[mesa.git] / src / glx / mini / miniglx.c

/**
 * \file miniglx.c
 * \brief Mini GLX interface functions.
 * \author Brian Paul
 *
 * The Mini GLX interface is a subset of the GLX interface, plus a
 * minimal set of Xlib functions.
 */

/*
 * Mesa 3-D graphics library
 * Version:  5.0
 *
 * Copyright (C) 1999-2003  Brian Paul   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/* $Id: miniglx.c,v 1.2 2003/10/21 06:05:40 jonsmirl Exp $ */

/**
 * \mainpage Mini GLX
 *
 * \section miniglxIntro Introduction
 *
 * The Mini GLX interface facilitates OpenGL rendering on embedded devices. The
 * interface is a subset of the GLX interface, plus a minimal set of Xlib-like
 * functions.
 *
 * Programs written to the Mini GLX specification should run unchanged
 * on systems with the X Window System and the GLX extension (after
 * recompilation). The intention is to allow flexibility for
 * prototyping and testing.
 *
 * The files in the src/miniglx/ directory are compiled to build the
 * libGL.so library.  This is the library which applications link with.
 * libGL.so in turn, loads the hardware-specific device driver.
 *
 *
 * \section miniglxDoxygen About Doxygen
 *
 * For a list of all files, select <b>File List</b>.  Choose a file from
 * the list for a list of all functions in the file.
 *
 * For a list of all functions, types, constants, etc.
 * select <b>File Members</b>.
 *
 *
 * \section miniglxReferences References
 *
 * - <A HREF="file:../../docs/MiniGLX.html">Mini GLX Specification</A>,
 *   Tungsten Graphics, Inc.
 * - OpenGL Graphics with the X Window System, Silicon Graphics, Inc.,
 *   ftp://ftp.sgi.com/opengl/doc/opengl1.2/glx1.3.ps
 * - Xlib - C Language X Interface, X Consortium Standard, X Version 11,
 *   Release 6.4, ftp://ftp.x.org/pub/R6.4/xc/doc/hardcopy/X11/xlib.PS.gz
 * - XFree86 Man pages, The XFree86 Project, Inc.,
 *   http://www.xfree86.org/current/manindex3.html
 *   
 */

/**
 * \page datatypes Notes on the XVisualInfo, Visual, and __GLXvisualConfig data types
 * 
 * -# X (unfortunately) has two (or three) data types which
 *    describe visuals.  Ideally, there would just be one.
 * -# We need the #__GLXvisualConfig type to augment #XVisualInfo and #Visual
 *    because we need to describe the GLX-specific attributes of visuals.
 * -# In this interface there is a one-to-one-to-one correspondence between
 *    the three types and they're all interconnected.
 * -# The #XVisualInfo type has a pointer to a #Visual.  The #Visual structure
 *    (aka MiniGLXVisualRec) has a pointer to the #__GLXvisualConfig.  The
 *    #Visual structure also has a pointer pointing back to the #XVisualInfo.
 * -# The #XVisualInfo structure is the only one who's contents are public.
 * -# The glXChooseVisual() and XGetVisualInfo() are the only functions that
 *    return #XVisualInfo structures.  They can be freed with XFree(), though
 *    there is a small memory leak.
 */


#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dlfcn.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <linux/kd.h>
#include <linux/vt.h>

#include "miniglxP.h"
#include "dri.h"

#include "glapi.h"
#include "xf86drm.h"


/**
 * \brief Current GLX context.
 *
 * \sa glXGetCurrentContext().
 */
static GLXContext CurrentContext = NULL;



static Display *SignalDisplay = 0;

static void SwitchVT(int sig)
{
   fprintf(stderr, "SwitchVT %d dpy %p\n", sig, SignalDisplay);

   if (SignalDisplay) {
      SignalDisplay->vtSignalFlag = 1;
      switch( sig )
      {
      case SIGUSR1:                                /* vt has been released */
         SignalDisplay->haveVT = 0;
         break;
      case SIGUSR2:                                /* vt has been acquired */
         SignalDisplay->haveVT = 1;
         break;
      }
   }
}

/**********************************************************************/
/** \name Framebuffer device functions                                */
/**********************************************************************/
/*@{*/

/**
 * \brief Do the first part of setting up the framebuffer device.
 *
 * \param dpy the display handle.
 * \param use_vt use a VT for display or not
 *
 * \return GL_TRUE on success, or GL_FALSE on failure.
 * 
 * \sa This is called during XOpenDisplay().
 *
 * \internal
 * Gets the VT number, opens the respective console TTY device. Saves its state
 * to restore when exiting and goes into graphics mode.
 *
 * Opens the framebuffer device and make a copy of the original variable screen
 * information and gets the fixed screen information.  Maps the framebuffer and
 * MMIO region into the process address space.
 */
static GLboolean
OpenFBDev( Display *dpy, int use_vt )
{
   char ttystr[1000];
   int fd, vtnumber, ttyfd;

   assert(dpy);

   if (geteuid()) {
      fprintf(stderr, "error: you need to be root\n");
      return GL_FALSE;
   }
   
   if (use_vt) {
       
       /* open /dev/tty0 and get the VT number */
       if ((fd = open("/dev/tty0", O_WRONLY, 0)) < 0) {
           fprintf(stderr, "error opening /dev/tty0\n");
           return GL_FALSE;
       }
       if (ioctl(fd, VT_OPENQRY, &vtnumber) < 0 || vtnumber < 0) {
           fprintf(stderr, "error: couldn't get a free vt\n");
           return GL_FALSE;
       }
       
       fprintf(stderr, "*** got vt nr: %d\n", vtnumber);
       close(fd);
       
       /* open the console tty */
       sprintf(ttystr, "/dev/tty%d", vtnumber);  /* /dev/tty1-64 */
       dpy->ConsoleFD = open(ttystr, O_RDWR | O_NDELAY, 0);
       if (dpy->ConsoleFD < 0) {
           fprintf(stderr, "error couldn't open console fd\n");
           return GL_FALSE;
       }
       
       /* save current vt number */
       {
           struct vt_stat vts;
           if (ioctl(dpy->ConsoleFD, VT_GETSTATE, &vts) == 0)
               dpy->OriginalVT = vts.v_active;
       }
       
       /* disconnect from controlling tty */
       ttyfd = open("/dev/tty", O_RDWR);
       if (ttyfd >= 0) {
           ioctl(ttyfd, TIOCNOTTY, 0);
           close(ttyfd);
       }
       
       /* some magic to restore the vt when we exit */
       {
           struct vt_mode vt;
           struct sigaction sig_tty;
           
           /* Set-up tty signal handler to catch the signal we request below */
           SignalDisplay = dpy;
           memset( &sig_tty, 0, sizeof( sig_tty ) );
           sig_tty.sa_handler = SwitchVT;
           sigemptyset( &sig_tty.sa_mask );
           if( sigaction( SIGUSR1, &sig_tty, &dpy->OrigSigUsr1 ) ||
               sigaction( SIGUSR2, &sig_tty, &dpy->OrigSigUsr2 ) )
           {
               fprintf(stderr, "error: can't set up signal handler (%s)",
                       strerror(errno) );
               return GL_FALSE;
           }
           
           
           
           vt.mode = VT_PROCESS;
           vt.waitv = 0;
           vt.relsig = SIGUSR1;
           vt.acqsig = SIGUSR2;
           if (ioctl(dpy->ConsoleFD, VT_SETMODE, &vt) < 0) {
               fprintf(stderr, "error: ioctl(VT_SETMODE) failed: %s\n",
                       strerror(errno));
               return GL_FALSE;
           }
           
           
           if (ioctl(dpy->ConsoleFD, VT_ACTIVATE, vtnumber) != 0)
               printf("ioctl VT_ACTIVATE: %s\n", strerror(errno));
           if (ioctl(dpy->ConsoleFD, VT_WAITACTIVE, vtnumber) != 0)
               printf("ioctl VT_WAITACTIVE: %s\n", strerror(errno));
           
           if (ioctl(dpy->ConsoleFD, VT_GETMODE, &vt) < 0) {
               fprintf(stderr, "error: ioctl VT_GETMODE: %s\n", strerror(errno));
               return GL_FALSE;
           }
           
           
           
       }
       
       /* go into graphics mode */
       if (ioctl(dpy->ConsoleFD, KDSETMODE, KD_GRAPHICS) < 0) {
           fprintf(stderr, "error: ioctl(KDSETMODE, KD_GRAPHICS) failed: %s\n",
                   strerror(errno));
           return GL_FALSE;
       }
   }

   /* open the framebuffer device */
   dpy->FrameBufferFD = open(dpy->fbdevDevice, O_RDWR);
   if (dpy->FrameBufferFD < 0) {
      fprintf(stderr, "Error opening /dev/fb0: %s\n", strerror(errno));
      return GL_FALSE;
   }

  /* get the original variable screen info */
   if (ioctl(dpy->FrameBufferFD, FBIOGET_VSCREENINFO, &dpy->OrigVarInfo)) {
      fprintf(stderr, "error: ioctl(FBIOGET_VSCREENINFO) failed: %s\n",
              strerror(errno));
      return GL_FALSE;
   }

   /* make copy */
   dpy->VarInfo = dpy->OrigVarInfo;  /* structure copy */

   /* Turn off hw accels (otherwise mmap of mmio region will be
    * refused)
    */
   dpy->VarInfo.accel_flags = 0; 
   if (ioctl(dpy->FrameBufferFD, FBIOPUT_VSCREENINFO, &dpy->VarInfo)) {
      fprintf(stderr, "error: ioctl(FBIOPUT_VSCREENINFO) failed: %s\n",
              strerror(errno));
      return GL_FALSE;
   }



   /* Get the fixed screen info */
   if (ioctl(dpy->FrameBufferFD, FBIOGET_FSCREENINFO, &dpy->FixedInfo)) {
      fprintf(stderr, "error: ioctl(FBIOGET_FSCREENINFO) failed: %s\n",
              strerror(errno));
      return GL_FALSE;
   }



   /* mmap the framebuffer into our address space */
   dpy->driverContext.FBStart = dpy->FixedInfo.smem_start;
   dpy->driverContext.FBSize = dpy->FixedInfo.smem_len;
   dpy->driverContext.shared.fbSize = dpy->FixedInfo.smem_len;
   dpy->driverContext.FBAddress = (caddr_t) mmap(0, /* start */
                                     dpy->driverContext.shared.fbSize, /* bytes */
                                     PROT_READ | PROT_WRITE, /* prot */
                                     MAP_SHARED, /* flags */
                                     dpy->FrameBufferFD, /* fd */
                                     0 /* offset */);
   if (dpy->driverContext.FBAddress == (caddr_t) - 1) {
      fprintf(stderr, "error: unable to mmap framebuffer: %s\n",
              strerror(errno));
      return GL_FALSE;
   }
            
   /* mmap the MMIO region into our address space */
   dpy->driverContext.MMIOStart = dpy->FixedInfo.mmio_start;
   dpy->driverContext.MMIOSize = dpy->FixedInfo.mmio_len;
   dpy->driverContext.MMIOAddress = (caddr_t) mmap(0, /* start */
                                     dpy->driverContext.MMIOSize, /* bytes */
                                     PROT_READ | PROT_WRITE, /* prot */
                                     MAP_SHARED, /* flags */
                                     dpy->FrameBufferFD, /* fd */
                                     dpy->FixedInfo.smem_len /* offset */);
   if (dpy->driverContext.MMIOAddress == (caddr_t) - 1) {
      fprintf(stderr, "error: unable to mmap mmio region: %s\n",
              strerror(errno));
      return GL_FALSE;
   }

   fprintf(stderr, "got MMIOAddress %p offset %d\n",
           dpy->driverContext.MMIOAddress,
           dpy->FixedInfo.smem_len);

   return GL_TRUE;
}




/**
 * \brief Setup up the desired framebuffer device mode.  
 *
 * \param dpy the display handle.
 * 
 * \return GL_TRUE on success, or GL_FALSE on failure.
 * 
 * \sa This is called during __miniglx_StartServer().
 *
 * \internal
 *
 * Bumps the size of the window the the next supported mode. Sets the
 * variable screen information according to the desired mode and asks
 * the driver to validate the mode. Certifies that a DirectColor or
 * TrueColor visual is used from the updated fixed screen information.
 * In the case of DirectColor visuals, sets up an 'identity' colormap to
 * mimic a TrueColor visual.
 *
 * Calls the driver hooks 'ValidateMode' and 'PostValidateMode' to
 * allow the driver to make modifications to the chosen mode according
 * to hardware constraints, or to save and restore videocard registers
 * that may be clobbered by the fbdev driver.
 *
 * \todo Timings are hard-coded in the source for a set of supported modes.
 */
static GLboolean
SetupFBDev( Display *dpy )
{
   int width, height;

   assert(dpy);

   width = dpy->driverContext.shared.virtualWidth;
   height = dpy->driverContext.shared.virtualHeight;
   
   /* Bump size up to next supported mode.
    */
   if (width <= 800 && height <= 600) {
      width = 800; height = 600; 
   }  
   else if (width <= 1024 && height <= 768) { 
      width = 1024; height = 768; 
   } 
   else if (width <= 768 && height <= 1024) {
      width = 768; height = 1024; 
   }  
   else if (width <= 1280 && height <= 1024) { 
      width = 1280; height = 1024; 
   } 


   dpy->driverContext.shared.virtualHeight = height;
   dpy->driverContext.shared.virtualWidth = width;
   dpy->driverContext.shared.fbStride = width * (dpy->driverContext.bpp / 8);
   
   /* set the depth, resolution, etc */
   dpy->VarInfo = dpy->OrigVarInfo;
   dpy->VarInfo.bits_per_pixel = dpy->driverContext.bpp;
   dpy->VarInfo.xres_virtual = dpy->driverContext.shared.virtualWidth;
   dpy->VarInfo.yres_virtual = dpy->driverContext.shared.virtualHeight;
   dpy->VarInfo.xres = width;
   dpy->VarInfo.yres = height;
   dpy->VarInfo.xoffset = 0;
   dpy->VarInfo.yoffset = 0;
   dpy->VarInfo.nonstd = 0;
   dpy->VarInfo.vmode &= ~FB_VMODE_YWRAP; /* turn off scrolling */

   if (dpy->VarInfo.bits_per_pixel == 32) {
      dpy->VarInfo.red.offset = 16;
      dpy->VarInfo.green.offset = 8;
      dpy->VarInfo.blue.offset = 0;
      dpy->VarInfo.transp.offset = 24;
      dpy->VarInfo.red.length = 8;
      dpy->VarInfo.green.length = 8;
      dpy->VarInfo.blue.length = 8;
      dpy->VarInfo.transp.length = 8;
   }
   else if (dpy->VarInfo.bits_per_pixel == 16) {
      dpy->VarInfo.red.offset = 11;
      dpy->VarInfo.green.offset = 5;
      dpy->VarInfo.blue.offset = 0;
      dpy->VarInfo.red.length = 5;
      dpy->VarInfo.green.length = 6;
      dpy->VarInfo.blue.length = 5;
      dpy->VarInfo.transp.offset = 0;
      dpy->VarInfo.transp.length = 0;
   }
   else {
      fprintf(stderr, "Only 32bpp and 16bpp modes supported at the moment\n");
      return 0;
   }

   if (!dpy->driver->validateMode( &dpy->driverContext )) {
      fprintf(stderr, "Driver validateMode() failed\n");
      return 0;
   }

   if (dpy->VarInfo.xres == 1280 && 
       dpy->VarInfo.yres == 1024) {
      /* timing values taken from /etc/fb.modes (1280x1024 @ 75Hz) */
      dpy->VarInfo.pixclock = 7408;
      dpy->VarInfo.left_margin = 248;
      dpy->VarInfo.right_margin = 16;
      dpy->VarInfo.upper_margin = 38;
      dpy->VarInfo.lower_margin = 1;
      dpy->VarInfo.hsync_len = 144;
      dpy->VarInfo.vsync_len = 3;
   }
   else if (dpy->VarInfo.xres == 1024 && 
            dpy->VarInfo.yres == 768) {
      /* timing values taken from /etc/fb.modes (1024x768 @ 75Hz) */
      dpy->VarInfo.pixclock = 12699;
      dpy->VarInfo.left_margin = 176;
      dpy->VarInfo.right_margin = 16;
      dpy->VarInfo.upper_margin = 28;
      dpy->VarInfo.lower_margin = 1;
      dpy->VarInfo.hsync_len = 96;
      dpy->VarInfo.vsync_len = 3;
   }
   else if (dpy->VarInfo.xres == 800 &&
            dpy->VarInfo.yres == 600) {
      /* timing values taken from /etc/fb.modes (800x600 @ 75Hz) */
      dpy->VarInfo.pixclock = 20203;
      dpy->VarInfo.left_margin = 160;
      dpy->VarInfo.right_margin = 16;
      dpy->VarInfo.upper_margin = 21;
      dpy->VarInfo.lower_margin = 1;
      dpy->VarInfo.hsync_len = 80;
      dpy->VarInfo.vsync_len = 3;
   }
   else if (dpy->VarInfo.xres == 768 &&
            dpy->VarInfo.yres == 1024) {
      /* timing values for 768x1024 @ 75Hz */
      dpy->VarInfo.pixclock = 11993;
      dpy->VarInfo.left_margin = 136;
      dpy->VarInfo.right_margin = 32;
      dpy->VarInfo.upper_margin = 41;
      dpy->VarInfo.lower_margin = 1;
      dpy->VarInfo.hsync_len = 80;
      dpy->VarInfo.vsync_len = 3;
   }
   else {
      /* XXX need timings for other screen sizes */
      fprintf(stderr, "XXXX screen size %d x %d not supported at this time!\n",
              dpy->VarInfo.xres, dpy->VarInfo.yres);
      return GL_FALSE;
   }

   fprintf(stderr, "[miniglx] Setting mode: visible %dx%d virtual %dx%dx%d\n",
           dpy->VarInfo.xres, dpy->VarInfo.yres,
           dpy->VarInfo.xres_virtual, dpy->VarInfo.yres_virtual,
           dpy->VarInfo.bits_per_pixel);

   /* set variable screen info */
   if (ioctl(dpy->FrameBufferFD, FBIOPUT_VSCREENINFO, &dpy->VarInfo)) {
      fprintf(stderr, "error: ioctl(FBIOPUT_VSCREENINFO) failed: %s\n",
              strerror(errno));
      return GL_FALSE;
   }

   /* get the variable screen info, in case it has been modified */
   if (ioctl(dpy->FrameBufferFD, FBIOGET_VSCREENINFO, &dpy->VarInfo)) {
      fprintf(stderr, "error: ioctl(FBIOGET_VSCREENINFO) failed: %s\n",
              strerror(errno));
      return GL_FALSE;
   }


   fprintf(stderr, "[miniglx] Readback mode: visible %dx%d virtual %dx%dx%d\n",
           dpy->VarInfo.xres, dpy->VarInfo.yres,
           dpy->VarInfo.xres_virtual, dpy->VarInfo.yres_virtual,
           dpy->VarInfo.bits_per_pixel);

   /* Get the fixed screen info */
   if (ioctl(dpy->FrameBufferFD, FBIOGET_FSCREENINFO, &dpy->FixedInfo)) {
      fprintf(stderr, "error: ioctl(FBIOGET_FSCREENINFO) failed: %s\n",
              strerror(errno));
      return GL_FALSE;
   }

   if (dpy->FixedInfo.visual != FB_VISUAL_TRUECOLOR &&
       dpy->FixedInfo.visual != FB_VISUAL_DIRECTCOLOR) {
      fprintf(stderr, "non-TRUECOLOR visuals not supported.\n");
      return GL_FALSE;
   }

   if (dpy->FixedInfo.visual == FB_VISUAL_DIRECTCOLOR) {
      struct fb_cmap cmap;
      unsigned short red[256], green[256], blue[256];
      int rcols = 1 << dpy->VarInfo.red.length;
      int gcols = 1 << dpy->VarInfo.green.length;
      int bcols = 1 << dpy->VarInfo.blue.length;
      int i;

      cmap.start = 0;      
      cmap.len = gcols;
      cmap.red   = red;
      cmap.green = green;
      cmap.blue  = blue;
      cmap.transp = NULL;

      for (i = 0; i < rcols ; i++) 
         red[i] = (65536/(rcols-1)) * i;

      for (i = 0; i < gcols ; i++) 
         green[i] = (65536/(gcols-1)) * i;

      for (i = 0; i < bcols ; i++) 
         blue[i] = (65536/(bcols-1)) * i;
      
      if (ioctl(dpy->FrameBufferFD, FBIOPUTCMAP, (void *) &cmap) < 0) {
         fprintf(stderr, "ioctl(FBIOPUTCMAP) failed [%d]\n", i);
         exit(1);
      }
   }

   /* May need to restore regs fbdev has clobbered:
    */
   if (!dpy->driver->postValidateMode( &dpy->driverContext )) {
      fprintf(stderr, "Driver postValidateMode() failed\n");
      return 0;
   }

   return GL_TRUE;
}


/**
 * \brief Restore the framebuffer device to state it was in before we started
 *
 * Undoes the work done by SetupFBDev().
 * 
 * \param dpy the display handle.
 *
 * \return GL_TRUE on success, or GL_FALSE on failure.
 * 
 * \sa Called from XDestroyWindow().
 *
 * \internal
 * Restores the original variable screen info.
 */
static GLboolean
RestoreFBDev( Display *dpy )
{
   /* restore original variable screen info */
   if (ioctl(dpy->FrameBufferFD, FBIOPUT_VSCREENINFO, &dpy->OrigVarInfo)) {
      fprintf(stderr, "ioctl(FBIOPUT_VSCREENINFO failed): %s\n",
              strerror(errno));
      return GL_FALSE;
   }
   dpy->VarInfo = dpy->OrigVarInfo;

   return GL_TRUE;
}


/**
 * \brief Close the framebuffer device.  
 *
 * \param dpy the display handle.
 * 
 * \sa Called from XCloseDisplay().
 *
 * \internal
 * Unmaps the framebuffer and MMIO region.  Restores the text mode and the
 * original virtual terminal. Closes the console and framebuffer devices.
 */
static void
CloseFBDev( Display *dpy )
{
   struct vt_mode VT;

   munmap(dpy->driverContext.FBAddress, dpy->driverContext.FBSize);
   munmap(dpy->driverContext.MMIOAddress, dpy->driverContext.MMIOSize);

   if (dpy->ConsoleFD) {
       /* restore text mode */
       ioctl(dpy->ConsoleFD, KDSETMODE, KD_TEXT);
       
       /* set vt */
       if (ioctl(dpy->ConsoleFD, VT_GETMODE, &VT) != -1) {
           VT.mode = VT_AUTO;
           ioctl(dpy->ConsoleFD, VT_SETMODE, &VT);
       }
       
       /* restore original vt */
       if (dpy->OriginalVT >= 0) {
           ioctl(dpy->ConsoleFD, VT_ACTIVATE, dpy->OriginalVT);
           dpy->OriginalVT = -1;
       }
       
       close(dpy->ConsoleFD);
   }
   close(dpy->FrameBufferFD);
}

/*@}*/


/**********************************************************************/
/** \name Misc functions needed for DRI drivers                       */
/**********************************************************************/
/*@{*/

/**
 * \brief Find the DRI screen dependent methods associated with the display.
 *
 * \param dpy a display handle, as returned by XOpenDisplay().
 * \param scrn the screen number. Not referenced.
 * 
 * \returns a pointer to a __DRIscreenRec structure.
 * 
 * \internal
 * Returns the MiniGLXDisplayRec::driScreen attribute.
 */
__DRIscreen *
__glXFindDRIScreen(Display *dpy, int scrn)
{
   (void) scrn;
   return dpy->driScreen;
}

/**
 * \brief Validate a drawable.
 *
 * \param dpy a display handle, as returned by XOpenDisplay().
 * \param draw drawable to validate.
 * 
 * \internal
 * Since Mini GLX only supports one window, compares the specified drawable with
 * the MiniGLXDisplayRec::TheWindow attribute.
 */
Bool
__glXWindowExists(Display *dpy, GLXDrawable draw)
{
   if (dpy->TheWindow == draw)
      return True;
   else
      return False;
}

/**
 * \brief Get current thread ID.
 *
 * \return thread ID.
 *
 * \internal
 * Always returns 0. 
 */
/*unsigned long
_glthread_GetID(void)
{
   return 0;
}*/

/*@}*/


/**
 * \brief Scan Linux /prog/bus/pci/devices file to determine hardware
 * chipset based on supplied bus ID.
 * 
 * \return probed chipset (non-zero) on success, zero otherwise.
 * 
 * \internal 
 */
static int get_chipset_from_busid( Display *dpy )
{
   char buf[0x200];
   FILE *file;
   const char *fname = "/proc/bus/pci/devices";
   int retval = 0;

   if (!(file = fopen(fname,"r"))) {
      fprintf(stderr, "couldn't open %s: %s\n", fname, strerror(errno));
      return 0;
   }

   while (fgets(buf, sizeof(buf)-1, file)) {
      unsigned int nr, bus, dev, fn, vendor, device, encode;
      nr = sscanf(buf, "%04x\t%04x%04x", &encode, 
                  &vendor, &device);
      
      bus = encode >> 8;
      dev = (encode & 0xFF) >> 3;
      fn = encode & 0x7;

      if (nr != 3)
         break;

      if (bus == dpy->driverContext.pciBus &&
          dev == dpy->driverContext.pciDevice &&
          fn  == dpy->driverContext.pciFunc) {
         retval = device;
         break;
      }
   }

   fclose(file);

   if (retval)
      fprintf(stderr, "[miniglx] probed chipset 0x%x\n", retval);
   else
      fprintf(stderr, "[miniglx] failed to probe chipset\n");

   return retval;
}


/**
 * \brief Read settings from a configuration file.
 * 
 * The configuration file is usually "/etc/miniglx.conf", but can be overridden
 * with the MINIGLX_CONF environment variable. 
 *
 * The format consists in \code option = value \endcode lines. The option names 
 * corresponds to the fields in MiniGLXDisplayRec.
 * 
 * \param dpy the display handle as.
 *
 * \return non-zero on success, zero otherwise.
 * 
 * \internal 
 * Sets some defaults. Opens and parses the the Mini GLX configuration file and
 * fills in the MiniGLXDisplayRec field that corresponds for each option.
 */
static int __read_config_file( Display *dpy )
{
   FILE *file;
   const char *fname;

   /* Fallback/defaults
    */
   dpy->fbdevDevice = "/dev/fb0";
   dpy->clientDriverName = "fb_dri.so";
   dpy->driverContext.pciBus = 0;
   dpy->driverContext.pciDevice = 0;
   dpy->driverContext.pciFunc = 0;
   dpy->driverContext.chipset = 0;   
   dpy->driverContext.pciBusID = 0;
   dpy->driverContext.shared.virtualWidth = 1280;
   dpy->driverContext.shared.virtualHeight = 1024;
   dpy->driverContext.bpp = 32;
   dpy->driverContext.cpp = 4;
   dpy->rotateMode = 0;

   fname = getenv("MINIGLX_CONF");
   if (!fname) fname = "/etc/miniglx.conf";

   file = fopen(fname, "r");
   if (!file) {
      fprintf(stderr, "couldn't open config file %s: %s\n", fname, strerror(errno));
      return 0;
   }


   while (!feof(file)) {
      char buf[81], *opt = buf, *val, *tmp1, *tmp2;
      fgets(buf, sizeof(buf), file); 

      /* Parse 'opt = val' -- must be easier ways to do this.
       */
      while (isspace(*opt)) opt++;
      val = opt;
      if (*val == '#') continue; /* comment */
      while (!isspace(*val) && *val != '=' && *val) val++;
      tmp1 = val;
      while (isspace(*val)) val++;
      if (*val != '=') continue;
      *tmp1 = 0; 
      val++;
      while (isspace(*val)) val++;
      tmp2 = val;
      while (!isspace(*tmp2) && *tmp2 != '\n' && *tmp2) tmp2++;
      *tmp2 = 0;


      if (strcmp(opt, "fbdevDevice") == 0) 
         dpy->fbdevDevice = strdup(val);
      else if (strcmp(opt, "clientDriverName") == 0)
         dpy->clientDriverName = strdup(val);
      else if (strcmp(opt, "rotateMode") == 0)
         dpy->rotateMode = atoi(val) ? 1 : 0;
      else if (strcmp(opt, "pciBusID") == 0) {
         if (sscanf(val, "PCI:%d:%d:%d",
                    &dpy->driverContext.pciBus,
                    &dpy->driverContext.pciDevice,
                    &dpy->driverContext.pciFunc) != 3) {
            fprintf(stderr, "malformed bus id: %s\n", val);
            continue;
         }
         dpy->driverContext.pciBusID = strdup(val);
      }
      else if (strcmp(opt, "chipset") == 0) {
         if (sscanf(val, "0x%x", &dpy->driverContext.chipset) != 1)
            fprintf(stderr, "malformed chipset: %s\n", opt);
      }
      else if (strcmp(opt, "virtualWidth") == 0) {
         if (sscanf(val, "%d", &dpy->driverContext.shared.virtualWidth) != 1)
            fprintf(stderr, "malformed virtualWidth: %s\n", opt);
      }
      else if (strcmp(opt, "virtualHeight") == 0) {
         if (sscanf(val, "%d", &dpy->driverContext.shared.virtualHeight) != 1)
            fprintf(stderr, "malformed virutalHeight: %s\n", opt);
      }
      else if (strcmp(opt, "bpp") == 0) {
         if (sscanf(val, "%d", &dpy->driverContext.bpp) != 1)
            fprintf(stderr, "malformed bpp: %s\n", opt);
         dpy->driverContext.cpp = dpy->driverContext.bpp / 8;
      }
   }

   fclose(file);

   if (dpy->driverContext.chipset == 0 && dpy->driverContext.pciBusID != 0) 
      dpy->driverContext.chipset = get_chipset_from_busid( dpy );

   return 1;
}

static int InitDriver( Display *dpy )
{
   /*
    * Begin DRI setup.
    * We're kind of combining the per-display and per-screen information
    * which was kept separate in XFree86/DRI's libGL.
    */
   dpy->dlHandle = dlopen(dpy->clientDriverName, RTLD_NOW | RTLD_GLOBAL);
   if (!dpy->dlHandle) {
      fprintf(stderr, "Unable to open %s: %s\n", dpy->clientDriverName,
              dlerror());
      return GL_FALSE;
   }

   /* Pull in Mini GLX specific hooks:
    */
   dpy->driver = (struct DRIDriverRec *) dlsym(dpy->dlHandle,
                                               "__driDriver");
   if (!dpy->driver) {
      fprintf(stderr, "Couldn't find __driDriver in %s\n",
              dpy->clientDriverName);
      dlclose(dpy->dlHandle);
      return GL_FALSE;
   }

   /* Pull in standard DRI client-side driver hooks:
    */
   dpy->createScreen = (driCreateScreenFunc*) dlsym(dpy->dlHandle,
                                                "__driCreateScreen");
   if (!dpy->createScreen) {
      fprintf(stderr, "Couldn't find __driCreateScreen in %s\n",
              dpy->clientDriverName);
      dlclose(dpy->dlHandle);
      return GL_FALSE;
   }

   return GL_TRUE;
}


/**********************************************************************/
/** \name Public API functions (Xlib and GLX)                         */
/**********************************************************************/
/*@{*/


/**
 * \brief Initialize the graphics system.
 * 
 * \param display_name currently ignored. It is recommended to pass it as NULL.
 * \return a pointer to a #Display if the function is able to initialize
 * the graphics system, NULL otherwise.
 * 
 * Allocates a MiniGLXDisplayRec structure and fills in with information from a
 * configuration file. 
 *
 * Calls OpenFBDev() to open the framebuffer device and calls
 * DRIDriverRec::initFBDev to do the client-side initialization on it.
 *
 * Loads the DRI driver and pulls in Mini GLX specific hooks into a
 * DRIDriverRec structure, and the standard DRI \e __driCreateScreen hook.
 * Asks the driver for a list of supported visuals.  Performs the per-screen
 * client-side initialization.  Also setups the callbacks in the screen private
 * information.
 *
 * Does the framebuffer device setup. Calls __miniglx_open_connections() to
 * serve clients.
 */
Display *
__miniglx_StartServer( const char *display_name )
{
   Display *dpy;
   int use_vt = 0;

   dpy = (Display *)calloc(1, sizeof(Display));
   if (!dpy)
      return NULL;

   dpy->IsClient = False;

   if (!__read_config_file( dpy )) {
      fprintf(stderr, "Couldn't get configuration details\n");
      free(dpy);
      return NULL;
   }

   /* Open the fbdev device
    */
   if (!OpenFBDev(dpy, use_vt)) {
      fprintf(stderr, "OpenFBDev failed\n");
      free(dpy);
      return NULL;
   }

   if (!InitDriver(dpy)) {
      fprintf(stderr, "InitDriver failed\n");
      free(dpy);
      return NULL;
   }

   /* Ask the driver for a list of supported configs:
   */
   dpy->driver->initContextModes( &dpy->driverContext, &dpy->numModes, &dpy->modes );

   /* Perform the initialization normally done in the X server 
    */
   if (!dpy->driver->initFBDev( &dpy->driverContext )) {
      fprintf(stderr, "%s: __driInitFBDev failed\n", __FUNCTION__);
      dlclose(dpy->dlHandle);
      return GL_FALSE;
   }

   /* do fbdev setup
    */
   if (!SetupFBDev(dpy)) {
      fprintf(stderr, "SetupFBDev failed\n");
      free(dpy);
      return NULL;
   }

   /* unlock here if not using VT -- JDS */
   if (!use_vt) {
       if (dpy->driver->restoreHardware)
           dpy->driver->restoreHardware( &dpy->driverContext ); 
       DRM_UNLOCK( dpy->driverContext.drmFD,
                   dpy->driverContext.pSAREA,
                   dpy->driverContext.serverContext );
       dpy->hwActive = 1;
   }

   /* Ready for clients:
    */
   if (!__miniglx_open_connections(dpy)) {
      free(dpy);
      return NULL;
   }
      
   return dpy;
}


/**
 * \brief Initialize the graphics system.
 * 
 * \param display_name currently ignored. It is recommended to pass it as NULL.
 * \return a pointer to a #Display if the function is able to initialize
 * the graphics system, NULL otherwise.
 * 
 * Allocates a MiniGLXDisplayRec structure and fills in with information from a
 * configuration file. 
 *
 * Calls __miniglx_open_connections() to connect to the server.
 * 
 * Loads the DRI driver and pulls in Mini GLX specific hooks into a
 * DRIDriverRec structure, and the standard DRI \e __driCreateScreen hook.
 * Asks the driver for a list of supported visuals.  Performs the per-screen
 * client-side initialization.  Also setups the callbacks in the screen private
 * information.
 *
 * \todo
 *   - read config file
 *      - what about virtualWidth, etc?
 *   - determine dpy->driverClientMsgSize,
 *   - allocate dpy->driverClientMsg
 */
Display *
XOpenDisplay( const char *display_name )
{
   Display *dpy;

   dpy = (Display *)calloc(1, sizeof(Display));
   if (!dpy)
      return NULL;

   dpy->IsClient = True;

   /* read config file 
    */
   if (!__read_config_file( dpy )) {
      fprintf(stderr, "Couldn't get configuration details\n");
      free(dpy);
      return NULL;
   }

   /* Connect to the server and receive driverClientMsg
    */
   if (!__miniglx_open_connections(dpy)) {
      free(dpy);
      return NULL;
   }

   /* dlopen the driver .so file
    */
   if (!InitDriver(dpy)) {
      fprintf(stderr, "InitDriver failed\n");
      free(dpy);
      return NULL;
   }

   /* Ask the driver for a list of supported configs:
   */
   dpy->driver->initContextModes( &dpy->driverContext, &dpy->numModes, &dpy->modes );
   
   /* Perform the client-side initialization.  
    *
    * Clearly there is a limit of one on the number of windows in
    * existence at any time.
    *
    * Need to shut down DRM and free DRI data in XDestroyWindow(), too.
    */
   dpy->driScreen = (*dpy->createScreen)(dpy->driver,
                                         &dpy->driverContext);
   if (!dpy->driScreen) {
      fprintf(stderr, "%s: __driCreateScreen failed\n", __FUNCTION__);
      dlclose(dpy->dlHandle);
      free(dpy);
      return NULL;
   }
   
   /* Anything more to do?
    */
   return dpy;
}


/**
 * \brief Release display resources.
 * 
 * When the application is about to exit, the resources associated with the
 * graphics system can be released by calling this function.
 * 
 * \param dpy display handle. It becomes invalid at this point.
 * 
 * Destroys the window if any, and destroys the per-screen
 * driver private information.
 * Calls __miniglx_close_connections().
 * 
 * If a server, puts the the framebuffer back into the initial state.
 *
 * Finally frees the display structure.
 */
void
XCloseDisplay( Display *dpy )
{
   glXMakeCurrent( dpy, NULL, NULL);

   if (dpy->NumWindows) 
      XDestroyWindow( dpy, dpy->TheWindow );

   /* As this is done in XOpenDisplay, need to undo it here:
    */
   (*dpy->driScreen->destroyScreen)(dpy->driScreen);

   __miniglx_close_connections( dpy );

   if (!dpy->IsClient) {
      /* put framebuffer back to initial state 
       */
      (*dpy->driver->haltFBDev)( &dpy->driverContext );
      RestoreFBDev(dpy);
      CloseFBDev(dpy);
   }

   dlclose(dpy->dlHandle);
   free(dpy);
}


/**
 * \brief Window creation.
 *
 * \param display a display handle, as returned by XOpenDisplay().
 * \param parent the parent window for the new window. For Mini GLX this should
 * be 
 * \code RootWindow(display, 0) \endcode
 * \param x the window abscissa. For Mini GLX, it should be zero.
 * \param y the window ordinate. For Mini GLX, it should be zero.
 * \param width the window width. For Mini GLX, this specifies the desired
 * screen width such as 1024 or 1280. 
 * \param height the window height. For Mini GLX, this specifies the desired
 * screen height such as 768 or 1024.
 * \param border_width the border width. For Mini GLX, it should be zero.
 * \param depth the window pixel depth. For Mini GLX, this should be the depth
 * found in the #XVisualInfo object returned by glXChooseVisual() 
 * \param class the window class. For Mini GLX this value should be
 * #InputOutput.
 * \param visual the visual type. It should be the visual field of the
 * #XVisualInfo object returned by glXChooseVisual().
 * \param valuemask which fields of the XSetWindowAttributes() are to be used.
 * For Mini GLX this is typically the bitmask 
 * \code CWBackPixel | CWBorderPixel | CWColormap \endcode
 * \param attributes initial window attributes. The
 * XSetWindowAttributes::background_pixel, XSetWindowAttributes::border_pixel
 * and XSetWindowAttributes::colormap fields should be set.
 *
 * \return a window handle if it succeeds or zero if it fails.
 * 
 * \note For Mini GLX, windows are full-screen; they cover the entire frame
 * buffer.  Also, Mini GLX imposes a limit of one window. A second window
 * cannot be created until the first one is destroyed.
 *
 * This function creates and initializes a ::MiniGLXWindowRec structure after
 * ensuring that there is no other window created.  Performs the per-drawable
 * client-side initialization calling the __DRIscreenRec::createDrawable
 * method.
 * 
 */
Window
XCreateWindow( Display *dpy, Window parent, int x, int y,
               unsigned int width, unsigned int height,
               unsigned int border_width, int depth, unsigned int class,
               Visual *visual, unsigned long valuemask,
               XSetWindowAttributes *attributes )
{
   Window win;

   /* ignored */
   (void) x;
   (void) y;
   (void) border_width;
   (void) depth;
   (void) class;
   (void) valuemask;
   (void) attributes;

   if (!dpy->IsClient) {
      fprintf(stderr, "Server process may not create windows (currently)\n");
      return NULL;
   }

   if (dpy->NumWindows > 0)
      return NULL;  /* only allow one window */

   assert(dpy->TheWindow == NULL);

   win = malloc(sizeof(struct MiniGLXWindowRec));
   if (!win)
      return NULL;

   /* In rotated mode, translate incoming x,y,width,height into
    * 'normal' coordinates.
    */
   if (dpy->rotateMode) {
      int tmp;
      tmp = width; width = height; height = tmp;
      tmp = x; x = y; y = tmp;
   }

   /* init other per-window fields */
   win->x = 0;
   win->y = 0;
   win->w = width;
   win->h = height;
   win->visual = visual;  /* ptr assignment */

   win->bytesPerPixel = dpy->driverContext.cpp;
   win->rowStride = dpy->driverContext.shared.virtualWidth * win->bytesPerPixel;
   win->size = win->rowStride * height; 
   win->frontStart = dpy->driverContext.FBAddress;
   win->frontBottom = (GLubyte *) win->frontStart + (height-1) * win->rowStride;

   /* This is incorrect: the hardware driver could put the backbuffer
    * just about anywhere.  These fields, including the above are
    * hardware dependent & don't really belong here.
    */
   if (visual->mode->doubleBufferMode) {
      win->backStart = (GLubyte *) win->frontStart +
         win->rowStride * dpy->driverContext.shared.virtualHeight;
      win->backBottom = (GLubyte *) win->backStart
         + (height - 1) * win->rowStride;
      win->curBottom = win->backBottom;
   }
   else {
      /* single buffered */
      win->backStart = NULL;
      win->backBottom = NULL;
      win->curBottom = win->frontBottom;
   }

   win->driDrawable = dpy->driScreen->createDrawable(dpy->driScreen, 
                                                     width, height, 
                                                     dpy->clientID, visual->mode);

   if (!win->driDrawable) {
      fprintf(stderr, "%s: dri.createDrawable failed\n", __FUNCTION__);
      free(win);
      return NULL;
   }

   dpy->NumWindows++;
   dpy->TheWindow = win;

   return win; 
}


/**
 * \brief Destroy window.
 *
 * \param display display handle.
 * \param w window handle.
 *
 * This function calls XUnmapWindow() and frees window \p w.
 * 
 * In case of destroying the current buffer first unbinds the GLX context
 * by calling glXMakeCurrent() with no drawable.
 */
void
XDestroyWindow( Display *display, Window win )
{
   if (display && display->IsClient && win) {
      /* check if destroying the current buffer */
      Window curDraw = glXGetCurrentDrawable();
      if (win == curDraw) {
         glXMakeCurrent( display, NULL, NULL);
      }

      XUnmapWindow( display, win );

      /* Destroy the drawable. */
      (*win->driDrawable->destroyDrawable)(win->driDrawable);
      free(win);
      
      /* unlink window from display */
      display->NumWindows--;
      assert(display->NumWindows == 0);
      display->TheWindow = NULL;
   }
}




/**
 * \brief Create color map structure.
 *
 * \param dpy the display handle as returned by XOpenDisplay().
 * \param w the window on whose screen you want to create a color map. This
 * parameter is ignored by Mini GLX but should be the value returned by the
 * \code RootWindow(display, 0) \endcode macro.
 * \param visual a visual type supported on the screen. This parameter is
 * ignored by Mini GLX but should be the XVisualInfo::visual returned by
 * glXChooseVisual().
 * \param alloc the color map entries to be allocated. This parameter is ignored
 * by Mini GLX but should be set to #AllocNone.
 *
 * \return the color map.
 * 
 * This function is only provided to ease porting.  Practically a no-op -
 * returns a pointer to a dynamically allocated chunk of memory (one byte).
 */
Colormap
XCreateColormap( Display *dpy, Window w, Visual *visual, int alloc )
{
   (void) dpy;
   (void) w;
   (void) visual;
   (void) alloc;
   return (Colormap) malloc(1);
}


/**
 * \brief Destroy color map structure.
 *
 * \param display The display handle as returned by XOpenDisplay().
 * \param colormap the color map to destroy.
 *
 * This function is only provided to ease porting.  Practically a no-op. 
 *
 * Frees the memory pointed by \p colormap.
 */
void
XFreeColormap( Display *display, Colormap colormap )
{
   (void) display;
   (void) colormap;
   free(colormap);
}


/**
 * \brief Free client data.
 *
 * \param data the data that is to be freed.
 *
 * Frees the memory pointed by \p data.
 */
void
XFree( void *data )
{
   free(data);
}


/**
 * \brief Query available visuals.
 *
 * \param dpy the display handle, as returned by XOpenDisplay().
 * \param vinfo_mask a bitmask indicating which fields of the \p vinfo_template
 * are to be matched.  The value must be \c VisualScreenMask.
 * \param vinfo_template a template whose fields indicate which visual
 * attributes must be matched by the results.  The XVisualInfo::screen field of
 * this structure must be zero.
 * \param nitens_return will hold the number of visuals returned.
 *
 * \return the address of an array of all available visuals.
 * 
 * An example of using XGetVisualInfo() to get all available visuals follows:
 * 
 * \code
 * XVisualInfo vinfo_template, *results;
 * int nitens_return;
 * Display *dpy = XOpenDisplay(NULL);
 * vinfo_template.screen = 0;
 * results = XGetVisualInfo(dpy, VisualScreenMask, &vinfo_template, &nitens_return);
 * \endcode
 * 
 * Returns the list of all ::XVisualInfo available, one per
 * ::__GLcontextMode stored in MiniGLXDisplayRec::modes.
 */
XVisualInfo *
XGetVisualInfo( Display *dpy, long vinfo_mask, XVisualInfo *vinfo_template, int *nitens_return )
{
   XVisualInfo *results;
   Visual *visResults;
   int i, n;

   ASSERT(vinfo_mask == VisualScreenMask);
   ASSERT(vinfo_template.screen == 0);

   n = dpy->numModes;
   results = (XVisualInfo *)calloc(1, n * sizeof(XVisualInfo));
   if (!results) {
      *nitens_return = 0;
      return NULL;
   }

   visResults = (Visual *)calloc(1, n * sizeof(Visual));
   if (!results) {
      free(results);
      *nitens_return = 0;
      return NULL;
   }

   for (i = 0; i < n; i++) {
      visResults[i].mode = dpy->modes + i;
      visResults[i].visInfo = results + i;
      visResults[i].dpy = dpy;

      if (dpy->driverContext.bpp == 32)
         visResults[i].pixelFormat = PF_B8G8R8A8; /* XXX: FIX ME */
      else
         visResults[i].pixelFormat = PF_B5G6R5; /* XXX: FIX ME */

      results[i].visual = visResults + i;
      results[i].visualid = i;
      results[i].class = TrueColor;
      results[i].depth = dpy->modes[i].redBits +
                         dpy->modes[i].redBits +
                         dpy->modes[i].redBits +
                         dpy->modes[i].redBits;
      results[i].bits_per_rgb = dpy->driverContext.bpp;
   }
   *nitens_return = n;
   return results;
}


/**
 * \brief Return a visual that matches specified attributes.
 *
 * \param dpy the display handle, as returned by XOpenDisplay().
 * \param screen the screen number. It is currently ignored by Mini GLX and
 * should be zero.
 * \param attribList a list of GLX attributes which describe the desired pixel
 * format. It is terminated by the token \c None. 
 *
 * The attributes are as follows:
 * \arg GLX_USE_GL:
 * This attribute should always be present in order to maintain compatibility
 * with GLX.
 * \arg GLX_RGBA:
 * If present, only RGBA pixel formats will be considered. Otherwise, only
 * color index formats are considered.
 * \arg GLX_DOUBLEBUFFER:
 * if present, only double-buffered pixel formats will be chosen.
 * \arg GLX_RED_SIZE \e n:
 * Must be followed by a non-negative integer indicating the minimum number of
 * bits per red pixel component that is acceptable.
 * \arg GLX_GREEN_SIZE \e n:
 * Must be followed by a non-negative integer indicating the minimum number of
 * bits per green pixel component that is acceptable.
 * \arg GLX_BLUE_SIZE \e n:
 * Must be followed by a non-negative integer indicating the minimum number of
 * bits per blue pixel component that is acceptable.
 * \arg GLX_ALPHA_SIZE \e n:
 * Must be followed by a non-negative integer indicating the minimum number of
 * bits per alpha pixel component that is acceptable.
 * \arg GLX_STENCIL_SIZE \e n:
 * Must be followed by a non-negative integer indicating the minimum number of
 * bits per stencil value that is acceptable.
 * \arg GLX_DEPTH_SIZE \e n:
 * Must be followed by a non-negative integer indicating the minimum number of
 * bits per depth component that is acceptable.
 * \arg None:
 * This token is used to terminate the attribute list.
 *
 * \return a pointer to an #XVisualInfo object which most closely matches the
 * requirements of the attribute list. If there is no visual which matches the
 * request, \c NULL will be returned.
 *
 * \note Visuals with accumulation buffers are not available.
 *
 * This function searches the list of available visual configurations in
 * MiniGLXDisplayRec::configs for a configuration which best matches the GLX
 * attribute list parameter.  A new ::XVisualInfo object is created which
 * describes the visual configuration.  The match criteria is described in the
 * specification.
 */
XVisualInfo*
glXChooseVisual( Display *dpy, int screen, int *attribList )
{
   Visual *vis;
   XVisualInfo *visInfo;
   const int *attrib;
   GLboolean rgbFlag = GL_FALSE, dbFlag = GL_FALSE, stereoFlag = GL_FALSE;
   GLint redBits = 0, greenBits = 0, blueBits = 0, alphaBits = 0;
   GLint indexBits = 0, depthBits = 0, stencilBits = 0;
   GLint numSamples = 0;
   int i;

   /*
    * XXX in the future, <screen> might be interpreted as a VT
    */
   ASSERT(dpy);
   ASSERT(screen == 0);

   vis = (Visual *)calloc(1, sizeof(Visual));
   if (!vis)
      return NULL;

   visInfo = (XVisualInfo *)malloc(sizeof(XVisualInfo));
   if (!visInfo) {
      free(vis);
      return NULL;
   }

   visInfo->visual = vis;
   vis->visInfo = visInfo;
   vis->dpy = dpy;

   /* parse the attribute list */
   for (attrib = attribList; attrib && *attrib != None; attrib++) {
      switch (attrib[0]) {
      case GLX_DOUBLEBUFFER:
         dbFlag = GL_TRUE;
         break;
      case GLX_RGBA:
         rgbFlag = GL_TRUE;
         break;
      case GLX_RED_SIZE:
         redBits = attrib[1];
         attrib++;
         break;
      case GLX_GREEN_SIZE:
         redBits = attrib[1];
         attrib++;
         break;
      case GLX_BLUE_SIZE:
         redBits = attrib[1];
         attrib++;
         break;
      case GLX_ALPHA_SIZE:
         redBits = attrib[1];
         attrib++;
         break;
      case GLX_STENCIL_SIZE:
         stencilBits = attrib[1];
         attrib++;
         break;
      case GLX_DEPTH_SIZE:
         depthBits = attrib[1];
         attrib++;
         break;
#if 0
      case GLX_ACCUM_RED_SIZE:
         accumRedBits = attrib[1];
         attrib++;
         break;
      case GLX_ACCUM_GREEN_SIZE:
         accumGreenBits = attrib[1];
         attrib++;
         break;
      case GLX_ACCUM_BLUE_SIZE:
         accumBlueBits = attrib[1];
         attrib++;
         break;
      case GLX_ACCUM_ALPHA_SIZE:
         accumAlphaBits = attrib[1];
         attrib++;
         break;
      case GLX_LEVEL:
         /* ignored for now */
         break;
#endif
      default:
         /* unexpected token */
         fprintf(stderr, "unexpected token in glXChooseVisual attrib list\n");
         free(vis);
         free(visInfo);
         return NULL;
      }
   }

   /* search screen configs for suitable visual */
   (void) numSamples;
   (void) indexBits;
   (void) redBits;
   (void) greenBits;
   (void) blueBits;
   (void) alphaBits;
   (void) stereoFlag;
   for (i = 0; i < dpy->numModes; i++) {
      const __GLcontextModes *mode = dpy->modes + i;
      if (mode->rgbMode == rgbFlag &&
          mode->redBits >= redBits &&
          mode->greenBits >= greenBits &&
          mode->blueBits >= blueBits &&
          mode->alphaBits >= alphaBits &&
          mode->depthBits >= depthBits &&
          mode->stencilBits >= stencilBits) {
         /* found it */
         visInfo->visualid = i;
         vis->mode = mode;
         break;
      }          
   }
   if (!vis->mode)
       return NULL;

   /* compute depth and bpp */
   if (rgbFlag) {
      /* XXX maybe support depth 16 someday */
      visInfo->class = TrueColor;
      visInfo->depth = dpy->driverContext.bpp;
      visInfo->bits_per_rgb = dpy->driverContext.bpp;
      if (dpy->driverContext.bpp == 32)
         vis->pixelFormat = PF_B8G8R8A8;
      else
         vis->pixelFormat = PF_B5G6R5;
   }
   else {
      /* color index mode */
      visInfo->class = PseudoColor;
      visInfo->depth = 8;
      visInfo->bits_per_rgb = 8;  /* bits/pixel */
      vis->pixelFormat = PF_CI8;
   }

   return visInfo;
}


/**
 * \brief Return information about GLX visuals.
 *
 * \param dpy the display handle, as returned by XOpenDisplay().
 * \param vis the visual to be queried, as returned by glXChooseVisual().
 * \param attrib the visual attribute to be returned.
 * \param value pointer to an integer in which the result of the query will be
 * stored.
 * 
 * \return zero if no error occurs, \c GLX_INVALID_ATTRIBUTE if the attribute
 * parameter is invalid, or \c GLX_BAD_VISUAL if the \p vis parameter is
 * invalid.
 *
 * Returns the appropriate attribute of ::__GLXvisualConfig pointed by
 * MiniGLXVisualRec::glxConfig of XVisualInfo::visual.
 *
 * \sa data types.
 */
int
glXGetConfig( Display *dpy, XVisualInfo *vis, int attrib, int *value )
{
   const __GLcontextModes *mode = vis->visual->mode;
   if (!mode) {
      *value = 0;
      return GLX_BAD_VISUAL;
   }

   switch (attrib) {
   case GLX_USE_GL:
      *value = True;
      return 0;
   case GLX_RGBA:
      *value = mode->rgbMode;
      return 0;
   case GLX_DOUBLEBUFFER:
      *value = mode->doubleBufferMode;
      return 0;
   case GLX_RED_SIZE:
      *value = mode->redBits;
      return 0;
   case GLX_GREEN_SIZE:
      *value = mode->greenBits;
      return 0;
   case GLX_BLUE_SIZE:
      *value = mode->blueBits;
      return 0;
   case GLX_ALPHA_SIZE:
      *value = mode->alphaBits;
      return 0;
   case GLX_DEPTH_SIZE:
      *value = mode->depthBits;
      return 0;
   case GLX_STENCIL_SIZE:
      *value = mode->stencilBits;
      return 0;
   default:
      *value = 0;
      return GLX_BAD_ATTRIBUTE;
   }
   return 0;
}


/**
 * \brief Create a new GLX rendering context.
 *
 * \param dpy the display handle, as returned by XOpenDisplay().
 * \param vis the visual that defines the frame buffer resources available to
 * the rendering context, as returned by glXChooseVisual().
 * \param shareList If non-zero, texture objects and display lists are shared
 * with the named rendering context. If zero, texture objects and display lists
 * will (initially) be private to this context. They may be shared when a
 * subsequent context is created.
 * \param direct whether direct or indirect rendering is desired. For Mini GLX
 * this value is ignored but it should be set to \c True.
 *
 * \return a ::GLXContext handle if it succeeds or zero if it fails due to
 * invalid parameter or insufficient resources.
 *
 * This function creates and initializes a ::MiniGLXContextRec structure and
 * calls the __DRIscreenRec::createContext method to initialize the client
 * private data.
 */ 
GLXContext
glXCreateContext( Display *dpy, XVisualInfo *vis,
                        GLXContext shareList, Bool direct )
{
   GLXContext ctx;
   void *sharePriv;

   ASSERT(vis);

   ctx = (struct MiniGLXContextRec *)calloc(1, sizeof(struct MiniGLXContextRec));
   if (!ctx)
      return NULL;

   ctx->vid = vis->visualid;
 
   if (shareList)
      sharePriv = shareList->driContext;
   else
      sharePriv = NULL;
   
   ctx->driContext = (*dpy->driScreen->createContext)(dpy->driScreen, 
                                                      vis->visual->mode,
                                                      sharePriv);
   if (!ctx->driContext) {
      free(ctx);
      return NULL;
   }

   return ctx;
}


/**
 * \brief Destroy a GLX context.
 *
 * \param dpy the display handle, as returned by XOpenDisplay().
 * \param ctx the GLX context to be destroyed.
 * 
 * This function frees the \p ctx parameter after unbinding the current context
 * by calling the __DRIcontextRec::bindContext method with zeros and calling
 * the __DRIcontextRec::destroyContext method.
 */
void
glXDestroyContext( Display *dpy, GLXContext ctx )
{
   GLXContext glxctx = glXGetCurrentContext();

   if (ctx) {
      if (glxctx == ctx) {
         /* destroying current context */
         (*ctx->driContext->bindContext)(dpy->driScreen, 0, 0);
         CurrentContext = 0;
      }
      (*ctx->driContext->destroyContext)(ctx->driContext);
      free(ctx);
   }
}


/**
 * \brief Bind a GLX context to a window or a pixmap.
 *
 * \param dpy the display handle, as returned by XOpenDisplay().
 * \param drawable the window or drawable to bind to the rendering context.
 * This should be the value returned by XCreateWindow().
 * \param ctx the GLX context to be destroyed.
 *
 * \return \c True if it succeeds, \c False otherwise to indicate an invalid
 * display, window or context parameter.
 *
 * The current rendering context may be unbound by calling glXMakeCurrent()
 * with the window and context parameters set to zero.
 * 
 * An application may create any number of rendering contexts and bind them as
 * needed. Note that binding a rendering context is generally not a
 * light-weight operation.  Most simple OpenGL applications create only one
 * rendering context.
 *
 * This function first unbinds any old context via
 * __DRIcontextRec::unbindContext and binds the new one via
 * __DRIcontextRec::bindContext.
 *
 * If \p drawable is zero it unbinds the GLX context by calling
 * __DRIcontextRec::bindContext with zeros.
 */
Bool
glXMakeCurrent( Display *dpy, GLXDrawable drawable, GLXContext ctx)
{
   if (dpy && drawable && ctx) {
      GLXContext oldContext = glXGetCurrentContext();
      GLXDrawable oldDrawable = glXGetCurrentDrawable();
      /* unbind old */
      if (oldContext) {
         (*oldContext->driContext->unbindContext)(oldDrawable->driDrawable, oldContext->driContext);
      }
      /* bind new */
      CurrentContext = ctx;
      (*ctx->driContext->bindContext)(dpy->driScreen, drawable->driDrawable, ctx->driContext);
      ctx->drawBuffer = drawable;
      ctx->curBuffer = drawable;
   }
   else if (ctx && dpy) {
      /* unbind */
      (*ctx->driContext->bindContext)(dpy->driScreen, 0, 0);
   }
   else if (dpy) {
      CurrentContext = 0;       /* kw:  this seems to be intended??? */
   }

   return True;
}


/**
 * \brief Exchange front and back buffers.
 * 
 * \param dpy the display handle, as returned by XOpenDisplay().
 * \param drawable the drawable whose buffers are to be swapped.
 * 
 * Any pending rendering commands will be completed before the buffer swap
 * takes place.
 * 
 * Calling glXSwapBuffers() on a window which is single-buffered has no effect.
 *
 * This function just calls the __DRIdrawableRec::swapBuffers method to do the
 * work.
 */
void
glXSwapBuffers( Display *dpy, GLXDrawable drawable )
{
   if (!dpy || !drawable)
      return;

   (*drawable->driDrawable->swapBuffers)(drawable->driDrawable);
}


/**
 * \brief Return the current context
 *
 * \return the current context, as specified by glXMakeCurrent(), or zero if no
 * context is currently bound.
 *
 * \sa glXCreateContext(), glXMakeCurrent()
 *
 * Returns the value of the ::CurrentContext global variable.
 */
GLXContext
glXGetCurrentContext( void )
{
   return CurrentContext;
}


/**
 * \brief Return the current drawable.
 *
 * \return the current drawable, as specified by glXMakeCurrent(), or zero if
 * no drawable is currently bound.
 *
 * This function gets the current context via glXGetCurrentContext() and
 * returns the MiniGLXContextRec::drawBuffer attribute.
 */
GLXDrawable
glXGetCurrentDrawable( void )
{
   GLXContext glxctx = glXGetCurrentContext();
   if (glxctx)
      return glxctx->drawBuffer;
   else
      return NULL;
}


/**
 * \brief Query function address.
 *
 * The glXGetProcAddress() function will return the address of any available
 * OpenGL or Mini GLX function.
 * 
 * \param procName name of the function to be returned.
 *
 * \return If \p procName is a valid function name, a pointer to that function
 * will be returned.  Otherwise, \c NULL will be returned.
 *
 * The purpose of glXGetProcAddress() is to facilitate using future extensions
 * to OpenGL or Mini GLX. If a future version of the library adds new extension
 * functions they'll be accessible via glXGetProcAddress(). The alternative is
 * to hard-code calls to the new functions in the application but doing so will
 * prevent linking the application with older versions of the library.
 * 
 * Returns the function address by looking up its name in a static (name,
 * address) pair list.
 */
const void *
glXGetProcAddress( const GLubyte *procName )
{
   struct name_address {
      const char *name;
      const void *func;
   };
   static const struct name_address functions[] = {
      { "glXChooseVisual", (void *) glXChooseVisual },
      { "glXCreateContext", (void *) glXCreateContext },
      { "glXDestroyContext", (void *) glXDestroyContext },
      { "glXMakeCurrent", (void *) glXMakeCurrent },
      { "glXSwapBuffers", (void *) glXSwapBuffers },
      { "glXGetCurrentContext", (void *) glXGetCurrentContext },
      { "glXGetCurrentDrawable", (void *) glXGetCurrentDrawable },
      { "glXGetProcAddress", (void *) glXGetProcAddress },
      { "XOpenDisplay", (void *) XOpenDisplay },
      { "XCloseDisplay", (void *) XCloseDisplay },
      { "XCreateWindow", (void *) XCreateWindow },
      { "XDestroyWindow", (void *) XDestroyWindow },
      { "XMapWindow", (void *) XMapWindow },
      { "XCreateColormap", (void *) XCreateColormap },
      { "XFreeColormap", (void *) XFreeColormap },
      { "XFree", (void *) XFree },
      { "XGetVisualinfo", (void *) XGetVisualInfo },
      { NULL, NULL }
   };
   const struct name_address *entry;
   for (entry = functions; entry->name; entry++) {
      if (strcmp(entry->name, (const char *) procName) == 0) {
         return entry->func;
      }
   }
   return _glapi_get_proc_address((const char *) procName);
}


/**
 * \brief Query the Mini GLX version.
 *
 * \param dpy the display handle. It is currently ignored, but should be the
 * value returned by XOpenDisplay().
 * \param major receives the major version number of Mini GLX.
 * \param minor receives the minor version number of Mini GLX.
 *
 * \return \c True if the function succeeds, \c False if the function fails due
 * to invalid parameters.
 *
 * \sa #MINI_GLX_VERSION_1_0.
 * 
 * Returns the hard-coded Mini GLX version.
 */
Bool
glXQueryVersion( Display *dpy, int *major, int *minor )
{
   (void) dpy;
   *major = 1;
   *minor = 0;
   return True;
}


/*@}*/