On 2018-04-10 10:03 AM, Bas Vermeulen wrote: > On Mon, Apr 9, 2018 at 11:19 PM, Gert Wollny <gw.foss...@gmail.com> wrote: >> Am Montag, den 09.04.2018, 14:03 -0400 schrieb Marek Olšák: >>> On Mon, Apr 9, 2018 at 10:51 AM, Bas Vermeulen <b...@daedalean.ai> > >> There is another option: Check at configuration time whether the bit >> field layout is like the low or the high endian layout you already >> implemented, and instead of basing the selection of the struct layout >> on the big/low-endianess of the architecture, base it on this test. >> >> It would probably be prudent to test both layouts and then fail >> configuration if non of the two reflect the actual layout (at which >> point one would have to thing about how to implement all the bit >> shifting properly). > > Or just keep the union dependent on endianness, and add an assert/check/test > to make sure that everything works as expected.
Again, it's nothing to do with endianness — the CPU always accesses the union in its native byte order. The issue is that the C standard doesn't define the memory layout of bit-fields, and the Linux powerpc architecture uses a different layout than x86. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
