/**************************************************************************
 *
 * Copyright 2008 VMware, Inc.
 * Copyright 2009-2010 Chia-I Wu <olvaffe@gmail.com>
 * Copyright 2010-2011 LunarG, Inc.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, 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 (including the
 * next paragraph) 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
 * THE AUTHORS OR COPYRIGHT HOLDERS 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.
 *
 **************************************************************************/


/**
 * Functions for choosing and opening/loading device drivers.
 */


#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include "c11/threads.h"

#include "egldefines.h"
#include "egldisplay.h"
#include "egldriver.h"
#include "egllog.h"

#include "util/debug.h"

static mtx_t _eglModuleMutex = _MTX_INITIALIZER_NP;
static _EGLDriver *_eglDriver;

static _EGLDriver *
_eglGetDriver(void)
{
   mtx_lock(&_eglModuleMutex);

   if (!_eglDriver) {
      _eglDriver = calloc(1, sizeof(*_eglDriver));
      if (!_eglDriver)
         return NULL;
      _eglInitDriverFallbacks(_eglDriver);
      _eglInitDriver(_eglDriver);
   }

   mtx_unlock(&_eglModuleMutex);

   return _eglDriver;
}

static _EGLDriver *
_eglMatchAndInitialize(_EGLDisplay *dpy)
{
   if (_eglGetDriver())
      if (_eglDriver->API.Initialize(_eglDriver, dpy))
         return _eglDriver;

   return NULL;
}

/**
 * Match a display to a driver.  The matching is done by finding the first
 * driver that can initialize the display.
 */
_EGLDriver *
_eglMatchDriver(_EGLDisplay *dpy)
{
   _EGLDriver *best_drv;

   assert(!dpy->Initialized);

   /* set options */
   dpy->Options.ForceSoftware =
      env_var_as_boolean("LIBGL_ALWAYS_SOFTWARE", false);

   best_drv = _eglMatchAndInitialize(dpy);
   if (!best_drv && !dpy->Options.ForceSoftware) {
      dpy->Options.ForceSoftware = EGL_TRUE;
      best_drv = _eglMatchAndInitialize(dpy);
   }

   if (best_drv) {
      _eglLog(_EGL_DEBUG, "the best driver is %s",
            best_drv->Name);
      dpy->Driver = best_drv;
      dpy->Initialized = EGL_TRUE;
   }

   return best_drv;
}

__eglMustCastToProperFunctionPointerType
_eglGetDriverProc(const char *procname)
{
   if (_eglGetDriver())
      return _eglDriver->API.GetProcAddress(_eglDriver, procname);

   return NULL;
}

/**
 * Unload all drivers.
 */
void
_eglUnloadDrivers(void)
{
   /* this is called at atexit time */
   free(_eglDriver);
   _eglDriver = NULL;
}