Re: [Sablevm-developer] powerpc port status

[David P. B. <db...@CS...>]

I found the source of the problem:

If you have:

int v =3D 0x1234ABCD;

On x86:

(unsigned char) v
and
(unsigned char*) &v
are both equivalent.
Both will return byte 0 of the word which 0xCD which is correct.


On PowerPC (big endian)
(unsigned char) v
and
*((unsigned char*) &v)
are different.
The first one will return correctly byte 3 that is 0xCD.
But the 2nd one returns byte 0 which is 0x12 on a big endian.


Accessing the value simply with:

params[0].jint =3D result[0].jint;

instead of

params[0].jint =3D *((jboolean *) &result[0]);
	 =20
and this should work if the field jint is always located at the beginning=
 of
the union in memory.

The other possible fix is to take byte at offset 3 for big endian
machines:
*(((unsigned char*) &v) + 3)
this does not rely on the layout of the union in memory.


David



On Thu, Dec 12, 2002 at 08:14:46PM -0500, Etienne M. Gagnon wrote:
> On Thu, Dec 12, 2002 at 08:09:23PM -0500, David Paul BELANGER wrote:
> > Hi,
> >=20
> > I got HelloWorld to work on sablevm 1.0.5!
>=20
> This is really great!  So, were there any endianness problem you had to=
 fix?
>=20
> Etienne
>=20
> --=20
> Etienne M. Gagnon                    http://www.info.uqam.ca/~egagnon/
> SableVM:                                       http://www.sablevm.org/
> SableCC:                                       http://www.sablecc.org/

--=20

---

David B=E9langer
Graduate Student
School of Computer Science
McGill University
Office: MC226

Web page:   http://www.cs.mcgill.ca/~dbelan2/
Public key: http://www.cs.mcgill.ca/~dbelan2/public_key.txt