generated file, called src/mesa/glapi/dispatch.h, is added. This file
contains three macros for each API function. It contains a GET, a SET, and
a CALL. Each of the macros take a pointer to the context and a pointer to
the dispatch table.
In several threads on mesa3d-dev we discussed replacing _glapi_add_entrypoint
with a new function called _glapi_add_dispatch. For this discussion, the
important difference between the two is that the caller of _glapi_add_dispatch
does *not* know what the dispatch offset will be at compile time. Because of
this callers need to track the dispatch offset returned by
_glapi_add_dispatch.
http://marc.theaimsgroup.com/?t=111947074700001&r=1&w=2
The downside is that driver code then has to access the dispatch table two
different ways. It accesses it using structure tags (e.g., exec->Begin) for
functions with fixed offsets and via a remap table (e.g., exec[
remap->NewExtensionFunction ]) for functions without fixed offsets. Yuck!
Using the macros allows both types of functions to be accessed
identically. If a driver needs to set a pointer for Begin, it does
'SET_Begin(ctx, exec, my_begin_function)'. If it needs to set a pointer
for NewExtensionFunction, it does 'SET_NewExtensionFunction(ctx, exec,
my_NewExtensionFunction_function)'. Furthermore, if at some point in
the future a static offset is assigned for NewExtensionFunction, only
the macros need to change (instead of every single place that accesses a
table for that function).
This code differs slightly from the originally posted patches in that the
CALL, GET, and SET marcos no longer take a context pointer as a parameter.
Brian Paul had suggested that the remap table could be stored as a global
since it would be set at CreateScreen time and would be constant for all
contexts. This change reflects that feedback.
http://marc.theaimsgroup.com/?t=112087194700001&r=1&w=2
is basically patch #2939 from X.org bugzilla #3379. This does *not*
fix the bug as it does not dynamically generate stubs at run-time. It
just gets things one step closer.
device-specific code. A new Python script
(src/mesa/glapi/extension_helper.py) generates a list of all
entry-points for all known extensions. Each driver the selects only
the extensions that it needs and enables the via either
driInitExtensions or driInitSingleExtension.
This code has been compile-tested on a drivers, but has only been
run-tested on mga and i915 (on i830 hardware).
These changes were discussed at length on the mesa3d-dev mailing list.
http://marc.theaimsgroup.com/?t=111947074700001&r=1&w=2
Pixel count can be negative (this could be fixed elsewhere), so adapt the
functions to work with such inputs correctly (same behaviour as non-optimized
functions).
Bugzilla #2317
Submitted by idr
Brian Paul