Does the keyword volatile work?

[Mike Stump]

On Monday, May 12, 2003, at 09:59 AM, Stephen P. Smith wrote:
> In the code fragment

Asking for help with code fragments is dangerous.  If you know exactly 
how to ask the question and the right person reads it, it can work 
fine.  If you don't, or they don't, it can fail.

There wasn't any sensible code that I could discern to help you with.

Try writing a 10 line program (or at least translation unit) that has 
no includes that is cross platform portable and ask us about it.

For example,

volatile int mailbox;

int foo(int i) {
	mailbox = i;
}

is such a best.  When I compile it, it works fine:

_foo:
         lis r2,ha16(_mailbox)
         stw r3,lo16(_mailbox)(r2)
         blr

as you can see, the variable is immediately fetched and stored.

I can guess all day long at what you really want to do, but every 
example I would come up with, would necessarily work:

int foo(int i) {
   int mailbox;
   (*(volatile *)&mailbox) = i;
}

gives:

_foo:
         stw r3,-16(r1)
         blr

so, I'm back at asking, what do you really want to do?  Is the fetch 
volatile, or is the store volatile?