> -----Original Message-----
> From: Mike Harrison [SMTP:mike@whitewing.co.uk]
> Sent: Tuesday, October 15, 2002 3:57 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [pic]: C pointer/union syntax
>
> >Personaly I rarely bother with using structures in this manner.  They can
> be
> >usefull, but one you start messing around with pointers it gets messy and
> >you might as well access the bytes within the long directly using
> pointers,
> >e.g.
> >
> >void readadc(long *result)
> >{
> >*(((unsigned char *)result)+0) = getbyte();
> >*(((unsigned char *)result)+1) = getbyte();
> >*(((unsigned char *)result)+2) = getbyte();
> >}
> Thanks for that hint - makes things much simpler!
> Incidentally is there a similar trick for accessing bytes within
> global longs without having to use a union,
> e.g.
> long reading;
>
> <some twiddlystuff+1> = byte1;
>
Yes, I use some macros to do this:

#define byte0(x)                (unsigned char)(*(((unsigned char *)&x)+0))
#define byte1(x)                (unsigned char)(*(((unsigned char *)&x)+1))
#define byte2(x)                (unsigned char)(*(((unsigned char *)&x)+2))
#define byte3(x)                (unsigned char)(*(((unsigned char *)&x)+3))

Cheers

Mike

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics