path: root/libretro.c

#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include "common.h"
#include "libco.h"
#include "libretro.h"
#include "memmap.h"


#if defined(VITA) && defined(HAVE_DYNAREC)
#include <psp2/kernel/sysmem.h>
static int translation_caches_inited = 0;
static inline int align(int x, int n) {
  return (((x >> n) + 1) << n );
}

#define FOUR_KB_ALIGN(x) align(x, 12)
#define MB_ALIGN(x) align(x, 20)

int _newlib_vm_size_user = ROM_TRANSLATION_CACHE_SIZE +
                           RAM_TRANSLATION_CACHE_SIZE + 
                           BIOS_TRANSLATION_CACHE_SIZE;

int getVMBlock();

#endif

#if defined(_3DS)
void* linearMemAlign(size_t size, size_t alignment);
void linearFree(void* mem);
#if defined(HAVE_DYNAREC)
#include <malloc.h>
#include "3ds/3ds_utils.h"
#define MEMOP_PROT   6
#define MEMOP_MAP 4
#define MEMOP_UNMAP 5
int32_t svcDuplicateHandle(uint32_t* out, uint32_t original);
int32_t svcCloseHandle(uint32_t handle);
int32_t svcControlProcessMemory(uint32_t process, void* addr0, void* addr1, uint32_t size, uint32_t type, uint32_t perm);
static int translation_caches_inited = 0;
#endif
#endif

#ifndef MAX_PATH
#define MAX_PATH (512)
#endif

// 59.72750057 hz
#define GBA_FPS ((float) GBC_BASE_RATE) / (308 * 228 * 4)
#define MAX_FRAME_TIME 1.0f / ((float) GBA_FPS)

frameskip_type current_frameskip_type = no_frameskip;
u32 frameskip_value = 4;
u32 random_skip = 0;

u32 skip_next_frame = 0;

u32 frameskip_counter = 0;

u32 num_skipped_frames = 0;

static float frame_time;

static retro_log_printf_t log_cb;
static retro_video_refresh_t video_cb;
static retro_input_poll_t input_poll_cb;
static retro_environment_t environ_cb;

struct retro_perf_callback perf_cb;

static cothread_t main_thread;
static cothread_t cpu_thread;
int dynarec_enable;

u32 idle_loop_target_pc = 0xFFFFFFFF;
u32 iwram_stack_optimize = 1;
u32 translation_gate_target_pc[MAX_TRANSLATION_GATES];
u32 translation_gate_targets = 0;

void switch_to_main_thread(void)
{
   co_switch(main_thread);
}

static inline void switch_to_cpu_thread(void)
{
   co_switch(cpu_thread);
}

static void cpu_thread_entry(void)
{
#ifdef HAVE_DYNAREC
   if (dynarec_enable)
      execute_arm_translate(execute_cycles);
#endif
   execute_arm(execute_cycles);
}

static inline void init_context_switch(void)
{
   main_thread = co_active();
   cpu_thread = co_create(0x20000, cpu_thread_entry);
}

static inline void deinit_context_switch(void)
{
   co_delete(cpu_thread);
}

static uint32_t next_pow2(uint32_t v)
{
   v--;
   v |= v >> 1;
   v |= v >> 2;
   v |= v >> 4;
   v |= v >> 8;
   v |= v >> 16;
   v++;
   return v;
}

static void video_run(void) {
#if defined(PSP)
   static unsigned int __attribute__((aligned(16))) d_list[32];
   void* texture_vram_p = NULL;
   int texture_size = (GBA_SCREEN_WIDTH*GBA_SCREEN_HEIGHT*2);
   
   texture_vram_p = (void*) (0x44200000 - texture_size); /* max VRAM address - frame size */

   sceKernelDcacheWritebackRange(gba_screen_pixels, texture_size);

   sceGuStart(GU_DIRECT, d_list);
   sceGuTexMode(GU_PSM_5650, 0, 0, GU_FALSE);
   sceGuCopyImage(GU_PSM_5650, 0, 0, GBA_SCREEN_WIDTH, GBA_SCREEN_HEIGHT, GBA_SCREEN_WIDTH,
               gba_screen_pixels, 0, 0, GBA_SCREEN_WIDTH, texture_vram_p);
	sceGuTexImage(0, next_pow2(GBA_SCREEN_WIDTH), next_pow2(GBA_SCREEN_HEIGHT), GBA_SCREEN_WIDTH, texture_vram_p);
	sceGuTexFunc(GU_TFX_REPLACE, GU_TCC_RGB);
   sceGuDisable(GU_BLEND);

   sceGuFinish();

   video_cb(texture_vram_p, GBA_SCREEN_WIDTH, GBA_SCREEN_HEIGHT,
            GBA_SCREEN_PITCH * 2);
#else 
   video_cb(gba_screen_pixels, GBA_SCREEN_WIDTH, GBA_SCREEN_HEIGHT,
            GBA_SCREEN_PITCH * 2);
#endif
}

#ifdef PERF_TEST

extern struct retro_perf_callback perf_cb;

#define RETRO_PERFORMANCE_INIT(X) \
   static struct retro_perf_counter X = {#X}; \
   do { \
      if (!(X).registered) \
         perf_cb.perf_register(&(X)); \
   } while(0)

#define RETRO_PERFORMANCE_START(X) perf_cb.perf_start(&(X))
#define RETRO_PERFORMANCE_STOP(X) perf_cb.perf_stop(&(X))
#else
#define RETRO_PERFORMANCE_INIT(X)
#define RETRO_PERFORMANCE_START(X)
#define RETRO_PERFORMANCE_STOP(X)

#endif

void retro_get_system_info(struct retro_system_info* info)
{
   info->library_name = "gpSP";
#ifndef GIT_VERSION
#define GIT_VERSION ""
#endif
   info->library_version = "v0.91" GIT_VERSION;
   info->need_fullpath = true;
   info->block_extract = false;
   info->valid_extensions = "gba|bin|agb|gbz" ;
}


void retro_get_system_av_info(struct retro_system_av_info* info)
{
   info->geometry.base_width = GBA_SCREEN_WIDTH;
   info->geometry.base_height = GBA_SCREEN_HEIGHT;
   info->geometry.max_width = GBA_SCREEN_WIDTH;
   info->geometry.max_height = GBA_SCREEN_HEIGHT;
   info->geometry.aspect_ratio = 0;
   info->timing.fps = ((float) GBA_FPS);
   info->timing.sample_rate = GBA_SOUND_FREQUENCY;
}

void retro_init(void)
{
  
#if defined(_3DS) && defined(HAVE_DYNAREC)
   if (__ctr_svchax && !translation_caches_inited)
   {
      uint32_t currentHandle;
      check_rosalina();
      
      rom_translation_cache_ptr  = memalign(0x1000, ROM_TRANSLATION_CACHE_SIZE);
      ram_translation_cache_ptr  = memalign(0x1000, RAM_TRANSLATION_CACHE_SIZE);
      bios_translation_cache_ptr = memalign(0x1000, BIOS_TRANSLATION_CACHE_SIZE);

      svcDuplicateHandle(&currentHandle, 0xFFFF8001);
      svcControlProcessMemory(currentHandle,
                              rom_translation_cache, rom_translation_cache_ptr,
                              ROM_TRANSLATION_CACHE_SIZE, MEMOP_MAP, 0b111);
      svcControlProcessMemory(currentHandle,
                              ram_translation_cache, ram_translation_cache_ptr,
                              RAM_TRANSLATION_CACHE_SIZE, MEMOP_MAP, 0b111);
      svcControlProcessMemory(currentHandle,
                              bios_translation_cache, bios_translation_cache_ptr,
                              BIOS_TRANSLATION_CACHE_SIZE, MEMOP_MAP, 0b111);
      svcCloseHandle(currentHandle);
      rom_translation_ptr = rom_translation_cache;
      ram_translation_ptr = ram_translation_cache;
      bios_translation_ptr = bios_translation_cache;
      ctr_flush_invalidate_cache();
      translation_caches_inited = 1;
   }
#endif

#if defined(VITA) && defined(HAVE_DYNAREC)
      if(!translation_caches_inited){
      void* currentHandle;

      sceBlock = getVMBlock();
      
      if (sceBlock < 0)
      {
        return;
      }

      // get base address
      int ret = sceKernelGetMemBlockBase(sceBlock, &currentHandle);
      if (ret < 0)
      {
        return;
      }

      rom_translation_cache  = (u8*)currentHandle;
      ram_translation_cache  = rom_translation_cache + ROM_TRANSLATION_CACHE_SIZE;
      bios_translation_cache = ram_translation_cache + RAM_TRANSLATION_CACHE_SIZE;
      rom_translation_ptr = rom_translation_cache;
      ram_translation_ptr = ram_translation_cache;
      bios_translation_ptr = bios_translation_cache;
      sceKernelOpenVMDomain();
      translation_caches_inited = 1;
}

#endif

   if (!gamepak_rom)
      init_gamepak_buffer();
   init_sound(1);

   if(!gba_screen_pixels)
#ifdef _3DS
      gba_screen_pixels = (uint16_t*)linearMemAlign(GBA_SCREEN_PITCH * GBA_SCREEN_HEIGHT * sizeof(uint16_t), 128);
#else
      gba_screen_pixels = (uint16_t*)malloc(GBA_SCREEN_PITCH * GBA_SCREEN_HEIGHT * sizeof(uint16_t));
#endif

}

void retro_deinit(void)
{
   perf_cb.perf_log();
   memory_term();

#if defined(HAVE_MMAP) && defined(HAVE_DYNAREC)
   munmap(rom_translation_cache, ROM_TRANSLATION_CACHE_SIZE);
   munmap(ram_translation_cache, RAM_TRANSLATION_CACHE_SIZE);
   munmap(bios_translation_cache, BIOS_TRANSLATION_CACHE_SIZE);
#endif
#if defined(_3DS) && defined(HAVE_DYNAREC)

   if (__ctr_svchax && translation_caches_inited)
   {
      uint32_t currentHandle;
      svcDuplicateHandle(&currentHandle, 0xFFFF8001);
      svcControlProcessMemory(currentHandle,
                              rom_translation_cache, rom_translation_cache_ptr,
                              ROM_TRANSLATION_CACHE_SIZE, MEMOP_UNMAP, 0b111);
      svcControlProcessMemory(currentHandle,
                              ram_translation_cache, ram_translation_cache_ptr,
                              RAM_TRANSLATION_CACHE_SIZE, MEMOP_UNMAP, 0b111);
      svcControlProcessMemory(currentHandle,
                              bios_translation_cache, bios_translation_cache_ptr,
                              BIOS_TRANSLATION_CACHE_SIZE, MEMOP_UNMAP, 0b111);
      svcCloseHandle(currentHandle);
      free(rom_translation_cache_ptr);
      free(ram_translation_cache_ptr);
      free(bios_translation_cache_ptr);
      translation_caches_inited = 0;
   }
#endif

#if defined(VITA) && defined(HAVE_DYNAREC)
    if(translation_caches_inited){
        translation_caches_inited = 0;
    }
#endif

#ifdef _3DS
   linearFree(gba_screen_pixels);
#else
   free(gba_screen_pixels);
#endif
   gba_screen_pixels = NULL;
}

static retro_time_t retro_perf_dummy_get_time_usec() { return 0; }
static retro_perf_tick_t retro_perf_dummy_get_counter() { return 0; }
static uint64_t retro_perf_dummy_get_cpu_features() { return 0; }
static void retro_perf_dummy_log() {}
static void retro_perf_dummy_counter(struct retro_perf_counter *counter) {};

void retro_set_environment(retro_environment_t cb)
{
   struct retro_log_callback log;

   static struct retro_variable vars[] = {
#ifdef HAVE_DYNAREC
      { "gpsp_drc", "Dynamic recompiler (restart); enabled|disabled" },
#endif
      { "gpsp_frameskip_type", "Frameskip type; off|manual|automatic" },
      { "gpsp_frameskip_value", "Frameskip value; 1|2|3|4|5|6|7|8|9" },
      { "gpsp_frameskip_variation", "Frameskip variation; uniform|random" },
      { NULL, NULL },
   };

#if defined(_3DS) && (HAVE_DYNAREC)
   if(!__ctr_svchax)
   {
      vars[0].key   = 0;
      vars[0].value = NULL;
   }
#endif

   environ_cb = cb;

   if (environ_cb(RETRO_ENVIRONMENT_GET_LOG_INTERFACE, &log))
      log_cb = log.log;
   else
      log_cb = NULL;

   perf_cb = (struct retro_perf_callback){
      retro_perf_dummy_get_time_usec,
      retro_perf_dummy_get_counter,
      retro_perf_dummy_get_cpu_features,
      retro_perf_dummy_counter,
      retro_perf_dummy_counter,
      retro_perf_dummy_counter,
      retro_perf_dummy_log,
   };
   environ_cb(RETRO_ENVIRONMENT_GET_PERF_INTERFACE, &perf_cb);
   environ_cb(RETRO_ENVIRONMENT_SET_VARIABLES, (void*)vars);
}

void retro_set_video_refresh(retro_video_refresh_t cb)
{
   video_cb = cb;
}
void retro_set_input_poll(retro_input_poll_t cb)
{
   input_poll_cb = cb;
}

void retro_set_controller_port_device(unsigned port, unsigned device) {}

void retro_reset(void)
{
   deinit_context_switch();

   update_backup();
   reset_gba();

   init_context_switch();
}

size_t retro_serialize_size(void)
{
   return GBA_STATE_MEM_SIZE;
}

bool retro_serialize(void* data, size_t size)
{
   if (size != GBA_STATE_MEM_SIZE)
      return false;

   memset (data,0, GBA_STATE_MEM_SIZE);
   gba_save_state(data);

   return true;
}

bool retro_unserialize(const void* data, size_t size)
{
   if (size != GBA_STATE_MEM_SIZE)
      return false;

   gba_load_state(data);

   return true;
}

void retro_cheat_reset(void)
{
}
void retro_cheat_set(unsigned index, bool enabled, const char* code) {}

void error_msg(const char* text)
{
   if (log_cb)
      log_cb(RETRO_LOG_ERROR, "[gpSP]: %s\n", text);
}

void info_msg(const char* text)
{
   if (log_cb)
      log_cb(RETRO_LOG_INFO, "[gpSP]: %s\n", text);
}

static void extract_directory(char* buf, const char* path, size_t size)
{
   strncpy(buf, path, size - 1);
   buf[size - 1] = '\0';

   char* base = strrchr(buf, '/');

   if (base)
      *base = '\0';
   else
      strncpy(buf, ".", size);
}

static void check_variables(int started_from_load)
{
   struct retro_variable var;

#ifdef HAVE_DYNAREC
   var.key = "gpsp_drc";
   var.value = NULL;

   if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
   {
      if (started_from_load)
      {
         if (strcmp(var.value, "disabled") == 0)
            dynarec_enable = 0;
         else if (strcmp(var.value, "enabled") == 0)
            dynarec_enable = 1;
      }
   }
   else
      dynarec_enable = 1;
#endif

   var.key = "gpsp_frameskip_value";
   var.value = 0;
   if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
      frameskip_value = strtol(var.value, NULL, 10);

   var.key = "gpsp_frameskip_type";
   var.value = NULL;
   if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
   {
      if (!strcmp(var.value, "off"))
         current_frameskip_type = no_frameskip;
      else if (!strcmp(var.value, "automatic"))
         current_frameskip_type = auto_frameskip;
      else if (!strcmp(var.value, "manual"))
         current_frameskip_type = manual_frameskip;
   }

   var.key = "gpsp_frameskip_variation";
   var.value = NULL;
   if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
   {
      if (!strcmp(var.value, "uniform"))
         random_skip = 0;
      else if (!strcmp(var.value, "random"))
         random_skip = 1;
   }
}

static void set_input_descriptors()
{
   struct retro_input_descriptor descriptors[] = {
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_LEFT,  "D-Pad Left" },
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_UP,    "D-Pad Up" },
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_DOWN,  "D-Pad Down" },
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_RIGHT, "D-Pad Right" },
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_B,     "B" },
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_A,     "A" },
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_SELECT,   "Select" },
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_START,    "Start" },
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_L, "L" },
      { 0, RETRO_DEVICE_JOYPAD, 0, RETRO_DEVICE_ID_JOYPAD_R, "R" },
      { 0 },
   };

   environ_cb(RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS, descriptors);
}

static void frame_time_cb(retro_usec_t usec)
{
   frame_time = usec / 1000000.0;
}

static void set_memory_descriptors(void)
{
   const uint64_t mem = RETRO_MEMORY_SYSTEM_RAM;
   struct retro_memory_descriptor desc[9] = {
      { mem, iwram, 0x00000 + 0x8000, 0x3000000, 0, 0, 0x8000, NULL },
      { mem, ewram, 0x00000 + 0x8000, 0x2000000, 0, 0, 0x8000, NULL },
      { mem, ewram, 0x10000 + 0x8000, 0x2008000, 0, 0, 0x8000, NULL },
      { mem, ewram, 0x20000 + 0x8000, 0x2010000, 0, 0, 0x8000, NULL },
      { mem, ewram, 0x30000 + 0x8000, 0x2018000, 0, 0, 0x8000, NULL },
      { mem, ewram, 0x40000 + 0x8000, 0x2020000, 0, 0, 0x8000, NULL },
      { mem, ewram, 0x50000 + 0x8000, 0x2028000, 0, 0, 0x8000, NULL },
      { mem, ewram, 0x60000 + 0x8000, 0x2030000, 0, 0, 0x8000, NULL },
      { mem, ewram, 0x70000 + 0x8000, 0x2038000, 0, 0, 0x8000, NULL }
   };
   struct retro_memory_map retromap = {
      desc,
      sizeof(desc) / sizeof(desc[0])
   };
   environ_cb(RETRO_ENVIRONMENT_SET_MEMORY_MAPS, &retromap);
}

bool retro_load_game(const struct retro_game_info* info)
{
   if (!info)
      return false;

   check_variables(1);
   set_input_descriptors();

#if defined(HAVE_DYNAREC)
   if (dynarec_enable)
   {
#if defined(HAVE_MMAP)

   rom_translation_cache = mmap(NULL, ROM_TRANSLATION_CACHE_SIZE,
                                PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_PRIVATE, -1, 0);
   ram_translation_cache = mmap(NULL, RAM_TRANSLATION_CACHE_SIZE,
                                PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_PRIVATE, -1, 0);
   bios_translation_cache = mmap(NULL, BIOS_TRANSLATION_CACHE_SIZE,
                                 PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_PRIVATE, -1, 0);

   rom_translation_ptr = rom_translation_cache;
   ram_translation_ptr = ram_translation_cache;
   bios_translation_ptr = bios_translation_cache;
#elif defined(_3DS)
   dynarec_enable = __ctr_svchax;
   rom_translation_ptr = rom_translation_cache;
   ram_translation_ptr = ram_translation_cache;
   bios_translation_ptr = bios_translation_cache;
#elif defined(PSP) || defined(VITA)
   dynarec_enable = 1;
   rom_translation_ptr = rom_translation_cache;
   ram_translation_ptr = ram_translation_cache;
   bios_translation_ptr = bios_translation_cache;
#endif
   }
   else
      dynarec_enable = 0;
#else
   dynarec_enable = 0;
#endif

   struct retro_frame_time_callback frame_cb = { frame_time_cb, 1000000 / ((float) GBA_FPS) };
   environ_cb(RETRO_ENVIRONMENT_SET_FRAME_TIME_CALLBACK, &frame_cb);

   char filename_bios[MAX_PATH];
   const char* dir = NULL;

   enum retro_pixel_format fmt = RETRO_PIXEL_FORMAT_RGB565;
   if (!environ_cb(RETRO_ENVIRONMENT_SET_PIXEL_FORMAT, &fmt))
      info_msg("RGB565 is not supported.");

   extract_directory(main_path, info->path, sizeof(main_path));

   if (environ_cb(RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY, &dir) && dir)
      strncpy(filename_bios, dir, sizeof(filename_bios));
   else
      strncpy(filename_bios, main_path, sizeof(filename_bios));

   strncat(filename_bios, "/gba_bios.bin", sizeof(filename_bios));


   if (environ_cb(RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY, &dir) && dir)
      strncpy(save_path, dir, sizeof(save_path));
   else
      strncpy(save_path, main_path, sizeof(save_path));

   if (load_bios(filename_bios) != 0)
   {
      error_msg("Could not load BIOS image file.");
      return false;
   }

   if (bios_rom[0] != 0x18)
   {
      info_msg("You have an incorrect BIOS image.");
      info_msg("While many games will work fine, some will not.");
      info_msg("It is strongly recommended that you obtain the correct BIOS file.");
   }

   gamepak_filename[0] = 0;
   if (load_gamepak(info, info->path) != 0)
   {
      error_msg("Could not load the game file.");
      return false;
   }

   reset_gba();

   init_context_switch();

   set_memory_descriptors();

   return true;
}


bool retro_load_game_special(unsigned game_type,
                             const struct retro_game_info* info, size_t num_info)
{
   return false;
}

void retro_unload_game(void)
{
   deinit_context_switch();
   update_backup();
}

unsigned retro_get_region(void)
{
   return RETRO_REGION_NTSC;
}

void* retro_get_memory_data(unsigned id)
{
   if ( id == RETRO_MEMORY_SYSTEM_RAM )
      return ewram ;
   //   switch (id)
   //   {
   //   case RETRO_MEMORY_SAVE_RAM:
   //      return gamepak_backup;
   //   }

   return 0;
}

size_t retro_get_memory_size(unsigned id)
{

   if ( id == RETRO_MEMORY_SYSTEM_RAM )
      return 1024 * 256 * 2 ;
  //   switch (id)
   //   {
   //   case RETRO_MEMORY_SAVE_RAM:
   //      switch(backup_type)
   //      {
   //      case BACKUP_SRAM:
   //         return sram_size;

   //      case BACKUP_FLASH:
   //         return flash_size;

   //      case BACKUP_EEPROM:
   //         return eeprom_size;

   //      case BACKUP_NONE:
   //         return 0x0;

   //      default:
   //         return 0x8000;
   //      }
   //   }

   return 0;
}

void retro_run(void)
{
   bool updated = false;

   update_input();

   input_poll_cb();

   s32 used_frameskip = frameskip_value;

   skip_next_frame = 0;

   if(current_frameskip_type == auto_frameskip)
   {
      if(frame_time > MAX_FRAME_TIME)
      {
         if(num_skipped_frames < frameskip_value)
         {
            skip_next_frame = 1;
            num_skipped_frames++;
         }
         else
         {
            num_skipped_frames = 0;
         }
      }
   }
   else if(current_frameskip_type == manual_frameskip)
   {
      frameskip_counter = (frameskip_counter + 1) %
      (used_frameskip + 1);
      if(random_skip)
      {
         if(frameskip_counter != (rand() % (used_frameskip + 1)))
         skip_next_frame = 1;
      }
      else
      {
         if(frameskip_counter)
         skip_next_frame = 1;
      }
   }

   switch_to_cpu_thread();

   render_audio();

   /* Skip the video callback when skipping frames so the frontend can properly report FPS */
   if (!skip_next_frame)
      video_run();

   if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE_UPDATE, &updated) && updated)
      check_variables(0);

}

unsigned retro_api_version(void)
{
   return RETRO_API_VERSION;
}