path: root/src/glx/x11/glxext.c

/* $XFree86: xc/lib/GL/glx/glxext.c,v 1.22 2003/12/08 17:35:28 dawes Exp $ */

/*
** License Applicability. Except to the extent portions of this file are
** made subject to an alternative license as permitted in the SGI Free
** Software License B, Version 1.1 (the "License"), the contents of this
** file are subject only to the provisions of the License. You may not use
** this file except in compliance with the License. You may obtain a copy
** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
** 
** http://oss.sgi.com/projects/FreeB
** 
** Note that, as provided in the License, the Software is distributed on an
** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
** 
** Original Code. The Original Code is: OpenGL Sample Implementation,
** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
** Copyright in any portions created by third parties is as indicated
** elsewhere herein. All Rights Reserved.
** 
** Additional Notice Provisions: The application programming interfaces
** established by SGI in conjunction with the Original Code are The
** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
** Window System(R) (Version 1.3), released October 19, 1998. This software
** was created using the OpenGL(R) version 1.2.1 Sample Implementation
** published by SGI, but has not been independently verified as being
** compliant with the OpenGL(R) version 1.2.1 Specification.
**
*/

/**
 * \file glxext.c
 * GLX protocol interface boot-strap code.
 *
 * Direct rendering support added by Precision Insight, Inc.
 *
 * \author Kevin E. Martin <kevin@precisioninsight.com>
 */     

#include "glxclient.h"
#include <stdio.h>
#include <X11/extensions/Xext.h>
#include <X11/extensions/extutil.h>
#include <X11/extensions/Xfixes.h>
#include <X11/extensions/Xdamage.h>
#include <assert.h>
#include "indirect_init.h"
#include "glapi.h"
#include "glxextensions.h"
#include "glcontextmodes.h"
#include "glheader.h"

#ifdef GLX_DIRECT_RENDERING
#include <inttypes.h>
#include <sys/mman.h>
#include "xf86dri.h"
#include "sarea.h"
#include "dri_glx.h"
#endif

#ifdef USE_XCB
#include <X11/Xlib-xcb.h>
#include <xcb/xcb.h>
#include <xcb/glx.h>
#endif

#include <assert.h>

#ifdef DEBUG
void __glXDumpDrawBuffer(__GLXcontext *ctx);
#endif

#ifdef USE_SPARC_ASM
/*
 * This is where our dispatch table's bounds are.
 * And the static mesa_init is taken directly from
 * Mesa's 'sparc.c' initializer.
 *
 * We need something like this here, because this version
 * of openGL/glx never initializes a Mesa context, and so
 * the address of the dispatch table pointer never gets stuffed
 * into the dispatch jump table otherwise.
 *
 * It matters only on SPARC, and only if you are using assembler
 * code instead of C-code indirect dispatch.
 *
 * -- FEM, 04.xii.03
 */
extern unsigned int _mesa_sparc_glapi_begin;
extern unsigned int _mesa_sparc_glapi_end;
extern void __glapi_sparc_icache_flush(unsigned int *);
static void _glx_mesa_init_sparc_glapi_relocs(void);
static int _mesa_sparc_needs_init = 1;
#define INIT_MESA_SPARC { \
    if(_mesa_sparc_needs_init) { \
      _glx_mesa_init_sparc_glapi_relocs(); \
      _mesa_sparc_needs_init = 0; \
  } \
}
#else
#define INIT_MESA_SPARC
#endif

#ifdef GLX_DIRECT_RENDERING
static __DRIscreen *__glXFindDRIScreen(__DRInativeDisplay *dpy, int scrn);
#endif /* GLX_DIRECT_RENDERING */

static Bool MakeContextCurrent(Display *dpy, GLXDrawable draw,
    GLXDrawable read, GLXContext gc);

/*
** We setup some dummy structures here so that the API can be used
** even if no context is current.
*/

static GLubyte dummyBuffer[__GLX_BUFFER_LIMIT_SIZE];

/*
** Dummy context used by small commands when there is no current context.
** All the
** gl and glx entry points are designed to operate as nop's when using
** the dummy context structure.
*/
static __GLXcontext dummyContext = {
    &dummyBuffer[0],
    &dummyBuffer[0],
    &dummyBuffer[0],
    &dummyBuffer[__GLX_BUFFER_LIMIT_SIZE],
    sizeof(dummyBuffer),
};


/*
** All indirect rendering contexts will share the same indirect dispatch table.
*/
static __GLapi *IndirectAPI = NULL;


/*
 * Current context management and locking
 */

#if defined( USE_XTHREADS )

/* thread safe */
static GLboolean TSDinitialized = GL_FALSE;
static xthread_key_t ContextTSD;

__GLXcontext *__glXGetCurrentContext(void)
{
   if (!TSDinitialized) {
      xthread_key_create(&ContextTSD, NULL);
      TSDinitialized = GL_TRUE;
      return &dummyContext;
   }
   else {
      void *p;
      xthread_get_specific(ContextTSD, &p);
      if (!p)
         return &dummyContext;
      else
         return (__GLXcontext *) p;
   }
}

void __glXSetCurrentContext(__GLXcontext *c)
{
   if (!TSDinitialized) {
      xthread_key_create(&ContextTSD, NULL);
      TSDinitialized = GL_TRUE;
   }
   xthread_set_specific(ContextTSD, c);
}


/* Used by the __glXLock() and __glXUnlock() macros */
xmutex_rec __glXmutex;

#elif defined( PTHREADS )

pthread_mutex_t __glXmutex = PTHREAD_MUTEX_INITIALIZER;

# if defined( GLX_USE_TLS )

/**
 * Per-thread GLX context pointer.
 * 
 * \c __glXSetCurrentContext is written is such a way that this pointer can
 * \b never be \c NULL.  This is important!  Because of this
 * \c __glXGetCurrentContext can be implemented as trivial macro.
 */
__thread void * __glX_tls_Context __attribute__((tls_model("initial-exec")))
    = &dummyContext;

void __glXSetCurrentContext( __GLXcontext * c )
{
    __glX_tls_Context = (c != NULL) ? c : &dummyContext;
}

# else

static pthread_once_t once_control = PTHREAD_ONCE_INIT;

/**
 * Per-thread data key.
 * 
 * Once \c init_thread_data has been called, the per-thread data key will
 * take a value of \c NULL.  As each new thread is created the default
 * value, in that thread, will be \c NULL.
 */
static pthread_key_t ContextTSD;

/**
 * Initialize the per-thread data key.
 * 
 * This function is called \b exactly once per-process (not per-thread!) to
 * initialize the per-thread data key.  This is ideally done using the
 * \c pthread_once mechanism.
 */
static void init_thread_data( void )
{
    if ( pthread_key_create( & ContextTSD, NULL ) != 0 ) {
	perror( "pthread_key_create" );
	exit( -1 );
    }
}

void __glXSetCurrentContext( __GLXcontext * c )
{
    pthread_once( & once_control, init_thread_data );
    pthread_setspecific( ContextTSD, c );
}

__GLXcontext * __glXGetCurrentContext( void )
{
    void * v;

    pthread_once( & once_control, init_thread_data );

    v = pthread_getspecific( ContextTSD );
    return (v == NULL) ? & dummyContext : (__GLXcontext *) v;
}

# endif /* defined( GLX_USE_TLS ) */

#elif defined( THREADS )

#error Unknown threading method specified.

#else

/* not thread safe */
__GLXcontext *__glXcurrentContext = &dummyContext;

#endif


/*
** You can set this cell to 1 to force the gl drawing stuff to be
** one command per packet
*/
int __glXDebug = 0;

/*
** forward prototype declarations
*/
int __glXCloseDisplay(Display *dpy, XExtCodes *codes);


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

/* Extension required boiler plate */

static char *__glXExtensionName = GLX_EXTENSION_NAME;
XExtensionInfo *__glXExtensionInfo = NULL;

static /* const */ char *error_list[] = {
    "GLXBadContext",
    "GLXBadContextState",
    "GLXBadDrawable",
    "GLXBadPixmap",
    "GLXBadContextTag",
    "GLXBadCurrentWindow",
    "GLXBadRenderRequest",
    "GLXBadLargeRequest",
    "GLXUnsupportedPrivateRequest",
    "GLXBadFBConfig",
    "GLXBadPbuffer",
    "GLXBadCurrentDrawable",
    "GLXBadWindow",
};

int __glXCloseDisplay(Display *dpy, XExtCodes *codes)
{
  GLXContext gc;

  gc = __glXGetCurrentContext();
  if (dpy == gc->currentDpy) {
    __glXSetCurrentContext(&dummyContext);
#ifdef GLX_DIRECT_RENDERING
    _glapi_set_dispatch(NULL);  /* no-op functions */
#endif
    __glXFreeContext(gc);
  }

  return XextRemoveDisplay(__glXExtensionInfo, dpy);
}


static XEXT_GENERATE_ERROR_STRING(__glXErrorString, __glXExtensionName,
				  __GLX_NUMBER_ERRORS, error_list)

static /* const */ XExtensionHooks __glXExtensionHooks = {
    NULL,				/* create_gc */
    NULL,				/* copy_gc */
    NULL,				/* flush_gc */
    NULL,				/* free_gc */
    NULL,				/* create_font */
    NULL,				/* free_font */
    __glXCloseDisplay,			/* close_display */
    NULL,				/* wire_to_event */
    NULL,				/* event_to_wire */
    NULL,				/* error */
    __glXErrorString,			/* error_string */
};

static
XEXT_GENERATE_FIND_DISPLAY(__glXFindDisplay, __glXExtensionInfo,
			   __glXExtensionName, &__glXExtensionHooks,
			   __GLX_NUMBER_EVENTS, NULL)

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

/*
** Free the per screen configs data as well as the array of
** __glXScreenConfigs.
*/
static void FreeScreenConfigs(__GLXdisplayPrivate *priv)
{
    __GLXscreenConfigs *psc;
    GLint i, screens;

    /* Free screen configuration information */
    psc = priv->screenConfigs;
    screens = ScreenCount(priv->dpy);
    for (i = 0; i < screens; i++, psc++) {
	if (psc->configs) {
	    _gl_context_modes_destroy( psc->configs );
	    if(psc->effectiveGLXexts)
		Xfree(psc->effectiveGLXexts);

	    psc->configs = NULL;	/* NOTE: just for paranoia */
	}
	Xfree((char*) psc->serverGLXexts);

#ifdef GLX_DIRECT_RENDERING
	/* Free the direct rendering per screen data */
	if (psc->driScreen.private)
	    (*psc->driScreen.destroyScreen)(priv->dpy, i,
					    psc->driScreen.private);
	psc->driScreen.private = NULL;
#endif
    }
    XFree((char*) priv->screenConfigs);
}

/*
** Release the private memory referred to in a display private
** structure.  The caller will free the extension structure.
*/
static int __glXFreeDisplayPrivate(XExtData *extension)
{
    __GLXdisplayPrivate *priv;

    priv = (__GLXdisplayPrivate*) extension->private_data;
    FreeScreenConfigs(priv);
    if(priv->serverGLXvendor) {
	Xfree((char*)priv->serverGLXvendor);
	priv->serverGLXvendor = 0x0; /* to protect against double free's */
    }
    if(priv->serverGLXversion) {
	Xfree((char*)priv->serverGLXversion);
	priv->serverGLXversion = 0x0; /* to protect against double free's */
    }

#ifdef GLX_DIRECT_RENDERING
    /* Free the direct rendering per display data */
    if (priv->driDisplay.private)
	(*priv->driDisplay.destroyDisplay)(priv->dpy,
					   priv->driDisplay.private);
    priv->driDisplay.private = NULL;
    if (priv->driDisplay.createNewScreen) {
        Xfree(priv->driDisplay.createNewScreen); /* free array of ptrs */
        priv->driDisplay.createNewScreen = NULL;
    }
#endif

    Xfree((char*) priv);
    return 0;
}

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

/*
** Query the version of the GLX extension.  This procedure works even if
** the client extension is not completely set up.
*/
static Bool QueryVersion(Display *dpy, int opcode, int *major, int *minor)
{
    xGLXQueryVersionReq *req;
    xGLXQueryVersionReply reply;

    /* Send the glXQueryVersion request */
    LockDisplay(dpy);
    GetReq(GLXQueryVersion,req);
    req->reqType = opcode;
    req->glxCode = X_GLXQueryVersion;
    req->majorVersion = GLX_MAJOR_VERSION;
    req->minorVersion = GLX_MINOR_VERSION;
    _XReply(dpy, (xReply*) &reply, 0, False);
    UnlockDisplay(dpy);
    SyncHandle();

    if (reply.majorVersion != GLX_MAJOR_VERSION) {
	/*
	** The server does not support the same major release as this
	** client.
	*/
	return GL_FALSE;
    }
    *major = reply.majorVersion;
    *minor = min(reply.minorVersion, GLX_MINOR_VERSION);
    return GL_TRUE;
}


void 
__glXInitializeVisualConfigFromTags( __GLcontextModes *config, int count, 
				     const INT32 *bp, Bool tagged_only,
				     Bool fbconfig_style_tags )
{
    int i;

    if (!tagged_only) {
	/* Copy in the first set of properties */
	config->visualID = *bp++;

	config->visualType = _gl_convert_from_x_visual_type( *bp++ );

	config->rgbMode = *bp++;

	config->redBits = *bp++;
	config->greenBits = *bp++;
	config->blueBits = *bp++;
	config->alphaBits = *bp++;
	config->accumRedBits = *bp++;
	config->accumGreenBits = *bp++;
	config->accumBlueBits = *bp++;
	config->accumAlphaBits = *bp++;

	config->doubleBufferMode = *bp++;
	config->stereoMode = *bp++;

	config->rgbBits = *bp++;
	config->depthBits = *bp++;
	config->stencilBits = *bp++;
	config->numAuxBuffers = *bp++;
	config->level = *bp++;

	count -= __GLX_MIN_CONFIG_PROPS;
    }

    /*
    ** Additional properties may be in a list at the end
    ** of the reply.  They are in pairs of property type
    ** and property value.
    */

#define FETCH_OR_SET(tag) \
    config-> tag = ( fbconfig_style_tags ) ? *bp++ : 1

    for (i = 0; i < count; i += 2 ) {
	switch(*bp++) {
	  case GLX_RGBA:
	    FETCH_OR_SET( rgbMode );
	    break;
	  case GLX_BUFFER_SIZE:
	    config->rgbBits = *bp++;
	    break;
	  case GLX_LEVEL:
	    config->level = *bp++;
	    break;
	  case GLX_DOUBLEBUFFER:
	    FETCH_OR_SET( doubleBufferMode );
	    break;
	  case GLX_STEREO:
	    FETCH_OR_SET( stereoMode );
	    break;
	  case GLX_AUX_BUFFERS:
	    config->numAuxBuffers = *bp++;
	    break;
	  case GLX_RED_SIZE:
	    config->redBits = *bp++;
	    break;
	  case GLX_GREEN_SIZE:
	    config->greenBits = *bp++;
	    break;
	  case GLX_BLUE_SIZE:
	    config->blueBits = *bp++;
	    break;
	  case GLX_ALPHA_SIZE:
	    config->alphaBits = *bp++;
	    break;
	  case GLX_DEPTH_SIZE:
	    config->depthBits = *bp++;
	    break;
	  case GLX_STENCIL_SIZE:
	    config->stencilBits = *bp++;
	    break;
	  case GLX_ACCUM_RED_SIZE:
	    config->accumRedBits = *bp++;
	    break;
	  case GLX_ACCUM_GREEN_SIZE:
	    config->accumGreenBits = *bp++;
	    break;
	  case GLX_ACCUM_BLUE_SIZE:
	    config->accumBlueBits = *bp++;
	    break;
	  case GLX_ACCUM_ALPHA_SIZE:
	    config->accumAlphaBits = *bp++;
	    break;
	  case GLX_VISUAL_CAVEAT_EXT:
	    config->visualRating = *bp++;    
	    break;
	  case GLX_X_VISUAL_TYPE:
	    config->visualType = *bp++;
	    break;
	  case GLX_TRANSPARENT_TYPE:
	    config->transparentPixel = *bp++;    
	    break;
	  case GLX_TRANSPARENT_INDEX_VALUE:
	    config->transparentIndex = *bp++;    
	    break;
	  case GLX_TRANSPARENT_RED_VALUE:
	    config->transparentRed = *bp++;    
	    break;
	  case GLX_TRANSPARENT_GREEN_VALUE:
	    config->transparentGreen = *bp++;    
	    break;
	  case GLX_TRANSPARENT_BLUE_VALUE:
	    config->transparentBlue = *bp++;    
	    break;
	  case GLX_TRANSPARENT_ALPHA_VALUE:
	    config->transparentAlpha = *bp++;    
	    break;
	  case GLX_VISUAL_ID:
	    config->visualID = *bp++;
	    break;
	  case GLX_DRAWABLE_TYPE:
	    config->drawableType = *bp++;
	    break;
	  case GLX_RENDER_TYPE:
	    config->renderType = *bp++;
	    break;
	  case GLX_X_RENDERABLE:
	    config->xRenderable = *bp++;
	    break;
	  case GLX_FBCONFIG_ID:
	    config->fbconfigID = *bp++;
	    break;
	  case GLX_MAX_PBUFFER_WIDTH:
	    config->maxPbufferWidth = *bp++;
	    break;
	  case GLX_MAX_PBUFFER_HEIGHT:
	    config->maxPbufferHeight = *bp++;
	    break;
	  case GLX_MAX_PBUFFER_PIXELS:
	    config->maxPbufferPixels = *bp++;
	    break;
	  case GLX_OPTIMAL_PBUFFER_WIDTH_SGIX:
	    config->optimalPbufferWidth = *bp++;
	    break;
	  case GLX_OPTIMAL_PBUFFER_HEIGHT_SGIX:
	    config->optimalPbufferHeight = *bp++;
	    break;
	  case GLX_VISUAL_SELECT_GROUP_SGIX:
	    config->visualSelectGroup = *bp++;
	    break;
	  case GLX_SWAP_METHOD_OML:
	    config->swapMethod = *bp++;
	    break;
	  case GLX_SAMPLE_BUFFERS_SGIS:
	    config->sampleBuffers = *bp++;
	    break;
	  case GLX_SAMPLES_SGIS:
	    config->samples = *bp++;
	    break;
	case GLX_BIND_TO_TEXTURE_RGB_EXT:
	    config->bindToTextureRgb = *bp++;
	    break;
	case GLX_BIND_TO_TEXTURE_RGBA_EXT:
	    config->bindToTextureRgba = *bp++;
	    break;
	case GLX_BIND_TO_MIPMAP_TEXTURE_EXT:
	    config->bindToMipmapTexture = *bp++;
	    break;
	case GLX_BIND_TO_TEXTURE_TARGETS_EXT:
	    config->bindToTextureTargets = *bp++;
	    break;
	case GLX_Y_INVERTED_EXT:
	    config->yInverted = *bp++;
	    break;
	  case None:
	    i = count;
	    break;
	  default:
	    break;
	}
    }

    config->renderType = (config->rgbMode) ? GLX_RGBA_BIT : GLX_COLOR_INDEX_BIT;

    config->haveAccumBuffer = ((config->accumRedBits +
			       config->accumGreenBits +
			       config->accumBlueBits +
			       config->accumAlphaBits) > 0);
    config->haveDepthBuffer = (config->depthBits > 0);
    config->haveStencilBuffer = (config->stencilBits > 0);
}


#ifdef GLX_DIRECT_RENDERING
static unsigned
filter_modes( __GLcontextModes ** server_modes,
	      const __GLcontextModes * driver_modes )
{
    __GLcontextModes * m;
    __GLcontextModes ** prev_next;
    const __GLcontextModes * check;
    unsigned modes_count = 0;

    if ( driver_modes == NULL ) {
	fprintf(stderr, "libGL warning: 3D driver returned no fbconfigs.\n");
	return 0;
    }

    /* For each mode in server_modes, check to see if a matching mode exists
     * in driver_modes.  If not, then the mode is not available.
     */

    prev_next = server_modes;
    for ( m = *prev_next ; m != NULL ; m = *prev_next ) {
	GLboolean do_delete = GL_TRUE;

	for ( check = driver_modes ; check != NULL ; check = check->next ) {
	    if ( _gl_context_modes_are_same( m, check ) ) {
		do_delete = GL_FALSE;
		break;
	    }
	}

	/* The 3D has to support all the modes that match the GLX visuals
	 * sent from the X server.
	 */
	if ( do_delete && (m->visualID != 0) ) {
	    do_delete = GL_FALSE;

	    fprintf(stderr, "libGL warning: 3D driver claims to not support "
		    "visual 0x%02x\n", m->visualID);
	}

	if ( do_delete ) {
	    *prev_next = m->next;

	    m->next = NULL;
	    _gl_context_modes_destroy( m );
	}
	else {
	    modes_count++;
	    prev_next = & m->next;
	}
    }

    return modes_count;
}


/**
 * Implement \c __DRIinterfaceMethods::getProcAddress.
 */
static __DRIfuncPtr get_proc_address( const char * proc_name )
{
    if (strcmp( proc_name, "glxEnableExtension" ) == 0) {
	return (__DRIfuncPtr) __glXScrEnableExtension;
    }
    
    return NULL;
}

#ifdef XDAMAGE_1_1_INTERFACE
static GLboolean has_damage_post(__DRInativeDisplay *dpy)
{
    static GLboolean inited = GL_FALSE;
    static GLboolean has_damage;

    if (!inited) {
	int major, minor;

	if (XDamageQueryVersion(dpy, &major, &minor) &&
	    major == 1 && minor >= 1)
	{
	    has_damage = GL_TRUE;
	} else {
	    has_damage = GL_FALSE;
	}
	inited = GL_TRUE;
    }

    return has_damage;
}
#endif /* XDAMAGE_1_1_INTERFACE */

static void __glXReportDamage(__DRInativeDisplay *dpy, int screen,
			      __DRIid drawable,
			      int x, int y,
			      drm_clip_rect_t *rects, int num_rects,
			      GLboolean front_buffer)
{
#ifdef XDAMAGE_1_1_INTERFACE
    XRectangle *xrects;
    XserverRegion region;
    int i;
    int x_off, y_off;

    if (!has_damage_post(dpy))
	return;

    if (front_buffer) {
	x_off = x;
	y_off = y;
	drawable = RootWindow(dpy, screen);
    } else{
	x_off = 0;
	y_off = 0;
    }

    xrects = malloc(sizeof(XRectangle) * num_rects);
    if (xrects == NULL)
	return;

    for (i = 0; i < num_rects; i++) {
	xrects[i].x = rects[i].x1 + x_off;
	xrects[i].y = rects[i].y1 + y_off;
	xrects[i].width = rects[i].x2 - rects[i].x1;
	xrects[i].height = rects[i].y2 - rects[i].y1;
    }
    region = XFixesCreateRegion(dpy, xrects, num_rects);
    free(xrects);
    XDamageAdd(dpy, drawable, region);
    XFixesDestroyRegion(dpy, region);
#endif
}

/**
 * Table of functions exported by the loader to the driver.
 */
static const __DRIinterfaceMethods interface_methods = {
    get_proc_address,

    _gl_context_modes_create,
    _gl_context_modes_destroy,
      
    __glXFindDRIScreen,
    __glXWindowExists,
      
    XF86DRICreateContextWithConfig,
    XF86DRIDestroyContext,

    XF86DRICreateDrawable,
    XF86DRIDestroyDrawable,
    XF86DRIGetDrawableInfo,

    __glXGetUST,
    __glXGetMscRateOML,

    __glXReportDamage,
};



/**
 * Perform the required libGL-side initialization and call the client-side
 * driver's \c __driCreateNewScreen function.
 * 
 * \param dpy    Display pointer.
 * \param scrn   Screen number on the display.
 * \param psc    DRI screen information.
 * \param driDpy DRI display information.
 * \param createNewScreen  Pointer to the client-side driver's
 *               \c __driCreateNewScreen function.
 * \returns A pointer to the \c __DRIscreenPrivate structure returned by
 *          the client-side driver on success, or \c NULL on failure.
 * 
 * \todo This function needs to be modified to remove context-modes from the
 *       list stored in the \c __GLXscreenConfigsRec to match the list
 *       returned by the client-side driver.
 */
static void *
CallCreateNewScreen(Display *dpy, int scrn, __DRIscreen *psc,
		    __DRIdisplay * driDpy,
		    PFNCREATENEWSCREENFUNC createNewScreen)
{
    __DRIscreenPrivate *psp = NULL;
#ifndef GLX_USE_APPLEGL
    drm_handle_t hSAREA;
    drmAddress pSAREA = MAP_FAILED;
    char *BusID;
    __DRIversion   ddx_version;
    __DRIversion   dri_version;
    __DRIversion   drm_version;
    __DRIframebuffer  framebuffer;
    int   fd = -1;
    int   status;
    const char * err_msg;
    const char * err_extra;
    int api_ver = __glXGetInternalVersion();


    dri_version.major = driDpy->private->driMajor;
    dri_version.minor = driDpy->private->driMinor;
    dri_version.patch = driDpy->private->driPatch;


    err_msg = "XF86DRIOpenConnection";
    err_extra = NULL;

    framebuffer.base = MAP_FAILED;
    framebuffer.dev_priv = NULL;

    if (XF86DRIOpenConnection(dpy, scrn, &hSAREA, &BusID)) {
        int newlyopened;
	fd = drmOpenOnce(NULL,BusID, &newlyopened);
	Xfree(BusID); /* No longer needed */

	err_msg = "open DRM";
	err_extra = strerror( -fd );

	if (fd >= 0) {
	    drm_magic_t magic;

	    err_msg = "drmGetMagic";
	    err_extra = NULL;

	    if (!drmGetMagic(fd, &magic)) {
		drmVersionPtr version = drmGetVersion(fd);
		if (version) {
		    drm_version.major = version->version_major;
		    drm_version.minor = version->version_minor;
		    drm_version.patch = version->version_patchlevel;
		    drmFreeVersion(version);
		}
		else {
		    drm_version.major = -1;
		    drm_version.minor = -1;
		    drm_version.patch = -1;
		}

		err_msg = "XF86DRIAuthConnection";
		if (!newlyopened || XF86DRIAuthConnection(dpy, scrn, magic)) {
		    char *driverName;

		    /*
		     * Get device name (like "tdfx") and the ddx version
		     * numbers.  We'll check the version in each DRI driver's
		     * "createNewScreen" function.
		     */
		    err_msg = "XF86DRIGetClientDriverName";
		    if (XF86DRIGetClientDriverName(dpy, scrn,
						   &ddx_version.major,
						   &ddx_version.minor,
						   &ddx_version.patch,
						   &driverName)) {
			drm_handle_t  hFB;
			int        junk;

			/* No longer needed. */
			Xfree( driverName );


			/*
			 * Get device-specific info.  pDevPriv will point to a struct
			 * (such as DRIRADEONRec in xfree86/driver/ati/radeon_dri.h)
			 * that has information about the screen size, depth, pitch,
			 * ancilliary buffers, DRM mmap handles, etc.
			 */
			err_msg = "XF86DRIGetDeviceInfo";
			if (XF86DRIGetDeviceInfo(dpy, scrn,
						 &hFB,
						 &junk,
						 &framebuffer.size,
						 &framebuffer.stride,
						 &framebuffer.dev_priv_size,
						 &framebuffer.dev_priv)) {
			    framebuffer.width = DisplayWidth(dpy, scrn);
			    framebuffer.height = DisplayHeight(dpy, scrn);

			    /*
			     * Map the framebuffer region.
			     */
			    status = drmMap(fd, hFB, framebuffer.size, 
					    (drmAddressPtr)&framebuffer.base);

			    err_msg = "drmMap of framebuffer";
			    err_extra = strerror( -status );

			    if ( status == 0 ) {
				/*
				 * Map the SAREA region.  Further mmap regions
				 * may be setup in each DRI driver's
				 * "createNewScreen" function.
				 */
				status = drmMap(fd, hSAREA, SAREA_MAX, 
						&pSAREA);

				err_msg = "drmMap of sarea";
				err_extra = strerror( -status );

				if ( status == 0 ) {
				    __GLcontextModes * driver_modes = NULL;
				    __GLXscreenConfigs *configs = psc->screenConfigs;

				    err_msg = "InitDriver";
				    err_extra = NULL;
				    psp = (*createNewScreen)(dpy, scrn,
							     psc,
							     configs->configs,
							     & ddx_version,
							     & dri_version,
							     & drm_version,
							     & framebuffer,
							     pSAREA,
							     fd,
							     api_ver,
							     & interface_methods,
							     & driver_modes );

				    filter_modes( & configs->configs,
						  driver_modes );
				    _gl_context_modes_destroy( driver_modes );
				}
			    }
			}
		    }
		}
	    }
	}
    }

    if ( psp == NULL ) {
	if ( pSAREA != MAP_FAILED ) {
	    (void)drmUnmap(pSAREA, SAREA_MAX);
	}

	if ( framebuffer.base != MAP_FAILED ) {
	    (void)drmUnmap((drmAddress)framebuffer.base, framebuffer.size);
	}

	if ( framebuffer.dev_priv != NULL ) {
	    Xfree(framebuffer.dev_priv);
	}

	if ( fd >= 0 ) {
	    (void)drmCloseOnce(fd);
	}

	(void)XF86DRICloseConnection(dpy, scrn);

	if ( err_extra != NULL ) {
	    fprintf(stderr, "libGL error: %s failed (%s)\n", err_msg,
		    err_extra);
	}
	else {
	    fprintf(stderr, "libGL error: %s failed\n", err_msg );
	}

        fprintf(stderr, "libGL error: reverting to (slow) indirect rendering\n");
    }
#endif /* !GLX_USE_APPLEGL */

    return psp;
}
#endif /* GLX_DIRECT_RENDERING */


/*
** Allocate the memory for the per screen configs for each screen.
** If that works then fetch the per screen configs data.
*/
static Bool AllocAndFetchScreenConfigs(Display *dpy, __GLXdisplayPrivate *priv)
{
    xGLXGetVisualConfigsReq *req;
    xGLXGetFBConfigsReq *fb_req;
    xGLXVendorPrivateWithReplyReq *vpreq;
    xGLXGetFBConfigsSGIXReq *sgi_req;
    xGLXGetVisualConfigsReply reply;
    __GLXscreenConfigs *psc;
    __GLcontextModes *config;
    GLint i, j, nprops, screens;
    INT32 buf[__GLX_TOTAL_CONFIG], *props;
    unsigned supported_request = 0;
    unsigned prop_size;

    /*
    ** First allocate memory for the array of per screen configs.
    */
    screens = ScreenCount(dpy);
    psc = (__GLXscreenConfigs*) Xmalloc(screens * sizeof(__GLXscreenConfigs));
    if (!psc) {
	return GL_FALSE;
    }
    memset(psc, 0, screens * sizeof(__GLXscreenConfigs));
    priv->screenConfigs = psc;
    
    priv->serverGLXversion = __glXGetStringFromServer(dpy, priv->majorOpcode,
					 X_GLXQueryServerString,
					 0, GLX_VERSION);
    if ( priv->serverGLXversion == NULL ) {
	FreeScreenConfigs(priv);
	return GL_FALSE;
    }

    if ( atof( priv->serverGLXversion ) >= 1.3 ) {
	supported_request = 1;
    }

    /*
    ** Now fetch each screens configs structures.  If a screen supports
    ** GL (by returning a numVisuals > 0) then allocate memory for our
    ** config structure and then fill it in.
    */
    for (i = 0; i < screens; i++, psc++) {
	if ( supported_request != 1 ) {
	    psc->serverGLXexts = __glXGetStringFromServer(dpy, priv->majorOpcode,
							  X_GLXQueryServerString,
							  i, GLX_EXTENSIONS);
	    if ( strstr( psc->serverGLXexts, "GLX_SGIX_fbconfig" ) != NULL ) {
		supported_request = 2;
	    }
	    else {
		supported_request = 3;
	    }
	}


	LockDisplay(dpy);
	switch( supported_request ) {
	    case 1:
	    GetReq(GLXGetFBConfigs,fb_req);
	    fb_req->reqType = priv->majorOpcode;
	    fb_req->glxCode = X_GLXGetFBConfigs;
	    fb_req->screen = i;
	    break;
	   
	    case 2:
	    GetReqExtra(GLXVendorPrivateWithReply,
			sz_xGLXGetFBConfigsSGIXReq-sz_xGLXVendorPrivateWithReplyReq,vpreq);
	    sgi_req = (xGLXGetFBConfigsSGIXReq *) vpreq;
	    sgi_req->reqType = priv->majorOpcode;
	    sgi_req->glxCode = X_GLXVendorPrivateWithReply;
	    sgi_req->vendorCode = X_GLXvop_GetFBConfigsSGIX;
	    sgi_req->screen = i;
	    break;

	    case 3:
	    GetReq(GLXGetVisualConfigs,req);
	    req->reqType = priv->majorOpcode;
	    req->glxCode = X_GLXGetVisualConfigs;
	    req->screen = i;
	    break;
 	}

	if (!_XReply(dpy, (xReply*) &reply, 0, False)) {
	    /* Something is busted. Punt. */
	    UnlockDisplay(dpy);
	    SyncHandle();
	    FreeScreenConfigs(priv);
	    return GL_FALSE;
	}

	if (!reply.numVisuals) {
	    /* This screen does not support GL rendering */
	    UnlockDisplay(dpy);
	    continue;
	}

	/* FIXME: Is the __GLX_MIN_CONFIG_PROPS test correct for
	 * FIXME: FBconfigs? 
	 */
	/* Check number of properties */
	nprops = reply.numProps;
	if ((nprops < __GLX_MIN_CONFIG_PROPS) ||
	    (nprops > __GLX_MAX_CONFIG_PROPS)) {
	    /* Huh?  Not in protocol defined limits.  Punt */
	    UnlockDisplay(dpy);
	    SyncHandle();
	    FreeScreenConfigs(priv);
	    return GL_FALSE;
	}

	/* Allocate memory for our config structure */
	psc->configs = _gl_context_modes_create(reply.numVisuals,
						sizeof(__GLcontextModes));
	if (!psc->configs) {
	    UnlockDisplay(dpy);
	    SyncHandle();
	    FreeScreenConfigs(priv);
	    return GL_FALSE;
	}

	/* Allocate memory for the properties, if needed */
	if ( supported_request != 3 ) {
	    nprops *= 2;
	}

	prop_size = nprops * __GLX_SIZE_INT32;

	if (prop_size <= sizeof(buf)) {
 	    props = buf;
 	} else {
	    props = (INT32 *) Xmalloc(prop_size);
 	} 

	/* Read each config structure and convert it into our format */
        config = psc->configs;
	for (j = 0; j < reply.numVisuals; j++) {
	    assert( config != NULL );
	    _XRead(dpy, (char *)props, prop_size);

	    if ( supported_request != 3 ) {
		config->rgbMode = GL_TRUE;
		config->drawableType = GLX_WINDOW_BIT;
	    }
	    else {
		config->drawableType = GLX_WINDOW_BIT | GLX_PIXMAP_BIT;
	    }

	    __glXInitializeVisualConfigFromTags( config, nprops, props,
						 (supported_request != 3),
						 GL_TRUE );
	    if ( config->fbconfigID == GLX_DONT_CARE ) {
		config->fbconfigID = config->visualID;
	    }
	    config->screen = i;
	    config = config->next;
	}
	if (props != buf) {
	    Xfree((char *)props);
	}
	UnlockDisplay(dpy);

#ifdef GLX_DIRECT_RENDERING
        /* Initialize per screen dynamic client GLX extensions */
	psc->ext_list_first_time = GL_TRUE;
	/* Initialize the direct rendering per screen data and functions */
	if (priv->driDisplay.private != NULL) {
	    /* FIXME: Should it be some sort of an error if createNewScreen[i]
	     * FIXME: is NULL?
	     */
	    if (priv->driDisplay.createNewScreen &&
		priv->driDisplay.createNewScreen[i]) {

		psc->driScreen.screenConfigs = (void *)psc;
		psc->driScreen.private =
		    CallCreateNewScreen(dpy, i, & psc->driScreen,
					& priv->driDisplay,
					priv->driDisplay.createNewScreen[i] );
	    }
	}
#endif
    }
    SyncHandle();
    return GL_TRUE;
}

/*
** Initialize the client side extension code.
*/
__GLXdisplayPrivate *__glXInitialize(Display* dpy)
{
    XExtDisplayInfo *info = __glXFindDisplay(dpy);
    XExtData **privList, *private, *found;
    __GLXdisplayPrivate *dpyPriv;
    XEDataObject dataObj;
    int major, minor;

#if defined(USE_XTHREADS)
    {
        static int firstCall = 1;
        if (firstCall) {
            /* initialize the GLX mutexes */
            xmutex_init(&__glXmutex);
            firstCall = 0;
        }
    }
#endif

    INIT_MESA_SPARC
    /* The one and only long long lock */
    __glXLock();

    if (!XextHasExtension(info)) {
	/* No GLX extension supported by this server. Oh well. */
	__glXUnlock();
	XMissingExtension(dpy, __glXExtensionName);
	return 0;
    }

    /* See if a display private already exists.  If so, return it */
    dataObj.display = dpy;
    privList = XEHeadOfExtensionList(dataObj);
    found = XFindOnExtensionList(privList, info->codes->extension);
    if (found) {
	__glXUnlock();
	return (__GLXdisplayPrivate *) found->private_data;
    }

    /* See if the versions are compatible */
    if (!QueryVersion(dpy, info->codes->major_opcode, &major, &minor)) {
	/* The client and server do not agree on versions.  Punt. */
	__glXUnlock();
	return 0;
    }

    /*
    ** Allocate memory for all the pieces needed for this buffer.
    */
    private = (XExtData *) Xmalloc(sizeof(XExtData));
    if (!private) {
	__glXUnlock();
	return 0;
    }
    dpyPriv = (__GLXdisplayPrivate *) Xcalloc(1, sizeof(__GLXdisplayPrivate));
    if (!dpyPriv) {
	__glXUnlock();
	Xfree((char*) private);
	return 0;
    }

    /*
    ** Init the display private and then read in the screen config
    ** structures from the server.
    */
    dpyPriv->majorOpcode = info->codes->major_opcode;
    dpyPriv->majorVersion = major;
    dpyPriv->minorVersion = minor;
    dpyPriv->dpy = dpy;

    dpyPriv->serverGLXvendor = 0x0; 
    dpyPriv->serverGLXversion = 0x0;

#ifdef GLX_DIRECT_RENDERING
    /*
    ** Initialize the direct rendering per display data and functions.
    ** Note: This _must_ be done before calling any other DRI routines
    ** (e.g., those called in AllocAndFetchScreenConfigs).
    */
    if (getenv("LIBGL_ALWAYS_INDIRECT") == NULL) {
        dpyPriv->driDisplay.private =
            driCreateDisplay(dpy, &dpyPriv->driDisplay);
    }
#endif

    if (!AllocAndFetchScreenConfigs(dpy, dpyPriv)) {
	__glXUnlock();
	Xfree((char*) dpyPriv);
	Xfree((char*) private);
	return 0;
    }

    /*
    ** Fill in the private structure.  This is the actual structure that
    ** hangs off of the Display structure.  Our private structure is
    ** referred to by this structure.  Got that?
    */
    private->number = info->codes->extension;
    private->next = 0;
    private->free_private = __glXFreeDisplayPrivate;
    private->private_data = (char *) dpyPriv;
    XAddToExtensionList(privList, private);

    if (dpyPriv->majorVersion == 1 && dpyPriv->minorVersion >= 1) {
        __glXClientInfo(dpy, dpyPriv->majorOpcode);
    }
    __glXUnlock();

    return dpyPriv;
}

/*
** Setup for sending a GLX command on dpy.  Make sure the extension is
** initialized.  Try to avoid calling __glXInitialize as its kinda slow.
*/
CARD8 __glXSetupForCommand(Display *dpy)
{
    GLXContext gc;
    __GLXdisplayPrivate *priv;

    /* If this thread has a current context, flush its rendering commands */
    gc = __glXGetCurrentContext();
    if (gc->currentDpy) {
	/* Flush rendering buffer of the current context, if any */
	(void) __glXFlushRenderBuffer(gc, gc->pc);

	if (gc->currentDpy == dpy) {
	    /* Use opcode from gc because its right */
	    INIT_MESA_SPARC
	    return gc->majorOpcode;
	} else {
	    /*
	    ** Have to get info about argument dpy because it might be to
	    ** a different server
	    */
	}
    }

    /* Forced to lookup extension via the slow initialize route */
    priv = __glXInitialize(dpy);
    if (!priv) {
	return 0;
    }
    return priv->majorOpcode;
}

/**
 * Flush the drawing command transport buffer.
 * 
 * \param ctx  Context whose transport buffer is to be flushed.
 * \param pc   Pointer to first unused buffer location.
 * 
 * \todo
 * Modify this function to use \c ctx->pc instead of the explicit
 * \c pc parameter.
 */
GLubyte *__glXFlushRenderBuffer(__GLXcontext *ctx, GLubyte *pc)
{
    Display * const dpy = ctx->currentDpy;
#ifdef USE_XCB
    xcb_connection_t *c = XGetXCBConnection(dpy);
#else
    xGLXRenderReq *req;
#endif /* USE_XCB */
    const GLint size = pc - ctx->buf;

    if ( (dpy != NULL) && (size > 0) ) {
#ifdef USE_XCB
	xcb_glx_render(c, ctx->currentContextTag, size, (char *)ctx->buf);
#else
	/* Send the entire buffer as an X request */
	LockDisplay(dpy);
	GetReq(GLXRender,req); 
	req->reqType = ctx->majorOpcode;
	req->glxCode = X_GLXRender; 
	req->contextTag = ctx->currentContextTag;
	req->length += (size + 3) >> 2;
	_XSend(dpy, (char *)ctx->buf, size);
	UnlockDisplay(dpy);
	SyncHandle();
#endif
    }

    /* Reset pointer and return it */
    ctx->pc = ctx->buf;
    return ctx->pc;
}


/**
 * Send a portion of a GLXRenderLarge command to the server.  The advantage of
 * this function over \c __glXSendLargeCommand is that callers can use the
 * data buffer in the GLX context and may be able to avoid allocating an
 * extra buffer.  The disadvantage is the clients will have to do more
 * GLX protocol work (i.e., calculating \c totalRequests, etc.).
 *
 * \sa __glXSendLargeCommand
 *
 * \param gc             GLX context
 * \param requestNumber  Which part of the whole command is this?  The first
 *                       request is 1.
 * \param totalRequests  How many requests will there be?
 * \param data           Command data.
 * \param dataLen        Size, in bytes, of the command data.
 */
void __glXSendLargeChunk(__GLXcontext *gc, GLint requestNumber, 
			 GLint totalRequests,
			 const GLvoid * data, GLint dataLen)
{
    Display *dpy = gc->currentDpy;
#ifdef USE_XCB
    xcb_connection_t *c = XGetXCBConnection(dpy);
    xcb_glx_render_large(c, gc->currentContextTag, requestNumber, totalRequests, dataLen, data);
#else
    xGLXRenderLargeReq *req;
    
    if ( requestNumber == 1 ) {
	LockDisplay(dpy);
    }

    GetReq(GLXRenderLarge,req); 
    req->reqType = gc->majorOpcode;
    req->glxCode = X_GLXRenderLarge; 
    req->contextTag = gc->currentContextTag;
    req->length += (dataLen + 3) >> 2;
    req->requestNumber = requestNumber;
    req->requestTotal = totalRequests;
    req->dataBytes = dataLen;
    Data(dpy, data, dataLen);

    if ( requestNumber == totalRequests ) {
	UnlockDisplay(dpy);
	SyncHandle();
    }
#endif /* USE_XCB */
}


/**
 * Send a command that is too large for the GLXRender protocol request.
 * 
 * Send a large command, one that is too large for some reason to
 * send using the GLXRender protocol request.  One reason to send
 * a large command is to avoid copying the data.
 * 
 * \param ctx        GLX context
 * \param header     Header data.
 * \param headerLen  Size, in bytes, of the header data.  It is assumed that
 *                   the header data will always be small enough to fit in
 *                   a single X protocol packet.
 * \param data       Command data.
 * \param dataLen    Size, in bytes, of the command data.
 */
void __glXSendLargeCommand(__GLXcontext *ctx,
			   const GLvoid *header, GLint headerLen,
			   const GLvoid *data, GLint dataLen)
{
    GLint maxSize;
    GLint totalRequests, requestNumber;

    /*
    ** Calculate the maximum amount of data can be stuffed into a single
    ** packet.  sz_xGLXRenderReq is added because bufSize is the maximum
    ** packet size minus sz_xGLXRenderReq.
    */
    maxSize = (ctx->bufSize + sz_xGLXRenderReq) - sz_xGLXRenderLargeReq;
    totalRequests = 1 + (dataLen / maxSize);
    if (dataLen % maxSize) totalRequests++;

    /*
    ** Send all of the command, except the large array, as one request.
    */
    assert( headerLen <= maxSize );
    __glXSendLargeChunk(ctx, 1, totalRequests, header, headerLen);

    /*
    ** Send enough requests until the whole array is sent.
    */
    for ( requestNumber = 2 ; requestNumber <= (totalRequests - 1) ; requestNumber++ ) {
	__glXSendLargeChunk(ctx, requestNumber, totalRequests, data, maxSize);
	data = (const GLvoid *) (((const GLubyte *) data) + maxSize);
	dataLen -= maxSize;
	assert( dataLen > 0 );
    }

    assert( dataLen <= maxSize );
    __glXSendLargeChunk(ctx, requestNumber, totalRequests, data, dataLen);
}

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

PUBLIC GLXContext glXGetCurrentContext(void)
{
    GLXContext cx = __glXGetCurrentContext();
    
    if (cx == &dummyContext) {
	return NULL;
    } else {
	return cx;
    }
}

PUBLIC GLXDrawable glXGetCurrentDrawable(void)
{
    GLXContext gc = __glXGetCurrentContext();
    return gc->currentDrawable;
}


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

#ifdef GLX_DIRECT_RENDERING
/* Return the DRI per screen structure */
__DRIscreen *__glXFindDRIScreen(__DRInativeDisplay *dpy, int scrn)
{
    __DRIscreen *pDRIScreen = NULL;
    XExtDisplayInfo *info = __glXFindDisplay(dpy);
    XExtData **privList, *found;
    __GLXdisplayPrivate *dpyPriv;
    XEDataObject dataObj;

    __glXLock();
    dataObj.display = dpy;
    privList = XEHeadOfExtensionList(dataObj);
    found = XFindOnExtensionList(privList, info->codes->extension);
    __glXUnlock();

    if (found) {
	dpyPriv = (__GLXdisplayPrivate *)found->private_data;
	pDRIScreen = &dpyPriv->screenConfigs[scrn].driScreen;
    }

    return pDRIScreen;
}
#endif

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

static Bool SendMakeCurrentRequest( Display *dpy, CARD8 opcode,
    GLXContextID gc, GLXContextTag old_gc, GLXDrawable draw, GLXDrawable read,
    xGLXMakeCurrentReply * reply );

/**
 * Sends a GLX protocol message to the specified display to make the context
 * and the drawables current.
 *
 * \param dpy     Display to send the message to.
 * \param opcode  Major opcode value for the display.
 * \param gc_id   Context tag for the context to be made current.
 * \param draw    Drawable ID for the "draw" drawable.
 * \param read    Drawable ID for the "read" drawable.
 * \param reply   Space to store the X-server's reply.
 *
 * \warning
 * This function assumes that \c dpy is locked with \c LockDisplay on entry.
 */
static Bool SendMakeCurrentRequest(Display *dpy, CARD8 opcode,
				   GLXContextID gc_id, GLXContextTag gc_tag,
				   GLXDrawable draw, GLXDrawable read,
				   xGLXMakeCurrentReply *reply)
{
    Bool ret;


    LockDisplay(dpy);

    if (draw == read) {
	xGLXMakeCurrentReq *req;

	GetReq(GLXMakeCurrent,req);
	req->reqType = opcode;
	req->glxCode = X_GLXMakeCurrent;
	req->drawable = draw;
	req->context = gc_id;
	req->oldContextTag = gc_tag;
    }
    else {
	__GLXdisplayPrivate *priv = __glXInitialize(dpy);

	/* If the server can support the GLX 1.3 version, we should
	 * perfer that.  Not only that, some servers support GLX 1.3 but
	 * not the SGI extension.
	 */

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

	    GetReq(GLXMakeContextCurrent,req);
	    req->reqType = opcode;
	    req->glxCode = X_GLXMakeContextCurrent;
	    req->drawable = draw;
	    req->readdrawable = read;
	    req->context = gc_id;
	    req->oldContextTag = gc_tag;
	}
	else {
	    xGLXVendorPrivateWithReplyReq *vpreq;
	    xGLXMakeCurrentReadSGIReq *req;

	    GetReqExtra(GLXVendorPrivateWithReply,
			sz_xGLXMakeCurrentReadSGIReq-sz_xGLXVendorPrivateWithReplyReq,vpreq);
	    req = (xGLXMakeCurrentReadSGIReq *)vpreq;
	    req->reqType = opcode;
	    req->glxCode = X_GLXVendorPrivateWithReply;
	    req->vendorCode = X_GLXvop_MakeCurrentReadSGI;
	    req->drawable = draw;
	    req->readable = read;
	    req->context = gc_id;
	    req->oldContextTag = gc_tag;
	}
    }

    ret = _XReply(dpy, (xReply*) reply, 0, False);

    UnlockDisplay(dpy);
    SyncHandle();

    return ret;
}


#ifdef GLX_DIRECT_RENDERING
static Bool BindContextWrapper( Display *dpy, GLXContext gc,
				GLXDrawable draw, GLXDrawable read )
{
    return (*gc->driContext.bindContext)(dpy, gc->screen, draw, read,
					 & gc->driContext);
}


static Bool UnbindContextWrapper( GLXContext gc )
{
    return (*gc->driContext.unbindContext)(gc->currentDpy, gc->screen, 
					   gc->currentDrawable,
					   gc->currentReadable,
					   & gc->driContext );
}
#endif /* GLX_DIRECT_RENDERING */


/**
 * Make a particular context current.
 * 
 * \note This is in this file so that it can access dummyContext.
 */
USED static Bool MakeContextCurrent(Display *dpy, GLXDrawable draw,
                                    GLXDrawable read, GLXContext gc)
{
    xGLXMakeCurrentReply reply;
    const GLXContext oldGC = __glXGetCurrentContext();
    const CARD8 opcode = __glXSetupForCommand(dpy);
    const CARD8 oldOpcode = ((gc == oldGC) || (oldGC == &dummyContext))
      ? opcode : __glXSetupForCommand(oldGC->currentDpy);
    Bool bindReturnValue;


    if (!opcode || !oldOpcode) {
	return GL_FALSE;
    }

    /* Make sure that the new context has a nonzero ID.  In the request,
     * a zero context ID is used only to mean that we bind to no current
     * context.
     */
    if ((gc != NULL) && (gc->xid == None)) {
	return GL_FALSE;
    }

#ifndef GLX_DIRECT_RENDERING
    if (gc && gc->isDirect) {
	return GL_FALSE;
    }
#endif

    _glapi_check_multithread();

#ifdef GLX_DIRECT_RENDERING
    /* Bind the direct rendering context to the drawable */
    if (gc && gc->isDirect) {
	bindReturnValue = (gc->driContext.private) 
	  ? BindContextWrapper(dpy, gc, draw, read)
	  : False;
    } else
#endif
    {
	/* Send a glXMakeCurrent request to bind the new context. */
	bindReturnValue = 
	  SendMakeCurrentRequest(dpy, opcode, gc ? gc->xid : None,
				 ((dpy != oldGC->currentDpy) || oldGC->isDirect)
				 ? None : oldGC->currentContextTag,
				 draw, read, &reply);
    }


    if (!bindReturnValue) {
	return False;
    }

    if ((dpy != oldGC->currentDpy || (gc && gc->isDirect)) &&
	!oldGC->isDirect && oldGC != &dummyContext) {
	xGLXMakeCurrentReply dummy_reply;

	/* We are either switching from one dpy to another and have to
	 * send a request to the previous dpy to unbind the previous
	 * context, or we are switching away from a indirect context to
	 * a direct context and have to send a request to the dpy to
	 * unbind the previous context.
	 */
	(void) SendMakeCurrentRequest(oldGC->currentDpy, oldOpcode, None,
				      oldGC->currentContextTag, None, None,
				      & dummy_reply);
    }
#ifdef GLX_DIRECT_RENDERING
    else if (oldGC->isDirect && oldGC->driContext.private) {
	(void) UnbindContextWrapper(oldGC);
    }
#endif


    /* Update our notion of what is current */
    __glXLock();
    if (gc == oldGC) {
	/* Even though the contexts are the same the drawable might have
	 * changed.  Note that gc cannot be the dummy, and that oldGC
	 * cannot be NULL, therefore if they are the same, gc is not
	 * NULL and not the dummy.
	 */
	gc->currentDrawable = draw;
	gc->currentReadable = read;
    } else {
	if (oldGC != &dummyContext) {
	    /* Old current context is no longer current to anybody */
	    oldGC->currentDpy = 0;
	    oldGC->currentDrawable = None;
	    oldGC->currentReadable = None;
	    oldGC->currentContextTag = 0;

	    if (oldGC->xid == None) {
		/* We are switching away from a context that was
		 * previously destroyed, so we need to free the memory
		 * for the old handle.
		 */
#ifdef GLX_DIRECT_RENDERING
		/* Destroy the old direct rendering context */
		if (oldGC->isDirect) {
		    if (oldGC->driContext.private) {
			(*oldGC->driContext.destroyContext)
			    (dpy, oldGC->screen, oldGC->driContext.private);
			oldGC->driContext.private = NULL;
		    }
		}
#endif
		__glXFreeContext(oldGC);
	    }
	}
	if (gc) {
	    __glXSetCurrentContext(gc);

	    gc->currentDpy = dpy;
	    gc->currentDrawable = draw;
	    gc->currentReadable = read;

            if (!gc->isDirect) {
               if (!IndirectAPI)
                  IndirectAPI = __glXNewIndirectAPI();
               _glapi_set_dispatch(IndirectAPI);

#ifdef GLX_USE_APPLEGL
               do {
                   extern void XAppleDRIUseIndirectDispatch(void);
                   XAppleDRIUseIndirectDispatch();
               } while (0);
#endif

		__GLXattribute *state = 
		  (__GLXattribute *)(gc->client_state_private);

		gc->currentContextTag = reply.contextTag;
		if (state->array_state == NULL) {
		    (void) glGetString(GL_EXTENSIONS);
		    (void) glGetString(GL_VERSION);
		    __glXInitVertexArrayState(gc);
		}
	    }
	    else {
		gc->currentContextTag = -1;
	    }
	} else {
	    __glXSetCurrentContext(&dummyContext);
#ifdef GLX_DIRECT_RENDERING
            _glapi_set_dispatch(NULL);  /* no-op functions */
#endif
	}
    }
    __glXUnlock();
    return GL_TRUE;
}


PUBLIC Bool glXMakeCurrent(Display *dpy, GLXDrawable draw, GLXContext gc)
{
    return MakeContextCurrent( dpy, draw, draw, gc );
}

PUBLIC GLX_ALIAS(Bool, glXMakeCurrentReadSGI,
	  (Display *dpy, GLXDrawable d, GLXDrawable r, GLXContext ctx),
	  (dpy, d, r, ctx), MakeContextCurrent)

PUBLIC GLX_ALIAS(Bool, glXMakeContextCurrent,
	  (Display *dpy, GLXDrawable d, GLXDrawable r, GLXContext ctx),
	  (dpy, d, r, ctx), MakeContextCurrent)


#ifdef DEBUG
void __glXDumpDrawBuffer(__GLXcontext *ctx)
{
    GLubyte *p = ctx->buf;
    GLubyte *end = ctx->pc;
    GLushort opcode, length;

    while (p < end) {
	/* Fetch opcode */
	opcode = *((GLushort*) p);
	length = *((GLushort*) (p + 2));
	printf("%2x: %5d: ", opcode, length);
	length -= 4;
	p += 4;
	while (length > 0) {
	    printf("%08x ", *((unsigned *) p));
	    p += 4;
	    length -= 4;
	}
	printf("\n");
    }	    
}
#endif

#ifdef  USE_SPARC_ASM
/*
 * Used only when we are sparc, using sparc assembler.
 *
 */

static void
_glx_mesa_init_sparc_glapi_relocs(void)
{
	unsigned int *insn_ptr, *end_ptr;
	unsigned long disp_addr;

	insn_ptr = &_mesa_sparc_glapi_begin;
	end_ptr = &_mesa_sparc_glapi_end;
	disp_addr = (unsigned long) &_glapi_Dispatch;

	/*
         * Verbatim from Mesa sparc.c.  It's needed because there doesn't
         * seem to be a better way to do this:
         *
         * UNCONDITIONAL_JUMP ( (*_glapi_Dispatch) + entry_offset )
         *
         * This code is patching in the ADDRESS of the pointer to the
         * dispatch table.  Hence, it must be called exactly once, because
         * that address is not going to change.
         *
         * What it points to can change, but Mesa (and hence, we) assume
         * that there is only one pointer.
         *
	 */
	while (insn_ptr < end_ptr) {
#if ( defined(__sparc_v9__) && ( !defined(__linux__) || defined(__linux_64__) ) )	
/*
	This code patches for 64-bit addresses.  This had better
	not happen for Sparc/Linux, no matter what architecture we
	are building for.  So, don't do this.

        The 'defined(__linux_64__)' is used here as a placeholder for
        when we do do 64-bit usermode on sparc linux.
	*/
		insn_ptr[0] |= (disp_addr >> (32 + 10));
		insn_ptr[1] |= ((disp_addr & 0xffffffff) >> 10);
		__glapi_sparc_icache_flush(&insn_ptr[0]);
		insn_ptr[2] |= ((disp_addr >> 32) & ((1 << 10) - 1));
		insn_ptr[3] |= (disp_addr & ((1 << 10) - 1));
		__glapi_sparc_icache_flush(&insn_ptr[2]);
		insn_ptr += 11;
#else
		insn_ptr[0] |= (disp_addr >> 10);
		insn_ptr[1] |= (disp_addr & ((1 << 10) - 1));
		__glapi_sparc_icache_flush(&insn_ptr[0]);
		insn_ptr += 5;
#endif
	}
}
#endif  /* sparc ASM in use */