Re: long long considered harmful?

[Daniel Jacobowitz <drow@mvista.com>]

I'd have to see exactly what you meant, but probably not.  These things
have to be an exact size, right?  Barring wackiness like the 32-bit
char platforms, which I shouldn't have brought into this.  So if you
run on a host with 64-bit "int", it will be wrong.

Not that we have any such hosts at the moment, but they're hardly
unreasonable in the next few years.  It's the principle that's really
the issue here, not any particular host.

On Wed, Apr 23, 2003 at 05:44:41PM -0400, Kris Warkentin wrote:
> Inquiry:
> 
> All of our register structures in debug.h are unioned with basic arrays
> guaranteed to be of sufficient size for storage.  Would it be acceptable to
> leave the structures with all the registers in them so that others can look
> and see how things are structured in Neutrino as long as the
> <arch>-nto-tdep.c files do what I do below with the offsets?  That way
> debug.h still matches our system headers but there is no code actually
> relying on how the compiler organizes those structures.
> 
> Kris
> 
> > > Was that really so hard?  And it's a lot clearer.
> >
> > Well, it's not really that hard.  I'm just being grumpy because it's
> snowing
> > outside and I really want to get this stuff committed one of these days.
> > I'd already done that to our i386 stuff both to remove the dependency on
> the
> > structure and to account for our weird ordering of registers.  See snippet
> > below:
> >
> > Kris
> >
> > /* Why 13?  Look in our debug.h header at the x86_cpu_registers structure
> >    and you'll see an 'exx' junk register that is just filler.  Don't ask
> >    me, ask the kernel guys.  */
> > #define NUM_GPREGS 13
> >
> > /* Map a GDB register number to an offset in the reg structure.  */
> > static int regmap[] = {
> >   (7 * 4),   /* %eax */
> >   (6 * 4),   /* %ecx */
> >   (5 * 4),   /* %edx */
> >   (4 * 4),   /* %ebx */
> >   (11 * 4),   /* %esp */
> >   (2 * 4),   /* %epb */
> >   (1 * 4),   /* %esi */
> >   (0 * 4),   /* %edi */
> >   (8 * 4),   /* %eip */
> >   (10 * 4),   /* %eflags */
> >   (9 * 4),   /* %cs */
> >   (12 * 4),   /* %ss */
> >   (-1 * 4)   /* filler */
> > };
> >
> > /* Perform mapping of gdb registers onto Neutrino registers.
> >    Actually works in reverse too which is why we make sure to
> >    return -1 if we're out of range.  */
> > int
> > gdb_to_os (int regno)
> > {
> >   return (regno >= 0 && regno < NUM_GPREGS) ? regmap[regno] >> 2 : -1;
> > }
> >
> > void
> > nto_supply_gregset (char *gpregs)
> > {
> >   unsigned regno;
> >
> >   for (regno = 0; regno < NUM_GPREGS - 1; regno++)
> >     {
> >       supply_register (regno, gpregs + regmap[regno]);
> >     }
> > }
> >
> >
> >
> 
> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer