Wrap every place that accesses a dispatch table with a macro. A new script-
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
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Ian Romanick