| ??? 07/14/07 08:24 Read: times |
#141868 - within a loop Responding to: ???'s previous message |
Erik Malund said:
now, visualize this one: if (flag)
{
....
}the compiler is fully justified in copying flag to a register and testing it there forever if flag is not declared volatile.Maybe it's better to extend the example to: while(1)
{
if (flag) //should be sampled many times
break;
}If flag is not volatile the compiler may deduce flag does not change within the loop and change this to:
if (!flag) //but is sampled only once
{
while(1) ;
}
|
| Topic | Author | Date |
| more to atomicity and such | 01/01/70 00:00 | |
| Interesting example ... | 01/01/70 00:00 | |
| which I did | 01/01/70 00:00 | |
| Aside: Keil - Atomic functions | 01/01/70 00:00 | |
| If you can afford it. | 01/01/70 00:00 | |
| volatile | 01/01/70 00:00 | |
| does this have some formal definition? | 01/01/70 00:00 | |
| sequence points and side effects | 01/01/70 00:00 | |
| what's exactly the value of volatile, then? | 01/01/70 00:00 | |
| example | 01/01/70 00:00 | |
| bu what is it good for then? | 01/01/70 00:00 | |
| Ok, visualize this one | 01/01/70 00:00 | |
| within a loop | 01/01/70 00:00 | |
| Memory Mapped I/O | 01/01/70 00:00 | |
OK I see it now, thanks. | 01/01/70 00:00 | |
| volatile switch | 01/01/70 00:00 |