Date: Mon, 03 Nov 1997 11:31:24 +1030 From: Mike Smith <mike@smith.net.au> To: jbryant@tfs.net Cc: jwm@CSUA.Berkeley.EDU (John Milford), freebsd-hackers@freebsd.org Subject: Re: gcc and bitfields Message-ID: <199711030101.LAA00660@word.smith.net.au> In-Reply-To: Your message of "Sun, 02 Nov 1997 16:13:20 MDT." <199711022213.QAA00245@argus.tfs.net>
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> > > struct C_OPEN {
> > > int a;
> > > int b;
> > > unsigned xdt:1;
> > > unsigned reserved:15;
> > > }
> > >
> > > The sizeof this structure is 10 under DOS (borland C)
> > > and evaluates to 12 under cc (gcc) on FreeBSD.
>
> ahem, DOG should show 6 bytes.
Yup, I missed this earlier.
> since he apparently uses 16 bits in the bitfield, I can assume that to
> be a short.
>
> thus:
>
> > struct C_OPEN {
> > int a;
> > int b;
> > unsigned short xdt:1; /* note addition of short */
> > unsigned short reserved:15; /* note addition of short */
> > } __attribute__ ((packed));
>
> should work.
Nope, but closer again. Unless he's using a BCC option to default his
'int' type to 32 bits (which *would* explain the initial size being 10),
he wants:
struct C_OPEN {
short a;
short b;
...
mike
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