Experimental Physics and
Industrial Control System

[email protected] (Jeff Hill) · Thu, 29 Jun 95 16:51:51 MDT

Rozelle,

> I notice that the drv src directory:
> is divided into ansi, old and combine, but dev is not
> divided, although some of the dev files have the ansi calling sequence
> and some do not.
> Do you know why?
>
> I am assuming, that I should use ansi for
> the new things I am writing.

Unfortunately, some parts of ioc core are still in traditional (and not
ANSI) C. With drivers we need to be particularly careful because
when talking to hardware we must use the ANSI C keyword volatile for
variables that are hardware registers. Otherwise with traditional C we
use gcc's -fvolatile and more or less turn off the optimizer.

The new drv/ansi directory allows new driver codes and codes that
have been updated to ANSI C to take full advantage of the optimizer.
Old codes in drv/old are still compiled with the -fvolatile flag
(because they dont declare the members of hardware overlay
structures with volatile).

In drv/combine we combine the objects into one library.

Since they dont use the -fvolatile flag in the dev directory
all codes there that touch hardware need to be using the
volatile data type modifier for all fields in structures that
are hardware overlays.

Jeff

______________________________________________________________________
Jeffrey O. Hill                 Internet        [email protected]
LANL MS H820                    Voice           505 665 1831
Los Alamos, NM 87545 USA        FAX             505 665 5107

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System