[Info-vax] Volatile, was: Re: yet another sys$qiow question

[John Reagan]

On Thursday, August 20, 2015 at 11:05:55 AM UTC-4, Craig A. Berry wrote:
> On 8/20/15 9:52 AM, JF Mezei wrote:
> > On 15-08-20 10:45, Craig A. Berry wrote:
> >> On 8/20/15 8:54 AM, JF Mezei wrote:
> >>> So, after reading this, I am still puzzled...
> >>>
> >>> in DEC-C, how does one declare a variable as "volatile" ?
> >>
> >> As with any C compiler, using the "volatile" keyword, obviously:
> >
> > This is the first I ever heard of it, or seen it. And been doing $QIOs
> > since late 1980s. Pretty scary eh ?
> 
> No, not really. If you do what you're supposed to you're fine. Only
> "busy-waiting" on the IOSB could run into the problems described in this
> thread. I've never seen code that does that. I'm not saying it doesn't
> exist, but I'm skeptical it's at all common.

Correct.  If all you do is declare the IOSB, pass it to $QIO and don't read it until the EF or AST is delivered, the lack of volatile is probably not important.