RetroArch/gfx/video_thread_wrapper.c

/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2010-2014 - Hans-Kristian Arntzen
 * 
 *  RetroArch is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with RetroArch.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

#include "video_thread_wrapper.h"
#include "../performance.h"
#include <stdlib.h>
#include <string.h>
#include <limits.h>


static void *thread_init_never_call(const video_info_t *video,
      const input_driver_t **input, void **input_data)
{
   (void)video;
   (void)input;
   (void)input_data;
   RARCH_ERR("Sanity check fail! Threaded mustn't be reinit.\n");
   abort();
   return NULL;
}

static void thread_reply(thread_video_t *thr, enum thread_cmd cmd)
{
   slock_lock(thr->lock);
   thr->reply_cmd = cmd;
   thr->send_cmd = CMD_NONE;
   scond_signal(thr->cond_cmd);
   slock_unlock(thr->lock);
}

static void thread_update_driver_state(thread_video_t *thr)
{
#if defined(HAVE_MENU)
   if (thr->texture.frame_updated)
   {
      if (thr->poke && thr->poke->set_texture_frame)
         thr->poke->set_texture_frame(thr->driver_data,
               thr->texture.frame, thr->texture.rgb32,
               thr->texture.width, thr->texture.height,
               thr->texture.alpha);
      thr->texture.frame_updated = false;
   }

   if (thr->poke && thr->poke->set_texture_enable)
      thr->poke->set_texture_enable(thr->driver_data,
            thr->texture.enable, thr->texture.full_screen);
#endif

#if defined(HAVE_OVERLAY)
   slock_lock(thr->alpha_lock);
   if (thr->alpha_update)
   {
      unsigned i;
      for (i = 0; i < thr->alpha_mods; i++)
      {
         if (thr->overlay && thr->overlay->set_alpha)
            thr->overlay->set_alpha(thr->driver_data, i, thr->alpha_mod[i]);
      }
      thr->alpha_update = false;
   }
   slock_unlock(thr->alpha_lock);
#endif

   if (thr->apply_state_changes)
   {
      if (thr->poke && thr->poke->apply_state_changes)
         thr->poke->apply_state_changes(thr->driver_data);
      thr->apply_state_changes = false;
   }
}

static void thread_loop(void *data)
{
   thread_video_t *thr = (thread_video_t*)data;
   unsigned i = 0;
   (void)i;

   for (;;)
   {
      bool ret = false;
      bool updated = false;
      slock_lock(thr->lock);
      while (thr->send_cmd == CMD_NONE && !thr->frame.updated)
         scond_wait(thr->cond_thread, thr->lock);
      if (thr->frame.updated)
         updated = true;

      /* To avoid race condition where send_cmd is updated 
       * right after the switch is checked. */

      enum thread_cmd send_cmd = thr->send_cmd;
      slock_unlock(thr->lock);

      switch (send_cmd)
      {
         case CMD_INIT:
            thr->driver_data = thr->driver->init(&thr->info,
                  thr->input, thr->input_data);
            thr->cmd_data.b = thr->driver_data;
            thr->driver->viewport_info(thr->driver_data, &thr->vp);
            thread_reply(thr, CMD_INIT);
            break;

         case CMD_FREE:
            if (thr->driver_data)
            {
               if (thr->driver && thr->driver->free)
                  thr->driver->free(thr->driver_data);
            }
            thr->driver_data = NULL;
            thread_reply(thr, CMD_FREE);
            return;

         case CMD_SET_ROTATION:
            if (thr->driver && thr->driver->set_rotation)
               thr->driver->set_rotation(thr->driver_data, thr->cmd_data.i);
            thread_reply(thr, CMD_SET_ROTATION);
            break;

         case CMD_READ_VIEWPORT:
         {
            struct rarch_viewport vp = {0};
            thr->driver->viewport_info(thr->driver_data, &vp);
            if (memcmp(&vp, &thr->read_vp, sizeof(vp)) == 0)
            {
               /* We can read safely
                *
                * read_viewport() in GL driver calls 
                * rarch_render_cached_frame() to be able to read from 
                * back buffer.
                *
                * This means frame() callback in threaded wrapper will 
                * be called from this thread, causing a timeout, and 
                * no frame to be rendered.
                *
                * To avoid this, set a flag so wrapper can see if 
                * it's called in this "special" way. */
               thr->frame.within_thread = true;

               if (thr->driver && thr->driver->read_viewport)
                  ret = thr->driver->read_viewport(thr->driver_data,
                        (uint8_t*)thr->cmd_data.v);

               thr->cmd_data.b = ret;
               thr->frame.within_thread = false;
               thread_reply(thr, CMD_READ_VIEWPORT);
            }
            else
            {
               /* Viewport dimensions changed right after main 
                * thread read the async value. Cannot read safely. */
               thr->cmd_data.b = false;
               thread_reply(thr, CMD_READ_VIEWPORT);
            }
            break;
         }
            
         case CMD_SET_SHADER:
            if (thr->driver && thr->driver->set_shader)
               ret = thr->driver->set_shader(thr->driver_data,
                        thr->cmd_data.set_shader.type,
                        thr->cmd_data.set_shader.path);

            thr->cmd_data.b = ret;
            thread_reply(thr, CMD_SET_SHADER);
            break;

         case CMD_ALIVE:
            if (thr->driver && thr->driver->alive)
               ret = thr->driver->alive(thr->driver_data);

            thr->cmd_data.b = ret;
            thread_reply(thr, CMD_ALIVE);
            break;

#ifdef HAVE_OVERLAY
         case CMD_OVERLAY_ENABLE:
            if (thr->overlay && thr->overlay->enable)
               thr->overlay->enable(thr->driver_data, thr->cmd_data.b);
            thread_reply(thr, CMD_OVERLAY_ENABLE);
            break;

         case CMD_OVERLAY_LOAD:

            if (thr->overlay && thr->overlay->load)
               ret = thr->overlay->load(thr->driver_data,
                     thr->cmd_data.image.data,
                     thr->cmd_data.image.num);

            thr->cmd_data.b = ret;
            thr->alpha_mods = thr->cmd_data.image.num;
            thr->alpha_mod = (float*)realloc(thr->alpha_mod,
                  thr->alpha_mods * sizeof(float));

            for (i = 0; i < thr->alpha_mods; i++)
            {
               /* Avoid temporary garbage data. */
               thr->alpha_mod[i] = 1.0f;
            }
            thread_reply(thr, CMD_OVERLAY_LOAD);

            break;

         case CMD_OVERLAY_TEX_GEOM:
            if (thr->overlay && thr->overlay->tex_geom)
               thr->overlay->tex_geom(thr->driver_data,
                     thr->cmd_data.rect.index,
                     thr->cmd_data.rect.x,
                     thr->cmd_data.rect.y,
                     thr->cmd_data.rect.w,
                     thr->cmd_data.rect.h);
            thread_reply(thr, CMD_OVERLAY_TEX_GEOM);
            break;

         case CMD_OVERLAY_VERTEX_GEOM:
            if (thr->overlay && thr->overlay->vertex_geom)
               thr->overlay->vertex_geom(thr->driver_data,
                     thr->cmd_data.rect.index,
                     thr->cmd_data.rect.x,
                     thr->cmd_data.rect.y,
                     thr->cmd_data.rect.w,
                     thr->cmd_data.rect.h);
            thread_reply(thr, CMD_OVERLAY_VERTEX_GEOM);
            break;

         case CMD_OVERLAY_FULL_SCREEN:
            if (thr->overlay && thr->overlay->full_screen)
               thr->overlay->full_screen(thr->driver_data,
                     thr->cmd_data.b);
            thread_reply(thr, CMD_OVERLAY_FULL_SCREEN);
            break;
#endif

         case CMD_POKE_SET_FILTERING:
            if (thr->poke && thr->poke->set_filtering)
               thr->poke->set_filtering(thr->driver_data,
                     thr->cmd_data.filtering.index,
                     thr->cmd_data.filtering.smooth);
            thread_reply(thr, CMD_POKE_SET_FILTERING);
            break;

         case CMD_POKE_SET_ASPECT_RATIO:
            thr->poke->set_aspect_ratio(thr->driver_data,
                  thr->cmd_data.i);
            thread_reply(thr, CMD_POKE_SET_ASPECT_RATIO);
            break;

         case CMD_POKE_SET_OSD_MSG:
            if (thr->poke && thr->poke->set_osd_msg)
               thr->poke->set_osd_msg(thr->driver_data,
                     thr->cmd_data.osd_message.msg,
                     &thr->cmd_data.osd_message.params);
            thread_reply(thr, CMD_POKE_SET_OSD_MSG);
            break;

         case CMD_CUSTOM_COMMAND:
            if (thr->cmd_data.custom_command.method)
               thr->cmd_data.custom_command.return_value =
                     thr->cmd_data.custom_command.method
                     (thr->cmd_data.custom_command.data);
            thread_reply(thr, CMD_CUSTOM_COMMAND);
            break;

         case CMD_NONE:
            /* Never reply on no command. Possible deadlock if 
             * thread sends command right after frame update. */
            break;

         default:
            thread_reply(thr, send_cmd);
            break;
      }

      if (updated)
      {
         slock_lock(thr->frame.lock);

         thread_update_driver_state(thr);
         bool ret = false;
         bool alive = false;
         bool focus = false;
         struct rarch_viewport vp = {0};
         
         thr->frame.within_thread = true;
         if (thr->driver && thr->driver->frame)
            ret = thr->driver->frame(thr->driver_data,
               thr->frame.buffer, thr->frame.width, thr->frame.height,
               thr->frame.pitch, *thr->frame.msg ? thr->frame.msg : NULL);
         thr->frame.within_thread = false;

         slock_unlock(thr->frame.lock);

         if (thr->driver && thr->driver->alive)
            alive = ret && thr->driver->alive(thr->driver_data);

         if (thr->driver && thr->driver->focus)
            focus = ret && thr->driver->focus(thr->driver_data);

         if (thr->driver && thr->driver->viewport_info)
            thr->driver->viewport_info(thr->driver_data, &vp);

         slock_lock(thr->lock);
         thr->alive = alive;
         thr->focus = focus;
         thr->frame.updated = false;
         thr->vp = vp;
         scond_signal(thr->cond_cmd);
         slock_unlock(thr->lock);
      }
   }
}

static void thread_send_cmd(thread_video_t *thr, enum thread_cmd cmd)
{
   slock_lock(thr->lock);
   thr->send_cmd = cmd;
   thr->reply_cmd = CMD_NONE;
   scond_signal(thr->cond_thread);
   slock_unlock(thr->lock);
}

static void thread_wait_reply(thread_video_t *thr, enum thread_cmd cmd)
{
   slock_lock(thr->lock);
   while (cmd != thr->reply_cmd)
      scond_wait(thr->cond_cmd, thr->lock);
   slock_unlock(thr->lock);
}

static bool thread_alive(void *data)
{
   thread_video_t *thr = (thread_video_t*)data;
   if (g_extern.is_paused)
   {
      thread_send_cmd(thr, CMD_ALIVE);
      thread_wait_reply(thr, CMD_ALIVE);
      return thr->cmd_data.b;
   }
   else
   {
      slock_lock(thr->lock);
      bool ret = thr->alive;
      slock_unlock(thr->lock);
      return ret;
   }
}

static bool thread_focus(void *data)
{
   thread_video_t *thr = (thread_video_t*)data;
   slock_lock(thr->lock);
   bool ret = thr->focus;
   slock_unlock(thr->lock);
   return ret;
}

static bool thread_frame(void *data, const void *frame_,
      unsigned width, unsigned height, unsigned pitch, const char *msg)
{
   thread_video_t *thr = (thread_video_t*)data;

   /* If called from within read_viewport, we're actually in the 
    * driver thread, so just render directly. */
   if (thr->frame.within_thread)
   {
      thread_update_driver_state(thr);

      if (thr->driver && thr->driver->frame)
         return thr->driver->frame(thr->driver_data, frame_,
               width, height, pitch, msg);
      return false;
   }

   RARCH_PERFORMANCE_INIT(thread_frame);
   RARCH_PERFORMANCE_START(thread_frame);

   unsigned copy_stride = width * (thr->info.rgb32 ?
         sizeof(uint32_t) : sizeof(uint16_t));

   const uint8_t *src = (const uint8_t*)frame_;
   uint8_t *dst = thr->frame.buffer;

   slock_lock(thr->lock);

   if (!thr->nonblock)
   {
      retro_time_t target_frame_time = (retro_time_t)
         roundf(1000000LL / g_settings.video.refresh_rate);
      retro_time_t target = thr->last_time + target_frame_time;

      /* Ideally, use absolute time, but that is only a good idea on POSIX. */
      while (thr->frame.updated)
      {
         retro_time_t current = rarch_get_time_usec();
         retro_time_t delta = target - current;

         if (delta <= 0)
            break;

         if (!scond_wait_timeout(thr->cond_cmd, thr->lock, delta))
            break;
      }
   }

   /* Drop frame if updated flag is still set, as thread is 
    * still working on last frame. */
   if (!thr->frame.updated)
   {
      if (src)
      {
         unsigned h;
         for (h = 0; h < height; h++, src += pitch, dst += copy_stride)
            memcpy(dst, src, copy_stride);
      }

      thr->frame.updated = true;
      thr->frame.width  = width;
      thr->frame.height = height;
      thr->frame.pitch  = copy_stride;

      if (msg)
         strlcpy(thr->frame.msg, msg, sizeof(thr->frame.msg));
      else
         *thr->frame.msg = '\0';

      scond_signal(thr->cond_thread);

#if defined(HAVE_MENU)
      if (thr->texture.enable)
      {
         while (thr->frame.updated)
            scond_wait(thr->cond_cmd, thr->lock);
      }
#endif
      thr->hit_count++;
   }
   else
      thr->miss_count++;

   slock_unlock(thr->lock);

   RARCH_PERFORMANCE_STOP(thread_frame);

   thr->last_time = rarch_get_time_usec();
   return true;
}

static void thread_set_nonblock_state(void *data, bool state)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->nonblock = state;
}

static bool thread_init(thread_video_t *thr, const video_info_t *info,
      const input_driver_t **input, void **input_data)
{
   thr->lock = slock_new();
   thr->alpha_lock = slock_new();
   thr->frame.lock = slock_new();
   thr->cond_cmd = scond_new();
   thr->cond_thread = scond_new();
   thr->input = input;
   thr->input_data = input_data;
   thr->info = *info;
   thr->alive = true;
   thr->focus = true;

   size_t max_size = info->input_scale * RARCH_SCALE_BASE;
   max_size *= max_size;
   max_size *= info->rgb32 ? sizeof(uint32_t) : sizeof(uint16_t);
   thr->frame.buffer = (uint8_t*)malloc(max_size);
   if (!thr->frame.buffer)
      return false;

   memset(thr->frame.buffer, 0x80, max_size);

   thr->last_time = rarch_get_time_usec();

   thr->thread = sthread_create(thread_loop, thr);
   if (!thr->thread)
      return false;
   thread_send_cmd(thr, CMD_INIT);
   thread_wait_reply(thr, CMD_INIT);

   thr->send_cmd_func = thread_send_cmd;
   thr->wait_reply_func = thread_wait_reply;

   return thr->cmd_data.b;
}

static bool thread_set_shader(void *data,
      enum rarch_shader_type type, const char *path)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.set_shader.type = type;
   thr->cmd_data.set_shader.path = path;
   thread_send_cmd(thr, CMD_SET_SHADER);
   thread_wait_reply(thr, CMD_SET_SHADER);
   return thr->cmd_data.b;
}

static void thread_set_rotation(void *data, unsigned rotation)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.i = rotation;
   thread_send_cmd(thr, CMD_SET_ROTATION);
   thread_wait_reply(thr, CMD_SET_ROTATION);
}

/* This value is set async as stalling on the video driver for 
 * every query is too slow.
 *
 * This means this value might not be correct, so viewport 
 * reads are not supported for now. */
static void thread_viewport_info(void *data, struct rarch_viewport *vp)
{
   thread_video_t *thr = (thread_video_t*)data;
   slock_lock(thr->lock);
   *vp = thr->vp;

   /* Explicitly mem-copied so we can use memcmp correctly later. */
   memcpy(&thr->read_vp, &thr->vp, sizeof(thr->vp));
   slock_unlock(thr->lock);
}

static bool thread_read_viewport(void *data, uint8_t *buffer)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.v = buffer;
   thread_send_cmd(thr, CMD_READ_VIEWPORT);
   thread_wait_reply(thr, CMD_READ_VIEWPORT);
   return thr->cmd_data.b;
}

static void thread_free(void *data)
{
   thread_video_t *thr = (thread_video_t*)data;
   if (!thr)
      return;

   thread_send_cmd(thr, CMD_FREE);
   thread_wait_reply(thr, CMD_FREE);
   sthread_join(thr->thread);

#if defined(HAVE_MENU)
   free(thr->texture.frame);
#endif
   free(thr->frame.buffer);
   slock_free(thr->frame.lock);
   slock_free(thr->lock);
   scond_free(thr->cond_cmd);
   scond_free(thr->cond_thread);

   free(thr->alpha_mod);
   slock_free(thr->alpha_lock);

   RARCH_LOG("Threaded video stats: Frames pushed: %u, Frames dropped: %u.\n",
         thr->hit_count, thr->miss_count);

   free(thr);
}

#ifdef HAVE_OVERLAY
static void thread_overlay_enable(void *data, bool state)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.b = state;
   thread_send_cmd(thr, CMD_OVERLAY_ENABLE);
   thread_wait_reply(thr, CMD_OVERLAY_ENABLE);
}

static bool thread_overlay_load(void *data,
      const struct texture_image *images, unsigned num_images)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.image.data = images;
   thr->cmd_data.image.num = num_images;
   thread_send_cmd(thr, CMD_OVERLAY_LOAD);
   thread_wait_reply(thr, CMD_OVERLAY_LOAD);
   return thr->cmd_data.b;
}

static void thread_overlay_tex_geom(void *data,
      unsigned index, float x, float y, float w, float h)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.rect.index = index;
   thr->cmd_data.rect.x = x;
   thr->cmd_data.rect.y = y;
   thr->cmd_data.rect.w = w;
   thr->cmd_data.rect.h = h;
   thread_send_cmd(thr, CMD_OVERLAY_TEX_GEOM);
   thread_wait_reply(thr, CMD_OVERLAY_TEX_GEOM);
}

static void thread_overlay_vertex_geom(void *data,
      unsigned index, float x, float y, float w, float h)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.rect.index = index;
   thr->cmd_data.rect.x = x;
   thr->cmd_data.rect.y = y;
   thr->cmd_data.rect.w = w;
   thr->cmd_data.rect.h = h;
   thread_send_cmd(thr, CMD_OVERLAY_VERTEX_GEOM);
   thread_wait_reply(thr, CMD_OVERLAY_VERTEX_GEOM);
}

static void thread_overlay_full_screen(void *data, bool enable)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.b = enable;
   thread_send_cmd(thr, CMD_OVERLAY_FULL_SCREEN);
   thread_wait_reply(thr, CMD_OVERLAY_FULL_SCREEN);
}

/* We cannot wait for this to complete. Totally blocks the main thread. */
static void thread_overlay_set_alpha(void *data, unsigned index, float mod)
{
   thread_video_t *thr = (thread_video_t*)data;
   slock_lock(thr->alpha_lock);
   thr->alpha_mod[index] = mod;
   thr->alpha_update = true;
   slock_unlock(thr->alpha_lock);
}

static const video_overlay_interface_t thread_overlay = {
   thread_overlay_enable,
   thread_overlay_load,
   thread_overlay_tex_geom,
   thread_overlay_vertex_geom,
   thread_overlay_full_screen,
   thread_overlay_set_alpha,
};

static void thread_get_overlay_interface(void *data,
      const video_overlay_interface_t **iface)
{
   thread_video_t *thr = (thread_video_t*)data;
   *iface = &thread_overlay;
   thr->driver->overlay_interface(thr->driver_data, &thr->overlay);
}
#endif

static void thread_set_filtering(void *data, unsigned index, bool smooth)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.filtering.index = index;
   thr->cmd_data.filtering.smooth = smooth;
   thread_send_cmd(thr, CMD_POKE_SET_FILTERING);
   thread_wait_reply(thr, CMD_POKE_SET_FILTERING);
}

static void thread_set_aspect_ratio(void *data, unsigned aspectratio_index)
{
   thread_video_t *thr = (thread_video_t*)data;
   thr->cmd_data.i = aspectratio_index;
   thread_send_cmd(thr, CMD_POKE_SET_ASPECT_RATIO);
   thread_wait_reply(thr, CMD_POKE_SET_ASPECT_RATIO);
}

#if defined(HAVE_MENU)
static void thread_set_texture_frame(void *data, const void *frame,
      bool rgb32, unsigned width, unsigned height, float alpha)
{
   thread_video_t *thr = (thread_video_t*)data;

   slock_lock(thr->frame.lock);
   size_t required = width * height * 
      (rgb32 ? sizeof(uint32_t) : sizeof(uint16_t));

   if (required > thr->texture.frame_cap)
   {
      thr->texture.frame = realloc(thr->texture.frame, required);
      thr->texture.frame_cap = required;
   }

   if (thr->texture.frame)
   {
      memcpy(thr->texture.frame, frame, required);
      thr->texture.frame_updated = true;
      thr->texture.rgb32  = rgb32;
      thr->texture.width  = width;
      thr->texture.height = height;
      thr->texture.alpha  = alpha;
   }
   slock_unlock(thr->frame.lock);
}

static void thread_set_texture_enable(void *data, bool state, bool full_screen)
{
   thread_video_t *thr = (thread_video_t*)data;

   slock_lock(thr->frame.lock);
   thr->texture.enable = state;
   thr->texture.full_screen = full_screen;
   slock_unlock(thr->frame.lock);
}
#endif

static void thread_set_osd_msg(void *data, const char *msg, const struct font_params *params)
{
   thread_video_t *thr = (thread_video_t*)data;
   if (thr->frame.within_thread)
   {
      if (thr->poke && thr->poke->set_osd_msg)
         thr->poke->set_osd_msg(thr->driver_data, msg, params);
   }
   else
   {
      strncpy(thr->cmd_data.osd_message.msg, msg, sizeof(thr->cmd_data.osd_message.msg));
      thr->cmd_data.osd_message.params = *params;
      thread_send_cmd(thr, CMD_POKE_SET_OSD_MSG);
      thread_wait_reply(thr, CMD_POKE_SET_OSD_MSG);
   }
}

static void thread_apply_state_changes(void *data)
{
   thread_video_t *thr = (thread_video_t*)data;
   slock_lock(thr->frame.lock);
   thr->apply_state_changes = true;
   slock_unlock(thr->frame.lock);
}

/* This is read-only state which should not 
 * have any kind of race condition. */
static struct gfx_shader *thread_get_current_shader(void *data)
{
   thread_video_t *thr = (thread_video_t*)data;
   return thr->poke ? thr->poke->get_current_shader(thr->driver_data) : NULL;
}

static const video_poke_interface_t thread_poke = {
   thread_set_filtering,
#ifdef HAVE_FBO
   NULL,
   NULL,
#endif
   thread_set_aspect_ratio,
   thread_apply_state_changes,
#if defined(HAVE_MENU)
   thread_set_texture_frame,
   thread_set_texture_enable,
#endif

   thread_set_osd_msg,
   NULL,
   NULL,

   thread_get_current_shader,
};

static void thread_get_poke_interface(void *data,
      const video_poke_interface_t **iface)
{
   thread_video_t *thr = (thread_video_t*)data;

   if (thr->driver->poke_interface)
   {
      *iface = &thread_poke;
      thr->driver->poke_interface(thr->driver_data, &thr->poke);
   }
   else
      *iface = NULL;
}

static const video_driver_t video_thread = {
   thread_init_never_call, /* Should never be called directly. */
   thread_frame,
   thread_set_nonblock_state,
   thread_alive,
   thread_focus,
   thread_set_shader,
   thread_free,
   "Thread wrapper",
   thread_set_rotation,
   thread_viewport_info,
   thread_read_viewport,
#ifdef HAVE_OVERLAY
   thread_get_overlay_interface, /* get_overlay_interface */
#endif
   thread_get_poke_interface,
};

static void thread_set_callbacks(thread_video_t *thr,
      const video_driver_t *driver)
{
   thr->video_thread = video_thread;

   /* Disable optional features if not present. */
   if (!driver->read_viewport)
      thr->video_thread.read_viewport = NULL;
   if (!driver->set_rotation)
      thr->video_thread.set_rotation = NULL;
   if (!driver->set_shader)
      thr->video_thread.set_shader = NULL;
#ifdef HAVE_OVERLAY
   if (!driver->overlay_interface)
      thr->video_thread.overlay_interface = NULL;
#endif

   /* Might have to optionally disable poke_interface features as well. */
   if (!thr->video_thread.poke_interface)
      thr->video_thread.poke_interface = NULL;
}

bool rarch_threaded_video_init(const video_driver_t **out_driver,
      void **out_data,  const input_driver_t **input, void **input_data,
      const video_driver_t *driver, const video_info_t *info)
{
   thread_video_t *thr = (thread_video_t*)calloc(1, sizeof(*thr));
   if (!thr)
      return false;

   thread_set_callbacks(thr, driver);

   thr->driver = driver;
   *out_driver = &thr->video_thread;
   *out_data   = thr;
   return thread_init(thr, info, input, input_data);
}

void *rarch_threaded_video_resolve(const video_driver_t **drv)
{
   const thread_video_t *thr = (const thread_video_t*)driver.video_data;

   if (drv)
      *drv = thr->driver;

   return thr->driver_data;
}