/*  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 "dynamic.h"
#include "general.h"
#include "compat/strl.h"
#include "compat/posix_string.h"
#include "retroarch_logger.h"
#include "performance.h"
#include "file.h"
#include <string.h>
#include <ctype.h>

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "boolean.h"
#include "libretro_private.h"
#include "dynamic_dummy.h"

#ifdef NEED_DYNAMIC
#ifdef _WIN32
#include <windows.h>
#else
#include <dlfcn.h>
#endif
#endif

#ifdef HAVE_DYNAMIC
#undef SYM
#define SYM(x) do { \
   function_t func = dylib_proc(lib_handle, #x); \
   memcpy(&p##x, &func, sizeof(func)); \
   if (p##x == NULL) { RARCH_ERR("Failed to load symbol: \"%s\"\n", #x); rarch_fail(1, "init_libretro_sym()"); } \
} while (0)

static dylib_t lib_handle;
#else
#define SYM(x) p##x = x
#endif

#define SYM_DUMMY(x) p##x = libretro_dummy_##x

void (*pretro_init)(void);
void (*pretro_deinit)(void);

unsigned (*pretro_api_version)(void);

void (*pretro_get_system_info)(struct retro_system_info*);
void (*pretro_get_system_av_info)(struct retro_system_av_info*);

void (*pretro_set_environment)(retro_environment_t);
void (*pretro_set_video_refresh)(retro_video_refresh_t);
void (*pretro_set_audio_sample)(retro_audio_sample_t);
void (*pretro_set_audio_sample_batch)(retro_audio_sample_batch_t);
void (*pretro_set_input_poll)(retro_input_poll_t);
void (*pretro_set_input_state)(retro_input_state_t);

void (*pretro_set_controller_port_device)(unsigned, unsigned);

void (*pretro_reset)(void);
void (*pretro_run)(void);

size_t (*pretro_serialize_size)(void);
bool (*pretro_serialize)(void*, size_t);
bool (*pretro_unserialize)(const void*, size_t);

void (*pretro_cheat_reset)(void);
void (*pretro_cheat_set)(unsigned, bool, const char*);

bool (*pretro_load_game)(const struct retro_game_info*);
bool (*pretro_load_game_special)(unsigned, const struct retro_game_info*, size_t);

void (*pretro_unload_game)(void);

unsigned (*pretro_get_region)(void);

void *(*pretro_get_memory_data)(unsigned);
size_t (*pretro_get_memory_size)(unsigned);

#ifdef HAVE_DYNAMIC
#if defined(__APPLE__)
#define DYNAMIC_EXT "dylib"
#elif defined(_WIN32)
#define DYNAMIC_EXT "dll"
#else
#define DYNAMIC_EXT "so"
#endif

static bool *load_no_content_hook;
static bool environ_cb_get_system_info(unsigned cmd, void *data)
{
   switch (cmd)
   {
      case RETRO_ENVIRONMENT_SET_SUPPORT_NO_GAME:
         *load_no_content_hook = *(const bool*)data;
         break;

      default:
         return false;
   }

   return true;
}

void libretro_get_environment_info(void (*func)(retro_environment_t), bool *load_no_content)
{
   load_no_content_hook = load_no_content;

   // load_no_content gets set in this callback.
   func(environ_cb_get_system_info);
}

static dylib_t libretro_get_system_info_lib(const char *path, struct retro_system_info *info, bool *load_no_content)
{
   dylib_t lib = dylib_load(path);
   if (!lib)
      return NULL;

   void (*proc)(struct retro_system_info*) =
      (void (*)(struct retro_system_info*))dylib_proc(lib, "retro_get_system_info");

   if (!proc)
   {
      dylib_close(lib);
      return NULL;
   }

   proc(info);

   if (load_no_content)
   {
      *load_no_content = false;
      void (*set_environ)(retro_environment_t) =
         (void (*)(retro_environment_t))dylib_proc(lib, "retro_set_environment");

      if (!set_environ)
         return lib;

      libretro_get_environment_info(set_environ, load_no_content);
   }

   return lib;
}

bool libretro_get_system_info(const char *path, struct retro_system_info *info,
   bool *load_no_content)
{
   struct retro_system_info dummy_info = {0};
   dylib_t lib = libretro_get_system_info_lib(path, &dummy_info, load_no_content);
   if (!lib)
      return false;

   memcpy(info, &dummy_info, sizeof(*info));
   info->library_name    = strdup(dummy_info.library_name);
   info->library_version = strdup(dummy_info.library_version);
   if (dummy_info.valid_extensions)
      info->valid_extensions = strdup(dummy_info.valid_extensions);
   dylib_close(lib);
   return true;
}

void libretro_free_system_info(struct retro_system_info *info)
{
   free((void*)info->library_name);
   free((void*)info->library_version);
   free((void*)info->valid_extensions);
   memset(info, 0, sizeof(*info));
}

#endif

const struct retro_subsystem_info *libretro_find_subsystem_info(const struct retro_subsystem_info *info, unsigned num_info,
      const char *ident)
{
   unsigned i;
   for (i = 0; i < num_info; i++)
   {
      if (!strcmp(info[i].ident, ident))
         return &info[i];
      else if (!strcmp(info[i].desc, ident)) // Doesn't hurt
         return &info[i];
   }

   return NULL;
}

const struct retro_controller_description *libretro_find_controller_description(const struct retro_controller_info *info, unsigned id)
{
   unsigned i;
   for (i = 0; i < info->num_types; i++)
   {
      if (info->types[i].id == id)
         return &info->types[i];
   }

   return NULL;
}

static void load_symbols(bool is_dummy)
{
   if (is_dummy)
   {
      SYM_DUMMY(retro_init);
      SYM_DUMMY(retro_deinit);

      SYM_DUMMY(retro_api_version);
      SYM_DUMMY(retro_get_system_info);
      SYM_DUMMY(retro_get_system_av_info);

      SYM_DUMMY(retro_set_environment);
      SYM_DUMMY(retro_set_video_refresh);
      SYM_DUMMY(retro_set_audio_sample);
      SYM_DUMMY(retro_set_audio_sample_batch);
      SYM_DUMMY(retro_set_input_poll);
      SYM_DUMMY(retro_set_input_state);

      SYM_DUMMY(retro_set_controller_port_device);

      SYM_DUMMY(retro_reset);
      SYM_DUMMY(retro_run);

      SYM_DUMMY(retro_serialize_size);
      SYM_DUMMY(retro_serialize);
      SYM_DUMMY(retro_unserialize);

      SYM_DUMMY(retro_cheat_reset);
      SYM_DUMMY(retro_cheat_set);

      SYM_DUMMY(retro_load_game);
      SYM_DUMMY(retro_load_game_special);

      SYM_DUMMY(retro_unload_game);
      SYM_DUMMY(retro_get_region);
      SYM_DUMMY(retro_get_memory_data);
      SYM_DUMMY(retro_get_memory_size);
   }
   else
   {
#ifdef HAVE_DYNAMIC
      // Need to use absolute path for this setting. It can be saved to content history,
      // and a relative path would break in that scenario.
      path_resolve_realpath(g_settings.libretro, sizeof(g_settings.libretro));

      RARCH_LOG("Loading dynamic libretro from: \"%s\"\n", g_settings.libretro);
      lib_handle = dylib_load(g_settings.libretro);
      if (!lib_handle)
      {
         RARCH_ERR("Failed to open dynamic library: \"%s\"\n", g_settings.libretro);
         rarch_fail(1, "load_dynamic()");
      }
#endif

      SYM(retro_init);
      SYM(retro_deinit);

      SYM(retro_api_version);
      SYM(retro_get_system_info);
      SYM(retro_get_system_av_info);

      SYM(retro_set_environment);
      SYM(retro_set_video_refresh);
      SYM(retro_set_audio_sample);
      SYM(retro_set_audio_sample_batch);
      SYM(retro_set_input_poll);
      SYM(retro_set_input_state);

      SYM(retro_set_controller_port_device);

      SYM(retro_reset);
      SYM(retro_run);

      SYM(retro_serialize_size);
      SYM(retro_serialize);
      SYM(retro_unserialize);

      SYM(retro_cheat_reset);
      SYM(retro_cheat_set);

      SYM(retro_load_game);
      SYM(retro_load_game_special);

      SYM(retro_unload_game);
      SYM(retro_get_region);
      SYM(retro_get_memory_data);
      SYM(retro_get_memory_size);
   }
}

void libretro_get_current_core_pathname(char *name, size_t size)
{
   size_t i;
   if (size == 0)
      return;

   struct retro_system_info info = {0};
   pretro_get_system_info(&info);
   const char *id = info.library_name ? info.library_name : "Unknown";

   if (!id || strlen(id) >= size)
   {
      name[0] = '\0';
      return;
   }

   name[strlen(id)] = '\0';

   for (i = 0; id[i] != '\0'; i++)
   {
      char c = id[i];
      if (isspace(c) || isblank(c))
         name[i] = '_';
      else
         name[i] = tolower(c);
   }
}

void init_libretro_sym(bool dummy)
{
   // Guarantee that we can do "dirty" casting.
   // Every OS that this program supports should pass this ...
   rarch_assert(sizeof(void*) == sizeof(void (*)(void)));

   if (!dummy)
   {
#ifdef HAVE_DYNAMIC
      // Try to verify that -lretro was not linked in from other modules
      // since loading it dynamically and with -l will fail hard.
      function_t sym = dylib_proc(NULL, "retro_init");
      if (sym)
      {
         RARCH_ERR("Serious problem. RetroArch wants to load libretro dyamically, but it is already linked.\n");
         RARCH_ERR("This could happen if other modules RetroArch depends on link against libretro directly.\n");
         RARCH_ERR("Proceeding could cause a crash. Aborting ...\n");
         rarch_fail(1, "init_libretro_sym()");
      }

      if (!*g_settings.libretro)
      {
         RARCH_ERR("RetroArch is built for dynamic libretro, but libretro_path is not set. Cannot continue.\n");
         rarch_fail(1, "init_libretro_sym()");
      }
#endif
   }

   load_symbols(dummy);

   pretro_set_environment(rarch_environment_cb);
}

void uninit_libretro_sym(void)
{
#ifdef HAVE_DYNAMIC
   if (lib_handle)
      dylib_close(lib_handle);
   lib_handle = NULL;
#endif

   if (g_extern.system.core_options)
   {
      core_option_flush(g_extern.system.core_options);
      core_option_free(g_extern.system.core_options);
   }

   // No longer valid.
   free(g_extern.system.special);
   free(g_extern.system.ports);
   memset(&g_extern.system, 0, sizeof(g_extern.system));
   g_extern.camera_active = false;
   g_extern.location_active = false;

   // Performance counters no longer valid.
   retro_perf_clear();
}

#ifdef NEED_DYNAMIC
// Platform independent dylib loading.
dylib_t dylib_load(const char *path)
{
#ifdef _WIN32
   dylib_t lib = LoadLibrary(path);
   if (!lib)
      RARCH_ERR("Failed to load library, error code: 0x%x\n", (unsigned)GetLastError());
   return lib;
#else
   dylib_t lib = dlopen(path, RTLD_LAZY);
   if (!lib)
      RARCH_ERR("dylib_load() failed: \"%s\".\n", dlerror());
   return lib;
#endif
}

function_t dylib_proc(dylib_t lib, const char *proc)
{
#ifdef _WIN32
   function_t sym = (function_t)GetProcAddress(lib ? (HMODULE)lib : GetModuleHandle(NULL), proc);
#else
   void *ptr_sym = NULL;
   if (lib)
      ptr_sym = dlsym(lib, proc);
   else
   {
      void *handle = dlopen(NULL, RTLD_LAZY);
      if (handle)
      {
         ptr_sym = dlsym(handle, proc);
         dlclose(handle);
      }
   }

   // Dirty hack to workaround the non-legality of (void*) -> fn-pointer casts.
   function_t sym;
   memcpy(&sym, &ptr_sym, sizeof(void*));
#endif

   return sym;
}

void dylib_close(dylib_t lib)
{
#ifdef _WIN32
   FreeLibrary((HMODULE)lib);
#else
   dlclose(lib);
#endif
}
#endif

static void rarch_log_libretro(enum retro_log_level level, const char *fmt, ...)
{
   if ((unsigned)level < g_settings.libretro_log_level)
      return;

   va_list vp;
   va_start(vp, fmt);

   switch (level)
   {
      case RETRO_LOG_DEBUG:
         RARCH_LOG_V("[libretro DEBUG] :: ", fmt, vp);
         break;

      case RETRO_LOG_INFO:
         RARCH_LOG_OUTPUT_V("[libretro INFO] :: ", fmt, vp);
         break;

      case RETRO_LOG_WARN:
         RARCH_WARN_V("[libretro WARN] :: ", fmt, vp);
         break;

      case RETRO_LOG_ERROR:
         RARCH_ERR_V("[libretro ERROR] :: ", fmt, vp);
         break;

      default:
         break;
   }

   va_end(vp);
}

bool rarch_environment_cb(unsigned cmd, void *data)
{
   unsigned p, id;
   switch (cmd)
   {
      case RETRO_ENVIRONMENT_GET_OVERSCAN:
         *(bool*)data = !g_settings.video.crop_overscan;
         RARCH_LOG("Environ GET_OVERSCAN: %u\n", (unsigned)!g_settings.video.crop_overscan);
         break;

      case RETRO_ENVIRONMENT_GET_CAN_DUPE:
         *(bool*)data = true;
         RARCH_LOG("Environ GET_CAN_DUPE: true\n");
         break;

      case RETRO_ENVIRONMENT_GET_VARIABLE:
      {
         struct retro_variable *var = (struct retro_variable*)data;
         RARCH_LOG("Environ GET_VARIABLE %s:\n", var->key);

         if (g_extern.system.core_options)
            core_option_get(g_extern.system.core_options, var);
         else
            var->value = NULL;

         RARCH_LOG("\t%s\n", var->value ? var->value : "N/A");
         break;
      }

      case RETRO_ENVIRONMENT_GET_VARIABLE_UPDATE:
         *(bool*)data = g_extern.system.core_options ?
            core_option_updated(g_extern.system.core_options) : false;
         break;

      case RETRO_ENVIRONMENT_SET_VARIABLES:
      {
         RARCH_LOG("Environ SET_VARIABLES.\n");

         if (g_extern.system.core_options)
         {
            core_option_flush(g_extern.system.core_options);
            core_option_free(g_extern.system.core_options);
         }

         const struct retro_variable *vars = (const struct retro_variable*)data;

         const char *options_path = g_settings.core_options_path;
         char buf[PATH_MAX];
         if (!*options_path && *g_extern.config_path)
         {
            fill_pathname_resolve_relative(buf, g_extern.config_path, "retroarch-core-options.cfg", sizeof(buf));
            options_path = buf;
         }
         g_extern.system.core_options = core_option_new(options_path, vars);

         break;
      }

      case RETRO_ENVIRONMENT_SET_MESSAGE:
      {
         const struct retro_message *msg = (const struct retro_message*)data;
         RARCH_LOG("Environ SET_MESSAGE: %s\n", msg->msg);
         if (g_extern.msg_queue)
         {
            msg_queue_clear(g_extern.msg_queue);
            msg_queue_push(g_extern.msg_queue, msg->msg, 1, msg->frames);
         }
         break;
      }

      case RETRO_ENVIRONMENT_SET_ROTATION:
      {
         unsigned rotation = *(const unsigned*)data;
         RARCH_LOG("Environ SET_ROTATION: %u\n", rotation);
         if (!g_settings.video.allow_rotate)
            break;

         g_extern.system.rotation = rotation;

         if (driver.video && driver.video->set_rotation)
         {
            if (driver.video_data)
               driver.video->set_rotation(driver.video_data, rotation);
         }
         else
            return false;
         break;
      }

      case RETRO_ENVIRONMENT_SHUTDOWN:
         RARCH_LOG("Environ SHUTDOWN.\n");
         g_extern.system.shutdown = true;
         break;

      case RETRO_ENVIRONMENT_SET_PERFORMANCE_LEVEL:
         g_extern.system.performance_level = *(const unsigned*)data;
         RARCH_LOG("Environ PERFORMANCE_LEVEL: %u.\n", g_extern.system.performance_level);
         break;

      case RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY:
         *(const char**)data = *g_settings.system_directory ? g_settings.system_directory : NULL;
         RARCH_LOG("Environ SYSTEM_DIRECTORY: \"%s\".\n", g_settings.system_directory);
         break;

      case RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY:
         *(const char**)data = *g_extern.savefile_dir ? g_extern.savefile_dir : NULL;
         RARCH_LOG("Environ SAVE_DIRECTORY: \"%s\".\n", g_extern.savefile_dir);
         break;

      case RETRO_ENVIRONMENT_GET_USERNAME:
         *(const char**)data = *g_settings.username ? g_settings.username : NULL;
         RARCH_LOG("Environ GET_USERNAME: \"%s\".\n", g_settings.username);
         break;

      case RETRO_ENVIRONMENT_GET_LANGUAGE:
         *(unsigned *)data = g_settings.user_language;
         RARCH_LOG("Environ GET_LANGUAGE: \"%d\".\n", g_settings.user_language);
         break;

      case RETRO_ENVIRONMENT_SET_PIXEL_FORMAT:
      {
         enum retro_pixel_format pix_fmt = *(const enum retro_pixel_format*)data;
         switch (pix_fmt)
         {
            case RETRO_PIXEL_FORMAT_0RGB1555:
               RARCH_LOG("Environ SET_PIXEL_FORMAT: 0RGB1555.\n");
               break;

            case RETRO_PIXEL_FORMAT_RGB565:
               RARCH_LOG("Environ SET_PIXEL_FORMAT: RGB565.\n");
               break;
            case RETRO_PIXEL_FORMAT_XRGB8888:
               RARCH_LOG("Environ SET_PIXEL_FORMAT: XRGB8888.\n");
               break;
            default:
               return false;
         }

         g_extern.system.pix_fmt = pix_fmt;
         break;
      }

      case RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS:
      {
         memset(g_extern.system.input_desc_btn, 0, sizeof(g_extern.system.input_desc_btn));

         const struct retro_input_descriptor *desc = (const struct retro_input_descriptor*)data;
         for (; desc->description; desc++)
         {
            if (desc->port >= MAX_PLAYERS)
               continue;

            if (desc->device != RETRO_DEVICE_JOYPAD) // Ignore all others for now.
               continue;

            if (desc->id >= RARCH_FIRST_CUSTOM_BIND)
               continue;

            g_extern.system.input_desc_btn[desc->port][desc->id] = desc->description;
         }

         static const char *libretro_btn_desc[] = {
            "B (bottom)", "Y (left)", "Select", "Start",
            "D-Pad Up", "D-Pad Down", "D-Pad Left", "D-Pad Right",
            "A (right)", "X (up)",
            "L", "R", "L2", "R2", "L3", "R3",
         };

         RARCH_LOG("Environ SET_INPUT_DESCRIPTORS:\n");
         for (p = 0; p < MAX_PLAYERS; p++)
         {
            for (id = 0; id < RARCH_FIRST_CUSTOM_BIND; id++)
            {
               const char *desc = g_extern.system.input_desc_btn[p][id];
               if (desc)
               {
                  RARCH_LOG("\tRetroPad, Player %u, Button \"%s\" => \"%s\"\n",
                        p + 1, libretro_btn_desc[id], desc);
               }
            }
         }

         break;
      }

      case RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK:
      {
         RARCH_LOG("Environ SET_KEYBOARD_CALLBACK.\n");
         const struct retro_keyboard_callback *info = (const struct retro_keyboard_callback*)data;
         g_extern.system.key_event = info->callback;
         break;
      }

      case RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE:
         RARCH_LOG("Environ SET_DISK_CONTROL_INTERFACE.\n");
         g_extern.system.disk_control = *(const struct retro_disk_control_callback*)data;
         break;

      case RETRO_ENVIRONMENT_SET_HW_RENDER:
      case RETRO_ENVIRONMENT_SET_HW_RENDER | RETRO_ENVIRONMENT_EXPERIMENTAL: // ABI compat
      {
         RARCH_LOG("Environ SET_HW_RENDER.\n");
         struct retro_hw_render_callback *cb = (struct retro_hw_render_callback*)data;
         switch (cb->context_type)
         {
            case RETRO_HW_CONTEXT_NONE:
               RARCH_LOG("Requesting no HW context.\n");
               break;

#if defined(HAVE_OPENGLES2)
            case RETRO_HW_CONTEXT_OPENGLES2:
#if defined(HAVE_OPENGLES3)
            case RETRO_HW_CONTEXT_OPENGLES3:
#endif
               RARCH_LOG("Requesting OpenGLES%u context.\n",
                     cb->context_type == RETRO_HW_CONTEXT_OPENGLES2 ? 2 : 3);
               break;

#if defined(HAVE_OPENGLES3)
            case RETRO_HW_CONTEXT_OPENGLES_VERSION:
               RARCH_LOG("Requesting OpenGLES%u.%u context.\n",
                     cb->version_major, cb->version_minor);
               break;
#endif

            case RETRO_HW_CONTEXT_OPENGL:
            case RETRO_HW_CONTEXT_OPENGL_CORE:
               RARCH_ERR("Requesting OpenGL context, but RetroArch is compiled against OpenGLES2. Cannot use HW context.\n");
               return false;
#elif defined(HAVE_OPENGL)
            case RETRO_HW_CONTEXT_OPENGLES2:
            case RETRO_HW_CONTEXT_OPENGLES3:
               RARCH_ERR("Requesting OpenGLES%u context, but RetroArch is compiled against OpenGL. Cannot use HW context.\n",
                     cb->context_type == RETRO_HW_CONTEXT_OPENGLES2 ? 2 : 3);
               return false;

            case RETRO_HW_CONTEXT_OPENGLES_VERSION:
               RARCH_ERR("Requesting OpenGLES%u.%u context, but RetroArch is compiled against OpenGL. Cannot use HW context.\n",
                     cb->version_major, cb->version_minor);
               return false;

            case RETRO_HW_CONTEXT_OPENGL:
               RARCH_LOG("Requesting OpenGL context.\n");
               break;

            case RETRO_HW_CONTEXT_OPENGL_CORE:
               RARCH_LOG("Requesting core OpenGL context (%u.%u).\n", cb->version_major, cb->version_minor);
               break;
#endif

            default:
               RARCH_LOG("Requesting unknown context.\n");
               return false;
         }
         cb->get_current_framebuffer = driver_get_current_framebuffer;
         cb->get_proc_address = driver_get_proc_address;

         if (cmd & RETRO_ENVIRONMENT_EXPERIMENTAL) // Old ABI. Don't copy garbage.
            memcpy(&g_extern.system.hw_render_callback, cb, offsetof(struct retro_hw_render_callback, stencil));
         else
            memcpy(&g_extern.system.hw_render_callback, cb, sizeof(*cb));
         break;
      }

      case RETRO_ENVIRONMENT_SET_SUPPORT_NO_GAME:
      {
         bool state = *(const bool*)data;
         RARCH_LOG("Environ SET_SUPPORT_NO_GAME: %s.\n", state ? "yes" : "no");
         g_extern.system.no_content = state;
         break;
      }

      case RETRO_ENVIRONMENT_GET_LIBRETRO_PATH:
      {
         const char **path = (const char**)data;
#ifdef HAVE_DYNAMIC
         *path = g_settings.libretro;
#else
         *path = NULL;
#endif
         break;
      }

      //FIXME - PS3 audio driver needs to be fixed so that threaded audio works correctly
      //(audio is already on a thread for PS3 audio driver so that's probably the problem)
#if defined(HAVE_THREADS) && !defined(__CELLOS_LV2__)
      case RETRO_ENVIRONMENT_SET_AUDIO_CALLBACK:
      {
         RARCH_LOG("Environ SET_AUDIO_CALLBACK.\n");
         const struct retro_audio_callback *info = (const struct retro_audio_callback*)data;

         if (g_extern.rec) // A/V sync is a must.
            return false;

#ifdef HAVE_NETPLAY
         if (g_extern.netplay_enable)
            return false;
#endif

         g_extern.system.audio_callback = *info;
         break;
      }
#endif

      case RETRO_ENVIRONMENT_SET_FRAME_TIME_CALLBACK:
      {
         RARCH_LOG("Environ SET_FRAME_TIME_CALLBACK.\n");

#ifdef HAVE_NETPLAY
         if (g_extern.netplay_enable) // retro_run() will be called in very strange and mysterious ways, have to disable it.
            return false;
#endif

         const struct retro_frame_time_callback *info = (const struct retro_frame_time_callback*)data;
         g_extern.system.frame_time = *info;
         break;
      }

      case RETRO_ENVIRONMENT_GET_RUMBLE_INTERFACE:
      {
         RARCH_LOG("Environ GET_RUMBLE_INTERFACE.\n");
         struct retro_rumble_interface *iface = (struct retro_rumble_interface*)data;
         iface->set_rumble_state = driver_set_rumble_state;
         break;
      }

      case RETRO_ENVIRONMENT_GET_INPUT_DEVICE_CAPABILITIES:
      {
         RARCH_LOG("Environ GET_INPUT_DEVICE_CAPABILITIES.\n");
         uint64_t *mask = (uint64_t*)data;
         if (driver.input && driver.input->get_capabilities && driver.input_data)
            *mask = driver.input->get_capabilities(driver.input_data);
         else
            return false;
         break;
      }

      case RETRO_ENVIRONMENT_GET_SENSOR_INTERFACE:
      {
         RARCH_LOG("Environ GET_SENSOR_INTERFACE.\n");
         struct retro_sensor_interface *iface = (struct retro_sensor_interface*)data;
         iface->set_sensor_state = driver_set_sensor_state;
         iface->get_sensor_input = driver_sensor_get_input;
         break;
      }

      case RETRO_ENVIRONMENT_GET_CAMERA_INTERFACE:
      {
         RARCH_LOG("Environ GET_CAMERA_INTERFACE.\n");
         struct retro_camera_callback *cb = (struct retro_camera_callback*)data;
         cb->start = driver_camera_start;
         cb->stop = driver_camera_stop;
         g_extern.system.camera_callback = *cb;
         g_extern.camera_active = cb->caps != 0;
         break;
      }

      case RETRO_ENVIRONMENT_GET_LOCATION_INTERFACE:
      {
         RARCH_LOG("Environ GET_LOCATION_INTERFACE.\n");
         struct retro_location_callback *cb = (struct retro_location_callback*)data;
         cb->start = driver_location_start;
         cb->stop = driver_location_stop;
         cb->get_position = driver_location_get_position;
         cb->set_interval = driver_location_set_interval;
         g_extern.system.location_callback = *cb;
         g_extern.location_active = true;
         break;
      }

      case RETRO_ENVIRONMENT_GET_LOG_INTERFACE:
      {
         RARCH_LOG("Environ GET_LOG_INTERFACE.\n");
         struct retro_log_callback *cb = (struct retro_log_callback*)data;
         cb->log = rarch_log_libretro;
         break;
      }

      case RETRO_ENVIRONMENT_GET_PERF_INTERFACE:
      {
         RARCH_LOG("Environ GET_PERF_INTERFACE.\n");
         struct retro_perf_callback *cb = (struct retro_perf_callback*)data;
         cb->get_time_usec    = rarch_get_time_usec;
         cb->get_cpu_features = rarch_get_cpu_features;
         cb->get_perf_counter = rarch_get_perf_counter;
         cb->perf_register    = retro_perf_register; // libretro specific path.
         cb->perf_start       = rarch_perf_start;
         cb->perf_stop        = rarch_perf_stop;
         cb->perf_log         = retro_perf_log; // libretro specific path.
         break;
      }

      case RETRO_ENVIRONMENT_GET_CONTENT_DIRECTORY:
      {
         const char **dir = (const char**)data;
         *dir = *g_settings.content_directory ? g_settings.content_directory : NULL;
         RARCH_LOG("Environ CONTENT_DIRECTORY: \"%s\".\n", g_settings.content_directory);
         break;
      }

      case RETRO_ENVIRONMENT_SET_SYSTEM_AV_INFO:
      {
         RARCH_LOG("Environ SET_SYSTEM_AV_INFO.\n");
         return driver_update_system_av_info((const struct retro_system_av_info*)data);
      }

      case RETRO_ENVIRONMENT_SET_SUBSYSTEM_INFO:
      {
         RARCH_LOG("Environ SET_SUBSYSTEM_INFO.\n");
         unsigned i, j;
         const struct retro_subsystem_info *info = (const struct retro_subsystem_info*)data;
         for (i = 0; info[i].ident; i++)
         {
            RARCH_LOG("Special game type: %s\n", info[i].desc);
            RARCH_LOG("  Ident: %s\n", info[i].ident);
            RARCH_LOG("  ID: %u\n", info[i].id);
            RARCH_LOG("  Content:\n");
            for (j = 0; j < info[i].num_roms; j++)
            {
               RARCH_LOG("    %s (%s)\n",
                     info[i].roms[j].desc, info[i].roms[j].required ? "required" : "optional");
            }
         }

         free(g_extern.system.special);
         g_extern.system.special = (struct retro_subsystem_info*)calloc(i, sizeof(*g_extern.system.special));
         if (!g_extern.system.special)
            return false;

         memcpy(g_extern.system.special, info, i * sizeof(*g_extern.system.special));
         g_extern.system.num_special = i;
         break;
      }

      case RETRO_ENVIRONMENT_SET_CONTROLLER_INFO:
      {
         RARCH_LOG("Environ SET_CONTROLLER_INFO.\n");
         unsigned i, j;
         const struct retro_controller_info *info = (const struct retro_controller_info*)data;
         for (i = 0; info[i].types; i++)
         {
            RARCH_LOG("Controller port: %u\n", i + 1);
            for (j = 0; j < info[i].num_types; j++)
               RARCH_LOG("   %s (ID: %u)\n", info[i].types[j].desc, info[i].types[j].id);
         }

         free(g_extern.system.ports);
         g_extern.system.ports = (struct retro_controller_info*)calloc(i, sizeof(*g_extern.system.ports));
         if (!g_extern.system.ports)
            return false;

         memcpy(g_extern.system.ports, info, i * sizeof(*g_extern.system.ports));
         g_extern.system.num_ports = i;
         break;
      }

      case RETRO_ENVIRONMENT_SET_GEOMETRY:
      {
         RARCH_LOG("Environ SET_GEOMETRY.\n");
         const struct retro_game_geometry *in_geom = (const struct retro_game_geometry*)data;
         struct retro_game_geometry *geom = &g_extern.system.av_info.geometry;

         // Can potentially be called every frame, don't do anything unless required.
         if (geom->base_width != in_geom->base_width ||
               geom->base_height != in_geom->base_height ||
               geom->aspect_ratio != in_geom->aspect_ratio)
         {
            geom->base_width   = in_geom->base_width;
            geom->base_height  = in_geom->base_height;
            geom->aspect_ratio = in_geom->aspect_ratio;
            RARCH_LOG("SET_GEOMETRY: %ux%u, aspect: %.3f.\n",
                  geom->base_width, geom->base_height, geom->aspect_ratio);

            // Forces recomputation of aspect ratios if using core-dependent aspect ratios.
            rarch_main_command(RARCH_CMD_VIDEO_SET_ASPECT_RATIO);
            
            // TODO: Figure out what to do, if anything, with recording.
         }
         break;
      }

      // Private extensions for internal use, not part of libretro API.
      case RETRO_ENVIRONMENT_SET_LIBRETRO_PATH:
         RARCH_LOG("Environ (Private) SET_LIBRETRO_PATH.\n");

         if (path_file_exists((const char*)data))
            strlcpy(g_settings.libretro, (const char*)data, sizeof(g_settings.libretro));
         else
            return false;
         break;

      case RETRO_ENVIRONMENT_EXEC:
      case RETRO_ENVIRONMENT_EXEC_ESCAPE:

         if (data)
            strlcpy(g_extern.fullpath, (const char*)data, sizeof(g_extern.fullpath));
         else
            *g_extern.fullpath = '\0';

#if defined(RARCH_CONSOLE)
         g_extern.lifecycle_state &= ~(1ULL << MODE_GAME);
         g_extern.lifecycle_state |= (1ULL << MODE_EXITSPAWN);
         g_extern.lifecycle_state |= (1ULL << MODE_EXITSPAWN_START_GAME);
#elif defined(HAVE_DYNAMIC)
         g_extern.lifecycle_state |= (1ULL << MODE_LOAD_GAME);
#endif

         if (cmd == RETRO_ENVIRONMENT_EXEC_ESCAPE)
         {
            RARCH_LOG("Environ (Private) EXEC_ESCAPE.\n");
            g_extern.exec = true;
         }
         else
            RARCH_LOG("Environ (Private) EXEC.\n");

         break;

      default:
         RARCH_LOG("Environ UNSUPPORTED (#%u).\n", cmd);
         return false;
   }

   return true;
}