn=3; break;         case 14:         case 18: hdivn=2; break;     }          switch(pdivn_val) {         case 11: pdivn=0; break;         case 12: pdivn=1; break;     }          //Uart_Printf("Clock division change [hdiv:%x, pdiv:%x]\n", hdivn, pdivn);     rCLKDIVN = (hdivn<<1) | pdivn;     //Uart_Printf("rCLKDIVN:%x]\n", rCLKDIVN);     switch(hdivn_val) {         case 16:        // when 1, HCLK=FCLK/6.             rCAMDIVN = (rCAMDIVN & ~(3<<8)) | (1<<8);         break;         case 18:     // when 1, HCLK=FCLK/8.             rCAMDIVN = (rCAMDIVN & ~(3<<8)) | (1<<9);         break;     }     //Uart_Printf("rCAMDIVN:%x]\n", rCAMDIVN);          if(hdivn!=0)         MMU_SetAsyncBusMode();     else         MMU_SetFastBusMode(); }