This fixes a problem where texturing from the same Pixmap more than
once per batchbuffer would hang the DRI driver.  We just use the region
associated with the front left renderbuffer of the __DRIdrawable for
texturing, which avoids creating different regions for the same BO.

This change also make GLX_EXT_texture_from_pixmap work for direct
rendering, since tracking the __DRIdrawable -> BO handle now uses
the standard DRI2 event buffer.  Of course, DRI2 direct rendering
doesn't exist yet.

Finally, this commit bumps the DRI interface version again, accounting
for the change in the DRI_TEX_BUFFER extension and the change in
commit 0bba0e5be7 to pass in the
event buffer head index on drawable creation.

The DRI driver needs to know where in the buffer to start reading.

When the DRI doesn't parse the event buffer for a while, the X server
may overwrite data that the driver didn't get a chance to look at.  The
reemitDrawableInfo callback requests that the X server reemit all info
for the specified drawable.  To make use of this, the drive needs to know
the new tail pointer so it know where to start reading from.

Instead of passing in a fixed struct, the loader now passes in a list
of __DRIextension structs, to advertise the functionality it can provide
to the driver.  Each extension is individually versioned and can be
extended or phased out as the interface develops.

Right now the DRI2 screen constructor takes 3 different versions:
DRI, DDX and DRM.  This is mostly useless, though:

  DRI: The DRI driver doesn't actually care about the DRI protocol,
  it only talks to the loader, which in turn speaks DRI protocol.  Thus,
  the DRI protocol version is of not interest to the DRI driver, but it
  needs to know what functionality the loader provides.  At this point
  that's reflected in the __DRIinterfaceMethods struct and the
  internal_version integer.

  DDX: The DDX version number is essentially used to track extensions
  to the SAREA.  With DRI2 the SAREA consists of a number of versioned,
  self-describing blocks, so the DDX version is no longer interesting.

  DRM: We have the fd, lets just ask the kernel ourselves.

Windows/DOS users should enable core.autocrlf from now on:

  git config --global core.autocrlf true

The DriverAPI is internal to the DRI drivers and GetDrawableMSC
obsoletes GetMSC.  Also, since the DRI driver interface has not yet
been released, just drop the getMSC function from the DRI interface
instead using the ABI preserving version mechanism.

Finally, using void pointer privates in the DRI interface is not allowed,
always pass the actual types around (__DRIdrawable in this case) to
enhance type safety and readability of the code.

Currently only implemented for intel hw.

The internal CreatePixmap API has been extended.

Consolidate support for synchronizing to and retrieving vblank counters.  Also
fix the core vblank code to return monotonic MSC counters, which are required
by some GLX extensions.  Adding support for multiple pipes to a low level
driver is fairly easy, the Intel 965 driver provides simple example code (see
intel_buffers.c:intelWindowMoved()).

The new code bumps the media stream counter extension version to 2 and adds a
new getDrawableMSC callback.  This callback takes a drawablePrivate pointer,
which is used to calculate the MSC value seen by clients based on the actual
vblank counter(s) returned from the kernel.  The new drawable private fields
are as follows:
  - vblSeq - used for tracking vblank counts for buffer swapping
  - vblFlags - flags (e.g. current pipe), updated by low level driver
  - msc_base - MSC counter from the last time the current pipe changed
  - vblank_base - kernel DRM vblank counter from the last time the pipe changed

Using the above variables, the core vblank code (in vblank.c) can calculate a
monotonic MSC value.  The low level DRI drivers are responsible for updating
the current pipe (by setting VBLANK_FLAG_SECONDARY for example in vblFlags)
along with msc_base and vblank_base whenever the pipe associated with a given
drawable changes (again, see intelWindowMoved for an example of this).

Drivers should fill in the GetDrawableMSC DriverAPIRec field to point to
driDrawableGetMSC32 and add code for pipe switching as outlined above to fully
support the new scheme.

This is for consistency with glproto. The GL_CORE defines should probably be
dropped.

----

Author: Alexander Gottwald <alexander.gottwald@s1999.tu-chemnitz.de>
Date:   Mon Jun 21 13:35:05 2004 +0000

    Bug 782: Merge native OpenGL for Windows from CYGWIN branch

This new API lets the loader examine DRI level extensions provided by the
driver in a forward compatible manner.

Much of the churn in the DRI interface is adding support for new
extensions or removing old, unused extensions.  This new extension
mechanism lets the loader query the extensions provided by the driver
and implement the extensions it knows about.  Deprecating extensions
is done by not exporting that extension in the list, which doesn't
require keeping old function pointers around to preserve ABI.

The entrypoints take a mix of __DRIscreen * and void * (screen private)
arguments (similarly for contexts and drawables).  This patch does away
with passing the private void pointer and always only passes the fully
typed __DRIscreen pointer and always as the first argument.

This makes the interface more consistent and increases type safety, and
catches a bug where we would pass a screen private to DRIdrawable::getSBC.

The screenConfigs field of __DRIscreen points back to the containing
__GLXscreenConfigs struct.  This is a serious abstraction violation; it
assumes that the loader is libGL and that there *is* a __GLXscreenConfigs
type in the loader.

Using the containerOf macro, we can get from the __DRIscreen pointer to
the containing __GLXscreenConfigs struct, at a place in the stack
where the above is a valid assumption.  Besides, the __DRI* structs shouldn't
hold state other than the private pointer.

As for createDrawable and destroyDrawable, these functions immediately
upon entry to driCreateNewContext and immediately before exit from
driDestroyContext.  Instead of passing function pointers back and forth
just obtain the drm_context_t prior to calling DRIscreen::createNewContext
and pass it as a parameter.

This change also lets us keep the DRI context XID in the libGL loader only.

All the DRI driver did was call the createDrawable callback immediately
upon entry to DRIscreen::createNewDrawable to get the drm_drawable_t.
We can just call that before calling into the DRI driver and pass the
returned drm_drawable_t as an argument to the DRI entry point.

Likewise for destroyDrawable.

Also, DRIdrawablePrivate::draw isn't used anywhere, and since the
driver no longer needs the XID of the drawable we can now drop that.

Many DRI entry points took a __DRInativeDisplay pointer and a screen
index as arguments.  The only use for the native display pointer was to
pass it back to the loader when looking up the __DRIscreen for the given
screen index.

Instead, let's just pass in the __DRIscreen pointer directly, which
let's drop the __DRInativeDisplay type and the getScreen function.

The assumption is now that the loader will be able to retrieve context
from the __DRIscreen pointer when necessary.

To be used by AIGLX for GLX_EXT_texture_from_pixmap without several
additional data copies.

Only build tested.

If an app (like progs/samples/blendxor.c) includes both gl.h and glext.h
this typedef will get hit in both headers, causing an error.
Possibly work around by bringing GL_NV_geometry_program4 items into gl.h.

It could only be called from XMesaCopySubBuffer but this function is not used
by XFree86.

It seems that XMesaPutImageHelper would handle sub-images but never got
finished. Proper sub-image helpers should be written if need be.

This uses xmesa.h as the GLcore interface and avoids adding an explicit GLcore
inteface which would not be a proper interface anyway.

It puts the declarations of the three functions specific for XMesa/XFree86 in
xmesa.h, we can push them down to xmesa_xf86.h if hiding behind XFree86Server
ifdef's is not enough.