On 04.12.2014 17:17, Iago Toral wrote:
On Wed, 2014-12-03 at 14:58 -0800, Jason Ekstrand wrote:On Wed, Dec 3, 2014 at 2:52 PM, Ian Romanick <i...@freedesktop.org> wrote: On 12/01/2014 03:04 AM, Iago Toral Quiroga wrote: > From: Jason Ekstrand <jason.ekstr...@intel.com>(...)> > +enum mesa_array_format_datatype { > + MESA_ARRAY_FORMAT_TYPE_UBYTE = 0x0, > + MESA_ARRAY_FORMAT_TYPE_USHORT = 0x1, > + MESA_ARRAY_FORMAT_TYPE_UINT = 0x2, > + MESA_ARRAY_FORMAT_TYPE_BYTE = 0x4, > + MESA_ARRAY_FORMAT_TYPE_SHORT = 0x5, > + MESA_ARRAY_FORMAT_TYPE_INT = 0x6, > + MESA_ARRAY_FORMAT_TYPE_HALF = 0xd, > + MESA_ARRAY_FORMAT_TYPE_FLOAT = 0xe, > +}; > + > +#define MESA_ARRAY_FORMAT_TYPE_IS_SIGNED 0x4 > +#define MESA_ARRAY_FORMAT_TYPE_IS_FLOAT 0x8 > +#define MESA_ARRAY_FORMAT_BIT 0x80000000 This... > + > +typedef union { > + struct { > + enum mesa_array_format_datatype type:4; > + bool normalized:1; > + unsigned num_channels:3; > + unsigned swizzle_x:3; > + unsigned swizzle_y:3; > + unsigned swizzle_z:3; > + unsigned swizzle_w:3; > + unsigned pad:11; > + unsigned array_format_bit:1; /* Must always be 1 */ ...and this are not correct on big-endian. Bah! I originally did this as a bitfield in a uint32_t and then decided that the union was easier. Probably best to go back to the bitfield...Wouldn't it be enough to rewrite the 3 definitions like this?: #define MESA_ARRAY_FORMAT_BIT (_mesa_little_endian() ? 0x80000000 : 0x00000080)
No. With the example above, setting the array_format_bit member to 1 sets the least significant bit of the aliased 32-bit integer on this PowerBook.
The C specification doesn't make any guarantees about the layout of bit-fields that would allow them to be used for something like this, so you have to stick to either using only bit-fields for flags, or only shifts and masks on integer values.
-- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
