• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 53 subscribers
  • Views 300 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

while() problem in ccs 6.1.1.00022

John Song43
Intellectual 470 points

Hi, 

Recently, I used CCS 6.1.1.00022 for F28377S launchPad. I found a problem in while() instruction. The program can't jump out the loop of while(). The codes are as following,

Read_Flag=1;
while(Read_Flag==1);

interrupt void spiRxFifoIsr(void)
{

Read_Data=SpiaRegs.SPIRXBUF; // Read data
Read_Flag=0;
PieCtrlRegs.PIEACK.all|=0x20; // Issue PIE ack

}

I have added Read_Flag into Watch Expression and see the Read_Flag is already change to 0. But the program still can't jump out this while(Read_Flag==1);. The program is stop in here. BTW, The program is correct if the code is change as follows.

Read_Flag=1;
while(1){
     if(Read_Flag==0)
         break;
};

But I still would like to know what reason cause the while(Read_Flag==1); can't jump out. I appreciate if you can tell me how to resolve this problem.

Thanks.

Regards,

John

 

  • 0
    Mastermind 9115 points
    Hi John,

    It is due to the C compiler and optimizer. They both will analyse your C source code and translate to assembly. Different optimisation level have different register optimisation method. To prevent this issue, you can declare Read_Flag as volatile by using "volatile int Read_Flag;" It will make the allocated register to be updated from memory every time before comparing with 1.