Thanks Ashley, I'll probably take up the macro idea, but  I think its
probably going to make the code size much bigger. I dont think the compiler
will optimise so it doesnt (for example) read the LSB from PORTB when Im
just doing an operation on the MSB-PORTD.

Maybe I'll just drink more coffee.

Jon

----- Original Message -----
From: "Ashley Roll"
Sent: Thursday, April 25, 2002 1:05 AM
Subject: Re: [PIC]: C query


> Hi Jon,
>
> Unfortunately not as they aren't continuos in memory.. However just write
a
> macro or even an inline function this should make it all much more
readable.
>
> for instance:
>
> #define WRITE_16BIT_PORT( val ) {PORTA = val & 0xff; PORTD = val >> 8;}
> #define READ_16BIT_PORT( val ) {val = (PORTD << 8) | PORTA;}
>
> Hope that helps..
>
> Cheers,
> Ash.
>
> ---
> Ashley Roll
> Digital Nemesis Pty Ltd
> www.digitalnemesis.com
> Mobile: +61 (0)417 705 718
>
>
>
>
> > -----Original Message-----
> > From: pic microcontroller discussion list
> > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Jon Baker
> > Sent: Thursday, 25 April 2002 9:02 AM
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: [PIC]: C query
> >
> >
> > I'm using an '877 on a 16bit bus, MSB is PortD, LSB is PortB.
> > I need to read or write to the bus, and I would like to know
> > if I can create a variable in C which references these two
> > ports as though they were a single 16bit unsigned int- so
> > instead of having to do msb and lsb operations individually.
> > PORTB = int & 255; PORTD = int >> 8;  I could use a single
> > variable [eg PORTDB ] in these operations: PORTDB = int;
> >
> > obviously the compiler will split it up into 2 8bit
> > operations, and I don't even care if the code is smaller or
> > (slightly) larger- but it would really make my code easier to
> > get my head around at the moment :)
> >
> > Thanks
> >
> > Jon Baker
> >
> > --
> > http://www.piclist.com hint: The PICList is archived three different
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> >
> >
> >
>
> --
> http://www.piclist.com hint: The PICList is archived three different
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>

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