view libretro.h @ 1971:80920c21bb52

Add an event log soft flush and call it twice per frame in between hard flushes to netplay latency when there are insufficient hardware updates to flush packets in the middle of a frame
author Michael Pavone <pavone@retrodev.com>
date Fri, 08 May 2020 11:40:30 -0700
parents 6c54bb5fe3b3
children
line wrap: on
line source

/* Copyright (C) 2010-2017 The RetroArch team
 *
 * ---------------------------------------------------------------------------------------
 * The following license statement only applies to this libretro API header (libretro.h).
 * ---------------------------------------------------------------------------------------
 *
 * 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 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.
 */

#ifndef LIBRETRO_H__
#define LIBRETRO_H__

#include <stdint.h>
#include <stddef.h>
#include <limits.h>

#ifdef __cplusplus
extern "C" {
#endif

#ifndef __cplusplus
#if defined(_MSC_VER) && _MSC_VER < 1800 && !defined(SN_TARGET_PS3)
/* Hack applied for MSVC when compiling in C89 mode
 * as it isn't C99-compliant. */
#define bool unsigned char
#define true 1
#define false 0
#else
#include <stdbool.h>
#endif
#endif

#ifndef RETRO_CALLCONV
#  if defined(__GNUC__) && defined(__i386__) && !defined(__x86_64__)
#    define RETRO_CALLCONV __attribute__((cdecl))
#  elif defined(_MSC_VER) && defined(_M_X86) && !defined(_M_X64)
#    define RETRO_CALLCONV __cdecl
#  else
#    define RETRO_CALLCONV /* all other platforms only have one calling convention each */
#  endif
#endif

#ifndef RETRO_API
#  if defined(_WIN32) || defined(__CYGWIN__) || defined(__MINGW32__)
#    ifdef RETRO_IMPORT_SYMBOLS
#      ifdef __GNUC__
#        define RETRO_API RETRO_CALLCONV __attribute__((__dllimport__))
#      else
#        define RETRO_API RETRO_CALLCONV __declspec(dllimport)
#      endif
#    else
#      ifdef __GNUC__
#        define RETRO_API RETRO_CALLCONV __attribute__((__dllexport__))
#      else
#        define RETRO_API RETRO_CALLCONV __declspec(dllexport)
#      endif
#    endif
#  else
#      if defined(__GNUC__) && __GNUC__ >= 4 && !defined(__CELLOS_LV2__)
#        define RETRO_API RETRO_CALLCONV __attribute__((__visibility__("default")))
#      else
#        define RETRO_API RETRO_CALLCONV
#      endif
#  endif
#endif

/* Used for checking API/ABI mismatches that can break libretro
 * implementations.
 * It is not incremented for compatible changes to the API.
 */
#define RETRO_API_VERSION         1

/*
 * Libretro's fundamental device abstractions.
 *
 * Libretro's input system consists of some standardized device types,
 * such as a joypad (with/without analog), mouse, keyboard, lightgun
 * and a pointer.
 *
 * The functionality of these devices are fixed, and individual cores
 * map their own concept of a controller to libretro's abstractions.
 * This makes it possible for frontends to map the abstract types to a
 * real input device, and not having to worry about binding input
 * correctly to arbitrary controller layouts.
 */

#define RETRO_DEVICE_TYPE_SHIFT         8
#define RETRO_DEVICE_MASK               ((1 << RETRO_DEVICE_TYPE_SHIFT) - 1)
#define RETRO_DEVICE_SUBCLASS(base, id) (((id + 1) << RETRO_DEVICE_TYPE_SHIFT) | base)

/* Input disabled. */
#define RETRO_DEVICE_NONE         0

/* The JOYPAD is called RetroPad. It is essentially a Super Nintendo
 * controller, but with additional L2/R2/L3/R3 buttons, similar to a
 * PS1 DualShock. */
#define RETRO_DEVICE_JOYPAD       1

/* The mouse is a simple mouse, similar to Super Nintendo's mouse.
 * X and Y coordinates are reported relatively to last poll (poll callback).
 * It is up to the libretro implementation to keep track of where the mouse
 * pointer is supposed to be on the screen.
 * The frontend must make sure not to interfere with its own hardware
 * mouse pointer.
 */
#define RETRO_DEVICE_MOUSE        2

/* KEYBOARD device lets one poll for raw key pressed.
 * It is poll based, so input callback will return with the current
 * pressed state.
 * For event/text based keyboard input, see
 * RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK.
 */
#define RETRO_DEVICE_KEYBOARD     3

/* LIGHTGUN device is similar to Guncon-2 for PlayStation 2.
 * It reports X/Y coordinates in screen space (similar to the pointer)
 * in the range [-0x8000, 0x7fff] in both axes, with zero being center.
 * As well as reporting on/off screen state. It features a trigger,
 * start/select buttons, auxiliary action buttons and a
 * directional pad. A forced off-screen shot can be requested for
 * auto-reloading function in some games.
 */
#define RETRO_DEVICE_LIGHTGUN     4

/* The ANALOG device is an extension to JOYPAD (RetroPad).
 * Similar to DualShock2 it adds two analog sticks and all buttons can
 * be analog. This is treated as a separate device type as it returns
 * axis values in the full analog range of [-0x8000, 0x7fff].
 * Positive X axis is right. Positive Y axis is down.
 * Buttons are returned in the range [0, 0x7fff].
 * Only use ANALOG type when polling for analog values.
 */
#define RETRO_DEVICE_ANALOG       5

/* Abstracts the concept of a pointing mechanism, e.g. touch.
 * This allows libretro to query in absolute coordinates where on the
 * screen a mouse (or something similar) is being placed.
 * For a touch centric device, coordinates reported are the coordinates
 * of the press.
 *
 * Coordinates in X and Y are reported as:
 * [-0x7fff, 0x7fff]: -0x7fff corresponds to the far left/top of the screen,
 * and 0x7fff corresponds to the far right/bottom of the screen.
 * The "screen" is here defined as area that is passed to the frontend and
 * later displayed on the monitor.
 *
 * The frontend is free to scale/resize this screen as it sees fit, however,
 * (X, Y) = (-0x7fff, -0x7fff) will correspond to the top-left pixel of the
 * game image, etc.
 *
 * To check if the pointer coordinates are valid (e.g. a touch display
 * actually being touched), PRESSED returns 1 or 0.
 *
 * If using a mouse on a desktop, PRESSED will usually correspond to the
 * left mouse button, but this is a frontend decision.
 * PRESSED will only return 1 if the pointer is inside the game screen.
 *
 * For multi-touch, the index variable can be used to successively query
 * more presses.
 * If index = 0 returns true for _PRESSED, coordinates can be extracted
 * with _X, _Y for index = 0. One can then query _PRESSED, _X, _Y with
 * index = 1, and so on.
 * Eventually _PRESSED will return false for an index. No further presses
 * are registered at this point. */
#define RETRO_DEVICE_POINTER      6

/* Buttons for the RetroPad (JOYPAD).
 * The placement of these is equivalent to placements on the
 * Super Nintendo controller.
 * L2/R2/L3/R3 buttons correspond to the PS1 DualShock.
 * Also used as id values for RETRO_DEVICE_INDEX_ANALOG_BUTTON */
#define RETRO_DEVICE_ID_JOYPAD_B        0
#define RETRO_DEVICE_ID_JOYPAD_Y        1
#define RETRO_DEVICE_ID_JOYPAD_SELECT   2
#define RETRO_DEVICE_ID_JOYPAD_START    3
#define RETRO_DEVICE_ID_JOYPAD_UP       4
#define RETRO_DEVICE_ID_JOYPAD_DOWN     5
#define RETRO_DEVICE_ID_JOYPAD_LEFT     6
#define RETRO_DEVICE_ID_JOYPAD_RIGHT    7
#define RETRO_DEVICE_ID_JOYPAD_A        8
#define RETRO_DEVICE_ID_JOYPAD_X        9
#define RETRO_DEVICE_ID_JOYPAD_L       10
#define RETRO_DEVICE_ID_JOYPAD_R       11
#define RETRO_DEVICE_ID_JOYPAD_L2      12
#define RETRO_DEVICE_ID_JOYPAD_R2      13
#define RETRO_DEVICE_ID_JOYPAD_L3      14
#define RETRO_DEVICE_ID_JOYPAD_R3      15

/* Index / Id values for ANALOG device. */
#define RETRO_DEVICE_INDEX_ANALOG_LEFT       0
#define RETRO_DEVICE_INDEX_ANALOG_RIGHT      1
#define RETRO_DEVICE_INDEX_ANALOG_BUTTON     2
#define RETRO_DEVICE_ID_ANALOG_X             0
#define RETRO_DEVICE_ID_ANALOG_Y             1

/* Id values for MOUSE. */
#define RETRO_DEVICE_ID_MOUSE_X                0
#define RETRO_DEVICE_ID_MOUSE_Y                1
#define RETRO_DEVICE_ID_MOUSE_LEFT             2
#define RETRO_DEVICE_ID_MOUSE_RIGHT            3
#define RETRO_DEVICE_ID_MOUSE_WHEELUP          4
#define RETRO_DEVICE_ID_MOUSE_WHEELDOWN        5
#define RETRO_DEVICE_ID_MOUSE_MIDDLE           6
#define RETRO_DEVICE_ID_MOUSE_HORIZ_WHEELUP    7
#define RETRO_DEVICE_ID_MOUSE_HORIZ_WHEELDOWN  8
#define RETRO_DEVICE_ID_MOUSE_BUTTON_4         9
#define RETRO_DEVICE_ID_MOUSE_BUTTON_5         10

/* Id values for LIGHTGUN. */
#define RETRO_DEVICE_ID_LIGHTGUN_SCREEN_X        13 /*Absolute Position*/
#define RETRO_DEVICE_ID_LIGHTGUN_SCREEN_Y        14 /*Absolute*/
#define RETRO_DEVICE_ID_LIGHTGUN_IS_OFFSCREEN    15 /*Status Check*/
#define RETRO_DEVICE_ID_LIGHTGUN_TRIGGER          2
#define RETRO_DEVICE_ID_LIGHTGUN_RELOAD          16 /*Forced off-screen shot*/
#define RETRO_DEVICE_ID_LIGHTGUN_AUX_A            3
#define RETRO_DEVICE_ID_LIGHTGUN_AUX_B            4
#define RETRO_DEVICE_ID_LIGHTGUN_START            6
#define RETRO_DEVICE_ID_LIGHTGUN_SELECT           7
#define RETRO_DEVICE_ID_LIGHTGUN_AUX_C            8
#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_UP          9
#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_DOWN       10
#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_LEFT       11
#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_RIGHT      12
/* deprecated */
#define RETRO_DEVICE_ID_LIGHTGUN_X                0 /*Relative Position*/
#define RETRO_DEVICE_ID_LIGHTGUN_Y                1 /*Relative*/
#define RETRO_DEVICE_ID_LIGHTGUN_CURSOR           3 /*Use Aux:A*/
#define RETRO_DEVICE_ID_LIGHTGUN_TURBO            4 /*Use Aux:B*/
#define RETRO_DEVICE_ID_LIGHTGUN_PAUSE            5 /*Use Start*/

/* Id values for POINTER. */
#define RETRO_DEVICE_ID_POINTER_X         0
#define RETRO_DEVICE_ID_POINTER_Y         1
#define RETRO_DEVICE_ID_POINTER_PRESSED   2

/* Returned from retro_get_region(). */
#define RETRO_REGION_NTSC  0
#define RETRO_REGION_PAL   1

/* Id values for LANGUAGE */
enum retro_language
{
   RETRO_LANGUAGE_ENGLISH             = 0,
   RETRO_LANGUAGE_JAPANESE            = 1,
   RETRO_LANGUAGE_FRENCH              = 2,
   RETRO_LANGUAGE_SPANISH             = 3,
   RETRO_LANGUAGE_GERMAN              = 4,
   RETRO_LANGUAGE_ITALIAN             = 5,
   RETRO_LANGUAGE_DUTCH               = 6,
   RETRO_LANGUAGE_PORTUGUESE_BRAZIL   = 7,
   RETRO_LANGUAGE_PORTUGUESE_PORTUGAL = 8,
   RETRO_LANGUAGE_RUSSIAN             = 9,
   RETRO_LANGUAGE_KOREAN              = 10,
   RETRO_LANGUAGE_CHINESE_TRADITIONAL = 11,
   RETRO_LANGUAGE_CHINESE_SIMPLIFIED  = 12,
   RETRO_LANGUAGE_ESPERANTO           = 13,
   RETRO_LANGUAGE_POLISH              = 14,
   RETRO_LANGUAGE_VIETNAMESE          = 15,
   RETRO_LANGUAGE_ARABIC              = 16,
   RETRO_LANGUAGE_LAST,

   /* Ensure sizeof(enum) == sizeof(int) */
   RETRO_LANGUAGE_DUMMY          = INT_MAX
};

/* Passed to retro_get_memory_data/size().
 * If the memory type doesn't apply to the
 * implementation NULL/0 can be returned.
 */
#define RETRO_MEMORY_MASK        0xff

/* Regular save RAM. This RAM is usually found on a game cartridge,
 * backed up by a battery.
 * If save game data is too complex for a single memory buffer,
 * the SAVE_DIRECTORY (preferably) or SYSTEM_DIRECTORY environment
 * callback can be used. */
#define RETRO_MEMORY_SAVE_RAM    0

/* Some games have a built-in clock to keep track of time.
 * This memory is usually just a couple of bytes to keep track of time.
 */
#define RETRO_MEMORY_RTC         1

/* System ram lets a frontend peek into a game systems main RAM. */
#define RETRO_MEMORY_SYSTEM_RAM  2

/* Video ram lets a frontend peek into a game systems video RAM (VRAM). */
#define RETRO_MEMORY_VIDEO_RAM   3

/* Keysyms used for ID in input state callback when polling RETRO_KEYBOARD. */
enum retro_key
{
   RETROK_UNKNOWN        = 0,
   RETROK_FIRST          = 0,
   RETROK_BACKSPACE      = 8,
   RETROK_TAB            = 9,
   RETROK_CLEAR          = 12,
   RETROK_RETURN         = 13,
   RETROK_PAUSE          = 19,
   RETROK_ESCAPE         = 27,
   RETROK_SPACE          = 32,
   RETROK_EXCLAIM        = 33,
   RETROK_QUOTEDBL       = 34,
   RETROK_HASH           = 35,
   RETROK_DOLLAR         = 36,
   RETROK_AMPERSAND      = 38,
   RETROK_QUOTE          = 39,
   RETROK_LEFTPAREN      = 40,
   RETROK_RIGHTPAREN     = 41,
   RETROK_ASTERISK       = 42,
   RETROK_PLUS           = 43,
   RETROK_COMMA          = 44,
   RETROK_MINUS          = 45,
   RETROK_PERIOD         = 46,
   RETROK_SLASH          = 47,
   RETROK_0              = 48,
   RETROK_1              = 49,
   RETROK_2              = 50,
   RETROK_3              = 51,
   RETROK_4              = 52,
   RETROK_5              = 53,
   RETROK_6              = 54,
   RETROK_7              = 55,
   RETROK_8              = 56,
   RETROK_9              = 57,
   RETROK_COLON          = 58,
   RETROK_SEMICOLON      = 59,
   RETROK_LESS           = 60,
   RETROK_EQUALS         = 61,
   RETROK_GREATER        = 62,
   RETROK_QUESTION       = 63,
   RETROK_AT             = 64,
   RETROK_LEFTBRACKET    = 91,
   RETROK_BACKSLASH      = 92,
   RETROK_RIGHTBRACKET   = 93,
   RETROK_CARET          = 94,
   RETROK_UNDERSCORE     = 95,
   RETROK_BACKQUOTE      = 96,
   RETROK_a              = 97,
   RETROK_b              = 98,
   RETROK_c              = 99,
   RETROK_d              = 100,
   RETROK_e              = 101,
   RETROK_f              = 102,
   RETROK_g              = 103,
   RETROK_h              = 104,
   RETROK_i              = 105,
   RETROK_j              = 106,
   RETROK_k              = 107,
   RETROK_l              = 108,
   RETROK_m              = 109,
   RETROK_n              = 110,
   RETROK_o              = 111,
   RETROK_p              = 112,
   RETROK_q              = 113,
   RETROK_r              = 114,
   RETROK_s              = 115,
   RETROK_t              = 116,
   RETROK_u              = 117,
   RETROK_v              = 118,
   RETROK_w              = 119,
   RETROK_x              = 120,
   RETROK_y              = 121,
   RETROK_z              = 122,
   RETROK_LEFTBRACE      = 123,
   RETROK_BAR            = 124,
   RETROK_RIGHTBRACE     = 125,
   RETROK_TILDE          = 126,
   RETROK_DELETE         = 127,

   RETROK_KP0            = 256,
   RETROK_KP1            = 257,
   RETROK_KP2            = 258,
   RETROK_KP3            = 259,
   RETROK_KP4            = 260,
   RETROK_KP5            = 261,
   RETROK_KP6            = 262,
   RETROK_KP7            = 263,
   RETROK_KP8            = 264,
   RETROK_KP9            = 265,
   RETROK_KP_PERIOD      = 266,
   RETROK_KP_DIVIDE      = 267,
   RETROK_KP_MULTIPLY    = 268,
   RETROK_KP_MINUS       = 269,
   RETROK_KP_PLUS        = 270,
   RETROK_KP_ENTER       = 271,
   RETROK_KP_EQUALS      = 272,

   RETROK_UP             = 273,
   RETROK_DOWN           = 274,
   RETROK_RIGHT          = 275,
   RETROK_LEFT           = 276,
   RETROK_INSERT         = 277,
   RETROK_HOME           = 278,
   RETROK_END            = 279,
   RETROK_PAGEUP         = 280,
   RETROK_PAGEDOWN       = 281,

   RETROK_F1             = 282,
   RETROK_F2             = 283,
   RETROK_F3             = 284,
   RETROK_F4             = 285,
   RETROK_F5             = 286,
   RETROK_F6             = 287,
   RETROK_F7             = 288,
   RETROK_F8             = 289,
   RETROK_F9             = 290,
   RETROK_F10            = 291,
   RETROK_F11            = 292,
   RETROK_F12            = 293,
   RETROK_F13            = 294,
   RETROK_F14            = 295,
   RETROK_F15            = 296,

   RETROK_NUMLOCK        = 300,
   RETROK_CAPSLOCK       = 301,
   RETROK_SCROLLOCK      = 302,
   RETROK_RSHIFT         = 303,
   RETROK_LSHIFT         = 304,
   RETROK_RCTRL          = 305,
   RETROK_LCTRL          = 306,
   RETROK_RALT           = 307,
   RETROK_LALT           = 308,
   RETROK_RMETA          = 309,
   RETROK_LMETA          = 310,
   RETROK_LSUPER         = 311,
   RETROK_RSUPER         = 312,
   RETROK_MODE           = 313,
   RETROK_COMPOSE        = 314,

   RETROK_HELP           = 315,
   RETROK_PRINT          = 316,
   RETROK_SYSREQ         = 317,
   RETROK_BREAK          = 318,
   RETROK_MENU           = 319,
   RETROK_POWER          = 320,
   RETROK_EURO           = 321,
   RETROK_UNDO           = 322,

   RETROK_LAST,

   RETROK_DUMMY          = INT_MAX /* Ensure sizeof(enum) == sizeof(int) */
};

enum retro_mod
{
   RETROKMOD_NONE       = 0x0000,

   RETROKMOD_SHIFT      = 0x01,
   RETROKMOD_CTRL       = 0x02,
   RETROKMOD_ALT        = 0x04,
   RETROKMOD_META       = 0x08,

   RETROKMOD_NUMLOCK    = 0x10,
   RETROKMOD_CAPSLOCK   = 0x20,
   RETROKMOD_SCROLLOCK  = 0x40,

   RETROKMOD_DUMMY = INT_MAX /* Ensure sizeof(enum) == sizeof(int) */
};

/* If set, this call is not part of the public libretro API yet. It can
 * change or be removed at any time. */
#define RETRO_ENVIRONMENT_EXPERIMENTAL 0x10000
/* Environment callback to be used internally in frontend. */
#define RETRO_ENVIRONMENT_PRIVATE 0x20000

/* Environment commands. */
#define RETRO_ENVIRONMENT_SET_ROTATION  1  /* const unsigned * --
                                            * Sets screen rotation of graphics.
                                            * Is only implemented if rotation can be accelerated by hardware.
                                            * Valid values are 0, 1, 2, 3, which rotates screen by 0, 90, 180,
                                            * 270 degrees counter-clockwise respectively.
                                            */
#define RETRO_ENVIRONMENT_GET_OVERSCAN  2  /* bool * --
                                            * Boolean value whether or not the implementation should use overscan,
                                            * or crop away overscan.
                                            */
#define RETRO_ENVIRONMENT_GET_CAN_DUPE  3  /* bool * --
                                            * Boolean value whether or not frontend supports frame duping,
                                            * passing NULL to video frame callback.
                                            */

                                           /* Environ 4, 5 are no longer supported (GET_VARIABLE / SET_VARIABLES),
                                            * and reserved to avoid possible ABI clash.
                                            */

#define RETRO_ENVIRONMENT_SET_MESSAGE   6  /* const struct retro_message * --
                                            * Sets a message to be displayed in implementation-specific manner
                                            * for a certain amount of 'frames'.
                                            * Should not be used for trivial messages, which should simply be
                                            * logged via RETRO_ENVIRONMENT_GET_LOG_INTERFACE (or as a
                                            * fallback, stderr).
                                            */
#define RETRO_ENVIRONMENT_SHUTDOWN      7  /* N/A (NULL) --
                                            * Requests the frontend to shutdown.
                                            * Should only be used if game has a specific
                                            * way to shutdown the game from a menu item or similar.
                                            */
#define RETRO_ENVIRONMENT_SET_PERFORMANCE_LEVEL 8
                                           /* const unsigned * --
                                            * Gives a hint to the frontend how demanding this implementation
                                            * is on a system. E.g. reporting a level of 2 means
                                            * this implementation should run decently on all frontends
                                            * of level 2 and up.
                                            *
                                            * It can be used by the frontend to potentially warn
                                            * about too demanding implementations.
                                            *
                                            * The levels are "floating".
                                            *
                                            * This function can be called on a per-game basis,
                                            * as certain games an implementation can play might be
                                            * particularly demanding.
                                            * If called, it should be called in retro_load_game().
                                            */
#define RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY 9
                                           /* const char ** --
                                            * Returns the "system" directory of the frontend.
                                            * This directory can be used to store system specific
                                            * content such as BIOSes, configuration data, etc.
                                            * The returned value can be NULL.
                                            * If so, no such directory is defined,
                                            * and it's up to the implementation to find a suitable directory.
                                            *
                                            * NOTE: Some cores used this folder also for "save" data such as
                                            * memory cards, etc, for lack of a better place to put it.
                                            * This is now discouraged, and if possible, cores should try to
                                            * use the new GET_SAVE_DIRECTORY.
                                            */
#define RETRO_ENVIRONMENT_SET_PIXEL_FORMAT 10
                                           /* const enum retro_pixel_format * --
                                            * Sets the internal pixel format used by the implementation.
                                            * The default pixel format is RETRO_PIXEL_FORMAT_0RGB1555.
                                            * This pixel format however, is deprecated (see enum retro_pixel_format).
                                            * If the call returns false, the frontend does not support this pixel
                                            * format.
                                            *
                                            * This function should be called inside retro_load_game() or
                                            * retro_get_system_av_info().
                                            */
#define RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS 11
                                           /* const struct retro_input_descriptor * --
                                            * Sets an array of retro_input_descriptors.
                                            * It is up to the frontend to present this in a usable way.
                                            * The array is terminated by retro_input_descriptor::description
                                            * being set to NULL.
                                            * This function can be called at any time, but it is recommended
                                            * to call it as early as possible.
                                            */
#define RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK 12
                                           /* const struct retro_keyboard_callback * --
                                            * Sets a callback function used to notify core about keyboard events.
                                            */
#define RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE 13
                                           /* const struct retro_disk_control_callback * --
                                            * Sets an interface which frontend can use to eject and insert
                                            * disk images.
                                            * This is used for games which consist of multiple images and
                                            * must be manually swapped out by the user (e.g. PSX).
                                            */
#define RETRO_ENVIRONMENT_SET_HW_RENDER 14
                                           /* struct retro_hw_render_callback * --
                                            * Sets an interface to let a libretro core render with
                                            * hardware acceleration.
                                            * Should be called in retro_load_game().
                                            * If successful, libretro cores will be able to render to a
                                            * frontend-provided framebuffer.
                                            * The size of this framebuffer will be at least as large as
                                            * max_width/max_height provided in get_av_info().
                                            * If HW rendering is used, pass only RETRO_HW_FRAME_BUFFER_VALID or
                                            * NULL to retro_video_refresh_t.
                                            */
#define RETRO_ENVIRONMENT_GET_VARIABLE 15
                                           /* struct retro_variable * --
                                            * Interface to acquire user-defined information from environment
                                            * that cannot feasibly be supported in a multi-system way.
                                            * 'key' should be set to a key which has already been set by
                                            * SET_VARIABLES.
                                            * 'data' will be set to a value or NULL.
                                            */
#define RETRO_ENVIRONMENT_SET_VARIABLES 16
                                           /* const struct retro_variable * --
                                            * Allows an implementation to signal the environment
                                            * which variables it might want to check for later using
                                            * GET_VARIABLE.
                                            * This allows the frontend to present these variables to
                                            * a user dynamically.
                                            * This should be called as early as possible (ideally in
                                            * retro_set_environment).
                                            *
                                            * 'data' points to an array of retro_variable structs
                                            * terminated by a { NULL, NULL } element.
                                            * retro_variable::key should be namespaced to not collide
                                            * with other implementations' keys. E.g. A core called
                                            * 'foo' should use keys named as 'foo_option'.
                                            * retro_variable::value should contain a human readable
                                            * description of the key as well as a '|' delimited list
                                            * of expected values.
                                            *
                                            * The number of possible options should be very limited,
                                            * i.e. it should be feasible to cycle through options
                                            * without a keyboard.
                                            *
                                            * First entry should be treated as a default.
                                            *
                                            * Example entry:
                                            * { "foo_option", "Speed hack coprocessor X; false|true" }
                                            *
                                            * Text before first ';' is description. This ';' must be
                                            * followed by a space, and followed by a list of possible
                                            * values split up with '|'.
                                            *
                                            * Only strings are operated on. The possible values will
                                            * generally be displayed and stored as-is by the frontend.
                                            */
#define RETRO_ENVIRONMENT_GET_VARIABLE_UPDATE 17
                                           /* bool * --
                                            * Result is set to true if some variables are updated by
                                            * frontend since last call to RETRO_ENVIRONMENT_GET_VARIABLE.
                                            * Variables should be queried with GET_VARIABLE.
                                            */
#define RETRO_ENVIRONMENT_SET_SUPPORT_NO_GAME 18
                                           /* const bool * --
                                            * If true, the libretro implementation supports calls to
                                            * retro_load_game() with NULL as argument.
                                            * Used by cores which can run without particular game data.
                                            * This should be called within retro_set_environment() only.
                                            */
#define RETRO_ENVIRONMENT_GET_LIBRETRO_PATH 19
                                           /* const char ** --
                                            * Retrieves the absolute path from where this libretro
                                            * implementation was loaded.
                                            * NULL is returned if the libretro was loaded statically
                                            * (i.e. linked statically to frontend), or if the path cannot be
                                            * determined.
                                            * Mostly useful in cooperation with SET_SUPPORT_NO_GAME as assets can
                                            * be loaded without ugly hacks.
                                            */

                                           /* Environment 20 was an obsolete version of SET_AUDIO_CALLBACK.
                                            * It was not used by any known core at the time,
                                            * and was removed from the API. */
#define RETRO_ENVIRONMENT_SET_AUDIO_CALLBACK 22
                                           /* const struct retro_audio_callback * --
                                            * Sets an interface which is used to notify a libretro core about audio
                                            * being available for writing.
                                            * The callback can be called from any thread, so a core using this must
                                            * have a thread safe audio implementation.
                                            * It is intended for games where audio and video are completely
                                            * asynchronous and audio can be generated on the fly.
                                            * This interface is not recommended for use with emulators which have
                                            * highly synchronous audio.
                                            *
                                            * The callback only notifies about writability; the libretro core still
                                            * has to call the normal audio callbacks
                                            * to write audio. The audio callbacks must be called from within the
                                            * notification callback.
                                            * The amount of audio data to write is up to the implementation.
                                            * Generally, the audio callback will be called continously in a loop.
                                            *
                                            * Due to thread safety guarantees and lack of sync between audio and
                                            * video, a frontend  can selectively disallow this interface based on
                                            * internal configuration. A core using this interface must also
                                            * implement the "normal" audio interface.
                                            *
                                            * A libretro core using SET_AUDIO_CALLBACK should also make use of
                                            * SET_FRAME_TIME_CALLBACK.
                                            */
#define RETRO_ENVIRONMENT_SET_FRAME_TIME_CALLBACK 21
                                           /* const struct retro_frame_time_callback * --
                                            * Lets the core know how much time has passed since last
                                            * invocation of retro_run().
                                            * The frontend can tamper with the timing to fake fast-forward,
                                            * slow-motion, frame stepping, etc.
                                            * In this case the delta time will use the reference value
                                            * in frame_time_callback..
                                            */
#define RETRO_ENVIRONMENT_GET_RUMBLE_INTERFACE 23
                                           /* struct retro_rumble_interface * --
                                            * Gets an interface which is used by a libretro core to set
                                            * state of rumble motors in controllers.
                                            * A strong and weak motor is supported, and they can be
                                            * controlled indepedently.
                                            */
#define RETRO_ENVIRONMENT_GET_INPUT_DEVICE_CAPABILITIES 24
                                           /* uint64_t * --
                                            * Gets a bitmask telling which device type are expected to be
                                            * handled properly in a call to retro_input_state_t.
                                            * Devices which are not handled or recognized always return
                                            * 0 in retro_input_state_t.
                                            * Example bitmask: caps = (1 << RETRO_DEVICE_JOYPAD) | (1 << RETRO_DEVICE_ANALOG).
                                            * Should only be called in retro_run().
                                            */
#define RETRO_ENVIRONMENT_GET_SENSOR_INTERFACE (25 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* struct retro_sensor_interface * --
                                            * Gets access to the sensor interface.
                                            * The purpose of this interface is to allow
                                            * setting state related to sensors such as polling rate,
                                            * enabling/disable it entirely, etc.
                                            * Reading sensor state is done via the normal
                                            * input_state_callback API.
                                            */
#define RETRO_ENVIRONMENT_GET_CAMERA_INTERFACE (26 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* struct retro_camera_callback * --
                                            * Gets an interface to a video camera driver.
                                            * A libretro core can use this interface to get access to a
                                            * video camera.
                                            * New video frames are delivered in a callback in same
                                            * thread as retro_run().
                                            *
                                            * GET_CAMERA_INTERFACE should be called in retro_load_game().
                                            *
                                            * Depending on the camera implementation used, camera frames
                                            * will be delivered as a raw framebuffer,
                                            * or as an OpenGL texture directly.
                                            *
                                            * The core has to tell the frontend here which types of
                                            * buffers can be handled properly.
                                            * An OpenGL texture can only be handled when using a
                                            * libretro GL core (SET_HW_RENDER).
                                            * It is recommended to use a libretro GL core when
                                            * using camera interface.
                                            *
                                            * The camera is not started automatically. The retrieved start/stop
                                            * functions must be used to explicitly
                                            * start and stop the camera driver.
                                            */
#define RETRO_ENVIRONMENT_GET_LOG_INTERFACE 27
                                           /* struct retro_log_callback * --
                                            * Gets an interface for logging. This is useful for
                                            * logging in a cross-platform way
                                            * as certain platforms cannot use stderr for logging.
                                            * It also allows the frontend to
                                            * show logging information in a more suitable way.
                                            * If this interface is not used, libretro cores should
                                            * log to stderr as desired.
                                            */
#define RETRO_ENVIRONMENT_GET_PERF_INTERFACE 28
                                           /* struct retro_perf_callback * --
                                            * Gets an interface for performance counters. This is useful
                                            * for performance logging in a cross-platform way and for detecting
                                            * architecture-specific features, such as SIMD support.
                                            */
#define RETRO_ENVIRONMENT_GET_LOCATION_INTERFACE 29
                                           /* struct retro_location_callback * --
                                            * Gets access to the location interface.
                                            * The purpose of this interface is to be able to retrieve
                                            * location-based information from the host device,
                                            * such as current latitude / longitude.
                                            */
#define RETRO_ENVIRONMENT_GET_CONTENT_DIRECTORY 30 /* Old name, kept for compatibility. */
#define RETRO_ENVIRONMENT_GET_CORE_ASSETS_DIRECTORY 30
                                           /* const char ** --
                                            * Returns the "core assets" directory of the frontend.
                                            * This directory can be used to store specific assets that the
                                            * core relies upon, such as art assets,
                                            * input data, etc etc.
                                            * The returned value can be NULL.
                                            * If so, no such directory is defined,
                                            * and it's up to the implementation to find a suitable directory.
                                            */
#define RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY 31
                                           /* const char ** --
                                            * Returns the "save" directory of the frontend.
                                            * This directory can be used to store SRAM, memory cards,
                                            * high scores, etc, if the libretro core
                                            * cannot use the regular memory interface (retro_get_memory_data()).
                                            *
                                            * NOTE: libretro cores used to check GET_SYSTEM_DIRECTORY for
                                            * similar things before.
                                            * They should still check GET_SYSTEM_DIRECTORY if they want to
                                            * be backwards compatible.
                                            * The path here can be NULL. It should only be non-NULL if the
                                            * frontend user has set a specific save path.
                                            */
#define RETRO_ENVIRONMENT_SET_SYSTEM_AV_INFO 32
                                           /* const struct retro_system_av_info * --
                                            * Sets a new av_info structure. This can only be called from
                                            * within retro_run().
                                            * This should *only* be used if the core is completely altering the
                                            * internal resolutions, aspect ratios, timings, sampling rate, etc.
                                            * Calling this can require a full reinitialization of video/audio
                                            * drivers in the frontend,
                                            *
                                            * so it is important to call it very sparingly, and usually only with
                                            * the users explicit consent.
                                            * An eventual driver reinitialize will happen so that video and
                                            * audio callbacks
                                            * happening after this call within the same retro_run() call will
                                            * target the newly initialized driver.
                                            *
                                            * This callback makes it possible to support configurable resolutions
                                            * in games, which can be useful to
                                            * avoid setting the "worst case" in max_width/max_height.
                                            *
                                            * ***HIGHLY RECOMMENDED*** Do not call this callback every time
                                            * resolution changes in an emulator core if it's
                                            * expected to be a temporary change, for the reasons of possible
                                            * driver reinitialization.
                                            * This call is not a free pass for not trying to provide
                                            * correct values in retro_get_system_av_info(). If you need to change
                                            * things like aspect ratio or nominal width/height,
                                            * use RETRO_ENVIRONMENT_SET_GEOMETRY, which is a softer variant
                                            * of SET_SYSTEM_AV_INFO.
                                            *
                                            * If this returns false, the frontend does not acknowledge a
                                            * changed av_info struct.
                                            */
#define RETRO_ENVIRONMENT_SET_PROC_ADDRESS_CALLBACK 33
                                           /* const struct retro_get_proc_address_interface * --
                                            * Allows a libretro core to announce support for the
                                            * get_proc_address() interface.
                                            * This interface allows for a standard way to extend libretro where
                                            * use of environment calls are too indirect,
                                            * e.g. for cases where the frontend wants to call directly into the core.
                                            *
                                            * If a core wants to expose this interface, SET_PROC_ADDRESS_CALLBACK
                                            * **MUST** be called from within retro_set_environment().
                                            */
#define RETRO_ENVIRONMENT_SET_SUBSYSTEM_INFO 34
                                           /* const struct retro_subsystem_info * --
                                            * This environment call introduces the concept of libretro "subsystems".
                                            * A subsystem is a variant of a libretro core which supports
                                            * different kinds of games.
                                            * The purpose of this is to support e.g. emulators which might
                                            * have special needs, e.g. Super Nintendo's Super GameBoy, Sufami Turbo.
                                            * It can also be used to pick among subsystems in an explicit way
                                            * if the libretro implementation is a multi-system emulator itself.
                                            *
                                            * Loading a game via a subsystem is done with retro_load_game_special(),
                                            * and this environment call allows a libretro core to expose which
                                            * subsystems are supported for use with retro_load_game_special().
                                            * A core passes an array of retro_game_special_info which is terminated
                                            * with a zeroed out retro_game_special_info struct.
                                            *
                                            * If a core wants to use this functionality, SET_SUBSYSTEM_INFO
                                            * **MUST** be called from within retro_set_environment().
                                            */
#define RETRO_ENVIRONMENT_SET_CONTROLLER_INFO 35
                                           /* const struct retro_controller_info * --
                                            * This environment call lets a libretro core tell the frontend
                                            * which controller types are recognized in calls to
                                            * retro_set_controller_port_device().
                                            *
                                            * Some emulators such as Super Nintendo
                                            * support multiple lightgun types which must be specifically
                                            * selected from.
                                            * It is therefore sometimes necessary for a frontend to be able
                                            * to tell the core about a special kind of input device which is
                                            * not covered by the libretro input API.
                                            *
                                            * In order for a frontend to understand the workings of an input device,
                                            * it must be a specialized type
                                            * of the generic device types already defined in the libretro API.
                                            *
                                            * Which devices are supported can vary per input port.
                                            * The core must pass an array of const struct retro_controller_info which
                                            * is terminated with a blanked out struct. Each element of the struct
                                            * corresponds to an ascending port index to
                                            * retro_set_controller_port_device().
                                            * Even if special device types are set in the libretro core,
                                            * libretro should only poll input based on the base input device types.
                                            */
#define RETRO_ENVIRONMENT_SET_MEMORY_MAPS (36 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* const struct retro_memory_map * --
                                            * This environment call lets a libretro core tell the frontend
                                            * about the memory maps this core emulates.
                                            * This can be used to implement, for example, cheats in a core-agnostic way.
                                            *
                                            * Should only be used by emulators; it doesn't make much sense for
                                            * anything else.
                                            * It is recommended to expose all relevant pointers through
                                            * retro_get_memory_* as well.
                                            *
                                            * Can be called from retro_init and retro_load_game.
                                            */
#define RETRO_ENVIRONMENT_SET_GEOMETRY 37
                                           /* const struct retro_game_geometry * --
                                            * This environment call is similar to SET_SYSTEM_AV_INFO for changing
                                            * video parameters, but provides a guarantee that drivers will not be
                                            * reinitialized.
                                            * This can only be called from within retro_run().
                                            *
                                            * The purpose of this call is to allow a core to alter nominal
                                            * width/heights as well as aspect ratios on-the-fly, which can be
                                            * useful for some emulators to change in run-time.
                                            *
                                            * max_width/max_height arguments are ignored and cannot be changed
                                            * with this call as this could potentially require a reinitialization or a
                                            * non-constant time operation.
                                            * If max_width/max_height are to be changed, SET_SYSTEM_AV_INFO is required.
                                            *
                                            * A frontend must guarantee that this environment call completes in
                                            * constant time.
                                            */
#define RETRO_ENVIRONMENT_GET_USERNAME 38
                                           /* const char **
                                            * Returns the specified username of the frontend, if specified by the user.
                                            * This username can be used as a nickname for a core that has online facilities
                                            * or any other mode where personalization of the user is desirable.
                                            * The returned value can be NULL.
                                            * If this environ callback is used by a core that requires a valid username,
                                            * a default username should be specified by the core.
                                            */
#define RETRO_ENVIRONMENT_GET_LANGUAGE 39
                                           /* unsigned * --
                                            * Returns the specified language of the frontend, if specified by the user.
                                            * It can be used by the core for localization purposes.
                                            */
#define RETRO_ENVIRONMENT_GET_CURRENT_SOFTWARE_FRAMEBUFFER (40 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* struct retro_framebuffer * --
                                            * Returns a preallocated framebuffer which the core can use for rendering
                                            * the frame into when not using SET_HW_RENDER.
                                            * The framebuffer returned from this call must not be used
                                            * after the current call to retro_run() returns.
                                            *
                                            * The goal of this call is to allow zero-copy behavior where a core
                                            * can render directly into video memory, avoiding extra bandwidth cost by copying
                                            * memory from core to video memory.
                                            *
                                            * If this call succeeds and the core renders into it,
                                            * the framebuffer pointer and pitch can be passed to retro_video_refresh_t.
                                            * If the buffer from GET_CURRENT_SOFTWARE_FRAMEBUFFER is to be used,
                                            * the core must pass the exact
                                            * same pointer as returned by GET_CURRENT_SOFTWARE_FRAMEBUFFER;
                                            * i.e. passing a pointer which is offset from the
                                            * buffer is undefined. The width, height and pitch parameters
                                            * must also match exactly to the values obtained from GET_CURRENT_SOFTWARE_FRAMEBUFFER.
                                            *
                                            * It is possible for a frontend to return a different pixel format
                                            * than the one used in SET_PIXEL_FORMAT. This can happen if the frontend
                                            * needs to perform conversion.
                                            *
                                            * It is still valid for a core to render to a different buffer
                                            * even if GET_CURRENT_SOFTWARE_FRAMEBUFFER succeeds.
                                            *
                                            * A frontend must make sure that the pointer obtained from this function is
                                            * writeable (and readable).
                                            */

#define RETRO_ENVIRONMENT_SET_HW_SHARED_CONTEXT (44 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* N/A (null) * --
                                            * The frontend will try to use a 'shared' hardware context (mostly applicable
                                            * to OpenGL) when a hardware context is being set up.
                                            *
                                            * Returns true if the frontend supports shared hardware contexts and false
                                            * if the frontend does not support shared hardware contexts.
                                            *
                                            * This will do nothing on its own until SET_HW_RENDER env callbacks are
                                            * being used.
                                            */

#define RETRO_ENVIRONMENT_GET_VFS_INTERFACE (45 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* struct retro_vfs_interface_info * --
                                            * Gets access to the VFS interface.
                                            * VFS presence needs to be queried prior to load_game or any
                                            * get_system/save/other_directory being called to let front end know
                                            * core supports VFS before it starts handing out paths.
                                            * It is recomended to do so in retro_set_environment */

/* VFS functionality */

/* File paths:
 * File paths passed as parameters when using this api shall be well formed unix-style,
 * using "/" (unquoted forward slash) as directory separator regardless of the platform's native separator.
 * Paths shall also include at least one forward slash ("game.bin" is an invalid path, use "./game.bin" instead).
 * Other than the directory separator, cores shall not make assumptions about path format:
 * "C:/path/game.bin", "http://example.com/game.bin", "#game/game.bin", "./game.bin" (without quotes) are all valid paths.
 * Cores may replace the basename or remove path components from the end, and/or add new components;
 * however, cores shall not append "./", "../" or multiple consecutive forward slashes ("//") to paths they request to front end.
 * The frontend is encouraged to make such paths work as well as it can, but is allowed to give up if the core alters paths too much.
 * Frontends are encouraged, but not required, to support native file system paths (modulo replacing the directory separator, if applicable).
 * Cores are allowed to try using them, but must remain functional if the front rejects such requests.
 * Cores are encouraged to use the libretro-common filestream functions for file I/O,
 * as they seamlessly integrate with VFS, deal with directory separator replacement as appropriate
 * and provide platform-specific fallbacks in cases where front ends do not support VFS. */

/* Opaque file handle
 * Introduced in VFS API v1 */
struct retro_vfs_file_handle;

/* File open flags
 * Introduced in VFS API v1 */
#define RETRO_VFS_FILE_ACCESS_READ            (1 << 0) /* Read only mode */
#define RETRO_VFS_FILE_ACCESS_WRITE           (1 << 1) /* Write only mode, discard contents and overwrites existing file unless RETRO_VFS_FILE_ACCESS_UPDATE is also specified */
#define RETRO_VFS_FILE_ACCESS_READ_WRITE      (RETRO_VFS_FILE_ACCESS_READ | RETRO_VFS_FILE_ACCESS_WRITE) /* Read-write mode, discard contents and overwrites existing file unless RETRO_VFS_FILE_ACCESS_UPDATE is also specified*/
#define RETRO_VFS_FILE_ACCESS_UPDATE_EXISTING (1 << 2) /* Prevents discarding content of existing files opened for writing */

/* These are only hints. The frontend may choose to ignore them. Other than RAM/CPU/etc use,
   and how they react to unlikely external interference (for example someone else writing to that file,
   or the file's server going down), behavior will not change. */
#define RETRO_VFS_FILE_ACCESS_HINT_NONE              (0)
/* Indicate that the file will be accessed many times. The frontend should aggressively cache everything. */
#define RETRO_VFS_FILE_ACCESS_HINT_FREQUENT_ACCESS   (1 << 0)

/* Seek positions */
#define RETRO_VFS_SEEK_POSITION_START    0
#define RETRO_VFS_SEEK_POSITION_CURRENT  1
#define RETRO_VFS_SEEK_POSITION_END      2

/* Get path from opaque handle. Returns the exact same path passed to file_open when getting the handle
 * Introduced in VFS API v1 */
typedef const char *(RETRO_CALLCONV *retro_vfs_get_path_t)(struct retro_vfs_file_handle *stream);

/* Open a file for reading or writing. If path points to a directory, this will
 * fail. Returns the opaque file handle, or NULL for error.
 * Introduced in VFS API v1 */
typedef struct retro_vfs_file_handle *(RETRO_CALLCONV *retro_vfs_open_t)(const char *path, unsigned mode, unsigned hints);

/* Close the file and release its resources. Must be called if open_file returns non-NULL. Returns 0 on succes, -1 on failure.
 * Whether the call succeeds ot not, the handle passed as parameter becomes invalid and should no longer be used.
 * Introduced in VFS API v1 */
typedef int (RETRO_CALLCONV *retro_vfs_close_t)(struct retro_vfs_file_handle *stream);

/* Return the size of the file in bytes, or -1 for error.
 * Introduced in VFS API v1 */
typedef int64_t (RETRO_CALLCONV *retro_vfs_size_t)(struct retro_vfs_file_handle *stream);

/* Get the current read / write position for the file. Returns - 1 for error.
 * Introduced in VFS API v1 */
typedef int64_t (RETRO_CALLCONV *retro_vfs_tell_t)(struct retro_vfs_file_handle *stream);

/* Set the current read/write position for the file. Returns the new position, -1 for error.
 * Introduced in VFS API v1 */
typedef int64_t (RETRO_CALLCONV *retro_vfs_seek_t)(struct retro_vfs_file_handle *stream, int64_t offset, int seek_position);

/* Read data from a file. Returns the number of bytes read, or -1 for error.
 * Introduced in VFS API v1 */
typedef int64_t (RETRO_CALLCONV *retro_vfs_read_t)(struct retro_vfs_file_handle *stream, void *s, uint64_t len);

/* Write data to a file. Returns the number of bytes written, or -1 for error.
 * Introduced in VFS API v1 */
typedef int64_t (RETRO_CALLCONV *retro_vfs_write_t)(struct retro_vfs_file_handle *stream, const void *s, uint64_t len);

/* Flush pending writes to file, if using buffered IO. Returns 0 on sucess, or -1 on failure.
 * Introduced in VFS API v1 */
typedef int (RETRO_CALLCONV *retro_vfs_flush_t)(struct retro_vfs_file_handle *stream);

/* Delete the specified file. Returns 0 on success, -1 on failure
 * Introduced in VFS API v1 */
typedef int (RETRO_CALLCONV *retro_vfs_remove_t)(const char *path);

/* Rename the specified file. Returns 0 on success, -1 on failure
 * Introduced in VFS API v1 */
typedef int (RETRO_CALLCONV *retro_vfs_rename_t)(const char *old_path, const char *new_path);

struct retro_vfs_interface
{
	retro_vfs_get_path_t get_path;
	retro_vfs_open_t open;
	retro_vfs_close_t close;
	retro_vfs_size_t size;
	retro_vfs_tell_t tell;
	retro_vfs_seek_t seek;
	retro_vfs_read_t read;
	retro_vfs_write_t write;
	retro_vfs_flush_t flush;
	retro_vfs_remove_t remove;
	retro_vfs_rename_t rename;
};

struct retro_vfs_interface_info
{
   /* Set by core: should this be higher than the version the front end supports,
    * front end will return false in the RETRO_ENVIRONMENT_GET_VFS_INTERFACE call
    * Introduced in VFS API v1 */
   uint32_t required_interface_version;

   /* Frontend writes interface pointer here. The frontend also sets the actual
    * version, must be at least required_interface_version.
    * Introduced in VFS API v1 */
   struct retro_vfs_interface *iface;
};

enum retro_hw_render_interface_type
{
   RETRO_HW_RENDER_INTERFACE_VULKAN = 0,
   RETRO_HW_RENDER_INTERFACE_DUMMY = INT_MAX
};

/* Base struct. All retro_hw_render_interface_* types
 * contain at least these fields. */
struct retro_hw_render_interface
{
   enum retro_hw_render_interface_type interface_type;
   unsigned interface_version;
};


#define RETRO_ENVIRONMENT_GET_LED_INTERFACE (46 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* struct retro_led_interface * --
                                            * Gets an interface which is used by a libretro core to set 
                                            * state of LEDs.
                                            */

typedef void (RETRO_CALLCONV *retro_set_led_state_t)(int led, int state);
struct retro_led_interface
{
    retro_set_led_state_t set_led_state;
};


#define RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE (41 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* const struct retro_hw_render_interface ** --
                                            * Returns an API specific rendering interface for accessing API specific data.
                                            * Not all HW rendering APIs support or need this.
                                            * The contents of the returned pointer is specific to the rendering API
                                            * being used. See the various headers like libretro_vulkan.h, etc.
                                            *
                                            * GET_HW_RENDER_INTERFACE cannot be called before context_reset has been called.
                                            * Similarly, after context_destroyed callback returns,
                                            * the contents of the HW_RENDER_INTERFACE are invalidated.
                                            */

#define RETRO_ENVIRONMENT_SET_SUPPORT_ACHIEVEMENTS (42 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* const bool * --
                                            * If true, the libretro implementation supports achievements
                                            * either via memory descriptors set with RETRO_ENVIRONMENT_SET_MEMORY_MAPS
                                            * or via retro_get_memory_data/retro_get_memory_size.
                                            *
                                            * This must be called before the first call to retro_run.
                                            */

enum retro_hw_render_context_negotiation_interface_type
{
   RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_VULKAN = 0,
   RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_DUMMY = INT_MAX
};

/* Base struct. All retro_hw_render_context_negotiation_interface_* types
 * contain at least these fields. */
struct retro_hw_render_context_negotiation_interface
{
   enum retro_hw_render_context_negotiation_interface_type interface_type;
   unsigned interface_version;
};
#define RETRO_ENVIRONMENT_SET_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE (43 | RETRO_ENVIRONMENT_EXPERIMENTAL)
                                           /* const struct retro_hw_render_context_negotiation_interface * --
                                            * Sets an interface which lets the libretro core negotiate with frontend how a context is created.
                                            * The semantics of this interface depends on which API is used in SET_HW_RENDER earlier.
                                            * This interface will be used when the frontend is trying to create a HW rendering context,
                                            * so it will be used after SET_HW_RENDER, but before the context_reset callback.
                                            */

/* Serialized state is incomplete in some way. Set if serialization is
 * usable in typical end-user cases but should not be relied upon to
 * implement frame-sensitive frontend features such as netplay or
 * rerecording. */
#define RETRO_SERIALIZATION_QUIRK_INCOMPLETE (1 << 0)
/* The core must spend some time initializing before serialization is
 * supported. retro_serialize() will initially fail; retro_unserialize()
 * and retro_serialize_size() may or may not work correctly either. */
#define RETRO_SERIALIZATION_QUIRK_MUST_INITIALIZE (1 << 1)
/* Serialization size may change within a session. */
#define RETRO_SERIALIZATION_QUIRK_CORE_VARIABLE_SIZE (1 << 2)
/* Set by the frontend to acknowledge that it supports variable-sized
 * states. */
#define RETRO_SERIALIZATION_QUIRK_FRONT_VARIABLE_SIZE (1 << 3)
/* Serialized state can only be loaded during the same session. */
#define RETRO_SERIALIZATION_QUIRK_SINGLE_SESSION (1 << 4)
/* Serialized state cannot be loaded on an architecture with a different
 * endianness from the one it was saved on. */
#define RETRO_SERIALIZATION_QUIRK_ENDIAN_DEPENDENT (1 << 5)
/* Serialized state cannot be loaded on a different platform from the one it
 * was saved on for reasons other than endianness, such as word size
 * dependence */
#define RETRO_SERIALIZATION_QUIRK_PLATFORM_DEPENDENT (1 << 6)

#define RETRO_ENVIRONMENT_SET_SERIALIZATION_QUIRKS 44
                                           /* uint64_t * --
                                            * Sets quirk flags associated with serialization. The frontend will zero any flags it doesn't
                                            * recognize or support. Should be set in either retro_init or retro_load_game, but not both.
                                            */

#define RETRO_MEMDESC_CONST     (1 << 0)   /* The frontend will never change this memory area once retro_load_game has returned. */
#define RETRO_MEMDESC_BIGENDIAN (1 << 1)   /* The memory area contains big endian data. Default is little endian. */
#define RETRO_MEMDESC_ALIGN_2   (1 << 16)  /* All memory access in this area is aligned to their own size, or 2, whichever is smaller. */
#define RETRO_MEMDESC_ALIGN_4   (2 << 16)
#define RETRO_MEMDESC_ALIGN_8   (3 << 16)
#define RETRO_MEMDESC_MINSIZE_2 (1 << 24)  /* All memory in this region is accessed at least 2 bytes at the time. */
#define RETRO_MEMDESC_MINSIZE_4 (2 << 24)
#define RETRO_MEMDESC_MINSIZE_8 (3 << 24)
struct retro_memory_descriptor
{
   uint64_t flags;

   /* Pointer to the start of the relevant ROM or RAM chip.
    * It's strongly recommended to use 'offset' if possible, rather than
    * doing math on the pointer.
    *
    * If the same byte is mapped my multiple descriptors, their descriptors
    * must have the same pointer.
    * If 'start' does not point to the first byte in the pointer, put the
    * difference in 'offset' instead.
    *
    * May be NULL if there's nothing usable here (e.g. hardware registers and
    * open bus). No flags should be set if the pointer is NULL.
    * It's recommended to minimize the number of descriptors if possible,
    * but not mandatory. */
   void *ptr;
   size_t offset;

   /* This is the location in the emulated address space
    * where the mapping starts. */
   size_t start;

   /* Which bits must be same as in 'start' for this mapping to apply.
    * The first memory descriptor to claim a certain byte is the one
    * that applies.
    * A bit which is set in 'start' must also be set in this.
    * Can be zero, in which case each byte is assumed mapped exactly once.
    * In this case, 'len' must be a power of two. */
   size_t select;

   /* If this is nonzero, the set bits are assumed not connected to the
    * memory chip's address pins. */
   size_t disconnect;

   /* This one tells the size of the current memory area.
    * If, after start+disconnect are applied, the address is higher than
    * this, the highest bit of the address is cleared.
    *
    * If the address is still too high, the next highest bit is cleared.
    * Can be zero, in which case it's assumed to be infinite (as limited
    * by 'select' and 'disconnect'). */
   size_t len;

   /* To go from emulated address to physical address, the following
    * order applies:
    * Subtract 'start', pick off 'disconnect', apply 'len', add 'offset'. */

   /* The address space name must consist of only a-zA-Z0-9_-,
    * should be as short as feasible (maximum length is 8 plus the NUL),
    * and may not be any other address space plus one or more 0-9A-F
    * at the end.
    * However, multiple memory descriptors for the same address space is
    * allowed, and the address space name can be empty. NULL is treated
    * as empty.
    *
    * Address space names are case sensitive, but avoid lowercase if possible.
    * The same pointer may exist in multiple address spaces.
    *
    * Examples:
    * blank+blank - valid (multiple things may be mapped in the same namespace)
    * 'Sp'+'Sp' - valid (multiple things may be mapped in the same namespace)
    * 'A'+'B' - valid (neither is a prefix of each other)
    * 'S'+blank - valid ('S' is not in 0-9A-F)
    * 'a'+blank - valid ('a' is not in 0-9A-F)
    * 'a'+'A' - valid (neither is a prefix of each other)
    * 'AR'+blank - valid ('R' is not in 0-9A-F)
    * 'ARB'+blank - valid (the B can't be part of the address either, because
    *                      there is no namespace 'AR')
    * blank+'B' - not valid, because it's ambigous which address space B1234
    *             would refer to.
    * The length can't be used for that purpose; the frontend may want
    * to append arbitrary data to an address, without a separator. */
   const char *addrspace;

   /* TODO: When finalizing this one, add a description field, which should be
    * "WRAM" or something roughly equally long. */

   /* TODO: When finalizing this one, replace 'select' with 'limit', which tells
    * which bits can vary and still refer to the same address (limit = ~select).
    * TODO: limit? range? vary? something else? */

   /* TODO: When finalizing this one, if 'len' is above what 'select' (or
    * 'limit') allows, it's bankswitched. Bankswitched data must have both 'len'
    * and 'select' != 0, and the mappings don't tell how the system switches the
    * banks. */

   /* TODO: When finalizing this one, fix the 'len' bit removal order.
    * For len=0x1800, pointer 0x1C00 should go to 0x1400, not 0x0C00.
    * Algorithm: Take bits highest to lowest, but if it goes above len, clear
    * the most recent addition and continue on the next bit.
    * TODO: Can the above be optimized? Is "remove the lowest bit set in both
    * pointer and 'len'" equivalent? */

   /* TODO: Some emulators (MAME?) emulate big endian systems by only accessing
    * the emulated memory in 32-bit chunks, native endian. But that's nothing
    * compared to Darek Mihocka <http://www.emulators.com/docs/nx07_vm101.htm>
    * (section Emulation 103 - Nearly Free Byte Reversal) - he flips the ENTIRE
    * RAM backwards! I'll want to represent both of those, via some flags.
    *
    * I suspect MAME either didn't think of that idea, or don't want the #ifdef.
    * Not sure which, nor do I really care. */

   /* TODO: Some of those flags are unused and/or don't really make sense. Clean
    * them up. */
};

/* The frontend may use the largest value of 'start'+'select' in a
 * certain namespace to infer the size of the address space.
 *
 * If the address space is larger than that, a mapping with .ptr=NULL
 * should be at the end of the array, with .select set to all ones for
 * as long as the address space is big.
 *
 * Sample descriptors (minus .ptr, and RETRO_MEMFLAG_ on the flags):
 * SNES WRAM:
 * .start=0x7E0000, .len=0x20000
 * (Note that this must be mapped before the ROM in most cases; some of the
 * ROM mappers
 * try to claim $7E0000, or at least $7E8000.)
 * SNES SPC700 RAM:
 * .addrspace="S", .len=0x10000
 * SNES WRAM mirrors:
 * .flags=MIRROR, .start=0x000000, .select=0xC0E000, .len=0x2000
 * .flags=MIRROR, .start=0x800000, .select=0xC0E000, .len=0x2000
 * SNES WRAM mirrors, alternate equivalent descriptor:
 * .flags=MIRROR, .select=0x40E000, .disconnect=~0x1FFF
 * (Various similar constructions can be created by combining parts of
 * the above two.)
 * SNES LoROM (512KB, mirrored a couple of times):
 * .flags=CONST, .start=0x008000, .select=0x408000, .disconnect=0x8000, .len=512*1024
 * .flags=CONST, .start=0x400000, .select=0x400000, .disconnect=0x8000, .len=512*1024
 * SNES HiROM (4MB):
 * .flags=CONST,                 .start=0x400000, .select=0x400000, .len=4*1024*1024
 * .flags=CONST, .offset=0x8000, .start=0x008000, .select=0x408000, .len=4*1024*1024
 * SNES ExHiROM (8MB):
 * .flags=CONST, .offset=0,                  .start=0xC00000, .select=0xC00000, .len=4*1024*1024
 * .flags=CONST, .offset=4*1024*1024,        .start=0x400000, .select=0xC00000, .len=4*1024*1024
 * .flags=CONST, .offset=0x8000,             .start=0x808000, .select=0xC08000, .len=4*1024*1024
 * .flags=CONST, .offset=4*1024*1024+0x8000, .start=0x008000, .select=0xC08000, .len=4*1024*1024
 * Clarify the size of the address space:
 * .ptr=NULL, .select=0xFFFFFF
 * .len can be implied by .select in many of them, but was included for clarity.
 */

struct retro_memory_map
{
   const struct retro_memory_descriptor *descriptors;
   unsigned num_descriptors;
};

struct retro_controller_description
{
   /* Human-readable description of the controller. Even if using a generic
    * input device type, this can be set to the particular device type the
    * core uses. */
   const char *desc;

   /* Device type passed to retro_set_controller_port_device(). If the device
    * type is a sub-class of a generic input device type, use the
    * RETRO_DEVICE_SUBCLASS macro to create an ID.
    *
    * E.g. RETRO_DEVICE_SUBCLASS(RETRO_DEVICE_JOYPAD, 1). */
   unsigned id;
};

struct retro_controller_info
{
   const struct retro_controller_description *types;
   unsigned num_types;
};

struct retro_subsystem_memory_info
{
   /* The extension associated with a memory type, e.g. "psram". */
   const char *extension;

   /* The memory type for retro_get_memory(). This should be at
    * least 0x100 to avoid conflict with standardized
    * libretro memory types. */
   unsigned type;
};

struct retro_subsystem_rom_info
{
   /* Describes what the content is (SGB BIOS, GB ROM, etc). */
   const char *desc;

   /* Same definition as retro_get_system_info(). */
   const char *valid_extensions;

   /* Same definition as retro_get_system_info(). */
   bool need_fullpath;

   /* Same definition as retro_get_system_info(). */
   bool block_extract;

   /* This is set if the content is required to load a game.
    * If this is set to false, a zeroed-out retro_game_info can be passed. */
   bool required;

   /* Content can have multiple associated persistent
    * memory types (retro_get_memory()). */
   const struct retro_subsystem_memory_info *memory;
   unsigned num_memory;
};

struct retro_subsystem_info
{
   /* Human-readable string of the subsystem type, e.g. "Super GameBoy" */
   const char *desc;

   /* A computer friendly short string identifier for the subsystem type.
    * This name must be [a-z].
    * E.g. if desc is "Super GameBoy", this can be "sgb".
    * This identifier can be used for command-line interfaces, etc.
    */
   const char *ident;

   /* Infos for each content file. The first entry is assumed to be the
    * "most significant" content for frontend purposes.
    * E.g. with Super GameBoy, the first content should be the GameBoy ROM,
    * as it is the most "significant" content to a user.
    * If a frontend creates new file paths based on the content used
    * (e.g. savestates), it should use the path for the first ROM to do so. */
   const struct retro_subsystem_rom_info *roms;

   /* Number of content files associated with a subsystem. */
   unsigned num_roms;

   /* The type passed to retro_load_game_special(). */
   unsigned id;
};

typedef void (RETRO_CALLCONV *retro_proc_address_t)(void);

/* libretro API extension functions:
 * (None here so far).
 *
 * Get a symbol from a libretro core.
 * Cores should only return symbols which are actual
 * extensions to the libretro API.
 *
 * Frontends should not use this to obtain symbols to standard
 * libretro entry points (static linking or dlsym).
 *
 * The symbol name must be equal to the function name,
 * e.g. if void retro_foo(void); exists, the symbol must be called "retro_foo".
 * The returned function pointer must be cast to the corresponding type.
 */
typedef retro_proc_address_t (RETRO_CALLCONV *retro_get_proc_address_t)(const char *sym);

struct retro_get_proc_address_interface
{
   retro_get_proc_address_t get_proc_address;
};

enum retro_log_level
{
   RETRO_LOG_DEBUG = 0,
   RETRO_LOG_INFO,
   RETRO_LOG_WARN,
   RETRO_LOG_ERROR,

   RETRO_LOG_DUMMY = INT_MAX
};

/* Logging function. Takes log level argument as well. */
typedef void (RETRO_CALLCONV *retro_log_printf_t)(enum retro_log_level level,
      const char *fmt, ...);

struct retro_log_callback
{
   retro_log_printf_t log;
};

/* Performance related functions */

/* ID values for SIMD CPU features */
#define RETRO_SIMD_SSE      (1 << 0)
#define RETRO_SIMD_SSE2     (1 << 1)
#define RETRO_SIMD_VMX      (1 << 2)
#define RETRO_SIMD_VMX128   (1 << 3)
#define RETRO_SIMD_AVX      (1 << 4)
#define RETRO_SIMD_NEON     (1 << 5)
#define RETRO_SIMD_SSE3     (1 << 6)
#define RETRO_SIMD_SSSE3    (1 << 7)
#define RETRO_SIMD_MMX      (1 << 8)
#define RETRO_SIMD_MMXEXT   (1 << 9)
#define RETRO_SIMD_SSE4     (1 << 10)
#define RETRO_SIMD_SSE42    (1 << 11)
#define RETRO_SIMD_AVX2     (1 << 12)
#define RETRO_SIMD_VFPU     (1 << 13)
#define RETRO_SIMD_PS       (1 << 14)
#define RETRO_SIMD_AES      (1 << 15)
#define RETRO_SIMD_VFPV3    (1 << 16)
#define RETRO_SIMD_VFPV4    (1 << 17)
#define RETRO_SIMD_POPCNT   (1 << 18)
#define RETRO_SIMD_MOVBE    (1 << 19)
#define RETRO_SIMD_CMOV     (1 << 20)
#define RETRO_SIMD_ASIMD    (1 << 21)

typedef uint64_t retro_perf_tick_t;
typedef int64_t retro_time_t;

struct retro_perf_counter
{
   const char *ident;
   retro_perf_tick_t start;
   retro_perf_tick_t total;
   retro_perf_tick_t call_cnt;

   bool registered;
};

/* Returns current time in microseconds.
 * Tries to use the most accurate timer available.
 */
typedef retro_time_t (RETRO_CALLCONV *retro_perf_get_time_usec_t)(void);

/* A simple counter. Usually nanoseconds, but can also be CPU cycles.
 * Can be used directly if desired (when creating a more sophisticated
 * performance counter system).
 * */
typedef retro_perf_tick_t (RETRO_CALLCONV *retro_perf_get_counter_t)(void);

/* Returns a bit-mask of detected CPU features (RETRO_SIMD_*). */
typedef uint64_t (RETRO_CALLCONV *retro_get_cpu_features_t)(void);

/* Asks frontend to log and/or display the state of performance counters.
 * Performance counters can always be poked into manually as well.
 */
typedef void (RETRO_CALLCONV *retro_perf_log_t)(void);

/* Register a performance counter.
 * ident field must be set with a discrete value and other values in
 * retro_perf_counter must be 0.
 * Registering can be called multiple times. To avoid calling to
 * frontend redundantly, you can check registered field first. */
typedef void (RETRO_CALLCONV *retro_perf_register_t)(struct retro_perf_counter *counter);

/* Starts a registered counter. */
typedef void (RETRO_CALLCONV *retro_perf_start_t)(struct retro_perf_counter *counter);

/* Stops a registered counter. */
typedef void (RETRO_CALLCONV *retro_perf_stop_t)(struct retro_perf_counter *counter);

/* For convenience it can be useful to wrap register, start and stop in macros.
 * E.g.:
 * #ifdef LOG_PERFORMANCE
 * #define RETRO_PERFORMANCE_INIT(perf_cb, name) static struct retro_perf_counter name = {#name}; if (!name.registered) perf_cb.perf_register(&(name))
 * #define RETRO_PERFORMANCE_START(perf_cb, name) perf_cb.perf_start(&(name))
 * #define RETRO_PERFORMANCE_STOP(perf_cb, name) perf_cb.perf_stop(&(name))
 * #else
 * ... Blank macros ...
 * #endif
 *
 * These can then be used mid-functions around code snippets.
 *
 * extern struct retro_perf_callback perf_cb;  * Somewhere in the core.
 *
 * void do_some_heavy_work(void)
 * {
 *    RETRO_PERFORMANCE_INIT(cb, work_1;
 *    RETRO_PERFORMANCE_START(cb, work_1);
 *    heavy_work_1();
 *    RETRO_PERFORMANCE_STOP(cb, work_1);
 *
 *    RETRO_PERFORMANCE_INIT(cb, work_2);
 *    RETRO_PERFORMANCE_START(cb, work_2);
 *    heavy_work_2();
 *    RETRO_PERFORMANCE_STOP(cb, work_2);
 * }
 *
 * void retro_deinit(void)
 * {
 *    perf_cb.perf_log();  * Log all perf counters here for example.
 * }
 */

struct retro_perf_callback
{
   retro_perf_get_time_usec_t    get_time_usec;
   retro_get_cpu_features_t      get_cpu_features;

   retro_perf_get_counter_t      get_perf_counter;
   retro_perf_register_t         perf_register;
   retro_perf_start_t            perf_start;
   retro_perf_stop_t             perf_stop;
   retro_perf_log_t              perf_log;
};

/* FIXME: Document the sensor API and work out behavior.
 * It will be marked as experimental until then.
 */
enum retro_sensor_action
{
   RETRO_SENSOR_ACCELEROMETER_ENABLE = 0,
   RETRO_SENSOR_ACCELEROMETER_DISABLE,

   RETRO_SENSOR_DUMMY = INT_MAX
};

/* Id values for SENSOR types. */
#define RETRO_SENSOR_ACCELEROMETER_X 0
#define RETRO_SENSOR_ACCELEROMETER_Y 1
#define RETRO_SENSOR_ACCELEROMETER_Z 2

typedef bool (RETRO_CALLCONV *retro_set_sensor_state_t)(unsigned port,
      enum retro_sensor_action action, unsigned rate);

typedef float (RETRO_CALLCONV *retro_sensor_get_input_t)(unsigned port, unsigned id);

struct retro_sensor_interface
{
   retro_set_sensor_state_t set_sensor_state;
   retro_sensor_get_input_t get_sensor_input;
};

enum retro_camera_buffer
{
   RETRO_CAMERA_BUFFER_OPENGL_TEXTURE = 0,
   RETRO_CAMERA_BUFFER_RAW_FRAMEBUFFER,

   RETRO_CAMERA_BUFFER_DUMMY = INT_MAX
};

/* Starts the camera driver. Can only be called in retro_run(). */
typedef bool (RETRO_CALLCONV *retro_camera_start_t)(void);

/* Stops the camera driver. Can only be called in retro_run(). */
typedef void (RETRO_CALLCONV *retro_camera_stop_t)(void);

/* Callback which signals when the camera driver is initialized
 * and/or deinitialized.
 * retro_camera_start_t can be called in initialized callback.
 */
typedef void (RETRO_CALLCONV *retro_camera_lifetime_status_t)(void);

/* A callback for raw framebuffer data. buffer points to an XRGB8888 buffer.
 * Width, height and pitch are similar to retro_video_refresh_t.
 * First pixel is top-left origin.
 */
typedef void (RETRO_CALLCONV *retro_camera_frame_raw_framebuffer_t)(const uint32_t *buffer,
      unsigned width, unsigned height, size_t pitch);

/* A callback for when OpenGL textures are used.
 *
 * texture_id is a texture owned by camera driver.
 * Its state or content should be considered immutable, except for things like
 * texture filtering and clamping.
 *
 * texture_target is the texture target for the GL texture.
 * These can include e.g. GL_TEXTURE_2D, GL_TEXTURE_RECTANGLE, and possibly
 * more depending on extensions.
 *
 * affine points to a packed 3x3 column-major matrix used to apply an affine
 * transform to texture coordinates. (affine_matrix * vec3(coord_x, coord_y, 1.0))
 * After transform, normalized texture coord (0, 0) should be bottom-left
 * and (1, 1) should be top-right (or (width, height) for RECTANGLE).
 *
 * GL-specific typedefs are avoided here to avoid relying on gl.h in
 * the API definition.
 */
typedef void (RETRO_CALLCONV *retro_camera_frame_opengl_texture_t)(unsigned texture_id,
      unsigned texture_target, const float *affine);

struct retro_camera_callback
{
   /* Set by libretro core.
    * Example bitmask: caps = (1 << RETRO_CAMERA_BUFFER_OPENGL_TEXTURE) | (1 << RETRO_CAMERA_BUFFER_RAW_FRAMEBUFFER).
    */
   uint64_t caps;

   /* Desired resolution for camera. Is only used as a hint. */
   unsigned width;
   unsigned height;

   /* Set by frontend. */
   retro_camera_start_t start;
   retro_camera_stop_t stop;

   /* Set by libretro core if raw framebuffer callbacks will be used. */
   retro_camera_frame_raw_framebuffer_t frame_raw_framebuffer;

   /* Set by libretro core if OpenGL texture callbacks will be used. */
   retro_camera_frame_opengl_texture_t frame_opengl_texture;

   /* Set by libretro core. Called after camera driver is initialized and
    * ready to be started.
    * Can be NULL, in which this callback is not called.
    */
   retro_camera_lifetime_status_t initialized;

   /* Set by libretro core. Called right before camera driver is
    * deinitialized.
    * Can be NULL, in which this callback is not called.
    */
   retro_camera_lifetime_status_t deinitialized;
};

/* Sets the interval of time and/or distance at which to update/poll
 * location-based data.
 *
 * To ensure compatibility with all location-based implementations,
 * values for both interval_ms and interval_distance should be provided.
 *
 * interval_ms is the interval expressed in milliseconds.
 * interval_distance is the distance interval expressed in meters.
 */
typedef void (RETRO_CALLCONV *retro_location_set_interval_t)(unsigned interval_ms,
      unsigned interval_distance);

/* Start location services. The device will start listening for changes to the
 * current location at regular intervals (which are defined with
 * retro_location_set_interval_t). */
typedef bool (RETRO_CALLCONV *retro_location_start_t)(void);

/* Stop location services. The device will stop listening for changes
 * to the current location. */
typedef void (RETRO_CALLCONV *retro_location_stop_t)(void);

/* Get the position of the current location. Will set parameters to
 * 0 if no new  location update has happened since the last time. */
typedef bool (RETRO_CALLCONV *retro_location_get_position_t)(double *lat, double *lon,
      double *horiz_accuracy, double *vert_accuracy);

/* Callback which signals when the location driver is initialized
 * and/or deinitialized.
 * retro_location_start_t can be called in initialized callback.
 */
typedef void (RETRO_CALLCONV *retro_location_lifetime_status_t)(void);

struct retro_location_callback
{
   retro_location_start_t         start;
   retro_location_stop_t          stop;
   retro_location_get_position_t  get_position;
   retro_location_set_interval_t  set_interval;

   retro_location_lifetime_status_t initialized;
   retro_location_lifetime_status_t deinitialized;
};

enum retro_rumble_effect
{
   RETRO_RUMBLE_STRONG = 0,
   RETRO_RUMBLE_WEAK = 1,

   RETRO_RUMBLE_DUMMY = INT_MAX
};

/* Sets rumble state for joypad plugged in port 'port'.
 * Rumble effects are controlled independently,
 * and setting e.g. strong rumble does not override weak rumble.
 * Strength has a range of [0, 0xffff].
 *
 * Returns true if rumble state request was honored.
 * Calling this before first retro_run() is likely to return false. */
typedef bool (RETRO_CALLCONV *retro_set_rumble_state_t)(unsigned port,
      enum retro_rumble_effect effect, uint16_t strength);

struct retro_rumble_interface
{
   retro_set_rumble_state_t set_rumble_state;
};

/* Notifies libretro that audio data should be written. */
typedef void (RETRO_CALLCONV *retro_audio_callback_t)(void);

/* True: Audio driver in frontend is active, and callback is
 * expected to be called regularily.
 * False: Audio driver in frontend is paused or inactive.
 * Audio callback will not be called until set_state has been
 * called with true.
 * Initial state is false (inactive).
 */
typedef void (RETRO_CALLCONV *retro_audio_set_state_callback_t)(bool enabled);

struct retro_audio_callback
{
   retro_audio_callback_t callback;
   retro_audio_set_state_callback_t set_state;
};

/* Notifies a libretro core of time spent since last invocation
 * of retro_run() in microseconds.
 *
 * It will be called right before retro_run() every frame.
 * The frontend can tamper with timing to support cases like
 * fast-forward, slow-motion and framestepping.
 *
 * In those scenarios the reference frame time value will be used. */
typedef int64_t retro_usec_t;
typedef void (RETRO_CALLCONV *retro_frame_time_callback_t)(retro_usec_t usec);
struct retro_frame_time_callback
{
   retro_frame_time_callback_t callback;
   /* Represents the time of one frame. It is computed as
    * 1000000 / fps, but the implementation will resolve the
    * rounding to ensure that framestepping, etc is exact. */
   retro_usec_t reference;
};

/* Pass this to retro_video_refresh_t if rendering to hardware.
 * Passing NULL to retro_video_refresh_t is still a frame dupe as normal.
 * */
#define RETRO_HW_FRAME_BUFFER_VALID ((void*)-1)

/* Invalidates the current HW context.
 * Any GL state is lost, and must not be deinitialized explicitly.
 * If explicit deinitialization is desired by the libretro core,
 * it should implement context_destroy callback.
 * If called, all GPU resources must be reinitialized.
 * Usually called when frontend reinits video driver.
 * Also called first time video driver is initialized,
 * allowing libretro core to initialize resources.
 */
typedef void (RETRO_CALLCONV *retro_hw_context_reset_t)(void);

/* Gets current framebuffer which is to be rendered to.
 * Could change every frame potentially.
 */
typedef uintptr_t (RETRO_CALLCONV *retro_hw_get_current_framebuffer_t)(void);

/* Get a symbol from HW context. */
typedef retro_proc_address_t (RETRO_CALLCONV *retro_hw_get_proc_address_t)(const char *sym);

enum retro_hw_context_type
{
   RETRO_HW_CONTEXT_NONE             = 0,
   /* OpenGL 2.x. Driver can choose to use latest compatibility context. */
   RETRO_HW_CONTEXT_OPENGL           = 1,
   /* OpenGL ES 2.0. */
   RETRO_HW_CONTEXT_OPENGLES2        = 2,
   /* Modern desktop core GL context. Use version_major/
    * version_minor fields to set GL version. */
   RETRO_HW_CONTEXT_OPENGL_CORE      = 3,
   /* OpenGL ES 3.0 */
   RETRO_HW_CONTEXT_OPENGLES3        = 4,
   /* OpenGL ES 3.1+. Set version_major/version_minor. For GLES2 and GLES3,
    * use the corresponding enums directly. */
   RETRO_HW_CONTEXT_OPENGLES_VERSION = 5,

   /* Vulkan, see RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE. */
   RETRO_HW_CONTEXT_VULKAN           = 6,

   RETRO_HW_CONTEXT_DUMMY = INT_MAX
};

struct retro_hw_render_callback
{
   /* Which API to use. Set by libretro core. */
   enum retro_hw_context_type context_type;

   /* Called when a context has been created or when it has been reset.
    * An OpenGL context is only valid after context_reset() has been called.
    *
    * When context_reset is called, OpenGL resources in the libretro
    * implementation are guaranteed to be invalid.
    *
    * It is possible that context_reset is called multiple times during an
    * application lifecycle.
    * If context_reset is called without any notification (context_destroy),
    * the OpenGL context was lost and resources should just be recreated
    * without any attempt to "free" old resources.
    */
   retro_hw_context_reset_t context_reset;

   /* Set by frontend.
    * TODO: This is rather obsolete. The frontend should not
    * be providing preallocated framebuffers. */
   retro_hw_get_current_framebuffer_t get_current_framebuffer;

   /* Set by frontend.
    * Can return all relevant functions, including glClear on Windows. */
   retro_hw_get_proc_address_t get_proc_address;

   /* Set if render buffers should have depth component attached.
    * TODO: Obsolete. */
   bool depth;

   /* Set if stencil buffers should be attached.
    * TODO: Obsolete. */
   bool stencil;

   /* If depth and stencil are true, a packed 24/8 buffer will be added.
    * Only attaching stencil is invalid and will be ignored. */

   /* Use conventional bottom-left origin convention. If false,
    * standard libretro top-left origin semantics are used.
    * TODO: Move to GL specific interface. */
   bool bottom_left_origin;

   /* Major version number for core GL context or GLES 3.1+. */
   unsigned version_major;

   /* Minor version number for core GL context or GLES 3.1+. */
   unsigned version_minor;

   /* If this is true, the frontend will go very far to avoid
    * resetting context in scenarios like toggling fullscreen, etc.
    * TODO: Obsolete? Maybe frontend should just always assume this ...
    */
   bool cache_context;

   /* The reset callback might still be called in extreme situations
    * such as if the context is lost beyond recovery.
    *
    * For optimal stability, set this to false, and allow context to be
    * reset at any time.
    */

   /* A callback to be called before the context is destroyed in a
    * controlled way by the frontend. */
   retro_hw_context_reset_t context_destroy;

   /* OpenGL resources can be deinitialized cleanly at this step.
    * context_destroy can be set to NULL, in which resources will
    * just be destroyed without any notification.
    *
    * Even when context_destroy is non-NULL, it is possible that
    * context_reset is called without any destroy notification.
    * This happens if context is lost by external factors (such as
    * notified by GL_ARB_robustness).
    *
    * In this case, the context is assumed to be already dead,
    * and the libretro implementation must not try to free any OpenGL
    * resources in the subsequent context_reset.
    */

   /* Creates a debug context. */
   bool debug_context;
};

/* Callback type passed in RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK.
 * Called by the frontend in response to keyboard events.
 * down is set if the key is being pressed, or false if it is being released.
 * keycode is the RETROK value of the char.
 * character is the text character of the pressed key. (UTF-32).
 * key_modifiers is a set of RETROKMOD values or'ed together.
 *
 * The pressed/keycode state can be indepedent of the character.
 * It is also possible that multiple characters are generated from a
 * single keypress.
 * Keycode events should be treated separately from character events.
 * However, when possible, the frontend should try to synchronize these.
 * If only a character is posted, keycode should be RETROK_UNKNOWN.
 *
 * Similarily if only a keycode event is generated with no corresponding
 * character, character should be 0.
 */
typedef void (RETRO_CALLCONV *retro_keyboard_event_t)(bool down, unsigned keycode,
      uint32_t character, uint16_t key_modifiers);

struct retro_keyboard_callback
{
   retro_keyboard_event_t callback;
};

/* Callbacks for RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE.
 * Should be set for implementations which can swap out multiple disk
 * images in runtime.
 *
 * If the implementation can do this automatically, it should strive to do so.
 * However, there are cases where the user must manually do so.
 *
 * Overview: To swap a disk image, eject the disk image with
 * set_eject_state(true).
 * Set the disk index with set_image_index(index). Insert the disk again
 * with set_eject_state(false).
 */

/* If ejected is true, "ejects" the virtual disk tray.
 * When ejected, the disk image index can be set.
 */
typedef bool (RETRO_CALLCONV *retro_set_eject_state_t)(bool ejected);

/* Gets current eject state. The initial state is 'not ejected'. */
typedef bool (RETRO_CALLCONV *retro_get_eject_state_t)(void);

/* Gets current disk index. First disk is index 0.
 * If return value is >= get_num_images(), no disk is currently inserted.
 */
typedef unsigned (RETRO_CALLCONV *retro_get_image_index_t)(void);

/* Sets image index. Can only be called when disk is ejected.
 * The implementation supports setting "no disk" by using an
 * index >= get_num_images().
 */
typedef bool (RETRO_CALLCONV *retro_set_image_index_t)(unsigned index);

/* Gets total number of images which are available to use. */
typedef unsigned (RETRO_CALLCONV *retro_get_num_images_t)(void);

struct retro_game_info;

/* Replaces the disk image associated with index.
 * Arguments to pass in info have same requirements as retro_load_game().
 * Virtual disk tray must be ejected when calling this.
 *
 * Replacing a disk image with info = NULL will remove the disk image
 * from the internal list.
 * As a result, calls to get_image_index() can change.
 *
 * E.g. replace_image_index(1, NULL), and previous get_image_index()
 * returned 4 before.
 * Index 1 will be removed, and the new index is 3.
 */
typedef bool (RETRO_CALLCONV *retro_replace_image_index_t)(unsigned index,
      const struct retro_game_info *info);

/* Adds a new valid index (get_num_images()) to the internal disk list.
 * This will increment subsequent return values from get_num_images() by 1.
 * This image index cannot be used until a disk image has been set
 * with replace_image_index. */
typedef bool (RETRO_CALLCONV *retro_add_image_index_t)(void);

struct retro_disk_control_callback
{
   retro_set_eject_state_t set_eject_state;
   retro_get_eject_state_t get_eject_state;

   retro_get_image_index_t get_image_index;
   retro_set_image_index_t set_image_index;
   retro_get_num_images_t  get_num_images;

   retro_replace_image_index_t replace_image_index;
   retro_add_image_index_t add_image_index;
};

enum retro_pixel_format
{
   /* 0RGB1555, native endian.
    * 0 bit must be set to 0.
    * This pixel format is default for compatibility concerns only.
    * If a 15/16-bit pixel format is desired, consider using RGB565. */
   RETRO_PIXEL_FORMAT_0RGB1555 = 0,

   /* XRGB8888, native endian.
    * X bits are ignored. */
   RETRO_PIXEL_FORMAT_XRGB8888 = 1,

   /* RGB565, native endian.
    * This pixel format is the recommended format to use if a 15/16-bit
    * format is desired as it is the pixel format that is typically
    * available on a wide range of low-power devices.
    *
    * It is also natively supported in APIs like OpenGL ES. */
   RETRO_PIXEL_FORMAT_RGB565   = 2,

   /* Ensure sizeof() == sizeof(int). */
   RETRO_PIXEL_FORMAT_UNKNOWN  = INT_MAX
};

struct retro_message
{
   const char *msg;        /* Message to be displayed. */
   unsigned    frames;     /* Duration in frames of message. */
};

/* Describes how the libretro implementation maps a libretro input bind
 * to its internal input system through a human readable string.
 * This string can be used to better let a user configure input. */
struct retro_input_descriptor
{
   /* Associates given parameters with a description. */
   unsigned port;
   unsigned device;
   unsigned index;
   unsigned id;

   /* Human readable description for parameters.
    * The pointer must remain valid until
    * retro_unload_game() is called. */
   const char *description;
};

struct retro_system_info
{
   /* All pointers are owned by libretro implementation, and pointers must
    * remain valid until retro_deinit() is called. */

   const char *library_name;      /* Descriptive name of library. Should not
                                   * contain any version numbers, etc. */
   const char *library_version;   /* Descriptive version of core. */

   const char *valid_extensions;  /* A string listing probably content
                                   * extensions the core will be able to
                                   * load, separated with pipe.
                                   * I.e. "bin|rom|iso".
                                   * Typically used for a GUI to filter
                                   * out extensions. */

   /* If true, retro_load_game() is guaranteed to provide a valid pathname
    * in retro_game_info::path.
    * ::data and ::size are both invalid.
    *
    * If false, ::data and ::size are guaranteed to be valid, but ::path
    * might not be valid.
    *
    * This is typically set to true for libretro implementations that must
    * load from file.
    * Implementations should strive for setting this to false, as it allows
    * the frontend to perform patching, etc. */
   bool        need_fullpath;

   /* If true, the frontend is not allowed to extract any archives before
    * loading the real content.
    * Necessary for certain libretro implementations that load games
    * from zipped archives. */
   bool        block_extract;
};

struct retro_game_geometry
{
   unsigned base_width;    /* Nominal video width of game. */
   unsigned base_height;   /* Nominal video height of game. */
   unsigned max_width;     /* Maximum possible width of game. */
   unsigned max_height;    /* Maximum possible height of game. */

   float    aspect_ratio;  /* Nominal aspect ratio of game. If
                            * aspect_ratio is <= 0.0, an aspect ratio
                            * of base_width / base_height is assumed.
                            * A frontend could override this setting,
                            * if desired. */
};

struct retro_system_timing
{
   double fps;             /* FPS of video content. */
   double sample_rate;     /* Sampling rate of audio. */
};

struct retro_system_av_info
{
   struct retro_game_geometry geometry;
   struct retro_system_timing timing;
};

struct retro_variable
{
   /* Variable to query in RETRO_ENVIRONMENT_GET_VARIABLE.
    * If NULL, obtains the complete environment string if more
    * complex parsing is necessary.
    * The environment string is formatted as key-value pairs
    * delimited by semicolons as so:
    * "key1=value1;key2=value2;..."
    */
   const char *key;

   /* Value to be obtained. If key does not exist, it is set to NULL. */
   const char *value;
};

struct retro_game_info
{
   const char *path;       /* Path to game, UTF-8 encoded.
                            * Sometimes used as a reference for building other paths.
                            * May be NULL if game was loaded from stdin or similar,
                            * but in this case some cores will be unable to load `data`.
                            * So, it is preferable to fabricate something here instead
                            * of passing NULL, which will help more cores to succeed.
                            * retro_system_info::need_fullpath requires
                            * that this path is valid. */
   const void *data;       /* Memory buffer of loaded game. Will be NULL
                            * if need_fullpath was set. */
   size_t      size;       /* Size of memory buffer. */
   const char *meta;       /* String of implementation specific meta-data. */
};

#define RETRO_MEMORY_ACCESS_WRITE (1 << 0)
   /* The core will write to the buffer provided by retro_framebuffer::data. */
#define RETRO_MEMORY_ACCESS_READ (1 << 1)
   /* The core will read from retro_framebuffer::data. */
#define RETRO_MEMORY_TYPE_CACHED (1 << 0)
   /* The memory in data is cached.
    * If not cached, random writes and/or reading from the buffer is expected to be very slow. */
struct retro_framebuffer
{
   void *data;                      /* The framebuffer which the core can render into.
                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER.
                                       The initial contents of data are unspecified. */
   unsigned width;                  /* The framebuffer width used by the core. Set by core. */
   unsigned height;                 /* The framebuffer height used by the core. Set by core. */
   size_t pitch;                    /* The number of bytes between the beginning of a scanline,
                                       and beginning of the next scanline.
                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
   enum retro_pixel_format format;  /* The pixel format the core must use to render into data.
                                       This format could differ from the format used in
                                       SET_PIXEL_FORMAT.
                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */

   unsigned access_flags;           /* How the core will access the memory in the framebuffer.
                                       RETRO_MEMORY_ACCESS_* flags.
                                       Set by core. */
   unsigned memory_flags;           /* Flags telling core how the memory has been mapped.
                                       RETRO_MEMORY_TYPE_* flags.
                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
};

/* Callbacks */

/* Environment callback. Gives implementations a way of performing
 * uncommon tasks. Extensible. */
typedef bool (RETRO_CALLCONV *retro_environment_t)(unsigned cmd, void *data);

/* Render a frame. Pixel format is 15-bit 0RGB1555 native endian
 * unless changed (see RETRO_ENVIRONMENT_SET_PIXEL_FORMAT).
 *
 * Width and height specify dimensions of buffer.
 * Pitch specifices length in bytes between two lines in buffer.
 *
 * For performance reasons, it is highly recommended to have a frame
 * that is packed in memory, i.e. pitch == width * byte_per_pixel.
 * Certain graphic APIs, such as OpenGL ES, do not like textures
 * that are not packed in memory.
 */
typedef void (RETRO_CALLCONV *retro_video_refresh_t)(const void *data, unsigned width,
      unsigned height, size_t pitch);

/* Renders a single audio frame. Should only be used if implementation
 * generates a single sample at a time.
 * Format is signed 16-bit native endian.
 */
typedef void (RETRO_CALLCONV *retro_audio_sample_t)(int16_t left, int16_t right);

/* Renders multiple audio frames in one go.
 *
 * One frame is defined as a sample of left and right channels, interleaved.
 * I.e. int16_t buf[4] = { l, r, l, r }; would be 2 frames.
 * Only one of the audio callbacks must ever be used.
 */
typedef size_t (RETRO_CALLCONV *retro_audio_sample_batch_t)(const int16_t *data,
      size_t frames);

/* Polls input. */
typedef void (RETRO_CALLCONV *retro_input_poll_t)(void);

/* Queries for input for player 'port'. device will be masked with
 * RETRO_DEVICE_MASK.
 *
 * Specialization of devices such as RETRO_DEVICE_JOYPAD_MULTITAP that
 * have been set with retro_set_controller_port_device()
 * will still use the higher level RETRO_DEVICE_JOYPAD to request input.
 */
typedef int16_t (RETRO_CALLCONV *retro_input_state_t)(unsigned port, unsigned device,
      unsigned index, unsigned id);

/* Sets callbacks. retro_set_environment() is guaranteed to be called
 * before retro_init().
 *
 * The rest of the set_* functions are guaranteed to have been called
 * before the first call to retro_run() is made. */
RETRO_API void retro_set_environment(retro_environment_t);
RETRO_API void retro_set_video_refresh(retro_video_refresh_t);
RETRO_API void retro_set_audio_sample(retro_audio_sample_t);
RETRO_API void retro_set_audio_sample_batch(retro_audio_sample_batch_t);
RETRO_API void retro_set_input_poll(retro_input_poll_t);
RETRO_API void retro_set_input_state(retro_input_state_t);

/* Library global initialization/deinitialization. */
RETRO_API void retro_init(void);
RETRO_API void retro_deinit(void);

/* Must return RETRO_API_VERSION. Used to validate ABI compatibility
 * when the API is revised. */
RETRO_API unsigned retro_api_version(void);

/* Gets statically known system info. Pointers provided in *info
 * must be statically allocated.
 * Can be called at any time, even before retro_init(). */
RETRO_API void retro_get_system_info(struct retro_system_info *info);

/* Gets information about system audio/video timings and geometry.
 * Can be called only after retro_load_game() has successfully completed.
 * NOTE: The implementation of this function might not initialize every
 * variable if needed.
 * E.g. geom.aspect_ratio might not be initialized if core doesn't
 * desire a particular aspect ratio. */
RETRO_API void retro_get_system_av_info(struct retro_system_av_info *info);

/* Sets device to be used for player 'port'.
 * By default, RETRO_DEVICE_JOYPAD is assumed to be plugged into all
 * available ports.
 * Setting a particular device type is not a guarantee that libretro cores
 * will only poll input based on that particular device type. It is only a
 * hint to the libretro core when a core cannot automatically detect the
 * appropriate input device type on its own. It is also relevant when a
 * core can change its behavior depending on device type. */
RETRO_API void retro_set_controller_port_device(unsigned port, unsigned device);

/* Resets the current game. */
RETRO_API void retro_reset(void);

/* Runs the game for one video frame.
 * During retro_run(), input_poll callback must be called at least once.
 *
 * If a frame is not rendered for reasons where a game "dropped" a frame,
 * this still counts as a frame, and retro_run() should explicitly dupe
 * a frame if GET_CAN_DUPE returns true.
 * In this case, the video callback can take a NULL argument for data.
 */
RETRO_API void retro_run(void);

/* Returns the amount of data the implementation requires to serialize
 * internal state (save states).
 * Between calls to retro_load_game() and retro_unload_game(), the
 * returned size is never allowed to be larger than a previous returned
 * value, to ensure that the frontend can allocate a save state buffer once.
 */
RETRO_API size_t retro_serialize_size(void);

/* Serializes internal state. If failed, or size is lower than
 * retro_serialize_size(), it should return false, true otherwise. */
RETRO_API bool retro_serialize(void *data, size_t size);
RETRO_API bool retro_unserialize(const void *data, size_t size);

RETRO_API void retro_cheat_reset(void);
RETRO_API void retro_cheat_set(unsigned index, bool enabled, const char *code);

/* Loads a game. */
RETRO_API bool retro_load_game(const struct retro_game_info *game);

/* Loads a "special" kind of game. Should not be used,
 * except in extreme cases. */
RETRO_API bool retro_load_game_special(
  unsigned game_type,
  const struct retro_game_info *info, size_t num_info
);

/* Unloads a currently loaded game. */
RETRO_API void retro_unload_game(void);

/* Gets region of game. */
RETRO_API unsigned retro_get_region(void);

/* Gets region of memory. */
RETRO_API void *retro_get_memory_data(unsigned id);
RETRO_API size_t retro_get_memory_size(unsigned id);

#ifdef __cplusplus
}
#endif

#endif