cochran_emc.h: packed structs

[Thiago Macieira]

On Tuesday 28 October 2014 08:09:20 Dirk Hohndel wrote:
> On October 28, 2014 8:05:20 AM "Lubomir I. Ivanov" <neolit123 at gmail.com> 
wrote:
> > On 28 October 2014 16:28, Dirk Hohndel <dirk at hohndel.org> wrote:
> > > On Tue, Oct 28, 2014 at 01:28:47PM +0200, Lubomir I. Ivanov wrote:
> > >> } __attribute__((packed));
> > >> is unreliable with MINGW > 4.6 up until 4.8.2 - the one i have bundled
> > >> with the Qt 5.3.
> > > 
> > > Yes, Jef pointed that out (with less detail) on the libdivecomputer
> > > mailing list.
> > > 
> > >> padding is added regardless and there is high potential for the code to
> > 
> > break.
> > 
> > >> one solution would be to branch / use "#pragma pack()" which is an
> > >> MSVC thing but recent MINGW supports it.
> > >> 
> > >> i'm CCing John Van Ostrand as the author, and posting this message so
> > >> that everyone knows.
> > >> perhaps there is a need for a SUBSURFACE_PACK_STRUCT(x) macro of sorts.
> > > 
> > > Is there a reliable way to do packed structures with mingw, msvc and
> > > gcc?
> > > If yes then I would love to have such a macro (or however this would be
> > > done).  Being able to do this would make code so much more readable.
> > > 
> > > We might even convince Jef to allow use of such a construct (after it's
> > > sufficiently tested) in libdivecomputer which would do wonders for my
> > > sanity :-)
> > 
> > here is a solution (found online) that uses 'gcc_struct'.
> > the attribute itself exists since 3.4.x.
> > by coupling with 'packed' it respects the forced packing - tested on
> > mingw 4.8.2!
> > 'packed' not working in general still remains a bug...
> > 
> > something to note - in the manual, they do not mention if it exists
> > for GCC-ARM, but i would assume it does.
> > also i have no idea if clang has it.
> 
> I can test clang. What about msvc?

__declspec(packed)

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
   Software Architect - Intel Open Source Technology Center
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358