[Mesa-dev] [PATCH 4/8] mesa: fill in signed cases and RGBA16 in _mesa_format_matches_format_and_type

[Marek Olšák]

On Wed, Jan 30, 2013 at 11:58 AM, Michel Dänzer <michel at daenzer.net> wrote:
> On Die, 2013-01-29 at 21:22 +0100, Marek Olšák wrote:
>> On Tue, Jan 29, 2013 at 4:31 PM, Michel Dänzer <michel at daenzer.net> wrote:
>> > On Die, 2013-01-29 at 14:43 +0100, Marek Olšák wrote:
>> >> ---
>> >>  src/mesa/main/formats.c |   30 ++++++++++++++++++++++++++----
>> >>  1 file changed, 26 insertions(+), 4 deletions(-)
>> >>
>> >> diff --git a/src/mesa/main/formats.c b/src/mesa/main/formats.c
>> >> index 0273425..b86fb9e 100644
>> >> --- a/src/mesa/main/formats.c
>> >> +++ b/src/mesa/main/formats.c
>> [...]
>> >> @@ -3264,12 +3270,17 @@ _mesa_format_matches_format_and_type(gl_format gl_format,
>> >>        return GL_FALSE;
>> >>
>> >>     case MESA_FORMAT_SIGNED_R16:
>> >> +      return format == GL_RED && type == GL_SHORT && littleEndian &&
>> >> +             !swapBytes;
>> >>     case MESA_FORMAT_SIGNED_GR1616:
>> >> +      return format == GL_RG && type == GL_SHORT && littleEndian && !swapBytes;
>> >
>> > GL_SHORT is in host byte order, so checking for littleEndian here
>> > incorrectly excludes big endian hosts.
>>
>> Does that apply only to X16, or even to X16Y16, or even to X16Y16Z16W16?
>
> Hmm. AFAICT MESA_FORMAT_*1616 are currently defined as 32 bit packed
> values, so the line you added for MESA_FORMAT_SIGNED_GR1616 is actually
> correct.
>
> OTOH e.g. MESA_FORMAT_RGBA_16 appears to be defined as an array of 16
> bit values, so that could be treated the same way as
> MESA_FORMAT_SIGNED_R16.
>
> I wonder if it wouldn't make sense to replace MESA_FORMAT_*1616 with
> array based formats as well. AFAICT there's nothing like GL_INT_16_16 in
> OpenGL.

I don't really get this distinction between array and non-array based
formats. Most Mesa formats map to Gallium formats and most of Gallium
ones are array-based regardless of how Mesa formats are defined,
right? As a matter of fact, I added lots of Mesa formats over the
years, e.g. MESA_FORMAT_SIGNED_GR1616, which may look like packed to
you, but all I ever cared about was that it was equivalent to
PIPE_FORMAT_R16G16_SNORM and I gave it a name which was consistent
with the naming of other Mesa formats. The way I understand it, the
component order in names of Mesa formats is written the other way
around compared to gallium formats. E.g. MESA_FORMAT_RGBA8888 =
PIPE_FORMAT_A8B8G8R8_UNORM. That's the case with most formats, except
deviations in naming like MESA_FORMAT_RGBA_16, where the component
order matches gallium.

Marek