Merge branch 'mesa_7_5_branch' into mesa_7_6_branch

[mesa.git] / src / glx / x11 / glxcmds.c

/*
 * SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008)
 * Copyright (C) 1991-2000 Silicon Graphics, Inc. All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice including the dates of first publication and
 * either this permission notice or a reference to
 * http://oss.sgi.com/projects/FreeB/
 * shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * SILICON GRAPHICS, INC. BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
 * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Except as contained in this notice, the name of Silicon Graphics, Inc.
 * shall not be used in advertising or otherwise to promote the sale, use or
 * other dealings in this Software without prior written authorization from
 * Silicon Graphics, Inc.
 */

/**
 * \file glxcmds.c
 * Client-side GLX interface.
 */

#include "glxclient.h"
#include "glapi.h"
#include "glxextensions.h"
#include "glcontextmodes.h"

#ifdef GLX_DIRECT_RENDERING
#include <sys/time.h>
#include <X11/extensions/xf86vmode.h>
#include "xf86dri.h"
#endif

#if defined(USE_XCB)
#include <X11/Xlib-xcb.h>
#include <xcb/xcb.h>
#include <xcb/glx.h>
#endif

static const char __glXGLXClientVendorName[] = "SGI";
static const char __glXGLXClientVersion[] = "1.4";


/****************************************************************************/

#ifdef GLX_DIRECT_RENDERING

static Bool windowExistsFlag;
static int
windowExistsErrorHandler(Display * dpy, XErrorEvent * xerr)
{
   if (xerr->error_code == BadWindow) {
      windowExistsFlag = GL_FALSE;
   }
   return 0;
}

/**
 * Find drawables in the local hash that have been destroyed on the
 * server.
 *
 * \param dpy    Display to destroy drawables for
 * \param screen Screen number to destroy drawables for
 */
static void
GarbageCollectDRIDrawables(Display * dpy, __GLXscreenConfigs * sc)
{
   XID draw;
   __GLXDRIdrawable *pdraw;
   XWindowAttributes xwa;
   int (*oldXErrorHandler) (Display *, XErrorEvent *);

   /* Set no-op error handler so Xlib doesn't bail out if the windows
    * has alreay been destroyed on the server. */
   XSync(dpy, GL_FALSE);
   oldXErrorHandler = XSetErrorHandler(windowExistsErrorHandler);

   if (__glxHashFirst(sc->drawHash, &draw, (void *) &pdraw) == 1) {
      do {
         windowExistsFlag = GL_TRUE;
         XGetWindowAttributes(dpy, draw, &xwa); /* dummy request */
         if (!windowExistsFlag) {
            /* Destroy the local drawable data, if the drawable no
               longer exists in the Xserver */
            (*pdraw->destroyDrawable) (pdraw);
            __glxHashDelete(sc->drawHash, draw);
         }
      } while (__glxHashNext(sc->drawHash, &draw, (void *) &pdraw) == 1);
   }

   XSync(dpy, GL_FALSE);
   XSetErrorHandler(oldXErrorHandler);
}

extern __GLXDRIdrawable *GetGLXDRIDrawable(Display * dpy,
                                           GLXDrawable drawable,
                                           int *const scrn_num);

/**
 * Get the __DRIdrawable for the drawable associated with a GLXContext
 *
 * \param dpy       The display associated with \c drawable.
 * \param drawable  GLXDrawable whose __DRIdrawable part is to be retrieved.
 * \param scrn_num  If non-NULL, the drawables screen is stored there
 * \returns  A pointer to the context's __DRIdrawable on success, or NULL if
 *           the drawable is not associated with a direct-rendering context.
 */
_X_HIDDEN __GLXDRIdrawable *
GetGLXDRIDrawable(Display * dpy, GLXDrawable drawable, int *const scrn_num)
{
   __GLXdisplayPrivate *priv = __glXInitialize(dpy);
   __GLXDRIdrawable *pdraw;
   const unsigned screen_count = ScreenCount(dpy);
   unsigned i;
   __GLXscreenConfigs *psc;

   if (priv == NULL)
      return NULL;

   for (i = 0; i < screen_count; i++) {
      psc = &priv->screenConfigs[i];
      if (psc->drawHash == NULL)
         continue;

      if (__glxHashLookup(psc->drawHash, drawable, (void *) &pdraw) == 0) {
         if (scrn_num != NULL)
            *scrn_num = i;
         return pdraw;
      }
   }

   return NULL;
}

#endif


/**
 * Get the GLX per-screen data structure associated with a GLX context.
 *
 * \param dpy   Display for which the GLX per-screen information is to be
 *              retrieved.
 * \param scrn  Screen on \c dpy for which the GLX per-screen information is
 *              to be retrieved.
 * \returns A pointer to the GLX per-screen data if \c dpy and \c scrn
 *          specify a valid GLX screen, or NULL otherwise.
 *
 * \todo Should this function validate that \c scrn is within the screen
 *       number range for \c dpy?
 */

static __GLXscreenConfigs *
GetGLXScreenConfigs(Display * dpy, int scrn)
{
   __GLXdisplayPrivate *const priv = __glXInitialize(dpy);

   return (priv
           && priv->screenConfigs !=
           NULL) ? &priv->screenConfigs[scrn] : NULL;
}


static int
GetGLXPrivScreenConfig(Display * dpy, int scrn, __GLXdisplayPrivate ** ppriv,
                       __GLXscreenConfigs ** ppsc)
{
   /* Initialize the extension, if needed .  This has the added value
    * of initializing/allocating the display private
    */

   if (dpy == NULL) {
      return GLX_NO_EXTENSION;
   }

   *ppriv = __glXInitialize(dpy);
   if (*ppriv == NULL) {
      return GLX_NO_EXTENSION;
   }

   /* Check screen number to see if its valid */
   if ((scrn < 0) || (scrn >= ScreenCount(dpy))) {
      return GLX_BAD_SCREEN;
   }

   /* Check to see if the GL is supported on this screen */
   *ppsc = &((*ppriv)->screenConfigs[scrn]);
   if ((*ppsc)->configs == NULL) {
      /* No support for GL on this screen regardless of visual */
      return GLX_BAD_VISUAL;
   }

   return Success;
}


/**
 * Determine if a \c GLXFBConfig supplied by the application is valid.
 *
 * \param dpy     Application supplied \c Display pointer.
 * \param config  Application supplied \c GLXFBConfig.
 *
 * \returns If the \c GLXFBConfig is valid, the a pointer to the matching
 *          \c __GLcontextModes structure is returned.  Otherwise, \c NULL
 *          is returned.
 */
static __GLcontextModes *
ValidateGLXFBConfig(Display * dpy, GLXFBConfig config)
{
   __GLXdisplayPrivate *const priv = __glXInitialize(dpy);
   const unsigned num_screens = ScreenCount(dpy);
   unsigned i;
   const __GLcontextModes *modes;


   if (priv != NULL) {
      for (i = 0; i < num_screens; i++) {
         for (modes = priv->screenConfigs[i].configs; modes != NULL;
              modes = modes->next) {
            if (modes == (__GLcontextModes *) config) {
               return (__GLcontextModes *) config;
            }
         }
      }
   }

   return NULL;
}


/**
 * \todo It should be possible to move the allocate of \c client_state_private
 * later in the function for direct-rendering contexts.  Direct-rendering
 * contexts don't need to track client state, so they don't need that memory
 * at all.
 *
 * \todo Eliminate \c __glXInitVertexArrayState.  Replace it with a new
 * function called \c __glXAllocateClientState that allocates the memory and
 * does all the initialization (including the pixel pack / unpack).
 */
static GLXContext
AllocateGLXContext(Display * dpy)
{
   GLXContext gc;
   int bufSize;
   CARD8 opcode;
   __GLXattribute *state;

   if (!dpy)
      return NULL;

   opcode = __glXSetupForCommand(dpy);
   if (!opcode) {
      return NULL;
   }

   /* Allocate our context record */
   gc = (GLXContext) Xmalloc(sizeof(struct __GLXcontextRec));
   if (!gc) {
      /* Out of memory */
      return NULL;
   }
   memset(gc, 0, sizeof(struct __GLXcontextRec));

   state = Xmalloc(sizeof(struct __GLXattributeRec));
   if (state == NULL) {
      /* Out of memory */
      Xfree(gc);
      return NULL;
   }
   gc->client_state_private = state;
   memset(gc->client_state_private, 0, sizeof(struct __GLXattributeRec));
   state->NoDrawArraysProtocol = (getenv("LIBGL_NO_DRAWARRAYS") != NULL);

   /*
    ** Create a temporary buffer to hold GLX rendering commands.  The size
    ** of the buffer is selected so that the maximum number of GLX rendering
    ** commands can fit in a single X packet and still have room in the X
    ** packet for the GLXRenderReq header.
    */

   bufSize = (XMaxRequestSize(dpy) * 4) - sz_xGLXRenderReq;
   gc->buf = (GLubyte *) Xmalloc(bufSize);
   if (!gc->buf) {
      Xfree(gc->client_state_private);
      Xfree(gc);
      return NULL;
   }
   gc->bufSize = bufSize;

   /* Fill in the new context */
   gc->renderMode = GL_RENDER;

   state->storePack.alignment = 4;
   state->storeUnpack.alignment = 4;

   gc->attributes.stackPointer = &gc->attributes.stack[0];

   /*
    ** PERFORMANCE NOTE: A mode dependent fill image can speed things up.
    ** Other code uses the fastImageUnpack bit, but it is never set
    ** to GL_TRUE.
    */
   gc->fastImageUnpack = GL_FALSE;
   gc->fillImage = __glFillImage;
   gc->pc = gc->buf;
   gc->bufEnd = gc->buf + bufSize;
   gc->isDirect = GL_FALSE;
   if (__glXDebug) {
      /*
       ** Set limit register so that there will be one command per packet
       */
      gc->limit = gc->buf;
   }
   else {
      gc->limit = gc->buf + bufSize - __GLX_BUFFER_LIMIT_SIZE;
   }
   gc->createDpy = dpy;
   gc->majorOpcode = opcode;

   /*
    ** Constrain the maximum drawing command size allowed to be
    ** transfered using the X_GLXRender protocol request.  First
    ** constrain by a software limit, then constrain by the protocl
    ** limit.
    */
   if (bufSize > __GLX_RENDER_CMD_SIZE_LIMIT) {
      bufSize = __GLX_RENDER_CMD_SIZE_LIMIT;
   }
   if (bufSize > __GLX_MAX_RENDER_CMD_SIZE) {
      bufSize = __GLX_MAX_RENDER_CMD_SIZE;
   }
   gc->maxSmallRenderCommandSize = bufSize;
   return gc;
}


/**
 * Create a new context.  Exactly one of \c vis and \c fbconfig should be
 * non-NULL.
 *
 * \param use_glx_1_3  For FBConfigs, should GLX 1.3 protocol or
 *                     SGIX_fbconfig protocol be used?
 * \param renderType   For FBConfigs, what is the rendering type?
 */

static GLXContext
CreateContext(Display * dpy, XVisualInfo * vis,
              const __GLcontextModes * const fbconfig,
              GLXContext shareList,
              Bool allowDirect, GLXContextID contextID,
              Bool use_glx_1_3, int renderType)
{
   GLXContext gc;
#ifdef GLX_DIRECT_RENDERING
   int screen = (fbconfig == NULL) ? vis->screen : fbconfig->screen;
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);
#endif

   if (dpy == NULL)
      return NULL;

   gc = AllocateGLXContext(dpy);
   if (!gc)
      return NULL;

   if (None == contextID) {
      if ((vis == NULL) && (fbconfig == NULL))
         return NULL;

#ifdef GLX_DIRECT_RENDERING
      if (allowDirect && psc->driScreen) {
         const __GLcontextModes *mode;

         if (fbconfig == NULL) {
            mode = _gl_context_modes_find_visual(psc->visuals, vis->visualid);
            if (mode == NULL) {
               xError error;

               error.errorCode = BadValue;
               error.resourceID = vis->visualid;
               error.sequenceNumber = dpy->request;
               error.type = X_Error;
               error.majorCode = gc->majorOpcode;
               error.minorCode = X_GLXCreateContext;
               _XError(dpy, &error);
               return None;
            }
         }
         else {
            mode = fbconfig;
         }

         gc->driContext = psc->driScreen->createContext(psc, mode, gc,
                                                        shareList,
                                                        renderType);
         if (gc->driContext != NULL) {
            gc->screen = mode->screen;
            gc->psc = psc;
            gc->mode = mode;
            gc->isDirect = GL_TRUE;
         }
      }
#endif

      LockDisplay(dpy);
      if (fbconfig == NULL) {
         xGLXCreateContextReq *req;

         /* Send the glXCreateContext request */
         GetReq(GLXCreateContext, req);
         req->reqType = gc->majorOpcode;
         req->glxCode = X_GLXCreateContext;
         req->context = gc->xid = XAllocID(dpy);
         req->visual = vis->visualid;
         req->screen = vis->screen;
         req->shareList = shareList ? shareList->xid : None;
#ifdef GLX_DIRECT_RENDERING
         req->isDirect = gc->driContext != NULL;
#else
         req->isDirect = 0;
#endif
      }
      else if (use_glx_1_3) {
         xGLXCreateNewContextReq *req;

         /* Send the glXCreateNewContext request */
         GetReq(GLXCreateNewContext, req);
         req->reqType = gc->majorOpcode;
         req->glxCode = X_GLXCreateNewContext;
         req->context = gc->xid = XAllocID(dpy);
         req->fbconfig = fbconfig->fbconfigID;
         req->screen = fbconfig->screen;
         req->renderType = renderType;
         req->shareList = shareList ? shareList->xid : None;
#ifdef GLX_DIRECT_RENDERING
         req->isDirect = gc->driContext != NULL;
#else
         req->isDirect = 0;
#endif
      }
      else {
         xGLXVendorPrivateWithReplyReq *vpreq;
         xGLXCreateContextWithConfigSGIXReq *req;

         /* Send the glXCreateNewContext request */
         GetReqExtra(GLXVendorPrivateWithReply,
                     sz_xGLXCreateContextWithConfigSGIXReq -
                     sz_xGLXVendorPrivateWithReplyReq, vpreq);
         req = (xGLXCreateContextWithConfigSGIXReq *) vpreq;
         req->reqType = gc->majorOpcode;
         req->glxCode = X_GLXVendorPrivateWithReply;
         req->vendorCode = X_GLXvop_CreateContextWithConfigSGIX;
         req->context = gc->xid = XAllocID(dpy);
         req->fbconfig = fbconfig->fbconfigID;
         req->screen = fbconfig->screen;
         req->renderType = renderType;
         req->shareList = shareList ? shareList->xid : None;
#ifdef GLX_DIRECT_RENDERING
         req->isDirect = gc->driContext != NULL;
#else
         req->isDirect = 0;
#endif
      }

      UnlockDisplay(dpy);
      SyncHandle();
      gc->imported = GL_FALSE;
   }
   else {
      gc->xid = contextID;
      gc->imported = GL_TRUE;
   }

   return gc;
}

PUBLIC GLXContext
glXCreateContext(Display * dpy, XVisualInfo * vis,
                 GLXContext shareList, Bool allowDirect)
{
   return CreateContext(dpy, vis, NULL, shareList, allowDirect, None,
                        False, 0);
}

_X_HIDDEN void
__glXFreeContext(__GLXcontext * gc)
{
   if (gc->vendor)
      XFree((char *) gc->vendor);
   if (gc->renderer)
      XFree((char *) gc->renderer);
   if (gc->version)
      XFree((char *) gc->version);
   if (gc->extensions)
      XFree((char *) gc->extensions);
   __glFreeAttributeState(gc);
   XFree((char *) gc->buf);
   Xfree((char *) gc->client_state_private);
   XFree((char *) gc);

}

/*
** Destroy the named context
*/
static void
DestroyContext(Display * dpy, GLXContext gc)
{
   xGLXDestroyContextReq *req;
   GLXContextID xid;
   CARD8 opcode;
   GLboolean imported;

   opcode = __glXSetupForCommand(dpy);
   if (!opcode || !gc) {
      return;
   }

   __glXLock();
   xid = gc->xid;
   imported = gc->imported;
   gc->xid = None;

#ifdef GLX_DIRECT_RENDERING
   /* Destroy the direct rendering context */
   if (gc->driContext) {
      (*gc->driContext->destroyContext) (gc->driContext, gc->psc, dpy);
      gc->driContext = NULL;
      GarbageCollectDRIDrawables(dpy, gc->psc);
   }
#endif

   __glXFreeVertexArrayState(gc);

   if (gc->currentDpy) {
      /* Have to free later cuz it's in use now */
      __glXUnlock();
   }
   else {
      /* Destroy the handle if not current to anybody */
      __glXUnlock();
      __glXFreeContext(gc);
   }

   if (!imported) {
      /*
       ** This dpy also created the server side part of the context.
       ** Send the glXDestroyContext request.
       */
      LockDisplay(dpy);
      GetReq(GLXDestroyContext, req);
      req->reqType = opcode;
      req->glxCode = X_GLXDestroyContext;
      req->context = xid;
      UnlockDisplay(dpy);
      SyncHandle();
   }
}

PUBLIC void
glXDestroyContext(Display * dpy, GLXContext gc)
{
   DestroyContext(dpy, gc);
}

/*
** Return the major and minor version #s for the GLX extension
*/
PUBLIC Bool
glXQueryVersion(Display * dpy, int *major, int *minor)
{
   __GLXdisplayPrivate *priv;

   /* Init the extension.  This fetches the major and minor version. */
   priv = __glXInitialize(dpy);
   if (!priv)
      return GL_FALSE;

   if (major)
      *major = priv->majorVersion;
   if (minor)
      *minor = priv->minorVersion;
   return GL_TRUE;
}

/*
** Query the existance of the GLX extension
*/
PUBLIC Bool
glXQueryExtension(Display * dpy, int *errorBase, int *eventBase)
{
   int major_op, erb, evb;
   Bool rv;

   rv = XQueryExtension(dpy, GLX_EXTENSION_NAME, &major_op, &evb, &erb);
   if (rv) {
      if (errorBase)
         *errorBase = erb;
      if (eventBase)
         *eventBase = evb;
   }
   return rv;
}

/*
** Put a barrier in the token stream that forces the GL to finish its
** work before X can proceed.
*/
PUBLIC void
glXWaitGL(void)
{
   xGLXWaitGLReq *req;
   GLXContext gc = __glXGetCurrentContext();
   Display *dpy = gc->currentDpy;

   if (!dpy)
      return;

   /* Flush any pending commands out */
   __glXFlushRenderBuffer(gc, gc->pc);

#ifdef GLX_DIRECT_RENDERING
   if (gc->driContext) {
      int screen;
      __GLXDRIdrawable *pdraw =
         GetGLXDRIDrawable(dpy, gc->currentDrawable, &screen);

      if (pdraw != NULL) {
         __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);
         glFlush();
         if (psc->driScreen->waitGL != NULL)
            (*psc->driScreen->waitGL) (pdraw);
      }
      return;
   }
#endif

   /* Send the glXWaitGL request */
   LockDisplay(dpy);
   GetReq(GLXWaitGL, req);
   req->reqType = gc->majorOpcode;
   req->glxCode = X_GLXWaitGL;
   req->contextTag = gc->currentContextTag;
   UnlockDisplay(dpy);
   SyncHandle();
}

/*
** Put a barrier in the token stream that forces X to finish its
** work before GL can proceed.
*/
PUBLIC void
glXWaitX(void)
{
   xGLXWaitXReq *req;
   GLXContext gc = __glXGetCurrentContext();
   Display *dpy = gc->currentDpy;

   if (!dpy)
      return;

   /* Flush any pending commands out */
   __glXFlushRenderBuffer(gc, gc->pc);

#ifdef GLX_DIRECT_RENDERING
   if (gc->driContext) {
      int screen;
      __GLXDRIdrawable *pdraw =
         GetGLXDRIDrawable(dpy, gc->currentDrawable, &screen);

      if (pdraw != NULL) {
         __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);
         if (psc->driScreen->waitX != NULL)
            (*psc->driScreen->waitX) (pdraw);
      }
      else
         XSync(dpy, False);
      return;
   }
#endif

   /*
    ** Send the glXWaitX request.
    */
   LockDisplay(dpy);
   GetReq(GLXWaitX, req);
   req->reqType = gc->majorOpcode;
   req->glxCode = X_GLXWaitX;
   req->contextTag = gc->currentContextTag;
   UnlockDisplay(dpy);
   SyncHandle();
}

PUBLIC void
glXUseXFont(Font font, int first, int count, int listBase)
{
   xGLXUseXFontReq *req;
   GLXContext gc = __glXGetCurrentContext();
   Display *dpy = gc->currentDpy;

   if (!dpy)
      return;

   /* Flush any pending commands out */
   (void) __glXFlushRenderBuffer(gc, gc->pc);

#ifdef GLX_DIRECT_RENDERING
   if (gc->driContext) {
      DRI_glXUseXFont(font, first, count, listBase);
      return;
   }
#endif

   /* Send the glXUseFont request */
   LockDisplay(dpy);
   GetReq(GLXUseXFont, req);
   req->reqType = gc->majorOpcode;
   req->glxCode = X_GLXUseXFont;
   req->contextTag = gc->currentContextTag;
   req->font = font;
   req->first = first;
   req->count = count;
   req->listBase = listBase;
   UnlockDisplay(dpy);
   SyncHandle();
}

/************************************************************************/

/*
** Copy the source context to the destination context using the
** attribute "mask".
*/
PUBLIC void
glXCopyContext(Display * dpy, GLXContext source,
               GLXContext dest, unsigned long mask)
{
   xGLXCopyContextReq *req;
   GLXContext gc = __glXGetCurrentContext();
   GLXContextTag tag;
   CARD8 opcode;

   opcode = __glXSetupForCommand(dpy);
   if (!opcode) {
      return;
   }

#ifdef GLX_DIRECT_RENDERING
   if (gc->driContext) {
      /* NOT_DONE: This does not work yet */
   }
#endif

   /*
    ** If the source is the current context, send its tag so that the context
    ** can be flushed before the copy.
    */
   if (source == gc && dpy == gc->currentDpy) {
      tag = gc->currentContextTag;
   }
   else {
      tag = 0;
   }

   /* Send the glXCopyContext request */
   LockDisplay(dpy);
   GetReq(GLXCopyContext, req);
   req->reqType = opcode;
   req->glxCode = X_GLXCopyContext;
   req->source = source ? source->xid : None;
   req->dest = dest ? dest->xid : None;
   req->mask = mask;
   req->contextTag = tag;
   UnlockDisplay(dpy);
   SyncHandle();
}


/**
 * Determine if a context uses direct rendering.
 *
 * \param dpy        Display where the context was created.
 * \param contextID  ID of the context to be tested.
 *
 * \returns \c GL_TRUE if the context is direct rendering or not.
 */
static Bool
__glXIsDirect(Display * dpy, GLXContextID contextID)
{
#if !defined(USE_XCB)
   xGLXIsDirectReq *req;
   xGLXIsDirectReply reply;
#endif
   CARD8 opcode;

   opcode = __glXSetupForCommand(dpy);
   if (!opcode) {
      return GL_FALSE;
   }

#ifdef USE_XCB
   xcb_connection_t *c = XGetXCBConnection(dpy);
   xcb_glx_is_direct_reply_t *reply = xcb_glx_is_direct_reply(c,
                                                              xcb_glx_is_direct
                                                              (c, contextID),
                                                              NULL);

   const Bool is_direct = reply->is_direct ? True : False;
   free(reply);

   return is_direct;
#else
   /* Send the glXIsDirect request */
   LockDisplay(dpy);
   GetReq(GLXIsDirect, req);
   req->reqType = opcode;
   req->glxCode = X_GLXIsDirect;
   req->context = contextID;
   _XReply(dpy, (xReply *) & reply, 0, False);
   UnlockDisplay(dpy);
   SyncHandle();

   return reply.isDirect;
#endif /* USE_XCB */
}

/**
 * \todo
 * Shouldn't this function \b always return \c GL_FALSE when
 * \c GLX_DIRECT_RENDERING is not defined?  Do we really need to bother with
 * the GLX protocol here at all?
 */
PUBLIC Bool
glXIsDirect(Display * dpy, GLXContext gc)
{
   if (!gc) {
      return GL_FALSE;
#ifdef GLX_DIRECT_RENDERING
   }
   else if (gc->driContext) {
      return GL_TRUE;
#endif
   }
   return __glXIsDirect(dpy, gc->xid);
}

PUBLIC GLXPixmap
glXCreateGLXPixmap(Display * dpy, XVisualInfo * vis, Pixmap pixmap)
{
   xGLXCreateGLXPixmapReq *req;
   GLXPixmap xid;
   CARD8 opcode;

   opcode = __glXSetupForCommand(dpy);
   if (!opcode) {
      return None;
   }

   /* Send the glXCreateGLXPixmap request */
   LockDisplay(dpy);
   GetReq(GLXCreateGLXPixmap, req);
   req->reqType = opcode;
   req->glxCode = X_GLXCreateGLXPixmap;
   req->screen = vis->screen;
   req->visual = vis->visualid;
   req->pixmap = pixmap;
   req->glxpixmap = xid = XAllocID(dpy);
   UnlockDisplay(dpy);
   SyncHandle();

#ifdef GLX_DIRECT_RENDERING
   do {
      /* FIXME: Maybe delay __DRIdrawable creation until the drawable
       * is actually bound to a context... */

      __GLXdisplayPrivate *const priv = __glXInitialize(dpy);
      __GLXDRIdrawable *pdraw;
      __GLXscreenConfigs *psc;
      __GLcontextModes *modes;

      psc = &priv->screenConfigs[vis->screen];
      if (psc->driScreen == NULL)
         break;
      modes = _gl_context_modes_find_visual(psc->visuals, vis->visualid);
      pdraw = psc->driScreen->createDrawable(psc, pixmap, req->glxpixmap, modes);
      if (pdraw == NULL) {
         fprintf(stderr, "failed to create pixmap\n");
         break;
      }

      if (__glxHashInsert(psc->drawHash, req->glxpixmap, pdraw)) {
         (*pdraw->destroyDrawable) (pdraw);
         return None;           /* FIXME: Check what we're supposed to do here... */
      }
   } while (0);
#endif

   return xid;
}

/*
** Destroy the named pixmap
*/
PUBLIC void
glXDestroyGLXPixmap(Display * dpy, GLXPixmap glxpixmap)
{
   xGLXDestroyGLXPixmapReq *req;
   CARD8 opcode;

   opcode = __glXSetupForCommand(dpy);
   if (!opcode) {
      return;
   }

   /* Send the glXDestroyGLXPixmap request */
   LockDisplay(dpy);
   GetReq(GLXDestroyGLXPixmap, req);
   req->reqType = opcode;
   req->glxCode = X_GLXDestroyGLXPixmap;
   req->glxpixmap = glxpixmap;
   UnlockDisplay(dpy);
   SyncHandle();

#ifdef GLX_DIRECT_RENDERING
   {
      int screen;
      __GLXdisplayPrivate *const priv = __glXInitialize(dpy);
      __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, glxpixmap, &screen);
      __GLXscreenConfigs *psc = &priv->screenConfigs[screen];

      if (pdraw != NULL) {
         (*pdraw->destroyDrawable) (pdraw);
         __glxHashDelete(psc->drawHash, glxpixmap);
      }
   }
#endif
}

PUBLIC void
glXSwapBuffers(Display * dpy, GLXDrawable drawable)
{
   GLXContext gc;
   GLXContextTag tag;
   CARD8 opcode;
#ifdef USE_XCB
   xcb_connection_t *c;
#else
   xGLXSwapBuffersReq *req;
#endif

#ifdef GLX_DIRECT_RENDERING
   __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, NULL);

   if (pdraw != NULL) {
      glFlush();
      (*pdraw->psc->driScreen->swapBuffers) (pdraw);
      return;
   }
#endif

   opcode = __glXSetupForCommand(dpy);
   if (!opcode) {
      return;
   }

   /*
    ** The calling thread may or may not have a current context.  If it
    ** does, send the context tag so the server can do a flush.
    */
   gc = __glXGetCurrentContext();
   if ((gc != NULL) && (dpy == gc->currentDpy) &&
       ((drawable == gc->currentDrawable)
        || (drawable == gc->currentReadable))) {
      tag = gc->currentContextTag;
   }
   else {
      tag = 0;
   }

#ifdef USE_XCB
   c = XGetXCBConnection(dpy);
   xcb_glx_swap_buffers(c, tag, drawable);
   xcb_flush(c);
#else
   /* Send the glXSwapBuffers request */
   LockDisplay(dpy);
   GetReq(GLXSwapBuffers, req);
   req->reqType = opcode;
   req->glxCode = X_GLXSwapBuffers;
   req->drawable = drawable;
   req->contextTag = tag;
   UnlockDisplay(dpy);
   SyncHandle();
   XFlush(dpy);
#endif /* USE_XCB */
}


/*
** Return configuration information for the given display, screen and
** visual combination.
*/
PUBLIC int
glXGetConfig(Display * dpy, XVisualInfo * vis, int attribute,
             int *value_return)
{
   __GLXdisplayPrivate *priv;
   __GLXscreenConfigs *psc;
   __GLcontextModes *modes;
   int status;

   status = GetGLXPrivScreenConfig(dpy, vis->screen, &priv, &psc);
   if (status == Success) {
      modes = _gl_context_modes_find_visual(psc->visuals, vis->visualid);

      /* Lookup attribute after first finding a match on the visual */
      if (modes != NULL) {
         return _gl_get_context_mode_data(modes, attribute, value_return);
      }

      status = GLX_BAD_VISUAL;
   }

   /*
    ** If we can't find the config for this visual, this visual is not
    ** supported by the OpenGL implementation on the server.
    */
   if ((status == GLX_BAD_VISUAL) && (attribute == GLX_USE_GL)) {
      *value_return = GL_FALSE;
      status = Success;
   }

   return status;
}

/************************************************************************/

static void
init_fbconfig_for_chooser(__GLcontextModes * config,
                          GLboolean fbconfig_style_tags)
{
   memset(config, 0, sizeof(__GLcontextModes));
   config->visualID = (XID) GLX_DONT_CARE;
   config->visualType = GLX_DONT_CARE;

   /* glXChooseFBConfig specifies different defaults for these two than
    * glXChooseVisual.
    */
   if (fbconfig_style_tags) {
      config->rgbMode = GL_TRUE;
      config->doubleBufferMode = GLX_DONT_CARE;
   }

   config->visualRating = GLX_DONT_CARE;
   config->transparentPixel = GLX_NONE;
   config->transparentRed = GLX_DONT_CARE;
   config->transparentGreen = GLX_DONT_CARE;
   config->transparentBlue = GLX_DONT_CARE;
   config->transparentAlpha = GLX_DONT_CARE;
   config->transparentIndex = GLX_DONT_CARE;

   config->drawableType = GLX_WINDOW_BIT;
   config->renderType =
      (config->rgbMode) ? GLX_RGBA_BIT : GLX_COLOR_INDEX_BIT;
   config->xRenderable = GLX_DONT_CARE;
   config->fbconfigID = (GLXFBConfigID) (GLX_DONT_CARE);

   config->swapMethod = GLX_DONT_CARE;
}

#define MATCH_DONT_CARE( param )        \
  do {                                  \
    if ( (a-> param != GLX_DONT_CARE)   \
         && (a-> param != b-> param) ) {        \
      return False;                             \
    }                                           \
  } while ( 0 )

#define MATCH_MINIMUM( param )                  \
  do {                                          \
    if ( (a-> param != GLX_DONT_CARE)           \
         && (a-> param > b-> param) ) {         \
      return False;                             \
    }                                           \
  } while ( 0 )

#define MATCH_EXACT( param )                    \
  do {                                          \
    if ( a-> param != b-> param) {              \
      return False;                             \
    }                                           \
  } while ( 0 )

/**
 * Determine if two GLXFBConfigs are compatible.
 *
 * \param a  Application specified config to test.
 * \param b  Server specified config to test against \c a.
 */
static Bool
fbconfigs_compatible(const __GLcontextModes * const a,
                     const __GLcontextModes * const b)
{
   MATCH_DONT_CARE(doubleBufferMode);
   MATCH_DONT_CARE(visualType);
   MATCH_DONT_CARE(visualRating);
   MATCH_DONT_CARE(xRenderable);
   MATCH_DONT_CARE(fbconfigID);
   MATCH_DONT_CARE(swapMethod);

   MATCH_MINIMUM(rgbBits);
   MATCH_MINIMUM(numAuxBuffers);
   MATCH_MINIMUM(redBits);
   MATCH_MINIMUM(greenBits);
   MATCH_MINIMUM(blueBits);
   MATCH_MINIMUM(alphaBits);
   MATCH_MINIMUM(depthBits);
   MATCH_MINIMUM(stencilBits);
   MATCH_MINIMUM(accumRedBits);
   MATCH_MINIMUM(accumGreenBits);
   MATCH_MINIMUM(accumBlueBits);
   MATCH_MINIMUM(accumAlphaBits);
   MATCH_MINIMUM(sampleBuffers);
   MATCH_MINIMUM(maxPbufferWidth);
   MATCH_MINIMUM(maxPbufferHeight);
   MATCH_MINIMUM(maxPbufferPixels);
   MATCH_MINIMUM(samples);

   MATCH_DONT_CARE(stereoMode);
   MATCH_EXACT(level);

   if (((a->drawableType & b->drawableType) == 0)
       || ((a->renderType & b->renderType) == 0)) {
      return False;
   }


   /* There is a bug in a few of the XFree86 DDX drivers.  They contain
    * visuals with a "transparent type" of 0 when they really mean GLX_NONE.
    * Technically speaking, it is a bug in the DDX driver, but there is
    * enough of an installed base to work around the problem here.  In any
    * case, 0 is not a valid value of the transparent type, so we'll treat 0
    * from the app as GLX_DONT_CARE. We'll consider GLX_NONE from the app and
    * 0 from the server to be a match to maintain backward compatibility with
    * the (broken) drivers.
    */

   if (a->transparentPixel != GLX_DONT_CARE && a->transparentPixel != 0) {
      if (a->transparentPixel == GLX_NONE) {
         if (b->transparentPixel != GLX_NONE && b->transparentPixel != 0)
            return False;
      }
      else {
         MATCH_EXACT(transparentPixel);
      }

      switch (a->transparentPixel) {
      case GLX_TRANSPARENT_RGB:
         MATCH_DONT_CARE(transparentRed);
         MATCH_DONT_CARE(transparentGreen);
         MATCH_DONT_CARE(transparentBlue);
         MATCH_DONT_CARE(transparentAlpha);
         break;

      case GLX_TRANSPARENT_INDEX:
         MATCH_DONT_CARE(transparentIndex);
         break;

      default:
         break;
      }
   }

   return True;
}


/* There's some trickly language in the GLX spec about how this is supposed
 * to work.  Basically, if a given component size is either not specified
 * or the requested size is zero, it is supposed to act like PERFER_SMALLER.
 * Well, that's really hard to do with the code as-is.  This behavior is
 * closer to correct, but still not technically right.
 */
#define PREFER_LARGER_OR_ZERO(comp)             \
  do {                                          \
    if ( ((*a)-> comp) != ((*b)-> comp) ) {     \
      if ( ((*a)-> comp) == 0 ) {               \
        return -1;                              \
      }                                         \
      else if ( ((*b)-> comp) == 0 ) {          \
        return 1;                               \
      }                                         \
      else {                                    \
        return ((*b)-> comp) - ((*a)-> comp) ;  \
      }                                         \
    }                                           \
  } while( 0 )

#define PREFER_LARGER(comp)                     \
  do {                                          \
    if ( ((*a)-> comp) != ((*b)-> comp) ) {     \
      return ((*b)-> comp) - ((*a)-> comp) ;    \
    }                                           \
  } while( 0 )

#define PREFER_SMALLER(comp)                    \
  do {                                          \
    if ( ((*a)-> comp) != ((*b)-> comp) ) {     \
      return ((*a)-> comp) - ((*b)-> comp) ;    \
    }                                           \
  } while( 0 )

/**
 * Compare two GLXFBConfigs.  This function is intended to be used as the
 * compare function passed in to qsort.
 *
 * \returns If \c a is a "better" config, according to the specification of
 *          SGIX_fbconfig, a number less than zero is returned.  If \c b is
 *          better, then a number greater than zero is return.  If both are
 *          equal, zero is returned.
 * \sa qsort, glXChooseVisual, glXChooseFBConfig, glXChooseFBConfigSGIX
 */
static int
fbconfig_compare(const __GLcontextModes * const *const a,
                 const __GLcontextModes * const *const b)
{
   /* The order of these comparisons must NOT change.  It is defined by
    * the GLX 1.3 spec and ARB_multisample.
    */

   PREFER_SMALLER(visualSelectGroup);

   /* The sort order for the visualRating is GLX_NONE, GLX_SLOW, and
    * GLX_NON_CONFORMANT_CONFIG.  It just so happens that this is the
    * numerical sort order of the enums (0x8000, 0x8001, and 0x800D).
    */
   PREFER_SMALLER(visualRating);

   /* This isn't quite right.  It is supposed to compare the sum of the
    * components the user specifically set minimums for.
    */
   PREFER_LARGER_OR_ZERO(redBits);
   PREFER_LARGER_OR_ZERO(greenBits);
   PREFER_LARGER_OR_ZERO(blueBits);
   PREFER_LARGER_OR_ZERO(alphaBits);

   PREFER_SMALLER(rgbBits);

   if (((*a)->doubleBufferMode != (*b)->doubleBufferMode)) {
      /* Prefer single-buffer.
       */
      return (!(*a)->doubleBufferMode) ? -1 : 1;
   }

   PREFER_SMALLER(numAuxBuffers);

   PREFER_LARGER_OR_ZERO(depthBits);
   PREFER_SMALLER(stencilBits);

   /* This isn't quite right.  It is supposed to compare the sum of the
    * components the user specifically set minimums for.
    */
   PREFER_LARGER_OR_ZERO(accumRedBits);
   PREFER_LARGER_OR_ZERO(accumGreenBits);
   PREFER_LARGER_OR_ZERO(accumBlueBits);
   PREFER_LARGER_OR_ZERO(accumAlphaBits);

   PREFER_SMALLER(visualType);

   /* None of the multisample specs say where this comparison should happen,
    * so I put it near the end.
    */
   PREFER_SMALLER(sampleBuffers);
   PREFER_SMALLER(samples);

   /* None of the pbuffer or fbconfig specs say that this comparison needs
    * to happen at all, but it seems like it should.
    */
   PREFER_LARGER(maxPbufferWidth);
   PREFER_LARGER(maxPbufferHeight);
   PREFER_LARGER(maxPbufferPixels);

   return 0;
}


/**
 * Selects and sorts a subset of the supplied configs based on the attributes.
 * This function forms to basis of \c glXChooseVisual, \c glXChooseFBConfig,
 * and \c glXChooseFBConfigSGIX.
 *
 * \param configs   Array of pointers to possible configs.  The elements of
 *                  this array that do not meet the criteria will be set to
 *                  NULL.  The remaining elements will be sorted according to
 *                  the various visual / FBConfig selection rules.
 * \param num_configs  Number of elements in the \c configs array.
 * \param attribList   Attributes used select from \c configs.  This array is
 *                     terminated by a \c None tag.  The array can either take
 *                     the form expected by \c glXChooseVisual (where boolean
 *                     tags do not have a value) or by \c glXChooseFBConfig
 *                     (where every tag has a value).
 * \param fbconfig_style_tags  Selects whether \c attribList is in
 *                             \c glXChooseVisual style or
 *                             \c glXChooseFBConfig style.
 * \returns The number of valid elements left in \c configs.
 *
 * \sa glXChooseVisual, glXChooseFBConfig, glXChooseFBConfigSGIX
 */
static int
choose_visual(__GLcontextModes ** configs, int num_configs,
              const int *attribList, GLboolean fbconfig_style_tags)
{
   __GLcontextModes test_config;
   int base;
   int i;

   /* This is a fairly direct implementation of the selection method
    * described by GLX_SGIX_fbconfig.  Start by culling out all the
    * configs that are not compatible with the selected parameter
    * list.
    */

   init_fbconfig_for_chooser(&test_config, fbconfig_style_tags);
   __glXInitializeVisualConfigFromTags(&test_config, 512,
                                       (const INT32 *) attribList,
                                       GL_TRUE, fbconfig_style_tags);

   base = 0;
   for (i = 0; i < num_configs; i++) {
      if (fbconfigs_compatible(&test_config, configs[i])) {
         configs[base] = configs[i];
         base++;
      }
   }

   if (base == 0) {
      return 0;
   }

   if (base < num_configs) {
      (void) memset(&configs[base], 0, sizeof(void *) * (num_configs - base));
   }

   /* After the incompatible configs are removed, the resulting
    * list is sorted according to the rules set out in the various
    * specifications.
    */

   qsort(configs, base, sizeof(__GLcontextModes *),
         (int (*)(const void *, const void *)) fbconfig_compare);
   return base;
}




/*
** Return the visual that best matches the template.  Return None if no
** visual matches the template.
*/
PUBLIC XVisualInfo *
glXChooseVisual(Display * dpy, int screen, int *attribList)
{
   XVisualInfo *visualList = NULL;
   __GLXdisplayPrivate *priv;
   __GLXscreenConfigs *psc;
   __GLcontextModes test_config;
   __GLcontextModes *modes;
   const __GLcontextModes *best_config = NULL;

   /*
    ** Get a list of all visuals, return if list is empty
    */
   if (GetGLXPrivScreenConfig(dpy, screen, &priv, &psc) != Success) {
      return None;
   }


   /*
    ** Build a template from the defaults and the attribute list
    ** Free visual list and return if an unexpected token is encountered
    */
   init_fbconfig_for_chooser(&test_config, GL_FALSE);
   __glXInitializeVisualConfigFromTags(&test_config, 512,
                                       (const INT32 *) attribList,
                                       GL_TRUE, GL_FALSE);

   /*
    ** Eliminate visuals that don't meet minimum requirements
    ** Compute a score for those that do
    ** Remember which visual, if any, got the highest score
    ** If no visual is acceptable, return None
    ** Otherwise, create an XVisualInfo list with just the selected X visual
    ** and return this.
    */
   for (modes = psc->visuals; modes != NULL; modes = modes->next) {
      if (fbconfigs_compatible(&test_config, modes)
          && ((best_config == NULL)
              ||
              (fbconfig_compare
               ((const __GLcontextModes * const *const) &modes,
                &best_config) < 0))) {
         XVisualInfo visualTemplate;
         XVisualInfo *newList;
         int i;

         visualTemplate.screen = screen;
         visualTemplate.visualid = modes->visualID;
         newList = XGetVisualInfo(dpy, VisualScreenMask | VisualIDMask,
                                  &visualTemplate, &i);

         if (newList) {
            Xfree(visualList);
            visualList = newList;
            best_config = modes;
         }
      }
   }

   return visualList;
}


PUBLIC const char *
glXQueryExtensionsString(Display * dpy, int screen)
{
   __GLXscreenConfigs *psc;
   __GLXdisplayPrivate *priv;

   if (GetGLXPrivScreenConfig(dpy, screen, &priv, &psc) != Success) {
      return NULL;
   }

   if (!psc->effectiveGLXexts) {
      if (!psc->serverGLXexts) {
         psc->serverGLXexts =
            __glXQueryServerString(dpy, priv->majorOpcode, screen,
                                   GLX_EXTENSIONS);
      }

      __glXCalculateUsableExtensions(psc,
#ifdef GLX_DIRECT_RENDERING
                                     (psc->driScreen != NULL),
#else
                                     GL_FALSE,
#endif
                                     priv->minorVersion);
   }

   return psc->effectiveGLXexts;
}

PUBLIC const char *
glXGetClientString(Display * dpy, int name)
{
   switch (name) {
   case GLX_VENDOR:
      return (__glXGLXClientVendorName);
   case GLX_VERSION:
      return (__glXGLXClientVersion);
   case GLX_EXTENSIONS:
      return (__glXGetClientExtensions());
   default:
      return NULL;
   }
}

PUBLIC const char *
glXQueryServerString(Display * dpy, int screen, int name)
{
   __GLXscreenConfigs *psc;
   __GLXdisplayPrivate *priv;
   const char **str;


   if (GetGLXPrivScreenConfig(dpy, screen, &priv, &psc) != Success) {
      return NULL;
   }

   switch (name) {
   case GLX_VENDOR:
      str = &priv->serverGLXvendor;
      break;
   case GLX_VERSION:
      str = &priv->serverGLXversion;
      break;
   case GLX_EXTENSIONS:
      str = &psc->serverGLXexts;
      break;
   default:
      return NULL;
   }

   if (*str == NULL) {
      *str = __glXQueryServerString(dpy, priv->majorOpcode, screen, name);
   }

   return *str;
}

void
__glXClientInfo(Display * dpy, int opcode)
{
   char *ext_str = __glXGetClientGLExtensionString();
   int size = strlen(ext_str) + 1;

#ifdef USE_XCB
   xcb_connection_t *c = XGetXCBConnection(dpy);
   xcb_glx_client_info(c,
                       GLX_MAJOR_VERSION, GLX_MINOR_VERSION, size, ext_str);
#else
   xGLXClientInfoReq *req;

   /* Send the glXClientInfo request */
   LockDisplay(dpy);
   GetReq(GLXClientInfo, req);
   req->reqType = opcode;
   req->glxCode = X_GLXClientInfo;
   req->major = GLX_MAJOR_VERSION;
   req->minor = GLX_MINOR_VERSION;

   req->length += (size + 3) >> 2;
   req->numbytes = size;
   Data(dpy, ext_str, size);

   UnlockDisplay(dpy);
   SyncHandle();
#endif /* USE_XCB */

   Xfree(ext_str);
}


/*
** EXT_import_context
*/

PUBLIC Display *
glXGetCurrentDisplay(void)
{
   GLXContext gc = __glXGetCurrentContext();
   if (NULL == gc)
      return NULL;
   return gc->currentDpy;
}

PUBLIC
GLX_ALIAS(Display *, glXGetCurrentDisplayEXT, (void), (),
          glXGetCurrentDisplay)

/**
 * Used internally by libGL to send \c xGLXQueryContextinfoExtReq requests
 * to the X-server.
 *
 * \param dpy  Display where \c ctx was created.
 * \param ctx  Context to query.
 * \returns  \c Success on success.  \c GLX_BAD_CONTEXT if \c ctx is invalid,
 *           or zero if the request failed due to internal problems (i.e.,
 *           unable to allocate temporary memory, etc.)
 *
 * \note
 * This function dynamically determines whether to use the EXT_import_context
 * version of the protocol or the GLX 1.3 version of the protocol.
 */
     static int __glXQueryContextInfo(Display * dpy, GLXContext ctx)
{
   __GLXdisplayPrivate *priv = __glXInitialize(dpy);
   xGLXQueryContextReply reply;
   CARD8 opcode;
   GLuint numValues;
   int retval;

   if (ctx == NULL) {
      return GLX_BAD_CONTEXT;
   }
   opcode = __glXSetupForCommand(dpy);
   if (!opcode) {
      return 0;
   }

   /* Send the glXQueryContextInfoEXT request */
   LockDisplay(dpy);

   if ((priv->majorVersion > 1) || (priv->minorVersion >= 3)) {
      xGLXQueryContextReq *req;

      GetReq(GLXQueryContext, req);

      req->reqType = opcode;
      req->glxCode = X_GLXQueryContext;
      req->context = (unsigned int) (ctx->xid);
   }
   else {
      xGLXVendorPrivateReq *vpreq;
      xGLXQueryContextInfoEXTReq *req;

      GetReqExtra(GLXVendorPrivate,
                  sz_xGLXQueryContextInfoEXTReq - sz_xGLXVendorPrivateReq,
                  vpreq);
      req = (xGLXQueryContextInfoEXTReq *) vpreq;
      req->reqType = opcode;
      req->glxCode = X_GLXVendorPrivateWithReply;
      req->vendorCode = X_GLXvop_QueryContextInfoEXT;
      req->context = (unsigned int) (ctx->xid);
   }

   _XReply(dpy, (xReply *) & reply, 0, False);

   numValues = reply.n;
   if (numValues == 0)
      retval = Success;
   else if (numValues > __GLX_MAX_CONTEXT_PROPS)
      retval = 0;
   else {
      int *propList, *pProp;
      int nPropListBytes;
      int i;

      nPropListBytes = numValues << 3;
      propList = (int *) Xmalloc(nPropListBytes);
      if (NULL == propList) {
         retval = 0;
      }
      else {
         _XRead(dpy, (char *) propList, nPropListBytes);
         pProp = propList;
         for (i = 0; i < numValues; i++) {
            switch (*pProp++) {
            case GLX_SHARE_CONTEXT_EXT:
               ctx->share_xid = *pProp++;
               break;
            case GLX_VISUAL_ID_EXT:
               ctx->mode =
                  _gl_context_modes_find_visual(ctx->psc->visuals, *pProp++);
               break;
            case GLX_SCREEN:
               ctx->screen = *pProp++;
               break;
            case GLX_FBCONFIG_ID:
               ctx->mode =
                  _gl_context_modes_find_fbconfig(ctx->psc->configs,
                                                  *pProp++);
               break;
            case GLX_RENDER_TYPE:
               ctx->renderType = *pProp++;
               break;
            default:
               pProp++;
               continue;
            }
         }
         Xfree((char *) propList);
         retval = Success;
      }
   }
   UnlockDisplay(dpy);
   SyncHandle();
   return retval;
}

PUBLIC int
glXQueryContext(Display * dpy, GLXContext ctx, int attribute, int *value)
{
   int retVal;

   /* get the information from the server if we don't have it already */
#ifdef GLX_DIRECT_RENDERING
   if (!ctx->driContext && (ctx->mode == NULL)) {
#else
   if (ctx->mode == NULL) {
#endif
      retVal = __glXQueryContextInfo(dpy, ctx);
      if (Success != retVal)
         return retVal;
   }
   switch (attribute) {
   case GLX_SHARE_CONTEXT_EXT:
      *value = (int) (ctx->share_xid);
      break;
   case GLX_VISUAL_ID_EXT:
      *value = ctx->mode ? ctx->mode->visualID : None;
      break;
   case GLX_SCREEN:
      *value = (int) (ctx->screen);
      break;
   case GLX_FBCONFIG_ID:
      *value = ctx->mode ? ctx->mode->fbconfigID : None;
      break;
   case GLX_RENDER_TYPE:
      *value = (int) (ctx->renderType);
      break;
   default:
      return GLX_BAD_ATTRIBUTE;
   }
   return Success;
}

PUBLIC
GLX_ALIAS(int, glXQueryContextInfoEXT,
          (Display * dpy, GLXContext ctx, int attribute, int *value),
          (dpy, ctx, attribute, value), glXQueryContext)

     PUBLIC GLXContextID glXGetContextIDEXT(const GLXContext ctx)
{
   return ctx->xid;
}

PUBLIC GLXContext
glXImportContextEXT(Display * dpy, GLXContextID contextID)
{
   GLXContext ctx;

   if (contextID == None) {
      return NULL;
   }
   if (__glXIsDirect(dpy, contextID)) {
      return NULL;
   }

   ctx = CreateContext(dpy, NULL, NULL, NULL, False, contextID, False, 0);
   if (NULL != ctx) {
      if (Success != __glXQueryContextInfo(dpy, ctx)) {
         return NULL;
      }
   }
   return ctx;
}

PUBLIC void
glXFreeContextEXT(Display * dpy, GLXContext ctx)
{
   DestroyContext(dpy, ctx);
}



/*
 * GLX 1.3 functions - these are just stubs for now!
 */

PUBLIC GLXFBConfig *
glXChooseFBConfig(Display * dpy, int screen,
                  const int *attribList, int *nitems)
{
   __GLcontextModes **config_list;
   int list_size;


   config_list = (__GLcontextModes **)
      glXGetFBConfigs(dpy, screen, &list_size);

   if ((config_list != NULL) && (list_size > 0) && (attribList != NULL)) {
      list_size = choose_visual(config_list, list_size, attribList, GL_TRUE);
      if (list_size == 0) {
         XFree(config_list);
         config_list = NULL;
      }
   }

   *nitems = list_size;
   return (GLXFBConfig *) config_list;
}


PUBLIC GLXContext
glXCreateNewContext(Display * dpy, GLXFBConfig config,
                    int renderType, GLXContext shareList, Bool allowDirect)
{
   return CreateContext(dpy, NULL, (__GLcontextModes *) config, shareList,
                        allowDirect, None, True, renderType);
}


PUBLIC GLXDrawable
glXGetCurrentReadDrawable(void)
{
   GLXContext gc = __glXGetCurrentContext();
   return gc->currentReadable;
}


PUBLIC GLXFBConfig *
glXGetFBConfigs(Display * dpy, int screen, int *nelements)
{
   __GLXdisplayPrivate *priv = __glXInitialize(dpy);
   __GLcontextModes **config = NULL;
   int i;

   *nelements = 0;
   if (priv && (priv->screenConfigs != NULL)
       && (screen >= 0) && (screen <= ScreenCount(dpy))
       && (priv->screenConfigs[screen].configs != NULL)
       && (priv->screenConfigs[screen].configs->fbconfigID != GLX_DONT_CARE)) {
      unsigned num_configs = 0;
      __GLcontextModes *modes;


      for (modes = priv->screenConfigs[screen].configs; modes != NULL;
           modes = modes->next) {
         if (modes->fbconfigID != GLX_DONT_CARE) {
            num_configs++;
         }
      }

      config = (__GLcontextModes **) Xmalloc(sizeof(__GLcontextModes *)
                                             * num_configs);
      if (config != NULL) {
         *nelements = num_configs;
         i = 0;
         for (modes = priv->screenConfigs[screen].configs; modes != NULL;
              modes = modes->next) {
            if (modes->fbconfigID != GLX_DONT_CARE) {
               config[i] = modes;
               i++;
            }
         }
      }
   }
   return (GLXFBConfig *) config;
}


PUBLIC int
glXGetFBConfigAttrib(Display * dpy, GLXFBConfig config,
                     int attribute, int *value)
{
   __GLcontextModes *const modes = ValidateGLXFBConfig(dpy, config);

   return (modes != NULL)
      ? _gl_get_context_mode_data(modes, attribute, value)
      : GLXBadFBConfig;
}


PUBLIC XVisualInfo *
glXGetVisualFromFBConfig(Display * dpy, GLXFBConfig config)
{
   XVisualInfo visualTemplate;
   __GLcontextModes *fbconfig = (__GLcontextModes *) config;
   int count;

   /*
    ** Get a list of all visuals, return if list is empty
    */
   visualTemplate.visualid = fbconfig->visualID;
   return XGetVisualInfo(dpy, VisualIDMask, &visualTemplate, &count);
}


/*
** GLX_SGI_swap_control
*/
static int
__glXSwapIntervalSGI(int interval)
{
   xGLXVendorPrivateReq *req;
   GLXContext gc = __glXGetCurrentContext();
   Display *dpy;
   CARD32 *interval_ptr;
   CARD8 opcode;

   if (gc == NULL) {
      return GLX_BAD_CONTEXT;
   }

   if (interval <= 0) {
      return GLX_BAD_VALUE;
   }

#ifdef __DRI_SWAP_CONTROL
   if (gc->driContext) {
      __GLXscreenConfigs *const psc = GetGLXScreenConfigs(gc->currentDpy,
                                                          gc->screen);
      __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(gc->currentDpy,
                                                  gc->currentDrawable,
                                                  NULL);
      if (psc->swapControl != NULL && pdraw != NULL) {
         psc->swapControl->setSwapInterval(pdraw->driDrawable, interval);
         return 0;
      }
      else {
         return GLX_BAD_CONTEXT;
      }
   }
#endif
   dpy = gc->currentDpy;
   opcode = __glXSetupForCommand(dpy);
   if (!opcode) {
      return 0;
   }

   /* Send the glXSwapIntervalSGI request */
   LockDisplay(dpy);
   GetReqExtra(GLXVendorPrivate, sizeof(CARD32), req);
   req->reqType = opcode;
   req->glxCode = X_GLXVendorPrivate;
   req->vendorCode = X_GLXvop_SwapIntervalSGI;
   req->contextTag = gc->currentContextTag;

   interval_ptr = (CARD32 *) (req + 1);
   *interval_ptr = interval;

   UnlockDisplay(dpy);
   SyncHandle();
   XFlush(dpy);

   return 0;
}


/*
** GLX_MESA_swap_control
*/
static int
__glXSwapIntervalMESA(unsigned int interval)
{
#ifdef __DRI_SWAP_CONTROL
   GLXContext gc = __glXGetCurrentContext();

   if (interval < 0) {
      return GLX_BAD_VALUE;
   }

   if (gc != NULL && gc->driContext) {
      __GLXscreenConfigs *const psc = GetGLXScreenConfigs(gc->currentDpy,
                                                          gc->screen);

      if ((psc != NULL) && (psc->driScreen != NULL)) {
         __GLXDRIdrawable *pdraw =
            GetGLXDRIDrawable(gc->currentDpy, gc->currentDrawable, NULL);
         if (psc->swapControl != NULL && pdraw != NULL) {
            psc->swapControl->setSwapInterval(pdraw->driDrawable, interval);
            return 0;
         }
      }
   }
#else
   (void) interval;
#endif

   return GLX_BAD_CONTEXT;
}


static int
__glXGetSwapIntervalMESA(void)
{
#ifdef __DRI_SWAP_CONTROL
   GLXContext gc = __glXGetCurrentContext();

   if (gc != NULL && gc->driContext) {
      __GLXscreenConfigs *const psc = GetGLXScreenConfigs(gc->currentDpy,
                                                          gc->screen);

      if ((psc != NULL) && (psc->driScreen != NULL)) {
         __GLXDRIdrawable *pdraw =
            GetGLXDRIDrawable(gc->currentDpy, gc->currentDrawable, NULL);
         if (psc->swapControl != NULL && pdraw != NULL) {
            return psc->swapControl->getSwapInterval(pdraw->driDrawable);
         }
      }
   }
#endif

   return 0;
}


/*
** GLX_MESA_swap_frame_usage
*/

static GLint
__glXBeginFrameTrackingMESA(Display * dpy, GLXDrawable drawable)
{
   int status = GLX_BAD_CONTEXT;
#ifdef __DRI_FRAME_TRACKING
   int screen = 0;
   __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, &screen);
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);

   if (pdraw != NULL && psc->frameTracking != NULL)
      status = psc->frameTracking->frameTracking(pdraw->driDrawable, GL_TRUE);
#else
   (void) dpy;
   (void) drawable;
#endif
   return status;
}


static GLint
__glXEndFrameTrackingMESA(Display * dpy, GLXDrawable drawable)
{
   int status = GLX_BAD_CONTEXT;
#ifdef __DRI_FRAME_TRACKING
   int screen = 0;
   __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, &screen);
   __GLXscreenConfigs *psc = GetGLXScreenConfigs(dpy, screen);

   if (pdraw != NULL && psc->frameTracking != NULL)
      status = psc->frameTracking->frameTracking(pdraw->driDrawable,
                                                 GL_FALSE);
#else
   (void) dpy;
   (void) drawable;
#endif
   return status;
}


static GLint
__glXGetFrameUsageMESA(Display * dpy, GLXDrawable drawable, GLfloat * usage)
{
   int status = GLX_BAD_CONTEXT;
#ifdef __DRI_FRAME_TRACKING
   int screen = 0;
   __GLXDRIdrawable *const pdraw = GetGLXDRIDrawable(dpy, drawable, &screen);
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);

   if (pdraw != NULL && psc->frameTracking != NULL) {
      int64_t sbc, missedFrames;
      float lastMissedUsage;

      status = psc->frameTracking->queryFrameTracking(pdraw->driDrawable,
                                                      &sbc,
                                                      &missedFrames,
                                                      &lastMissedUsage,
                                                      usage);
   }
#else
   (void) dpy;
   (void) drawable;
   (void) usage;
#endif
   return status;
}


static GLint
__glXQueryFrameTrackingMESA(Display * dpy, GLXDrawable drawable,
                            int64_t * sbc, int64_t * missedFrames,
                            GLfloat * lastMissedUsage)
{
   int status = GLX_BAD_CONTEXT;
#ifdef __DRI_FRAME_TRACKING
   int screen = 0;
   __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, &screen);
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);

   if (pdraw != NULL && psc->frameTracking != NULL) {
      float usage;

      status = psc->frameTracking->queryFrameTracking(pdraw->driDrawable,
                                                      sbc, missedFrames,
                                                      lastMissedUsage,
                                                      &usage);
   }
#else
   (void) dpy;
   (void) drawable;
   (void) sbc;
   (void) missedFrames;
   (void) lastMissedUsage;
#endif
   return status;
}


/*
** GLX_SGI_video_sync
*/
static int
__glXGetVideoSyncSGI(unsigned int *count)
{
   /* FIXME: Looking at the GLX_SGI_video_sync spec in the extension registry,
    * FIXME: there should be a GLX encoding for this call.  I can find no
    * FIXME: documentation for the GLX encoding.
    */
#ifdef __DRI_MEDIA_STREAM_COUNTER
   GLXContext gc = __glXGetCurrentContext();


   if (gc != NULL && gc->driContext) {
      __GLXscreenConfigs *const psc = GetGLXScreenConfigs(gc->currentDpy,
                                                          gc->screen);
      if (psc->msc && psc->driScreen) {
         __GLXDRIdrawable *pdraw =
            GetGLXDRIDrawable(gc->currentDpy, gc->currentDrawable, NULL);
         int64_t temp;
         int ret;

         ret = (*psc->msc->getDrawableMSC) (psc->__driScreen,
                                            pdraw->driDrawable, &temp);
         *count = (unsigned) temp;

         return (ret == 0) ? 0 : GLX_BAD_CONTEXT;
      }
   }
#else
   (void) count;
#endif
   return GLX_BAD_CONTEXT;
}

static int
__glXWaitVideoSyncSGI(int divisor, int remainder, unsigned int *count)
{
#ifdef __DRI_MEDIA_STREAM_COUNTER
   GLXContext gc = __glXGetCurrentContext();

   if (divisor <= 0 || remainder < 0)
      return GLX_BAD_VALUE;

   if (gc != NULL && gc->driContext) {
      __GLXscreenConfigs *const psc = GetGLXScreenConfigs(gc->currentDpy,
                                                          gc->screen);
      if (psc->msc != NULL && psc->driScreen) {
         __GLXDRIdrawable *pdraw =
            GetGLXDRIDrawable(gc->currentDpy, gc->currentDrawable, NULL);
         int ret;
         int64_t msc;
         int64_t sbc;

         ret = (*psc->msc->waitForMSC) (pdraw->driDrawable, 0,
                                        divisor, remainder, &msc, &sbc);
         *count = (unsigned) msc;
         return (ret == 0) ? 0 : GLX_BAD_CONTEXT;
      }
   }
#else
   (void) count;
#endif
   return GLX_BAD_CONTEXT;
}


/*
** GLX_SGIX_fbconfig
** Many of these functions are aliased to GLX 1.3 entry points in the 
** GLX_functions table.
*/

PUBLIC
GLX_ALIAS(int, glXGetFBConfigAttribSGIX,
          (Display * dpy, GLXFBConfigSGIX config, int attribute, int *value),
          (dpy, config, attribute, value), glXGetFBConfigAttrib)

     PUBLIC GLX_ALIAS(GLXFBConfigSGIX *, glXChooseFBConfigSGIX,
                      (Display * dpy, int screen, int *attrib_list,
                       int *nelements), (dpy, screen, attrib_list, nelements),
                      glXChooseFBConfig)

     PUBLIC GLX_ALIAS(XVisualInfo *, glXGetVisualFromFBConfigSGIX,
                      (Display * dpy, GLXFBConfigSGIX config),
                      (dpy, config), glXGetVisualFromFBConfig)

     PUBLIC GLXPixmap glXCreateGLXPixmapWithConfigSGIX(Display * dpy,
                                                       GLXFBConfigSGIX config,
                                                       Pixmap pixmap)
{
   xGLXVendorPrivateWithReplyReq *vpreq;
   xGLXCreateGLXPixmapWithConfigSGIXReq *req;
   GLXPixmap xid = None;
   CARD8 opcode;
   const __GLcontextModes *const fbconfig = (__GLcontextModes *) config;
   __GLXscreenConfigs *psc;


   if ((dpy == NULL) || (config == NULL)) {
      return None;
   }

   psc = GetGLXScreenConfigs(dpy, fbconfig->screen);
   if ((psc != NULL)
       && __glXExtensionBitIsEnabled(psc, SGIX_fbconfig_bit)) {
      opcode = __glXSetupForCommand(dpy);
      if (!opcode) {
         return None;
      }

      /* Send the glXCreateGLXPixmapWithConfigSGIX request */
      LockDisplay(dpy);
      GetReqExtra(GLXVendorPrivateWithReply,
                  sz_xGLXCreateGLXPixmapWithConfigSGIXReq -
                  sz_xGLXVendorPrivateWithReplyReq, vpreq);
      req = (xGLXCreateGLXPixmapWithConfigSGIXReq *) vpreq;
      req->reqType = opcode;
      req->glxCode = X_GLXVendorPrivateWithReply;
      req->vendorCode = X_GLXvop_CreateGLXPixmapWithConfigSGIX;
      req->screen = fbconfig->screen;
      req->fbconfig = fbconfig->fbconfigID;
      req->pixmap = pixmap;
      req->glxpixmap = xid = XAllocID(dpy);
      UnlockDisplay(dpy);
      SyncHandle();
   }

   return xid;
}

PUBLIC GLXContext
glXCreateContextWithConfigSGIX(Display * dpy,
                               GLXFBConfigSGIX config, int renderType,
                               GLXContext shareList, Bool allowDirect)
{
   GLXContext gc = NULL;
   const __GLcontextModes *const fbconfig = (__GLcontextModes *) config;
   __GLXscreenConfigs *psc;


   if ((dpy == NULL) || (config == NULL)) {
      return None;
   }

   psc = GetGLXScreenConfigs(dpy, fbconfig->screen);
   if ((psc != NULL)
       && __glXExtensionBitIsEnabled(psc, SGIX_fbconfig_bit)) {
      gc = CreateContext(dpy, NULL, (__GLcontextModes *) config, shareList,
                         allowDirect, None, False, renderType);
   }

   return gc;
}


PUBLIC GLXFBConfigSGIX
glXGetFBConfigFromVisualSGIX(Display * dpy, XVisualInfo * vis)
{
   __GLXdisplayPrivate *priv;
   __GLXscreenConfigs *psc = NULL;

   if ((GetGLXPrivScreenConfig(dpy, vis->screen, &priv, &psc) != Success)
       && __glXExtensionBitIsEnabled(psc, SGIX_fbconfig_bit)
       && (psc->configs->fbconfigID != GLX_DONT_CARE)) {
      return (GLXFBConfigSGIX) _gl_context_modes_find_visual(psc->configs,
                                                             vis->visualid);
   }

   return NULL;
}


/*
** GLX_SGIX_swap_group
*/
static void
__glXJoinSwapGroupSGIX(Display * dpy, GLXDrawable drawable,
                       GLXDrawable member)
{
   (void) dpy;
   (void) drawable;
   (void) member;
}


/*
** GLX_SGIX_swap_barrier
*/
static void
__glXBindSwapBarrierSGIX(Display * dpy, GLXDrawable drawable, int barrier)
{
   (void) dpy;
   (void) drawable;
   (void) barrier;
}

static Bool
__glXQueryMaxSwapBarriersSGIX(Display * dpy, int screen, int *max)
{
   (void) dpy;
   (void) screen;
   (void) max;
   return False;
}


/*
** GLX_OML_sync_control
*/
static Bool
__glXGetSyncValuesOML(Display * dpy, GLXDrawable drawable,
                      int64_t * ust, int64_t * msc, int64_t * sbc)
{
#if defined(__DRI_SWAP_BUFFER_COUNTER) && defined(__DRI_MEDIA_STREAM_COUNTER)
   __GLXdisplayPrivate *const priv = __glXInitialize(dpy);

   if (priv != NULL) {
      int i;
      __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, &i);
      __GLXscreenConfigs *const psc = &priv->screenConfigs[i];

      assert((pdraw == NULL) || (i != -1));
      return ((pdraw && psc->sbc && psc->msc)
              && ((*psc->msc->getMSC) (psc->driScreen, msc) == 0)
              && ((*psc->sbc->getSBC) (pdraw->driDrawable, sbc) == 0)
              && (__glXGetUST(ust) == 0));
   }
#else
   (void) dpy;
   (void) drawable;
   (void) ust;
   (void) msc;
   (void) sbc;
#endif
   return False;
}

#ifdef GLX_DIRECT_RENDERING
_X_HIDDEN GLboolean
__driGetMscRateOML(__DRIdrawable * draw,
                   int32_t * numerator, int32_t * denominator, void *private)
{
#ifdef XF86VIDMODE
   __GLXscreenConfigs *psc;
   XF86VidModeModeLine mode_line;
   int dot_clock;
   int i;
   __GLXDRIdrawable *glxDraw = private;

   psc = glxDraw->psc;
   if (XF86VidModeQueryVersion(psc->dpy, &i, &i) &&
       XF86VidModeGetModeLine(psc->dpy, psc->scr, &dot_clock, &mode_line)) {
      unsigned n = dot_clock * 1000;
      unsigned d = mode_line.vtotal * mode_line.htotal;

# define V_INTERLACE 0x010
# define V_DBLSCAN   0x020

      if (mode_line.flags & V_INTERLACE)
         n *= 2;
      else if (mode_line.flags & V_DBLSCAN)
         d *= 2;

      /* The OML_sync_control spec requires that if the refresh rate is a
       * whole number, that the returned numerator be equal to the refresh
       * rate and the denominator be 1.
       */

      if (n % d == 0) {
         n /= d;
         d = 1;
      }
      else {
         static const unsigned f[] = { 13, 11, 7, 5, 3, 2, 0 };

         /* This is a poor man's way to reduce a fraction.  It's far from
          * perfect, but it will work well enough for this situation.
          */

         for (i = 0; f[i] != 0; i++) {
            while (n % f[i] == 0 && d % f[i] == 0) {
               d /= f[i];
               n /= f[i];
            }
         }
      }

      *numerator = n;
      *denominator = d;

      return True;
   }
   else
      return False;
#else
   return False;
#endif
}
#endif

/**
 * Determine the refresh rate of the specified drawable and display.
 *
 * \param dpy          Display whose refresh rate is to be determined.
 * \param drawable     Drawable whose refresh rate is to be determined.
 * \param numerator    Numerator of the refresh rate.
 * \param demoninator  Denominator of the refresh rate.
 * \return  If the refresh rate for the specified display and drawable could
 *          be calculated, True is returned.  Otherwise False is returned.
 *
 * \note This function is implemented entirely client-side.  A lot of other
 *       functionality is required to export GLX_OML_sync_control, so on
 *       XFree86 this function can be called for direct-rendering contexts
 *       when GLX_OML_sync_control appears in the client extension string.
 */

_X_HIDDEN GLboolean
__glXGetMscRateOML(Display * dpy, GLXDrawable drawable,
                   int32_t * numerator, int32_t * denominator)
{
#if defined( GLX_DIRECT_RENDERING ) && defined( XF86VIDMODE )
   __GLXDRIdrawable *draw = GetGLXDRIDrawable(dpy, drawable, NULL);

   if (draw == NULL)
      return False;

   return __driGetMscRateOML(draw->driDrawable, numerator, denominator, draw);
#else
   (void) dpy;
   (void) drawable;
   (void) numerator;
   (void) denominator;
#endif
   return False;
}


static int64_t
__glXSwapBuffersMscOML(Display * dpy, GLXDrawable drawable,
                       int64_t target_msc, int64_t divisor, int64_t remainder)
{
#ifdef __DRI_SWAP_BUFFER_COUNTER
   int screen;
   __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, &screen);
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);

   /* The OML_sync_control spec says these should "generate a GLX_BAD_VALUE
    * error", but it also says "It [glXSwapBuffersMscOML] will return a value
    * of -1 if the function failed because of errors detected in the input
    * parameters"
    */
   if (divisor < 0 || remainder < 0 || target_msc < 0)
      return -1;
   if (divisor > 0 && remainder >= divisor)
      return -1;

   if (pdraw != NULL && psc->counters != NULL)
      return (*psc->sbc->swapBuffersMSC) (pdraw->driDrawable, target_msc,
                                          divisor, remainder);

#else
   (void) dpy;
   (void) drawable;
   (void) target_msc;
   (void) divisor;
   (void) remainder;
#endif
   return 0;
}


static Bool
__glXWaitForMscOML(Display * dpy, GLXDrawable drawable,
                   int64_t target_msc, int64_t divisor,
                   int64_t remainder, int64_t * ust,
                   int64_t * msc, int64_t * sbc)
{
#ifdef __DRI_MEDIA_STREAM_COUNTER
   int screen = 0;
   __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, &screen);
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);
   int ret;

   /* The OML_sync_control spec says these should "generate a GLX_BAD_VALUE
    * error", but the return type in the spec is Bool.
    */
   if (divisor < 0 || remainder < 0 || target_msc < 0)
      return False;
   if (divisor > 0 && remainder >= divisor)
      return False;

   if (pdraw != NULL && psc->msc != NULL) {
      ret = (*psc->msc->waitForMSC) (pdraw->driDrawable, target_msc,
                                     divisor, remainder, msc, sbc);

      /* __glXGetUST returns zero on success and non-zero on failure.
       * This function returns True on success and False on failure.
       */
      return ((ret == 0) && (__glXGetUST(ust) == 0));
   }
#else
   (void) dpy;
   (void) drawable;
   (void) target_msc;
   (void) divisor;
   (void) remainder;
   (void) ust;
   (void) msc;
   (void) sbc;
#endif
   return False;
}


static Bool
__glXWaitForSbcOML(Display * dpy, GLXDrawable drawable,
                   int64_t target_sbc, int64_t * ust,
                   int64_t * msc, int64_t * sbc)
{
#ifdef __DRI_SWAP_BUFFER_COUNTER
   int screen;
   __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, &screen);
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);
   int ret;

   /* The OML_sync_control spec says this should "generate a GLX_BAD_VALUE
    * error", but the return type in the spec is Bool.
    */
   if (target_sbc < 0)
      return False;

   if (pdraw != NULL && psc->sbc != NULL) {
      ret =
         (*psc->sbc->waitForSBC) (pdraw->driDrawable, target_sbc, msc, sbc);

      /* __glXGetUST returns zero on success and non-zero on failure.
       * This function returns True on success and False on failure.
       */
      return ((ret == 0) && (__glXGetUST(ust) == 0));
   }
#else
   (void) dpy;
   (void) drawable;
   (void) target_sbc;
   (void) ust;
   (void) msc;
   (void) sbc;
#endif
   return False;
}


/**
 * GLX_MESA_allocate_memory
 */
/*@{*/

PUBLIC void *
glXAllocateMemoryMESA(Display * dpy, int scrn,
                      size_t size, float readFreq,
                      float writeFreq, float priority)
{
#ifdef __DRI_ALLOCATE
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, scrn);

   if (psc && psc->allocate)
      return (*psc->allocate->allocateMemory) (psc->__driScreen, size,
                                               readFreq, writeFreq, priority);

#else
   (void) dpy;
   (void) scrn;
   (void) size;
   (void) readFreq;
   (void) writeFreq;
   (void) priority;
#endif /* GLX_DIRECT_RENDERING */

   return NULL;
}


PUBLIC void
glXFreeMemoryMESA(Display * dpy, int scrn, void *pointer)
{
#ifdef __DRI_ALLOCATE
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, scrn);

   if (psc && psc->allocate)
      (*psc->allocate->freeMemory) (psc->__driScreen, pointer);

#else
   (void) dpy;
   (void) scrn;
   (void) pointer;
#endif /* GLX_DIRECT_RENDERING */
}


PUBLIC GLuint
glXGetMemoryOffsetMESA(Display * dpy, int scrn, const void *pointer)
{
#ifdef __DRI_ALLOCATE
   __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, scrn);

   if (psc && psc->allocate)
      return (*psc->allocate->memoryOffset) (psc->__driScreen, pointer);

#else
   (void) dpy;
   (void) scrn;
   (void) pointer;
#endif /* GLX_DIRECT_RENDERING */

   return ~0L;
}

/*@}*/


/**
 * Mesa extension stubs.  These will help reduce portability problems.
 */
/*@{*/

/**
 * Release all buffers associated with the specified GLX drawable.
 *
 * \todo
 * This function was intended for stand-alone Mesa.  The issue there is that
 * the library doesn't get any notification when a window is closed.  In
 * DRI there is a similar but slightly different issue.  When GLX 1.3 is
 * supported, there are 3 different functions to destroy a drawable.  It
 * should be possible to create GLX protocol (or have it determine which
 * protocol to use based on the type of the drawable) to have one function
 * do the work of 3.  For the direct-rendering case, this function could
 * just call the driver's \c __DRIdrawableRec::destroyDrawable function.
 * This would reduce the frequency with which \c __driGarbageCollectDrawables
 * would need to be used.  This really should be done as part of the new DRI
 * interface work.
 *
 * \sa http://oss.sgi.com/projects/ogl-sample/registry/MESA/release_buffers.txt
 *     __driGarbageCollectDrawables
 *     glXDestroyGLXPixmap
 *     glXDestroyPbuffer glXDestroyPixmap glXDestroyWindow
 *     glXDestroyGLXPbufferSGIX glXDestroyGLXVideoSourceSGIX
 */
static Bool
__glXReleaseBuffersMESA(Display * dpy, GLXDrawable d)
{
   (void) dpy;
   (void) d;
   return False;
}


PUBLIC GLXPixmap
glXCreateGLXPixmapMESA(Display * dpy, XVisualInfo * visual,
                       Pixmap pixmap, Colormap cmap)
{
   (void) dpy;
   (void) visual;
   (void) pixmap;
   (void) cmap;
   return 0;
}

/*@}*/


/**
 * GLX_MESA_copy_sub_buffer
 */
#define X_GLXvop_CopySubBufferMESA 5154 /* temporary */
static void
__glXCopySubBufferMESA(Display * dpy, GLXDrawable drawable,
                       int x, int y, int width, int height)
{
   xGLXVendorPrivateReq *req;
   GLXContext gc;
   GLXContextTag tag;
   CARD32 *drawable_ptr;
   INT32 *x_ptr, *y_ptr, *w_ptr, *h_ptr;
   CARD8 opcode;

#ifdef __DRI_COPY_SUB_BUFFER
   int screen;
   __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, &screen);
   if (pdraw != NULL) {
      __GLXscreenConfigs *const psc = GetGLXScreenConfigs(dpy, screen);
      if (psc->driScreen->copySubBuffer != NULL) {
         glFlush();
         (*psc->driScreen->copySubBuffer) (pdraw, x, y, width, height);
      }

      return;
   }
#endif

   opcode = __glXSetupForCommand(dpy);
   if (!opcode)
      return;

   /*
    ** The calling thread may or may not have a current context.  If it
    ** does, send the context tag so the server can do a flush.
    */
   gc = __glXGetCurrentContext();
   if ((gc != NULL) && (dpy == gc->currentDpy) &&
       ((drawable == gc->currentDrawable) ||
        (drawable == gc->currentReadable))) {
      tag = gc->currentContextTag;
   }
   else {
      tag = 0;
   }

   LockDisplay(dpy);
   GetReqExtra(GLXVendorPrivate, sizeof(CARD32) + sizeof(INT32) * 4, req);
   req->reqType = opcode;
   req->glxCode = X_GLXVendorPrivate;
   req->vendorCode = X_GLXvop_CopySubBufferMESA;
   req->contextTag = tag;

   drawable_ptr = (CARD32 *) (req + 1);
   x_ptr = (INT32 *) (drawable_ptr + 1);
   y_ptr = (INT32 *) (drawable_ptr + 2);
   w_ptr = (INT32 *) (drawable_ptr + 3);
   h_ptr = (INT32 *) (drawable_ptr + 4);

   *drawable_ptr = drawable;
   *x_ptr = x;
   *y_ptr = y;
   *w_ptr = width;
   *h_ptr = height;

   UnlockDisplay(dpy);
   SyncHandle();
}


/**
 * GLX_EXT_texture_from_pixmap
 */
/*@{*/
static void
__glXBindTexImageEXT(Display * dpy,
                     GLXDrawable drawable, int buffer, const int *attrib_list)
{
   xGLXVendorPrivateReq *req;
   GLXContext gc = __glXGetCurrentContext();
   CARD32 *drawable_ptr;
   INT32 *buffer_ptr;
   CARD32 *num_attrib_ptr;
   CARD32 *attrib_ptr;
   CARD8 opcode;
   unsigned int i;

   if (gc == NULL)
      return;

   i = 0;
   if (attrib_list) {
      while (attrib_list[i * 2] != None)
         i++;
   }

#ifdef GLX_DIRECT_RENDERING
   if (gc->driContext) {
      __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, NULL);

      if (pdraw != NULL) {
         if (pdraw->psc->texBuffer->base.version >= 2 &&
             pdraw->psc->texBuffer->setTexBuffer2 != NULL) {
            (*pdraw->psc->texBuffer->setTexBuffer2) (gc->__driContext,
                                                     pdraw->textureTarget,
                                                     pdraw->textureFormat,
                                                     pdraw->driDrawable);
         }
         else {
            (*pdraw->psc->texBuffer->setTexBuffer) (gc->__driContext,
                                                    pdraw->textureTarget,
                                                    pdraw->driDrawable);
         }
      }
      return;
   }
#endif

   opcode = __glXSetupForCommand(dpy);
   if (!opcode)
      return;

   LockDisplay(dpy);
   GetReqExtra(GLXVendorPrivate, 12 + 8 * i, req);
   req->reqType = opcode;
   req->glxCode = X_GLXVendorPrivate;
   req->vendorCode = X_GLXvop_BindTexImageEXT;
   req->contextTag = gc->currentContextTag;

   drawable_ptr = (CARD32 *) (req + 1);
   buffer_ptr = (INT32 *) (drawable_ptr + 1);
   num_attrib_ptr = (CARD32 *) (buffer_ptr + 1);
   attrib_ptr = (CARD32 *) (num_attrib_ptr + 1);

   *drawable_ptr = drawable;
   *buffer_ptr = buffer;
   *num_attrib_ptr = (CARD32) i;

   i = 0;
   if (attrib_list) {
      while (attrib_list[i * 2] != None) {
         *attrib_ptr++ = (CARD32) attrib_list[i * 2 + 0];
         *attrib_ptr++ = (CARD32) attrib_list[i * 2 + 1];
         i++;
      }
   }

   UnlockDisplay(dpy);
   SyncHandle();
}

static void
__glXReleaseTexImageEXT(Display * dpy, GLXDrawable drawable, int buffer)
{
   xGLXVendorPrivateReq *req;
   GLXContext gc = __glXGetCurrentContext();
   CARD32 *drawable_ptr;
   INT32 *buffer_ptr;
   CARD8 opcode;

   if (gc == NULL)
      return;

#ifdef GLX_DIRECT_RENDERING
   if (gc->driContext)
      return;
#endif

   opcode = __glXSetupForCommand(dpy);
   if (!opcode)
      return;

   LockDisplay(dpy);
   GetReqExtra(GLXVendorPrivate, sizeof(CARD32) + sizeof(INT32), req);
   req->reqType = opcode;
   req->glxCode = X_GLXVendorPrivate;
   req->vendorCode = X_GLXvop_ReleaseTexImageEXT;
   req->contextTag = gc->currentContextTag;

   drawable_ptr = (CARD32 *) (req + 1);
   buffer_ptr = (INT32 *) (drawable_ptr + 1);

   *drawable_ptr = drawable;
   *buffer_ptr = buffer;

   UnlockDisplay(dpy);
   SyncHandle();
}

/*@}*/

/**
 * \c strdup is actually not a standard ANSI C or POSIX routine.
 * Irix will not define it if ANSI mode is in effect.
 *
 * \sa strdup
 */
_X_HIDDEN char *
__glXstrdup(const char *str)
{
   char *copy;
   copy = (char *) Xmalloc(strlen(str) + 1);
   if (!copy)
      return NULL;
   strcpy(copy, str);
   return copy;
}

/*
** glXGetProcAddress support
*/

struct name_address_pair
{
   const char *Name;
   GLvoid *Address;
};

#define GLX_FUNCTION(f) { # f, (GLvoid *) f }
#define GLX_FUNCTION2(n,f) { # n, (GLvoid *) f }

static const struct name_address_pair GLX_functions[] = {
   /*** GLX_VERSION_1_0 ***/
   GLX_FUNCTION(glXChooseVisual),
   GLX_FUNCTION(glXCopyContext),
   GLX_FUNCTION(glXCreateContext),
   GLX_FUNCTION(glXCreateGLXPixmap),
   GLX_FUNCTION(glXDestroyContext),
   GLX_FUNCTION(glXDestroyGLXPixmap),
   GLX_FUNCTION(glXGetConfig),
   GLX_FUNCTION(glXGetCurrentContext),
   GLX_FUNCTION(glXGetCurrentDrawable),
   GLX_FUNCTION(glXIsDirect),
   GLX_FUNCTION(glXMakeCurrent),
   GLX_FUNCTION(glXQueryExtension),
   GLX_FUNCTION(glXQueryVersion),
   GLX_FUNCTION(glXSwapBuffers),
   GLX_FUNCTION(glXUseXFont),
   GLX_FUNCTION(glXWaitGL),
   GLX_FUNCTION(glXWaitX),

   /*** GLX_VERSION_1_1 ***/
   GLX_FUNCTION(glXGetClientString),
   GLX_FUNCTION(glXQueryExtensionsString),
   GLX_FUNCTION(glXQueryServerString),

   /*** GLX_VERSION_1_2 ***/
   GLX_FUNCTION(glXGetCurrentDisplay),

   /*** GLX_VERSION_1_3 ***/
   GLX_FUNCTION(glXChooseFBConfig),
   GLX_FUNCTION(glXCreateNewContext),
   GLX_FUNCTION(glXCreatePbuffer),
   GLX_FUNCTION(glXCreatePixmap),
   GLX_FUNCTION(glXCreateWindow),
   GLX_FUNCTION(glXDestroyPbuffer),
   GLX_FUNCTION(glXDestroyPixmap),
   GLX_FUNCTION(glXDestroyWindow),
   GLX_FUNCTION(glXGetCurrentReadDrawable),
   GLX_FUNCTION(glXGetFBConfigAttrib),
   GLX_FUNCTION(glXGetFBConfigs),
   GLX_FUNCTION(glXGetSelectedEvent),
   GLX_FUNCTION(glXGetVisualFromFBConfig),
   GLX_FUNCTION(glXMakeContextCurrent),
   GLX_FUNCTION(glXQueryContext),
   GLX_FUNCTION(glXQueryDrawable),
   GLX_FUNCTION(glXSelectEvent),

   /*** GLX_SGI_swap_control ***/
   GLX_FUNCTION2(glXSwapIntervalSGI, __glXSwapIntervalSGI),

   /*** GLX_SGI_video_sync ***/
   GLX_FUNCTION2(glXGetVideoSyncSGI, __glXGetVideoSyncSGI),
   GLX_FUNCTION2(glXWaitVideoSyncSGI, __glXWaitVideoSyncSGI),

   /*** GLX_SGI_make_current_read ***/
   GLX_FUNCTION2(glXMakeCurrentReadSGI, glXMakeContextCurrent),
   GLX_FUNCTION2(glXGetCurrentReadDrawableSGI, glXGetCurrentReadDrawable),

   /*** GLX_EXT_import_context ***/
   GLX_FUNCTION(glXFreeContextEXT),
   GLX_FUNCTION(glXGetContextIDEXT),
   GLX_FUNCTION2(glXGetCurrentDisplayEXT, glXGetCurrentDisplay),
   GLX_FUNCTION(glXImportContextEXT),
   GLX_FUNCTION2(glXQueryContextInfoEXT, glXQueryContext),

   /*** GLX_SGIX_fbconfig ***/
   GLX_FUNCTION2(glXGetFBConfigAttribSGIX, glXGetFBConfigAttrib),
   GLX_FUNCTION2(glXChooseFBConfigSGIX, glXChooseFBConfig),
   GLX_FUNCTION(glXCreateGLXPixmapWithConfigSGIX),
   GLX_FUNCTION(glXCreateContextWithConfigSGIX),
   GLX_FUNCTION2(glXGetVisualFromFBConfigSGIX, glXGetVisualFromFBConfig),
   GLX_FUNCTION(glXGetFBConfigFromVisualSGIX),

   /*** GLX_SGIX_pbuffer ***/
   GLX_FUNCTION(glXCreateGLXPbufferSGIX),
   GLX_FUNCTION(glXDestroyGLXPbufferSGIX),
   GLX_FUNCTION(glXQueryGLXPbufferSGIX),
   GLX_FUNCTION(glXSelectEventSGIX),
   GLX_FUNCTION(glXGetSelectedEventSGIX),

   /*** GLX_SGIX_swap_group ***/
   GLX_FUNCTION2(glXJoinSwapGroupSGIX, __glXJoinSwapGroupSGIX),

   /*** GLX_SGIX_swap_barrier ***/
   GLX_FUNCTION2(glXBindSwapBarrierSGIX, __glXBindSwapBarrierSGIX),
   GLX_FUNCTION2(glXQueryMaxSwapBarriersSGIX, __glXQueryMaxSwapBarriersSGIX),

   /*** GLX_MESA_allocate_memory ***/
   GLX_FUNCTION(glXAllocateMemoryMESA),
   GLX_FUNCTION(glXFreeMemoryMESA),
   GLX_FUNCTION(glXGetMemoryOffsetMESA),

   /*** GLX_MESA_copy_sub_buffer ***/
   GLX_FUNCTION2(glXCopySubBufferMESA, __glXCopySubBufferMESA),

   /*** GLX_MESA_pixmap_colormap ***/
   GLX_FUNCTION(glXCreateGLXPixmapMESA),

   /*** GLX_MESA_release_buffers ***/
   GLX_FUNCTION2(glXReleaseBuffersMESA, __glXReleaseBuffersMESA),

   /*** GLX_MESA_swap_control ***/
   GLX_FUNCTION2(glXSwapIntervalMESA, __glXSwapIntervalMESA),
   GLX_FUNCTION2(glXGetSwapIntervalMESA, __glXGetSwapIntervalMESA),

   /*** GLX_MESA_swap_frame_usage ***/
   GLX_FUNCTION2(glXBeginFrameTrackingMESA, __glXBeginFrameTrackingMESA),
   GLX_FUNCTION2(glXEndFrameTrackingMESA, __glXEndFrameTrackingMESA),
   GLX_FUNCTION2(glXGetFrameUsageMESA, __glXGetFrameUsageMESA),
   GLX_FUNCTION2(glXQueryFrameTrackingMESA, __glXQueryFrameTrackingMESA),

   /*** GLX_ARB_get_proc_address ***/
   GLX_FUNCTION(glXGetProcAddressARB),

   /*** GLX 1.4 ***/
   GLX_FUNCTION2(glXGetProcAddress, glXGetProcAddressARB),

   /*** GLX_OML_sync_control ***/
   GLX_FUNCTION2(glXWaitForSbcOML, __glXWaitForSbcOML),
   GLX_FUNCTION2(glXWaitForMscOML, __glXWaitForMscOML),
   GLX_FUNCTION2(glXSwapBuffersMscOML, __glXSwapBuffersMscOML),
   GLX_FUNCTION2(glXGetMscRateOML, __glXGetMscRateOML),
   GLX_FUNCTION2(glXGetSyncValuesOML, __glXGetSyncValuesOML),

   /*** GLX_EXT_texture_from_pixmap ***/
   GLX_FUNCTION2(glXBindTexImageEXT, __glXBindTexImageEXT),
   GLX_FUNCTION2(glXReleaseTexImageEXT, __glXReleaseTexImageEXT),

#ifdef GLX_DIRECT_RENDERING
   /*** DRI configuration ***/
   GLX_FUNCTION(glXGetScreenDriver),
   GLX_FUNCTION(glXGetDriverConfig),
#endif

   {NULL, NULL}                 /* end of list */
};


static const GLvoid *
get_glx_proc_address(const char *funcName)
{
   GLuint i;

   /* try static functions */
   for (i = 0; GLX_functions[i].Name; i++) {
      if (strcmp(GLX_functions[i].Name, funcName) == 0)
         return GLX_functions[i].Address;
   }

   return NULL;
}


/**
 * Get the address of a named GL function.  This is the pre-GLX 1.4 name for
 * \c glXGetProcAddress.
 *
 * \param procName  Name of a GL or GLX function.
 * \returns         A pointer to the named function
 *
 * \sa glXGetProcAddress
 */
PUBLIC void (*glXGetProcAddressARB(const GLubyte * procName)) (void)
{
   typedef void (*gl_function) (void);
   gl_function f;


   /* Search the table of GLX and internal functions first.  If that
    * fails and the supplied name could be a valid core GL name, try
    * searching the core GL function table.  This check is done to prevent
    * DRI based drivers from searching the core GL function table for
    * internal API functions.
    */

   f = (gl_function) get_glx_proc_address((const char *) procName);
   if ((f == NULL) && (procName[0] == 'g') && (procName[1] == 'l')
       && (procName[2] != 'X')) {
      f = (gl_function) _glapi_get_proc_address((const char *) procName);
   }

   return f;
}

/**
 * Get the address of a named GL function.  This is the GLX 1.4 name for
 * \c glXGetProcAddressARB.
 *
 * \param procName  Name of a GL or GLX function.
 * \returns         A pointer to the named function
 *
 * \sa glXGetProcAddressARB
 */
PUBLIC void (*glXGetProcAddress(const GLubyte * procName)) (void)
#if defined(__GNUC__) && !defined(GLX_ALIAS_UNSUPPORTED)
   __attribute__ ((alias("glXGetProcAddressARB")));
#else
{
   return glXGetProcAddressARB(procName);
}
#endif /* __GNUC__ */


#ifdef GLX_DIRECT_RENDERING
/**
 * Get the unadjusted system time (UST).  Currently, the UST is measured in
 * microseconds since Epoc.  The actual resolution of the UST may vary from
 * system to system, and the units may vary from release to release.
 * Drivers should not call this function directly.  They should instead use
 * \c glXGetProcAddress to obtain a pointer to the function.
 *
 * \param ust Location to store the 64-bit UST
 * \returns Zero on success or a negative errno value on failure.
 *
 * \sa glXGetProcAddress, PFNGLXGETUSTPROC
 *
 * \since Internal API version 20030317.
 */
_X_HIDDEN int
__glXGetUST(int64_t * ust)
{
   struct timeval tv;

   if (ust == NULL) {
      return -EFAULT;
   }

   if (gettimeofday(&tv, NULL) == 0) {
      ust[0] = (tv.tv_sec * 1000000) + tv.tv_usec;
      return 0;
   }
   else {
      return -errno;
   }
}
#endif /* GLX_DIRECT_RENDERING */