Add support for pthreads and TLS to libGL for __glXLock / __glXUnlock and

[mesa.git] / 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 <Xext.h>
#include <extutil.h>
#include <assert.h>
#include "indirect_init.h"
#include "glapi.h"
#ifdef XTHREADS
# include "Xthreads.h"
#elif defined(PTHREADS)
# include <pthread.h>
#endif
#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

#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

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( 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);

static GLboolean FillInVisuals( __GLXscreenConfigs * psc );

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

/* 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",
};

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);

            if ( psc->old_configs != NULL ) {
                Xfree( psc->old_configs );
                psc->old_configs = NULL;
                psc->numOldConfigs = 0;
            }

            psc->configs = NULL;        /* NOTE: just for paranoia */
        }

#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 */
    }

#if 0 /* 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;
#endif

#ifdef GLX_DIRECT_RENDERING
    XFree(priv->driDisplay.createScreen);
#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;
}


/**
 * Determine if a \c __GLcontextModes structure has the right mojo to be
 * converted to a \c __GLXvisualConfig to be sent to an "old" style DRI
 * driver.
 */
#define MODE_HAS_MOJO(m) \
    ((m)->visualID != GLX_DONT_CARE) \
        && ((m)->sampleBuffers == 0) \
        && ((m)->samples == 0) \
        && (((m)->drawableType & GLX_WINDOW_BIT) != 0) \
        && (((m)->xRenderable == GL_TRUE) \
            || ((m)->xRenderable == GLX_DONT_CARE))


/**
 * Convert the FBConfigs associated with a screen into an array of
 * \c __GLXvisualConfig structures.  These structures are passed into DRI
 * drivers that use the "old" interface.  The old-style drivers had a fairly
 * strict set of visual types that could be supported.  FBConfigs that
 * cannot be supported are not converted.
 *
 * \param psc  Screen whose FBConfigs need to be swizzled.
 *
 * \returns 
 * If memory could be allocated and at least one FBConfig could be converted
 * to a \c __GLXvisualConfig structure, \c GL_TRUE is returned.  Otherwise,
 * \c GL_FALSE is returned.
 *
 * \todo
 * When the old DRI driver interface is no longer supported, this function
 * can be removed.
 */
static GLboolean
FillInVisuals( __GLXscreenConfigs * psc )
{
    __GLcontextModes *modes;
    int glx_visual_count;


    glx_visual_count = 0;
    for ( modes = psc->configs ; modes != NULL ; modes = modes->next ) {
        if ( MODE_HAS_MOJO( modes ) ) {
            glx_visual_count++;
        }
    }

    psc->old_configs = (__GLXvisualConfig *)
        Xmalloc( sizeof( __GLXvisualConfig ) * glx_visual_count );
    if ( psc->old_configs == NULL ) {
        return GL_FALSE;
    }

    glx_visual_count = 0;
    for ( modes = psc->configs ; modes != NULL ; modes = modes->next ) {
        if ( MODE_HAS_MOJO( modes ) ) {

#define COPY_VALUE(src_tag,dst_tag) \
    psc->old_configs[glx_visual_count]. dst_tag = modes-> src_tag

            COPY_VALUE( visualID,  vid );
            COPY_VALUE( rgbMode,   rgba );
            COPY_VALUE( stereoMode, stereo );
            COPY_VALUE( doubleBufferMode, doubleBuffer );

            psc->old_configs[glx_visual_count].class = 
                _gl_convert_to_x_visual_type( modes->visualType );

            COPY_VALUE( level, level );
            COPY_VALUE( numAuxBuffers, auxBuffers );

            COPY_VALUE( redBits,        redSize );
            COPY_VALUE( greenBits,      greenSize );
            COPY_VALUE( blueBits,       blueSize );
            COPY_VALUE( alphaBits,      alphaSize );
            COPY_VALUE( rgbBits,        bufferSize );
            COPY_VALUE( accumRedBits,   accumRedSize );
            COPY_VALUE( accumGreenBits, accumGreenSize );
            COPY_VALUE( accumBlueBits,  accumBlueSize );
            COPY_VALUE( accumAlphaBits, accumAlphaSize );
            COPY_VALUE( depthBits,      depthSize );
            COPY_VALUE( stencilBits,    stencilSize );

            COPY_VALUE( visualRating, visualRating );
            COPY_VALUE( transparentPixel, transparentPixel );
            COPY_VALUE( transparentRed,   transparentRed );
            COPY_VALUE( transparentGreen, transparentGreen );
            COPY_VALUE( transparentBlue,  transparentBlue );
            COPY_VALUE( transparentAlpha, transparentAlpha );
            COPY_VALUE( transparentIndex, transparentIndex );

#undef COPY_VALUE

            glx_visual_count++;
        }
    }

    psc->numOldConfigs = glx_visual_count;
    if ( glx_visual_count == 0 ) {
        Xfree( psc->old_configs );
        psc->old_configs = NULL;
    }

    return (glx_visual_count != 0);
}


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 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;
}



/**
 * 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,
                    CreateNewScreenFunc createNewScreen)
{
    __DRIscreenPrivate *psp = NULL;
#ifndef GLX_USE_APPLEGL
    drm_handle_t hSAREA;
    drmAddress pSAREA;
    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.dev_priv = NULL;

    if (XF86DRIOpenConnection(dpy, scrn, &hSAREA, &BusID)) {
        fd = drmOpen(NULL,BusID);
        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 (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 "createScreen"
                     * 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 "createScreen" 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,
                                                             & 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)drmClose(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);
            FreeScreenConfigs(priv);
            return GL_FALSE;
        }

        UnlockDisplay(dpy);
        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) {
            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] );
            }
            else if (priv->driDisplay.createScreen &&
                     priv->driDisplay.createScreen[i]) {
                /* screen initialization (bootstrap the driver) */
                if ( (psc->old_configs == NULL)
                     && !FillInVisuals(psc) ) {
                    FreeScreenConfigs(priv);
                    return GL_FALSE;
                }

                psc->driScreen.screenConfigs = (void *)psc;
                psc->driScreen.private =
                    (*(priv->driDisplay.createScreen[i]))(dpy, i, &psc->driScreen,
                                                          psc->numOldConfigs,
                                                          psc->old_configs);
            }
        }
#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(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 *) Xmalloc(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")) {
        /* Assinging zero here assures we'll never go direct */
        dpyPriv->driDisplay.private = 0;
        dpyPriv->driDisplay.destroyDisplay = 0;
        dpyPriv->driDisplay.createScreen = 0;
    }
    else {
        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;
    xGLXRenderReq *req;
    const GLint size = pc - ctx->buf;

    if ( (dpy != NULL) && (size > 0) ) {
        /* 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();
    }

    /* 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;
    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();
    }
}


/**
 * 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);
}

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

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

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 )
{
    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;
        }
    }

    return _XReply(dpy, (xReply*) reply, 0, False);
}


static Bool BindContextWrapper( Display *dpy, GLXContext gc,
                                GLXDrawable draw, GLXDrawable read )
{
#ifdef GLX_DIRECT_RENDERING
    if ( gc->driContext.bindContext3 != NULL ) {
        return (*gc->driContext.bindContext3)(dpy, gc->screen, draw, read, 
                                              & gc->driContext);
    }
#ifndef DRI_NEW_INTERFACE_ONLY
    else {
        return (*gc->driContext.bindContext2)(dpy, gc->screen, draw, read,
                                              gc);
    }
#endif
#endif
    return GL_FALSE;
}


static Bool UnbindContextWrapper( Display *dpy, GLXContext gc )
{
#ifdef GLX_DIRECT_RENDERING
    if ( gc->driContext.unbindContext3 != NULL ) {
        return (*gc->driContext.unbindContext3)(dpy, gc->screen, 
                                                gc->currentDrawable,
                                                gc->currentReadable,
                                                & gc->driContext );
    }
#ifndef DRI_NEW_INTERFACE_ONLY
    else {
        return (*gc->driContext.unbindContext2)(dpy, gc->screen,
                                                gc->currentDrawable,
                                                gc->currentReadable, gc);
    }
#endif
#endif
    return GL_FALSE;
}


/*
** 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;
    GLXContext oldGC;
    CARD8 opcode, oldOpcode;
    Bool sentRequestToOldDpy = False;
    Bool bindReturnValue = True;

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

    oldGC = __glXGetCurrentContext();
    oldOpcode = (gc == oldGC) ? opcode : __glXSetupForCommand(dpy);
    if (!oldOpcode) {
        return GL_FALSE;
    }

    if ((dpy != oldGC->currentDpy || (gc && gc->isDirect)) &&
        !oldGC->isDirect && oldGC != &dummyContext) {
        /*
        ** 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.
        */
        sentRequestToOldDpy = True;
        LockDisplay(oldGC->currentDpy);
        if ( ! SendMakeCurrentRequest( oldGC->currentDpy, oldOpcode, None,
                                       oldGC->currentContextTag, None, None,
                                       &reply ) ) {
            /* The make current failed.  Just return GL_FALSE. */
            UnlockDisplay(oldGC->currentDpy);
            SyncHandle();
            return GL_FALSE;
        }

        oldGC->currentContextTag = 0;
    }
    
#ifdef GLX_DIRECT_RENDERING
    /* Unbind the old direct rendering context */
    if (oldGC->isDirect) {
        if (oldGC->driContext.private) {
            if (! UnbindContextWrapper( oldGC->currentDpy, oldGC )) {
                /* The make current failed.  Just return GL_FALSE. */
                return GL_FALSE;
            }
        }
        oldGC->currentContextTag = 0;
    }

    /* Bind the direct rendering context to the drawable */
    if (gc && gc->isDirect) {
        if (gc->driContext.private) {
            bindReturnValue = BindContextWrapper( dpy, gc, draw, read );
        }
    } else {
#endif
        _glapi_check_multithread();
        /* Send a glXMakeCurrent request to bind the new context. */
        LockDisplay(dpy);

        bindReturnValue = SendMakeCurrentRequest( dpy, opcode, 
                                                  gc ? gc->xid : None,
                                                  oldGC->currentContextTag,
                                                  draw, read, &reply );
        UnlockDisplay(dpy);
#ifdef GLX_DIRECT_RENDERING
    }
#endif


    if (!bindReturnValue) {
        /* The make current failed. */
        if (gc && !gc->isDirect) {
            SyncHandle();
        }

#ifdef GLX_DIRECT_RENDERING
        /* If the old context was direct rendering, then re-bind to it. */
        if (oldGC->isDirect) {
            if (oldGC->driContext.private) {
                if (! BindContextWrapper( oldGC->currentDpy, oldGC,
                                          oldGC->currentDrawable,
                                          oldGC->currentReadable )) {
                    /*
                    ** The request failed; this cannot happen with the
                    ** current API.  If in the future the API is
                    ** extended to allow context sharing between
                    ** clients, then this may fail (because another
                    ** client may have grabbed the context); in that
                    ** case, we cannot undo the previous request, and
                    ** cannot adhere to the "no-op" behavior.
                    */
                }
            }
        } else
#endif
        /*
        ** If we had just sent a request to a previous dpy, we have to
        ** undo that request (because if a command fails, it should act
        ** like a no-op) by making current to the previous context and
        ** drawable.
        */
        if (sentRequestToOldDpy) {
            if ( !SendMakeCurrentRequest( oldGC->currentDpy, oldOpcode,
                                          oldGC->xid, 0, 
                                          oldGC->currentDrawable,
                                          oldGC->currentReadable, &reply ) ) {
                UnlockDisplay(oldGC->currentDpy);
                SyncHandle();
                /*
                ** The request failed; this cannot happen with the
                ** current API.  If in the future the API is extended to
                ** allow context sharing between clients, then this may
                ** fail (because another client may have grabbed the
                ** context); in that case, we cannot undo the previous
                ** request, and cannot adhere to the "no-op" behavior.
                */
            }
            else {
                UnlockDisplay(oldGC->currentDpy);
            }
            oldGC->currentContextTag = reply.contextTag;
        }
        return GL_FALSE;
    }

    /* 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);
#ifdef GLX_DIRECT_RENDERING
            if (!gc->isDirect) {
               if (!IndirectAPI)
                  IndirectAPI = __glXNewIndirectAPI();
               _glapi_set_dispatch(IndirectAPI);
# ifdef GLX_USE_APPLEGL
               do {
                   extern void XAppleDRIUseIndirectDispatch(void);
                   XAppleDRIUseIndirectDispatch();
               } while (0);
# endif
            }
#else
            /* if not direct rendering, always need indirect dispatch */
            if (!IndirectAPI)
               IndirectAPI = __glXNewIndirectAPI();
            _glapi_set_dispatch(IndirectAPI);
#endif
            gc->currentDpy = dpy;
            gc->currentDrawable = draw;
            gc->currentReadable = read;

            if ( ! gc->isDirect ) {
                __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 GLX_PREFIX(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 */