Re: libopcode endian and subarch inconsistencies?

["Dr. David Alan Gilbert" <dave at treblig dot org>]

* Maciej W. Rozycki (macro@linux-mips.org) wrote:
> On Sun, 10 Jun 2012, Dr. David Alan Gilbert wrote:

Hi Maciej,
  Thanks for the reply.

> > 2) The 'binary' target
> >   The 'binary' target has it's flags set as BFD_ENDIAN_UNKNOWN;
> > but there again there is a comment that says it's only for
> > use as output not by input; so other than ignoring that
> > comment (as I did) - what's the right way to use libopcode
> > to disassemble from a byte stream?
> 
>  See how `objdump' drives opcodes -- it has -EB/-EL options to select the 
> endianness regardless of the target chosen.

Yes, I think that might have been where I originally saw the trick I used;
from the objdump code:

  if (endian != BFD_ENDIAN_UNKNOWN)
    {
      struct bfd_target *xvec;

      xvec = (struct bfd_target *) xmalloc (sizeof (struct bfd_target));
      memcpy (xvec, abfd->xvec, sizeof (struct bfd_target));
      xvec->byteorder = endian;
      abfd->xvec = xvec;
    }

and then later:

  if (bfd_big_endian (abfd))
    disasm_info.display_endian = disasm_info.endian = BFD_ENDIAN_BIG;
  else if (bfd_little_endian (abfd))
    disasm_info.display_endian = disasm_info.endian = BFD_ENDIAN_LITTLE;

My point really is that memcpying and tweeking xvec feels a horrible
hack, especially when you also have disasm_info.endian which feels
like the place you'd expect to set the endianness because it exists.

I'd think that there should only be one of them that a caller to libopcode
should have to set.

> It can disassemble from the 
> "binary" target just fine.

Yes, my point about 'binary' was that there is the comment in binary.c:
   'It may only be used for output, not input.'

Dave
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