Re: RE: [avr-gcc-list] for loop problem

[Volkmar Dierkes]

Adrian,

what is the exact problem? Does it hang in the loop (I can't imagine) or does 
gcc optimize the loop to nothing (deleted it)? In the last case it might be 
neccessary to include a
asm("nop");
(instead of your msdelay(1)) in the loop. With this it shouldn't delete it. 
Maybe there are other/better ways, but I think this should help. And even 
sometimes it helps if you look at the generated code what the compiler creates. 
Which optimization level do you using?

Volkmar

"address@hidden" <address@hidden> schrieb am 17.01.03 13:40:33:
> 
> I have tryed changing the flag rto static volatile and volatile. this seems 
> to have corrected the UART loop problem but not the other loop problem
> 
> while(Timeout_Flag != 0xFF && Element_Pulse_Flag != 0xFF)
>   {
>       int i;
>       for(i=0;i<10;i++)
>       {
>       //msdelay(1);
>       }
> 
>   }
> 
> this still needs the delay in to work
> 
> any idea?
> 
> thanks
> 
> adrian
> 
> 
> Adrian,
> 
> > I have the function below (well part of it) and it waits in a loop until
> > the UART flag is flagged.  If i put a 100ms delay in or do something like 
> > send a byte to the uart it works fine, but as soon as i leave a empty for 
> > loop it crashed and needs resettting.
> ...
> > int Pulse_Handler(void)
> > {
> > int i;
> > uart_send_byte(33);
> >   while(UART_Flag == 0)
> >   {
> >     msdelay(1);
> >  //uart_send_byte(46);
> >   }
> >   UART_Flag = 0 ;                           
> >   uart_send_byte(85);
> 
> You need to define UART_Flag as volatile. If you look at the generated code 
> you can see that without volatile it checks only once for UART_Flag and 
> runs than into an endless loop. With the volatile you can see that the 
> compare is included into the loop.
> 
> Volkmar
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