Andy David wrote:

> >         your structure of bit definitions is ok (although I think you
> >         should consider using "unsigned int <name> :1" rather than
> >         just "unsigned <name> :1"), but you can't have a pointer to
> >         a bit (K&R page 150).

Francisco Ares wrote:

> Check the <pic.h> files to see how they do this things with ports
> and registers.


        Francisco,

        just to clarify: I meant that you can't have a _pointer_
        to a bit in C, I wasn't commenting on the ability of
        the PIC architecture to set/clear and test bits. C does
        allow some operations on bit field types, but & isn't
        one of them. If...:


        struct {
         unsigned notify : 1;
         unsigned valid : 1;
         unsigned finish : 1;
         unsigned demo : 1;
         unsigned alert : 1;
         unsigned encourage : 1;
         unsigned exercise : 1;
         unsigned grace : 1;
         } flags;

                pointer = &flags.notify;


        ... really does work with HT-PICC18, it's an extension to C,
        probably because the bit addressing modes of the PIC18
        core are more sophisticated than the other PIC cores, making
        a pointer to a bitfield a more reasonable proposition than
        on the other cores.

        Apologies if my post wasn't clear.


- Andy.
----------------------------------------------
Andrew David, Software Manager, Ultronics Ltd
http://www.Ultronics.com

_____________________________________________________________________
This message has been checked for all known viruses by Star Internet
delivered through the MessageLabs Virus Scanning Service. For further
information visit http://www.star.net.uk/stats.asp or alternatively call
Star Internet for details on the Virus Scanning Service.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads