mesa: Fix _mesa_swizzle_and_convert integer conversions to clamp properly

Fix various conversion paths that involved integer data types of different
sizes (uint16_t to uint8_t, int16_t to uint8_t, etc) that were not
being clamped properly.

Also, one of the paths was incorrectly assigning the value 12, instead of 1,
to the constant "one".

v2:
- Create auxiliary clamping functions and use them in all paths that
  required clamp because of different source and destination sizes
  and signed-unsigned conversions.

v3:
- Create MIN_INT macro and use it.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
swrast: Remove unused variable.
mesa: Add a concept of an array format

An array format is a 32-bit integer format identifier that can represent
any format that can be represented as an array of standard GL datatypes.
While the MESA_FORMAT enums provide several of these, they don't account
for all of them.

v2 by Iago Toral Quiroga <itoral@igalia.com>:
- Set pad to 0 and array_format_bit to 1 for all mesa array formats.
- Fix array_format_flip_channels, since it was not doing what was expected.
mesa: Let _mesa_get_format_base_format also handle mesa_array_format.

If we need the base format for a mesa_array_format we have to find the
matching mesa_format first. This is expensive because it requires
to loop through all existing mesa formats until we find the right match.

We can resolve the base format of an array format directly by looking
at its swizzle information. Also, we can have _mesa_get_format_base_format
accept an uint32_t which can pack either a mesa_format or a mesa_array_format
and resolve the base format for either type. This way clients do not need to
check if they have a mesa_format or a mesa_array_format and call different
functions depending on the case.

Another reason to resolve the base format for array formats directly is that
we don't have matching mesa_format enums for every possible array format, so
for some GL format/type combinations we can produce array formats that don't
have a corresponding mesa format, in which case we would not be able to
find the base format. Example format=GL_RGB, type=GL_UNSIGNED_SHORT. This type
would map to something like MESA_FORMAT_RGB_UNORM16, but we don't have that.
mesa: Add a _mesa_is_format_color_format helper
mesa: Autogenerate most of format_pack.c

We were auto-generating it before.  The problem was that the autogeneration
tool we were using was called "copy, paste, and edit".  Let's use a more
sensible solution.

Signed-off-by: Jason Ekstrand <jason.ekstrand@intel.com>

v2 by Samuel Iglesias <siglesias@igalia.com>
- Remove format_pack.c as it is now autogenerated
- Add usage of INDENT_FLAGS in Makefile.am
- Remove trailing blank line

v3 by Samuel Iglesias <siglesias@igalia.com>
- Merge format_convert.py into format_parser.py
   - Adapt pack_*_* function generations
- Fix out-of-tree build

v4 by Samuel Iglesias <siglesias@igalia.com>
- _get_datatype() is now a helper function

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa: Autogenerate format_unpack.c

Signed-off-by: Jason Ekstrand <jason.ekstrand@intel.com>

v2 by Samuel Iglesias <siglesias@igalia.com>:
- Add usage of INDENT_FLAGS in Makefile.am

v3 by Samuel Iglesias <siglesias@igalia.com>:
- Modify unpack_float_*() and unpack_ubyte_*() function generation
to use c.datatype() and f.datatype()
- Fix out-of-tree build

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
configure: require python mako module

It is now a hard dependency because of the autogeneration of
format pack and unpack functions.

Update the documentation to reflect this change.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa: Add _mesa_pack_uint_rgba_row() format conversion function

We will use this later on to handle uint conversion scenarios in a master
convert function.

v2:
- Modify pack_uint_*() function generation to use c.datatype() and
  f.datatype().
- Remove UINT_TO_FLOAT() macro usage from pack_uint*()
- Remove "if not f.is_normalized()" conditional as pack_uint*()
  functions are only autogenerated for non normalized formats.

v3:
- Add clamping for non-normalized integer formats in pack_uint*()

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa: Add non-normalized formats support for ubyte packing functions

v2:
- Add clamping for non-normalized integer formats in pack_ubyte*()

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa/format_pack: Add _mesa_pack_int_rgba_row()

This will be used to unify code in pack.c.

v2:
- Modify pack_int_*() function generator to use c.datatype() and
  f.datatype()

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa/formats: add new mesa formats and their pack/unpack functions.

This  will be used to refactor code in pack.c and support conversion
to/from these types in a master convert function that will be added
later.

v2:
- Fix autogeneration of MESA_FORMAT_A2R10G10B10_UNORM pack/unpack
  functions

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa: use format conversion functions in swrast

This commit adds a macro to facilitate the task of using
format conversions functions but keeps the same API.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa/pack: use autogenerated format_pack functions

Take advantage of new mesa formats and new format_pack functions to
reduce source code in _mesa_pack_rgba_span_from_ints() and
_mesa_pack_rgba_span_from_uints().

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa/main/pack_tmp.h: Add float conversion support

We will use this in a later patch to refactor _mesa_pack_rgba_span_float.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa/pack: refactor _mesa_pack_rgba_span_float()

Use autogenerated format pack functions and take advantage of some
macros to reduce source code, facilitating its maintenance.

Unfortunately, dstType == GL_UNSIGNED_SHORT cannot simplified like
the others, so keep it as it is.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
mesa: Add an implementation of a master convert function.

v2 by Iago Toral <itoral@igalia.com>:

- When testing if we can directly pack we should use the src format to check
  if we are packing from an RGBA format. The original code used the dst format
  for the ubyte case by mistake.
- Fixed incorrect number of bits for dst, it was computed using the src format
  instead of the dst format.
- If the dst format is an array format, check if it is signed. We were only
  checking this for the case where it was not an array format, but we need
  to know this in both scenarios.
- Fixed incorrect swizzle transform for the cases where we convert between
  array formats.
- Compute is_signed and bits only once and for the dst format. We were
  computing these for the src format too but they were overwritten by the
  dst values immediately after.
- Be more careful when selecting the integer path. Specifically, check that
  both src and dst are integer types. Checking only one of them should suffice
  since OpenGL does not allow conversions between normalized and integer types,
  but putting extra care here makes sense and also makes the actual requirements
  for this path more clear.
- The format argument for pack functions is the destination format we are
  packing to, not the source format (which has to be RGBA).
- Expose RGBA8888_* to other files. These will come in handy when in need to
  test if a given array format is RGBA or in need to pass RGBA formats to
  mesa_format_convert.

v3 by Samuel Iglesias <siglesias@igalia.com>:

- Add an RGBA8888_INT definition.

v4 by Iago Toral <itoral@igalia.com> after review by Jason Ekstrand:

- Added documentation for _mesa_format_convert.
- Added additional explanatory comments for integer conversions.
- Ensure that we use _messa_swizzle_and_convert for all signed source formats.
- Squashed: do not directly (un)pack to RGBA UINT if the source is not unsigned.
mesa: Set normalized=true for float array formats.

In order to check if a format is normalized Mesa does something like this:
normalized = !_mesa_is_enum_format_integer(srcFormat);

So all float types will set normalized to true. Since our mesa_array_format
includes a normalized flag for each type we want to make it consistent with
this.
mesa: Expose compute_component_mapping as _mesa_compute_component_mapping

This is necessary to handle conversions between array types where
the driver does not support the dst format requested by the client and
chooses a different format instead.

We will need this in _mesa_format_convert, so move it to format_utils.c,
prefix it with '_mesa_' and make it available to other files.
mesa: Add a rebase_swizzle parameter to _mesa_format_convert

The new parameter allows callers to provide a rebase swizzle that
the function needs to use to match the requirements of the base
internal format involved. This is necessary when the source or
destination internal formats (depending on whether we are doing
the conversion for a pixel download or a pixel upload respectively)
do not match the base formats of the source or destination
formats of the conversion. This can happen when the driver does not
support the internal formats and uses a different format to store
pixel data internally.

For example, a texture upload from RGB to Luminance in a driver
that does not support textures with a Luminance format may decide
to store the Luminance data as RGBA. In this case we want to store
the RGBA values as (R,R,R,1). Following the same example, when we
download from that texture to RGBA we want to read (R,0,0,1). The
rebase_swizzle parameter allows these transforms to happen.