Re: [avr-gcc-list] Strange thing...

[Dave Hansen]

From: John Yannakopoulos <address@hidden>

[...]
> unsigned short value = 62;
> unsigned short i;
>
> start_timer();
> for (i = 0; i < value; i++) ;
> stop_timer();

[...]
> When 'value' equals to 62, I get a time value of 190 cycles. When I
> set 'value' to 64, the time measured is 16 cycles! What am I doing wrong?

Hard to say.

What do start_timer and stop_timer do?  I mean specifically, beyond the 
obvious "starting and stopping the timer."  What timer?  How do you start 
it?  How do you stop it?  How are you reading the results?

How are you calculating cycles?  Are you getting overflow on an 8-bit timer 
or variable?

Are you getting interrupts during your timing loop?

Regards,
  -=Dave

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