Abel, Thanks for the suggesting those changes. When I said I didn't see any easy way to fix it, I had your method in mind as the "hard" way. It sure is a lot easier to let the compiler take care of the little details like that. But I guess that's the price you have to pay for portability. I went ahead and tested your changes, and since the structures are referenced too many times, it wasn't as bad as I thought. Other than changing "4+" to "2+" in your defines, your code worked pretty much out of the box.
The new code seems to work OK, but I don't think it's a good idea to submit it just before the 1.0.9 code freeze. I'll commit the CVS changes to the next release. -- Peter Fales On Sat, Oct 12, 2002 at 12:04:39PM +0200, abel deuring wrote: > Peter Fales wrote: > >I've made this change. I don't see any easy way to fix it > >in portable way, and more importantly I don't have any way to > >test it. I'll be glad to take patches if someone wants to supply > >them. > > > > > >On Fri, Oct 11, 2002 at 06:50:14PM +0200, Petter Reinholdtsen wrote: > > > >> > >>I just discovered this code when trying to find out why the CVS > >>version of sane-backends fail to compile on HP/UX using the native > >>compiler. > >> > >> #ifdef __GNUC__ > >> #define UNUSEDARG __attribute__ ((unused)) > >> #define PACKED __attribute__ ((packed)) > >> #else > >> #define UNUSEDARG > >> /* You need to figure out a way to ensure that there are no holes > >> * in the following dir_buf structure - it has to match data read from > >> * the camera. gcc does this with __attribute__ ((packed)) > >> */ > >> #error > >> #endif > >> > >> > > Well, perhaps I don't get the point -- but looking through dc240.h, it > seems to me that all you want to achieve is that struct dir_buf does not > have any padding bytes between members of the struct. > > All the SCSI backends have to deal with the same problem for SCSI > command and data buffers: you may have non-32-bit-aligned 32 bit > integers, and the integers are perhaps not in the "native" byte order of > the machine. > > Regading struct dir_buf, what about the following (written without a > serious look into dc240.c -- please bear with me, if I'm writing > nonsense...): > > #define CAMDIRENTRYSIZE 20 > #define DIRENTRIES 1000 > > SANE_Byte dir_buf[2 + CAMDIRENTRYSIZE * DIRENTRIES]; > > #define get_name(entry) (SANE_Char*) &dir_buf[4+CAMDIRENTRYSIZE*(entry)] > #define get_attr(entry) dir_buf[4+11+CAMDIRENTRYSIZE*(entry)] > #define get_create_time(entry) \ > ( dir_buf[4+12+CAMDIRENTRYSIZE*(entry)] << 8 \ > + dir_buf[4+13+CAMDIRENTRYSIZE*(entry)]) > > > Abel
