cscg22-gearboy

CSCG 2022 Challenge 'Gearboy'
git clone https://git.sinitax.com/sinitax/cscg22-gearboy
Log | Files | Refs | sfeed.txt

libretro.h (161782B)


      1/* Copyright (C) 2010-2020 The RetroArch team
      2 *
      3 * ---------------------------------------------------------------------------------------
      4 * The following license statement only applies to this libretro API header (libretro.h).
      5 * ---------------------------------------------------------------------------------------
      6 *
      7 * Permission is hereby granted, free of charge,
      8 * to any person obtaining a copy of this software and associated documentation files (the "Software"),
      9 * to deal in the Software without restriction, including without limitation the rights to
     10 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
     11 * and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
     12 *
     13 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
     14 *
     15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
     16 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
     18 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
     19 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     21 */
     22
     23#ifndef LIBRETRO_H__
     24#define LIBRETRO_H__
     25
     26#include <stdint.h>
     27#include <stddef.h>
     28#include <limits.h>
     29
     30#ifdef __cplusplus
     31extern "C" {
     32#endif
     33
     34#ifndef __cplusplus
     35#if defined(_MSC_VER) && _MSC_VER < 1800 && !defined(SN_TARGET_PS3)
     36/* Hack applied for MSVC when compiling in C89 mode
     37 * as it isn't C99-compliant. */
     38#define bool unsigned char
     39#define true 1
     40#define false 0
     41#else
     42#include <stdbool.h>
     43#endif
     44#endif
     45
     46#ifndef RETRO_CALLCONV
     47#  if defined(__GNUC__) && defined(__i386__) && !defined(__x86_64__)
     48#    define RETRO_CALLCONV __attribute__((cdecl))
     49#  elif defined(_MSC_VER) && defined(_M_X86) && !defined(_M_X64)
     50#    define RETRO_CALLCONV __cdecl
     51#  else
     52#    define RETRO_CALLCONV /* all other platforms only have one calling convention each */
     53#  endif
     54#endif
     55
     56#ifndef RETRO_API
     57#  if defined(_WIN32) || defined(__CYGWIN__) || defined(__MINGW32__)
     58#    ifdef RETRO_IMPORT_SYMBOLS
     59#      ifdef __GNUC__
     60#        define RETRO_API RETRO_CALLCONV __attribute__((__dllimport__))
     61#      else
     62#        define RETRO_API RETRO_CALLCONV __declspec(dllimport)
     63#      endif
     64#    else
     65#      ifdef __GNUC__
     66#        define RETRO_API RETRO_CALLCONV __attribute__((__dllexport__))
     67#      else
     68#        define RETRO_API RETRO_CALLCONV __declspec(dllexport)
     69#      endif
     70#    endif
     71#  else
     72#      if defined(__GNUC__) && __GNUC__ >= 4
     73#        define RETRO_API RETRO_CALLCONV __attribute__((__visibility__("default")))
     74#      else
     75#        define RETRO_API RETRO_CALLCONV
     76#      endif
     77#  endif
     78#endif
     79
     80/* Used for checking API/ABI mismatches that can break libretro
     81 * implementations.
     82 * It is not incremented for compatible changes to the API.
     83 */
     84#define RETRO_API_VERSION         1
     85
     86/*
     87 * Libretro's fundamental device abstractions.
     88 *
     89 * Libretro's input system consists of some standardized device types,
     90 * such as a joypad (with/without analog), mouse, keyboard, lightgun
     91 * and a pointer.
     92 *
     93 * The functionality of these devices are fixed, and individual cores
     94 * map their own concept of a controller to libretro's abstractions.
     95 * This makes it possible for frontends to map the abstract types to a
     96 * real input device, and not having to worry about binding input
     97 * correctly to arbitrary controller layouts.
     98 */
     99
    100#define RETRO_DEVICE_TYPE_SHIFT         8
    101#define RETRO_DEVICE_MASK               ((1 << RETRO_DEVICE_TYPE_SHIFT) - 1)
    102#define RETRO_DEVICE_SUBCLASS(base, id) (((id + 1) << RETRO_DEVICE_TYPE_SHIFT) | base)
    103
    104/* Input disabled. */
    105#define RETRO_DEVICE_NONE         0
    106
    107/* The JOYPAD is called RetroPad. It is essentially a Super Nintendo
    108 * controller, but with additional L2/R2/L3/R3 buttons, similar to a
    109 * PS1 DualShock. */
    110#define RETRO_DEVICE_JOYPAD       1
    111
    112/* The mouse is a simple mouse, similar to Super Nintendo's mouse.
    113 * X and Y coordinates are reported relatively to last poll (poll callback).
    114 * It is up to the libretro implementation to keep track of where the mouse
    115 * pointer is supposed to be on the screen.
    116 * The frontend must make sure not to interfere with its own hardware
    117 * mouse pointer.
    118 */
    119#define RETRO_DEVICE_MOUSE        2
    120
    121/* KEYBOARD device lets one poll for raw key pressed.
    122 * It is poll based, so input callback will return with the current
    123 * pressed state.
    124 * For event/text based keyboard input, see
    125 * RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK.
    126 */
    127#define RETRO_DEVICE_KEYBOARD     3
    128
    129/* LIGHTGUN device is similar to Guncon-2 for PlayStation 2.
    130 * It reports X/Y coordinates in screen space (similar to the pointer)
    131 * in the range [-0x8000, 0x7fff] in both axes, with zero being center and
    132 * -0x8000 being out of bounds.
    133 * As well as reporting on/off screen state. It features a trigger,
    134 * start/select buttons, auxiliary action buttons and a
    135 * directional pad. A forced off-screen shot can be requested for
    136 * auto-reloading function in some games.
    137 */
    138#define RETRO_DEVICE_LIGHTGUN     4
    139
    140/* The ANALOG device is an extension to JOYPAD (RetroPad).
    141 * Similar to DualShock2 it adds two analog sticks and all buttons can
    142 * be analog. This is treated as a separate device type as it returns
    143 * axis values in the full analog range of [-0x7fff, 0x7fff],
    144 * although some devices may return -0x8000.
    145 * Positive X axis is right. Positive Y axis is down.
    146 * Buttons are returned in the range [0, 0x7fff].
    147 * Only use ANALOG type when polling for analog values.
    148 */
    149#define RETRO_DEVICE_ANALOG       5
    150
    151/* Abstracts the concept of a pointing mechanism, e.g. touch.
    152 * This allows libretro to query in absolute coordinates where on the
    153 * screen a mouse (or something similar) is being placed.
    154 * For a touch centric device, coordinates reported are the coordinates
    155 * of the press.
    156 *
    157 * Coordinates in X and Y are reported as:
    158 * [-0x7fff, 0x7fff]: -0x7fff corresponds to the far left/top of the screen,
    159 * and 0x7fff corresponds to the far right/bottom of the screen.
    160 * The "screen" is here defined as area that is passed to the frontend and
    161 * later displayed on the monitor.
    162 *
    163 * The frontend is free to scale/resize this screen as it sees fit, however,
    164 * (X, Y) = (-0x7fff, -0x7fff) will correspond to the top-left pixel of the
    165 * game image, etc.
    166 *
    167 * To check if the pointer coordinates are valid (e.g. a touch display
    168 * actually being touched), PRESSED returns 1 or 0.
    169 *
    170 * If using a mouse on a desktop, PRESSED will usually correspond to the
    171 * left mouse button, but this is a frontend decision.
    172 * PRESSED will only return 1 if the pointer is inside the game screen.
    173 *
    174 * For multi-touch, the index variable can be used to successively query
    175 * more presses.
    176 * If index = 0 returns true for _PRESSED, coordinates can be extracted
    177 * with _X, _Y for index = 0. One can then query _PRESSED, _X, _Y with
    178 * index = 1, and so on.
    179 * Eventually _PRESSED will return false for an index. No further presses
    180 * are registered at this point. */
    181#define RETRO_DEVICE_POINTER      6
    182
    183/* Buttons for the RetroPad (JOYPAD).
    184 * The placement of these is equivalent to placements on the
    185 * Super Nintendo controller.
    186 * L2/R2/L3/R3 buttons correspond to the PS1 DualShock.
    187 * Also used as id values for RETRO_DEVICE_INDEX_ANALOG_BUTTON */
    188#define RETRO_DEVICE_ID_JOYPAD_B        0
    189#define RETRO_DEVICE_ID_JOYPAD_Y        1
    190#define RETRO_DEVICE_ID_JOYPAD_SELECT   2
    191#define RETRO_DEVICE_ID_JOYPAD_START    3
    192#define RETRO_DEVICE_ID_JOYPAD_UP       4
    193#define RETRO_DEVICE_ID_JOYPAD_DOWN     5
    194#define RETRO_DEVICE_ID_JOYPAD_LEFT     6
    195#define RETRO_DEVICE_ID_JOYPAD_RIGHT    7
    196#define RETRO_DEVICE_ID_JOYPAD_A        8
    197#define RETRO_DEVICE_ID_JOYPAD_X        9
    198#define RETRO_DEVICE_ID_JOYPAD_L       10
    199#define RETRO_DEVICE_ID_JOYPAD_R       11
    200#define RETRO_DEVICE_ID_JOYPAD_L2      12
    201#define RETRO_DEVICE_ID_JOYPAD_R2      13
    202#define RETRO_DEVICE_ID_JOYPAD_L3      14
    203#define RETRO_DEVICE_ID_JOYPAD_R3      15
    204
    205#define RETRO_DEVICE_ID_JOYPAD_MASK    256
    206
    207/* Index / Id values for ANALOG device. */
    208#define RETRO_DEVICE_INDEX_ANALOG_LEFT       0
    209#define RETRO_DEVICE_INDEX_ANALOG_RIGHT      1
    210#define RETRO_DEVICE_INDEX_ANALOG_BUTTON     2
    211#define RETRO_DEVICE_ID_ANALOG_X             0
    212#define RETRO_DEVICE_ID_ANALOG_Y             1
    213
    214/* Id values for MOUSE. */
    215#define RETRO_DEVICE_ID_MOUSE_X                0
    216#define RETRO_DEVICE_ID_MOUSE_Y                1
    217#define RETRO_DEVICE_ID_MOUSE_LEFT             2
    218#define RETRO_DEVICE_ID_MOUSE_RIGHT            3
    219#define RETRO_DEVICE_ID_MOUSE_WHEELUP          4
    220#define RETRO_DEVICE_ID_MOUSE_WHEELDOWN        5
    221#define RETRO_DEVICE_ID_MOUSE_MIDDLE           6
    222#define RETRO_DEVICE_ID_MOUSE_HORIZ_WHEELUP    7
    223#define RETRO_DEVICE_ID_MOUSE_HORIZ_WHEELDOWN  8
    224#define RETRO_DEVICE_ID_MOUSE_BUTTON_4         9
    225#define RETRO_DEVICE_ID_MOUSE_BUTTON_5         10
    226
    227/* Id values for LIGHTGUN. */
    228#define RETRO_DEVICE_ID_LIGHTGUN_SCREEN_X        13 /*Absolute Position*/
    229#define RETRO_DEVICE_ID_LIGHTGUN_SCREEN_Y        14 /*Absolute*/
    230#define RETRO_DEVICE_ID_LIGHTGUN_IS_OFFSCREEN    15 /*Status Check*/
    231#define RETRO_DEVICE_ID_LIGHTGUN_TRIGGER          2
    232#define RETRO_DEVICE_ID_LIGHTGUN_RELOAD          16 /*Forced off-screen shot*/
    233#define RETRO_DEVICE_ID_LIGHTGUN_AUX_A            3
    234#define RETRO_DEVICE_ID_LIGHTGUN_AUX_B            4
    235#define RETRO_DEVICE_ID_LIGHTGUN_START            6
    236#define RETRO_DEVICE_ID_LIGHTGUN_SELECT           7
    237#define RETRO_DEVICE_ID_LIGHTGUN_AUX_C            8
    238#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_UP          9
    239#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_DOWN       10
    240#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_LEFT       11
    241#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_RIGHT      12
    242/* deprecated */
    243#define RETRO_DEVICE_ID_LIGHTGUN_X                0 /*Relative Position*/
    244#define RETRO_DEVICE_ID_LIGHTGUN_Y                1 /*Relative*/
    245#define RETRO_DEVICE_ID_LIGHTGUN_CURSOR           3 /*Use Aux:A*/
    246#define RETRO_DEVICE_ID_LIGHTGUN_TURBO            4 /*Use Aux:B*/
    247#define RETRO_DEVICE_ID_LIGHTGUN_PAUSE            5 /*Use Start*/
    248
    249/* Id values for POINTER. */
    250#define RETRO_DEVICE_ID_POINTER_X         0
    251#define RETRO_DEVICE_ID_POINTER_Y         1
    252#define RETRO_DEVICE_ID_POINTER_PRESSED   2
    253#define RETRO_DEVICE_ID_POINTER_COUNT     3
    254
    255/* Returned from retro_get_region(). */
    256#define RETRO_REGION_NTSC  0
    257#define RETRO_REGION_PAL   1
    258
    259/* Id values for LANGUAGE */
    260enum retro_language
    261{
    262   RETRO_LANGUAGE_ENGLISH             = 0,
    263   RETRO_LANGUAGE_JAPANESE            = 1,
    264   RETRO_LANGUAGE_FRENCH              = 2,
    265   RETRO_LANGUAGE_SPANISH             = 3,
    266   RETRO_LANGUAGE_GERMAN              = 4,
    267   RETRO_LANGUAGE_ITALIAN             = 5,
    268   RETRO_LANGUAGE_DUTCH               = 6,
    269   RETRO_LANGUAGE_PORTUGUESE_BRAZIL   = 7,
    270   RETRO_LANGUAGE_PORTUGUESE_PORTUGAL = 8,
    271   RETRO_LANGUAGE_RUSSIAN             = 9,
    272   RETRO_LANGUAGE_KOREAN              = 10,
    273   RETRO_LANGUAGE_CHINESE_TRADITIONAL = 11,
    274   RETRO_LANGUAGE_CHINESE_SIMPLIFIED  = 12,
    275   RETRO_LANGUAGE_ESPERANTO           = 13,
    276   RETRO_LANGUAGE_POLISH              = 14,
    277   RETRO_LANGUAGE_VIETNAMESE          = 15,
    278   RETRO_LANGUAGE_ARABIC              = 16,
    279   RETRO_LANGUAGE_GREEK               = 17,
    280   RETRO_LANGUAGE_TURKISH             = 18,
    281   RETRO_LANGUAGE_SLOVAK              = 19,
    282   RETRO_LANGUAGE_PERSIAN             = 20,
    283   RETRO_LANGUAGE_HEBREW              = 21,
    284   RETRO_LANGUAGE_ASTURIAN            = 22,
    285   RETRO_LANGUAGE_FINNISH             = 23,
    286   RETRO_LANGUAGE_LAST,
    287
    288   /* Ensure sizeof(enum) == sizeof(int) */
    289   RETRO_LANGUAGE_DUMMY          = INT_MAX
    290};
    291
    292/* Passed to retro_get_memory_data/size().
    293 * If the memory type doesn't apply to the
    294 * implementation NULL/0 can be returned.
    295 */
    296#define RETRO_MEMORY_MASK        0xff
    297
    298/* Regular save RAM. This RAM is usually found on a game cartridge,
    299 * backed up by a battery.
    300 * If save game data is too complex for a single memory buffer,
    301 * the SAVE_DIRECTORY (preferably) or SYSTEM_DIRECTORY environment
    302 * callback can be used. */
    303#define RETRO_MEMORY_SAVE_RAM    0
    304
    305/* Some games have a built-in clock to keep track of time.
    306 * This memory is usually just a couple of bytes to keep track of time.
    307 */
    308#define RETRO_MEMORY_RTC         1
    309
    310/* System ram lets a frontend peek into a game systems main RAM. */
    311#define RETRO_MEMORY_SYSTEM_RAM  2
    312
    313/* Video ram lets a frontend peek into a game systems video RAM (VRAM). */
    314#define RETRO_MEMORY_VIDEO_RAM   3
    315
    316/* Keysyms used for ID in input state callback when polling RETRO_KEYBOARD. */
    317enum retro_key
    318{
    319   RETROK_UNKNOWN        = 0,
    320   RETROK_FIRST          = 0,
    321   RETROK_BACKSPACE      = 8,
    322   RETROK_TAB            = 9,
    323   RETROK_CLEAR          = 12,
    324   RETROK_RETURN         = 13,
    325   RETROK_PAUSE          = 19,
    326   RETROK_ESCAPE         = 27,
    327   RETROK_SPACE          = 32,
    328   RETROK_EXCLAIM        = 33,
    329   RETROK_QUOTEDBL       = 34,
    330   RETROK_HASH           = 35,
    331   RETROK_DOLLAR         = 36,
    332   RETROK_AMPERSAND      = 38,
    333   RETROK_QUOTE          = 39,
    334   RETROK_LEFTPAREN      = 40,
    335   RETROK_RIGHTPAREN     = 41,
    336   RETROK_ASTERISK       = 42,
    337   RETROK_PLUS           = 43,
    338   RETROK_COMMA          = 44,
    339   RETROK_MINUS          = 45,
    340   RETROK_PERIOD         = 46,
    341   RETROK_SLASH          = 47,
    342   RETROK_0              = 48,
    343   RETROK_1              = 49,
    344   RETROK_2              = 50,
    345   RETROK_3              = 51,
    346   RETROK_4              = 52,
    347   RETROK_5              = 53,
    348   RETROK_6              = 54,
    349   RETROK_7              = 55,
    350   RETROK_8              = 56,
    351   RETROK_9              = 57,
    352   RETROK_COLON          = 58,
    353   RETROK_SEMICOLON      = 59,
    354   RETROK_LESS           = 60,
    355   RETROK_EQUALS         = 61,
    356   RETROK_GREATER        = 62,
    357   RETROK_QUESTION       = 63,
    358   RETROK_AT             = 64,
    359   RETROK_LEFTBRACKET    = 91,
    360   RETROK_BACKSLASH      = 92,
    361   RETROK_RIGHTBRACKET   = 93,
    362   RETROK_CARET          = 94,
    363   RETROK_UNDERSCORE     = 95,
    364   RETROK_BACKQUOTE      = 96,
    365   RETROK_a              = 97,
    366   RETROK_b              = 98,
    367   RETROK_c              = 99,
    368   RETROK_d              = 100,
    369   RETROK_e              = 101,
    370   RETROK_f              = 102,
    371   RETROK_g              = 103,
    372   RETROK_h              = 104,
    373   RETROK_i              = 105,
    374   RETROK_j              = 106,
    375   RETROK_k              = 107,
    376   RETROK_l              = 108,
    377   RETROK_m              = 109,
    378   RETROK_n              = 110,
    379   RETROK_o              = 111,
    380   RETROK_p              = 112,
    381   RETROK_q              = 113,
    382   RETROK_r              = 114,
    383   RETROK_s              = 115,
    384   RETROK_t              = 116,
    385   RETROK_u              = 117,
    386   RETROK_v              = 118,
    387   RETROK_w              = 119,
    388   RETROK_x              = 120,
    389   RETROK_y              = 121,
    390   RETROK_z              = 122,
    391   RETROK_LEFTBRACE      = 123,
    392   RETROK_BAR            = 124,
    393   RETROK_RIGHTBRACE     = 125,
    394   RETROK_TILDE          = 126,
    395   RETROK_DELETE         = 127,
    396
    397   RETROK_KP0            = 256,
    398   RETROK_KP1            = 257,
    399   RETROK_KP2            = 258,
    400   RETROK_KP3            = 259,
    401   RETROK_KP4            = 260,
    402   RETROK_KP5            = 261,
    403   RETROK_KP6            = 262,
    404   RETROK_KP7            = 263,
    405   RETROK_KP8            = 264,
    406   RETROK_KP9            = 265,
    407   RETROK_KP_PERIOD      = 266,
    408   RETROK_KP_DIVIDE      = 267,
    409   RETROK_KP_MULTIPLY    = 268,
    410   RETROK_KP_MINUS       = 269,
    411   RETROK_KP_PLUS        = 270,
    412   RETROK_KP_ENTER       = 271,
    413   RETROK_KP_EQUALS      = 272,
    414
    415   RETROK_UP             = 273,
    416   RETROK_DOWN           = 274,
    417   RETROK_RIGHT          = 275,
    418   RETROK_LEFT           = 276,
    419   RETROK_INSERT         = 277,
    420   RETROK_HOME           = 278,
    421   RETROK_END            = 279,
    422   RETROK_PAGEUP         = 280,
    423   RETROK_PAGEDOWN       = 281,
    424
    425   RETROK_F1             = 282,
    426   RETROK_F2             = 283,
    427   RETROK_F3             = 284,
    428   RETROK_F4             = 285,
    429   RETROK_F5             = 286,
    430   RETROK_F6             = 287,
    431   RETROK_F7             = 288,
    432   RETROK_F8             = 289,
    433   RETROK_F9             = 290,
    434   RETROK_F10            = 291,
    435   RETROK_F11            = 292,
    436   RETROK_F12            = 293,
    437   RETROK_F13            = 294,
    438   RETROK_F14            = 295,
    439   RETROK_F15            = 296,
    440
    441   RETROK_NUMLOCK        = 300,
    442   RETROK_CAPSLOCK       = 301,
    443   RETROK_SCROLLOCK      = 302,
    444   RETROK_RSHIFT         = 303,
    445   RETROK_LSHIFT         = 304,
    446   RETROK_RCTRL          = 305,
    447   RETROK_LCTRL          = 306,
    448   RETROK_RALT           = 307,
    449   RETROK_LALT           = 308,
    450   RETROK_RMETA          = 309,
    451   RETROK_LMETA          = 310,
    452   RETROK_LSUPER         = 311,
    453   RETROK_RSUPER         = 312,
    454   RETROK_MODE           = 313,
    455   RETROK_COMPOSE        = 314,
    456
    457   RETROK_HELP           = 315,
    458   RETROK_PRINT          = 316,
    459   RETROK_SYSREQ         = 317,
    460   RETROK_BREAK          = 318,
    461   RETROK_MENU           = 319,
    462   RETROK_POWER          = 320,
    463   RETROK_EURO           = 321,
    464   RETROK_UNDO           = 322,
    465   RETROK_OEM_102        = 323,
    466
    467   RETROK_LAST,
    468
    469   RETROK_DUMMY          = INT_MAX /* Ensure sizeof(enum) == sizeof(int) */
    470};
    471
    472enum retro_mod
    473{
    474   RETROKMOD_NONE       = 0x0000,
    475
    476   RETROKMOD_SHIFT      = 0x01,
    477   RETROKMOD_CTRL       = 0x02,
    478   RETROKMOD_ALT        = 0x04,
    479   RETROKMOD_META       = 0x08,
    480
    481   RETROKMOD_NUMLOCK    = 0x10,
    482   RETROKMOD_CAPSLOCK   = 0x20,
    483   RETROKMOD_SCROLLOCK  = 0x40,
    484
    485   RETROKMOD_DUMMY = INT_MAX /* Ensure sizeof(enum) == sizeof(int) */
    486};
    487
    488/* If set, this call is not part of the public libretro API yet. It can
    489 * change or be removed at any time. */
    490#define RETRO_ENVIRONMENT_EXPERIMENTAL 0x10000
    491/* Environment callback to be used internally in frontend. */
    492#define RETRO_ENVIRONMENT_PRIVATE 0x20000
    493
    494/* Environment commands. */
    495#define RETRO_ENVIRONMENT_SET_ROTATION  1  /* const unsigned * --
    496                                            * Sets screen rotation of graphics.
    497                                            * Valid values are 0, 1, 2, 3, which rotates screen by 0, 90, 180,
    498                                            * 270 degrees counter-clockwise respectively.
    499                                            */
    500#define RETRO_ENVIRONMENT_GET_OVERSCAN  2  /* bool * --
    501                                            * NOTE: As of 2019 this callback is considered deprecated in favor of
    502                                            * using core options to manage overscan in a more nuanced, core-specific way.
    503                                            *
    504                                            * Boolean value whether or not the implementation should use overscan,
    505                                            * or crop away overscan.
    506                                            */
    507#define RETRO_ENVIRONMENT_GET_CAN_DUPE  3  /* bool * --
    508                                            * Boolean value whether or not frontend supports frame duping,
    509                                            * passing NULL to video frame callback.
    510                                            */
    511
    512                                           /* Environ 4, 5 are no longer supported (GET_VARIABLE / SET_VARIABLES),
    513                                            * and reserved to avoid possible ABI clash.
    514                                            */
    515
    516#define RETRO_ENVIRONMENT_SET_MESSAGE   6  /* const struct retro_message * --
    517                                            * Sets a message to be displayed in implementation-specific manner
    518                                            * for a certain amount of 'frames'.
    519                                            * Should not be used for trivial messages, which should simply be
    520                                            * logged via RETRO_ENVIRONMENT_GET_LOG_INTERFACE (or as a
    521                                            * fallback, stderr).
    522                                            */
    523#define RETRO_ENVIRONMENT_SHUTDOWN      7  /* N/A (NULL) --
    524                                            * Requests the frontend to shutdown.
    525                                            * Should only be used if game has a specific
    526                                            * way to shutdown the game from a menu item or similar.
    527                                            */
    528#define RETRO_ENVIRONMENT_SET_PERFORMANCE_LEVEL 8
    529                                           /* const unsigned * --
    530                                            * Gives a hint to the frontend how demanding this implementation
    531                                            * is on a system. E.g. reporting a level of 2 means
    532                                            * this implementation should run decently on all frontends
    533                                            * of level 2 and up.
    534                                            *
    535                                            * It can be used by the frontend to potentially warn
    536                                            * about too demanding implementations.
    537                                            *
    538                                            * The levels are "floating".
    539                                            *
    540                                            * This function can be called on a per-game basis,
    541                                            * as certain games an implementation can play might be
    542                                            * particularly demanding.
    543                                            * If called, it should be called in retro_load_game().
    544                                            */
    545#define RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY 9
    546                                           /* const char ** --
    547                                            * Returns the "system" directory of the frontend.
    548                                            * This directory can be used to store system specific
    549                                            * content such as BIOSes, configuration data, etc.
    550                                            * The returned value can be NULL.
    551                                            * If so, no such directory is defined,
    552                                            * and it's up to the implementation to find a suitable directory.
    553                                            *
    554                                            * NOTE: Some cores used this folder also for "save" data such as
    555                                            * memory cards, etc, for lack of a better place to put it.
    556                                            * This is now discouraged, and if possible, cores should try to
    557                                            * use the new GET_SAVE_DIRECTORY.
    558                                            */
    559#define RETRO_ENVIRONMENT_SET_PIXEL_FORMAT 10
    560                                           /* const enum retro_pixel_format * --
    561                                            * Sets the internal pixel format used by the implementation.
    562                                            * The default pixel format is RETRO_PIXEL_FORMAT_0RGB1555.
    563                                            * This pixel format however, is deprecated (see enum retro_pixel_format).
    564                                            * If the call returns false, the frontend does not support this pixel
    565                                            * format.
    566                                            *
    567                                            * This function should be called inside retro_load_game() or
    568                                            * retro_get_system_av_info().
    569                                            */
    570#define RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS 11
    571                                           /* const struct retro_input_descriptor * --
    572                                            * Sets an array of retro_input_descriptors.
    573                                            * It is up to the frontend to present this in a usable way.
    574                                            * The array is terminated by retro_input_descriptor::description
    575                                            * being set to NULL.
    576                                            * This function can be called at any time, but it is recommended
    577                                            * to call it as early as possible.
    578                                            */
    579#define RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK 12
    580                                           /* const struct retro_keyboard_callback * --
    581                                            * Sets a callback function used to notify core about keyboard events.
    582                                            */
    583#define RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE 13
    584                                           /* const struct retro_disk_control_callback * --
    585                                            * Sets an interface which frontend can use to eject and insert
    586                                            * disk images.
    587                                            * This is used for games which consist of multiple images and
    588                                            * must be manually swapped out by the user (e.g. PSX).
    589                                            */
    590#define RETRO_ENVIRONMENT_SET_HW_RENDER 14
    591                                           /* struct retro_hw_render_callback * --
    592                                            * Sets an interface to let a libretro core render with
    593                                            * hardware acceleration.
    594                                            * Should be called in retro_load_game().
    595                                            * If successful, libretro cores will be able to render to a
    596                                            * frontend-provided framebuffer.
    597                                            * The size of this framebuffer will be at least as large as
    598                                            * max_width/max_height provided in get_av_info().
    599                                            * If HW rendering is used, pass only RETRO_HW_FRAME_BUFFER_VALID or
    600                                            * NULL to retro_video_refresh_t.
    601                                            */
    602#define RETRO_ENVIRONMENT_GET_VARIABLE 15
    603                                           /* struct retro_variable * --
    604                                            * Interface to acquire user-defined information from environment
    605                                            * that cannot feasibly be supported in a multi-system way.
    606                                            * 'key' should be set to a key which has already been set by
    607                                            * SET_VARIABLES.
    608                                            * 'data' will be set to a value or NULL.
    609                                            */
    610#define RETRO_ENVIRONMENT_SET_VARIABLES 16
    611                                           /* const struct retro_variable * --
    612                                            * Allows an implementation to signal the environment
    613                                            * which variables it might want to check for later using
    614                                            * GET_VARIABLE.
    615                                            * This allows the frontend to present these variables to
    616                                            * a user dynamically.
    617                                            * This should be called the first time as early as
    618                                            * possible (ideally in retro_set_environment).
    619                                            * Afterward it may be called again for the core to communicate
    620                                            * updated options to the frontend, but the number of core
    621                                            * options must not change from the number in the initial call.
    622                                            *
    623                                            * 'data' points to an array of retro_variable structs
    624                                            * terminated by a { NULL, NULL } element.
    625                                            * retro_variable::key should be namespaced to not collide
    626                                            * with other implementations' keys. E.g. A core called
    627                                            * 'foo' should use keys named as 'foo_option'.
    628                                            * retro_variable::value should contain a human readable
    629                                            * description of the key as well as a '|' delimited list
    630                                            * of expected values.
    631                                            *
    632                                            * The number of possible options should be very limited,
    633                                            * i.e. it should be feasible to cycle through options
    634                                            * without a keyboard.
    635                                            *
    636                                            * First entry should be treated as a default.
    637                                            *
    638                                            * Example entry:
    639                                            * { "foo_option", "Speed hack coprocessor X; false|true" }
    640                                            *
    641                                            * Text before first ';' is description. This ';' must be
    642                                            * followed by a space, and followed by a list of possible
    643                                            * values split up with '|'.
    644                                            *
    645                                            * Only strings are operated on. The possible values will
    646                                            * generally be displayed and stored as-is by the frontend.
    647                                            */
    648#define RETRO_ENVIRONMENT_GET_VARIABLE_UPDATE 17
    649                                           /* bool * --
    650                                            * Result is set to true if some variables are updated by
    651                                            * frontend since last call to RETRO_ENVIRONMENT_GET_VARIABLE.
    652                                            * Variables should be queried with GET_VARIABLE.
    653                                            */
    654#define RETRO_ENVIRONMENT_SET_SUPPORT_NO_GAME 18
    655                                           /* const bool * --
    656                                            * If true, the libretro implementation supports calls to
    657                                            * retro_load_game() with NULL as argument.
    658                                            * Used by cores which can run without particular game data.
    659                                            * This should be called within retro_set_environment() only.
    660                                            */
    661#define RETRO_ENVIRONMENT_GET_LIBRETRO_PATH 19
    662                                           /* const char ** --
    663                                            * Retrieves the absolute path from where this libretro
    664                                            * implementation was loaded.
    665                                            * NULL is returned if the libretro was loaded statically
    666                                            * (i.e. linked statically to frontend), or if the path cannot be
    667                                            * determined.
    668                                            * Mostly useful in cooperation with SET_SUPPORT_NO_GAME as assets can
    669                                            * be loaded without ugly hacks.
    670                                            */
    671
    672                                           /* Environment 20 was an obsolete version of SET_AUDIO_CALLBACK.
    673                                            * It was not used by any known core at the time,
    674                                            * and was removed from the API. */
    675#define RETRO_ENVIRONMENT_SET_FRAME_TIME_CALLBACK 21
    676                                           /* const struct retro_frame_time_callback * --
    677                                            * Lets the core know how much time has passed since last
    678                                            * invocation of retro_run().
    679                                            * The frontend can tamper with the timing to fake fast-forward,
    680                                            * slow-motion, frame stepping, etc.
    681                                            * In this case the delta time will use the reference value
    682                                            * in frame_time_callback..
    683                                            */
    684#define RETRO_ENVIRONMENT_SET_AUDIO_CALLBACK 22
    685                                           /* const struct retro_audio_callback * --
    686                                            * Sets an interface which is used to notify a libretro core about audio
    687                                            * being available for writing.
    688                                            * The callback can be called from any thread, so a core using this must
    689                                            * have a thread safe audio implementation.
    690                                            * It is intended for games where audio and video are completely
    691                                            * asynchronous and audio can be generated on the fly.
    692                                            * This interface is not recommended for use with emulators which have
    693                                            * highly synchronous audio.
    694                                            *
    695                                            * The callback only notifies about writability; the libretro core still
    696                                            * has to call the normal audio callbacks
    697                                            * to write audio. The audio callbacks must be called from within the
    698                                            * notification callback.
    699                                            * The amount of audio data to write is up to the implementation.
    700                                            * Generally, the audio callback will be called continously in a loop.
    701                                            *
    702                                            * Due to thread safety guarantees and lack of sync between audio and
    703                                            * video, a frontend  can selectively disallow this interface based on
    704                                            * internal configuration. A core using this interface must also
    705                                            * implement the "normal" audio interface.
    706                                            *
    707                                            * A libretro core using SET_AUDIO_CALLBACK should also make use of
    708                                            * SET_FRAME_TIME_CALLBACK.
    709                                            */
    710#define RETRO_ENVIRONMENT_GET_RUMBLE_INTERFACE 23
    711                                           /* struct retro_rumble_interface * --
    712                                            * Gets an interface which is used by a libretro core to set
    713                                            * state of rumble motors in controllers.
    714                                            * A strong and weak motor is supported, and they can be
    715                                            * controlled indepedently.
    716                                            * Should be called from either retro_init() or retro_load_game().
    717                                            * Should not be called from retro_set_environment().
    718                                            * Returns false if rumble functionality is unavailable.
    719                                            */
    720#define RETRO_ENVIRONMENT_GET_INPUT_DEVICE_CAPABILITIES 24
    721                                           /* uint64_t * --
    722                                            * Gets a bitmask telling which device type are expected to be
    723                                            * handled properly in a call to retro_input_state_t.
    724                                            * Devices which are not handled or recognized always return
    725                                            * 0 in retro_input_state_t.
    726                                            * Example bitmask: caps = (1 << RETRO_DEVICE_JOYPAD) | (1 << RETRO_DEVICE_ANALOG).
    727                                            * Should only be called in retro_run().
    728                                            */
    729#define RETRO_ENVIRONMENT_GET_SENSOR_INTERFACE (25 | RETRO_ENVIRONMENT_EXPERIMENTAL)
    730                                           /* struct retro_sensor_interface * --
    731                                            * Gets access to the sensor interface.
    732                                            * The purpose of this interface is to allow
    733                                            * setting state related to sensors such as polling rate,
    734                                            * enabling/disable it entirely, etc.
    735                                            * Reading sensor state is done via the normal
    736                                            * input_state_callback API.
    737                                            */
    738#define RETRO_ENVIRONMENT_GET_CAMERA_INTERFACE (26 | RETRO_ENVIRONMENT_EXPERIMENTAL)
    739                                           /* struct retro_camera_callback * --
    740                                            * Gets an interface to a video camera driver.
    741                                            * A libretro core can use this interface to get access to a
    742                                            * video camera.
    743                                            * New video frames are delivered in a callback in same
    744                                            * thread as retro_run().
    745                                            *
    746                                            * GET_CAMERA_INTERFACE should be called in retro_load_game().
    747                                            *
    748                                            * Depending on the camera implementation used, camera frames
    749                                            * will be delivered as a raw framebuffer,
    750                                            * or as an OpenGL texture directly.
    751                                            *
    752                                            * The core has to tell the frontend here which types of
    753                                            * buffers can be handled properly.
    754                                            * An OpenGL texture can only be handled when using a
    755                                            * libretro GL core (SET_HW_RENDER).
    756                                            * It is recommended to use a libretro GL core when
    757                                            * using camera interface.
    758                                            *
    759                                            * The camera is not started automatically. The retrieved start/stop
    760                                            * functions must be used to explicitly
    761                                            * start and stop the camera driver.
    762                                            */
    763#define RETRO_ENVIRONMENT_GET_LOG_INTERFACE 27
    764                                           /* struct retro_log_callback * --
    765                                            * Gets an interface for logging. This is useful for
    766                                            * logging in a cross-platform way
    767                                            * as certain platforms cannot use stderr for logging.
    768                                            * It also allows the frontend to
    769                                            * show logging information in a more suitable way.
    770                                            * If this interface is not used, libretro cores should
    771                                            * log to stderr as desired.
    772                                            */
    773#define RETRO_ENVIRONMENT_GET_PERF_INTERFACE 28
    774                                           /* struct retro_perf_callback * --
    775                                            * Gets an interface for performance counters. This is useful
    776                                            * for performance logging in a cross-platform way and for detecting
    777                                            * architecture-specific features, such as SIMD support.
    778                                            */
    779#define RETRO_ENVIRONMENT_GET_LOCATION_INTERFACE 29
    780                                           /* struct retro_location_callback * --
    781                                            * Gets access to the location interface.
    782                                            * The purpose of this interface is to be able to retrieve
    783                                            * location-based information from the host device,
    784                                            * such as current latitude / longitude.
    785                                            */
    786#define RETRO_ENVIRONMENT_GET_CONTENT_DIRECTORY 30 /* Old name, kept for compatibility. */
    787#define RETRO_ENVIRONMENT_GET_CORE_ASSETS_DIRECTORY 30
    788                                           /* const char ** --
    789                                            * Returns the "core assets" directory of the frontend.
    790                                            * This directory can be used to store specific assets that the
    791                                            * core relies upon, such as art assets,
    792                                            * input data, etc etc.
    793                                            * The returned value can be NULL.
    794                                            * If so, no such directory is defined,
    795                                            * and it's up to the implementation to find a suitable directory.
    796                                            */
    797#define RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY 31
    798                                           /* const char ** --
    799                                            * Returns the "save" directory of the frontend, unless there is no
    800                                            * save directory available. The save directory should be used to
    801                                            * store SRAM, memory cards, high scores, etc, if the libretro core
    802                                            * cannot use the regular memory interface (retro_get_memory_data()).
    803                                            *
    804                                            * If the frontend cannot designate a save directory, it will return
    805                                            * NULL to indicate that the core should attempt to operate without a
    806                                            * save directory set.
    807                                            *
    808                                            * NOTE: early libretro cores used the system directory for save
    809                                            * files. Cores that need to be backwards-compatible can still check
    810                                            * GET_SYSTEM_DIRECTORY.
    811                                            */
    812#define RETRO_ENVIRONMENT_SET_SYSTEM_AV_INFO 32
    813                                           /* const struct retro_system_av_info * --
    814                                            * Sets a new av_info structure. This can only be called from
    815                                            * within retro_run().
    816                                            * This should *only* be used if the core is completely altering the
    817                                            * internal resolutions, aspect ratios, timings, sampling rate, etc.
    818                                            * Calling this can require a full reinitialization of video/audio
    819                                            * drivers in the frontend,
    820                                            *
    821                                            * so it is important to call it very sparingly, and usually only with
    822                                            * the users explicit consent.
    823                                            * An eventual driver reinitialize will happen so that video and
    824                                            * audio callbacks
    825                                            * happening after this call within the same retro_run() call will
    826                                            * target the newly initialized driver.
    827                                            *
    828                                            * This callback makes it possible to support configurable resolutions
    829                                            * in games, which can be useful to
    830                                            * avoid setting the "worst case" in max_width/max_height.
    831                                            *
    832                                            * ***HIGHLY RECOMMENDED*** Do not call this callback every time
    833                                            * resolution changes in an emulator core if it's
    834                                            * expected to be a temporary change, for the reasons of possible
    835                                            * driver reinitialization.
    836                                            * This call is not a free pass for not trying to provide
    837                                            * correct values in retro_get_system_av_info(). If you need to change
    838                                            * things like aspect ratio or nominal width/height,
    839                                            * use RETRO_ENVIRONMENT_SET_GEOMETRY, which is a softer variant
    840                                            * of SET_SYSTEM_AV_INFO.
    841                                            *
    842                                            * If this returns false, the frontend does not acknowledge a
    843                                            * changed av_info struct.
    844                                            */
    845#define RETRO_ENVIRONMENT_SET_PROC_ADDRESS_CALLBACK 33
    846                                           /* const struct retro_get_proc_address_interface * --
    847                                            * Allows a libretro core to announce support for the
    848                                            * get_proc_address() interface.
    849                                            * This interface allows for a standard way to extend libretro where
    850                                            * use of environment calls are too indirect,
    851                                            * e.g. for cases where the frontend wants to call directly into the core.
    852                                            *
    853                                            * If a core wants to expose this interface, SET_PROC_ADDRESS_CALLBACK
    854                                            * **MUST** be called from within retro_set_environment().
    855                                            */
    856#define RETRO_ENVIRONMENT_SET_SUBSYSTEM_INFO 34
    857                                           /* const struct retro_subsystem_info * --
    858                                            * This environment call introduces the concept of libretro "subsystems".
    859                                            * A subsystem is a variant of a libretro core which supports
    860                                            * different kinds of games.
    861                                            * The purpose of this is to support e.g. emulators which might
    862                                            * have special needs, e.g. Super Nintendo's Super GameBoy, Sufami Turbo.
    863                                            * It can also be used to pick among subsystems in an explicit way
    864                                            * if the libretro implementation is a multi-system emulator itself.
    865                                            *
    866                                            * Loading a game via a subsystem is done with retro_load_game_special(),
    867                                            * and this environment call allows a libretro core to expose which
    868                                            * subsystems are supported for use with retro_load_game_special().
    869                                            * A core passes an array of retro_game_special_info which is terminated
    870                                            * with a zeroed out retro_game_special_info struct.
    871                                            *
    872                                            * If a core wants to use this functionality, SET_SUBSYSTEM_INFO
    873                                            * **MUST** be called from within retro_set_environment().
    874                                            */
    875#define RETRO_ENVIRONMENT_SET_CONTROLLER_INFO 35
    876                                           /* const struct retro_controller_info * --
    877                                            * This environment call lets a libretro core tell the frontend
    878                                            * which controller subclasses are recognized in calls to
    879                                            * retro_set_controller_port_device().
    880                                            *
    881                                            * Some emulators such as Super Nintendo support multiple lightgun
    882                                            * types which must be specifically selected from. It is therefore
    883                                            * sometimes necessary for a frontend to be able to tell the core
    884                                            * about a special kind of input device which is not specifcally
    885                                            * provided by the Libretro API.
    886                                            *
    887                                            * In order for a frontend to understand the workings of those devices,
    888                                            * they must be defined as a specialized subclass of the generic device
    889                                            * types already defined in the libretro API.
    890                                            *
    891                                            * The core must pass an array of const struct retro_controller_info which
    892                                            * is terminated with a blanked out struct. Each element of the
    893                                            * retro_controller_info struct corresponds to the ascending port index
    894                                            * that is passed to retro_set_controller_port_device() when that function
    895                                            * is called to indicate to the core that the frontend has changed the
    896                                            * active device subclass. SEE ALSO: retro_set_controller_port_device()
    897                                            *
    898                                            * The ascending input port indexes provided by the core in the struct
    899                                            * are generally presented by frontends as ascending User # or Player #,
    900                                            * such as Player 1, Player 2, Player 3, etc. Which device subclasses are
    901                                            * supported can vary per input port.
    902                                            *
    903                                            * The first inner element of each entry in the retro_controller_info array
    904                                            * is a retro_controller_description struct that specifies the names and
    905                                            * codes of all device subclasses that are available for the corresponding
    906                                            * User or Player, beginning with the generic Libretro device that the
    907                                            * subclasses are derived from. The second inner element of each entry is the
    908                                            * total number of subclasses that are listed in the retro_controller_description.
    909                                            *
    910                                            * NOTE: Even if special device types are set in the libretro core,
    911                                            * libretro should only poll input based on the base input device types.
    912                                            */
    913#define RETRO_ENVIRONMENT_SET_MEMORY_MAPS (36 | RETRO_ENVIRONMENT_EXPERIMENTAL)
    914                                           /* const struct retro_memory_map * --
    915                                            * This environment call lets a libretro core tell the frontend
    916                                            * about the memory maps this core emulates.
    917                                            * This can be used to implement, for example, cheats in a core-agnostic way.
    918                                            *
    919                                            * Should only be used by emulators; it doesn't make much sense for
    920                                            * anything else.
    921                                            * It is recommended to expose all relevant pointers through
    922                                            * retro_get_memory_* as well.
    923                                            *
    924                                            * Can be called from retro_init and retro_load_game.
    925                                            */
    926#define RETRO_ENVIRONMENT_SET_GEOMETRY 37
    927                                           /* const struct retro_game_geometry * --
    928                                            * This environment call is similar to SET_SYSTEM_AV_INFO for changing
    929                                            * video parameters, but provides a guarantee that drivers will not be
    930                                            * reinitialized.
    931                                            * This can only be called from within retro_run().
    932                                            *
    933                                            * The purpose of this call is to allow a core to alter nominal
    934                                            * width/heights as well as aspect ratios on-the-fly, which can be
    935                                            * useful for some emulators to change in run-time.
    936                                            *
    937                                            * max_width/max_height arguments are ignored and cannot be changed
    938                                            * with this call as this could potentially require a reinitialization or a
    939                                            * non-constant time operation.
    940                                            * If max_width/max_height are to be changed, SET_SYSTEM_AV_INFO is required.
    941                                            *
    942                                            * A frontend must guarantee that this environment call completes in
    943                                            * constant time.
    944                                            */
    945#define RETRO_ENVIRONMENT_GET_USERNAME 38
    946                                           /* const char **
    947                                            * Returns the specified username of the frontend, if specified by the user.
    948                                            * This username can be used as a nickname for a core that has online facilities
    949                                            * or any other mode where personalization of the user is desirable.
    950                                            * The returned value can be NULL.
    951                                            * If this environ callback is used by a core that requires a valid username,
    952                                            * a default username should be specified by the core.
    953                                            */
    954#define RETRO_ENVIRONMENT_GET_LANGUAGE 39
    955                                           /* unsigned * --
    956                                            * Returns the specified language of the frontend, if specified by the user.
    957                                            * It can be used by the core for localization purposes.
    958                                            */
    959#define RETRO_ENVIRONMENT_GET_CURRENT_SOFTWARE_FRAMEBUFFER (40 | RETRO_ENVIRONMENT_EXPERIMENTAL)
    960                                           /* struct retro_framebuffer * --
    961                                            * Returns a preallocated framebuffer which the core can use for rendering
    962                                            * the frame into when not using SET_HW_RENDER.
    963                                            * The framebuffer returned from this call must not be used
    964                                            * after the current call to retro_run() returns.
    965                                            *
    966                                            * The goal of this call is to allow zero-copy behavior where a core
    967                                            * can render directly into video memory, avoiding extra bandwidth cost by copying
    968                                            * memory from core to video memory.
    969                                            *
    970                                            * If this call succeeds and the core renders into it,
    971                                            * the framebuffer pointer and pitch can be passed to retro_video_refresh_t.
    972                                            * If the buffer from GET_CURRENT_SOFTWARE_FRAMEBUFFER is to be used,
    973                                            * the core must pass the exact
    974                                            * same pointer as returned by GET_CURRENT_SOFTWARE_FRAMEBUFFER;
    975                                            * i.e. passing a pointer which is offset from the
    976                                            * buffer is undefined. The width, height and pitch parameters
    977                                            * must also match exactly to the values obtained from GET_CURRENT_SOFTWARE_FRAMEBUFFER.
    978                                            *
    979                                            * It is possible for a frontend to return a different pixel format
    980                                            * than the one used in SET_PIXEL_FORMAT. This can happen if the frontend
    981                                            * needs to perform conversion.
    982                                            *
    983                                            * It is still valid for a core to render to a different buffer
    984                                            * even if GET_CURRENT_SOFTWARE_FRAMEBUFFER succeeds.
    985                                            *
    986                                            * A frontend must make sure that the pointer obtained from this function is
    987                                            * writeable (and readable).
    988                                            */
    989#define RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE (41 | RETRO_ENVIRONMENT_EXPERIMENTAL)
    990                                           /* const struct retro_hw_render_interface ** --
    991                                            * Returns an API specific rendering interface for accessing API specific data.
    992                                            * Not all HW rendering APIs support or need this.
    993                                            * The contents of the returned pointer is specific to the rendering API
    994                                            * being used. See the various headers like libretro_vulkan.h, etc.
    995                                            *
    996                                            * GET_HW_RENDER_INTERFACE cannot be called before context_reset has been called.
    997                                            * Similarly, after context_destroyed callback returns,
    998                                            * the contents of the HW_RENDER_INTERFACE are invalidated.
    999                                            */
   1000#define RETRO_ENVIRONMENT_SET_SUPPORT_ACHIEVEMENTS (42 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1001                                           /* const bool * --
   1002                                            * If true, the libretro implementation supports achievements
   1003                                            * either via memory descriptors set with RETRO_ENVIRONMENT_SET_MEMORY_MAPS
   1004                                            * or via retro_get_memory_data/retro_get_memory_size.
   1005                                            *
   1006                                            * This must be called before the first call to retro_run.
   1007                                            */
   1008#define RETRO_ENVIRONMENT_SET_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE (43 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1009                                           /* const struct retro_hw_render_context_negotiation_interface * --
   1010                                            * Sets an interface which lets the libretro core negotiate with frontend how a context is created.
   1011                                            * The semantics of this interface depends on which API is used in SET_HW_RENDER earlier.
   1012                                            * This interface will be used when the frontend is trying to create a HW rendering context,
   1013                                            * so it will be used after SET_HW_RENDER, but before the context_reset callback.
   1014                                            */
   1015#define RETRO_ENVIRONMENT_SET_SERIALIZATION_QUIRKS 44
   1016                                           /* uint64_t * --
   1017                                            * Sets quirk flags associated with serialization. The frontend will zero any flags it doesn't
   1018                                            * recognize or support. Should be set in either retro_init or retro_load_game, but not both.
   1019                                            */
   1020#define RETRO_ENVIRONMENT_SET_HW_SHARED_CONTEXT (44 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1021                                           /* N/A (null) * --
   1022                                            * The frontend will try to use a 'shared' hardware context (mostly applicable
   1023                                            * to OpenGL) when a hardware context is being set up.
   1024                                            *
   1025                                            * Returns true if the frontend supports shared hardware contexts and false
   1026                                            * if the frontend does not support shared hardware contexts.
   1027                                            *
   1028                                            * This will do nothing on its own until SET_HW_RENDER env callbacks are
   1029                                            * being used.
   1030                                            */
   1031#define RETRO_ENVIRONMENT_GET_VFS_INTERFACE (45 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1032                                           /* struct retro_vfs_interface_info * --
   1033                                            * Gets access to the VFS interface.
   1034                                            * VFS presence needs to be queried prior to load_game or any
   1035                                            * get_system/save/other_directory being called to let front end know
   1036                                            * core supports VFS before it starts handing out paths.
   1037                                            * It is recomended to do so in retro_set_environment
   1038                                            */
   1039#define RETRO_ENVIRONMENT_GET_LED_INTERFACE (46 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1040                                           /* struct retro_led_interface * --
   1041                                            * Gets an interface which is used by a libretro core to set
   1042                                            * state of LEDs.
   1043                                            */
   1044#define RETRO_ENVIRONMENT_GET_AUDIO_VIDEO_ENABLE (47 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1045                                           /* int * --
   1046                                            * Tells the core if the frontend wants audio or video.
   1047                                            * If disabled, the frontend will discard the audio or video,
   1048                                            * so the core may decide to skip generating a frame or generating audio.
   1049                                            * This is mainly used for increasing performance.
   1050                                            * Bit 0 (value 1): Enable Video
   1051                                            * Bit 1 (value 2): Enable Audio
   1052                                            * Bit 2 (value 4): Use Fast Savestates.
   1053                                            * Bit 3 (value 8): Hard Disable Audio
   1054                                            * Other bits are reserved for future use and will default to zero.
   1055                                            * If video is disabled:
   1056                                            * * The frontend wants the core to not generate any video,
   1057                                            *   including presenting frames via hardware acceleration.
   1058                                            * * The frontend's video frame callback will do nothing.
   1059                                            * * After running the frame, the video output of the next frame should be
   1060                                            *   no different than if video was enabled, and saving and loading state
   1061                                            *   should have no issues.
   1062                                            * If audio is disabled:
   1063                                            * * The frontend wants the core to not generate any audio.
   1064                                            * * The frontend's audio callbacks will do nothing.
   1065                                            * * After running the frame, the audio output of the next frame should be
   1066                                            *   no different than if audio was enabled, and saving and loading state
   1067                                            *   should have no issues.
   1068                                            * Fast Savestates:
   1069                                            * * Guaranteed to be created by the same binary that will load them.
   1070                                            * * Will not be written to or read from the disk.
   1071                                            * * Suggest that the core assumes loading state will succeed.
   1072                                            * * Suggest that the core updates its memory buffers in-place if possible.
   1073                                            * * Suggest that the core skips clearing memory.
   1074                                            * * Suggest that the core skips resetting the system.
   1075                                            * * Suggest that the core may skip validation steps.
   1076                                            * Hard Disable Audio:
   1077                                            * * Used for a secondary core when running ahead.
   1078                                            * * Indicates that the frontend will never need audio from the core.
   1079                                            * * Suggests that the core may stop synthesizing audio, but this should not
   1080                                            *   compromise emulation accuracy.
   1081                                            * * Audio output for the next frame does not matter, and the frontend will
   1082                                            *   never need an accurate audio state in the future.
   1083                                            * * State will never be saved when using Hard Disable Audio.
   1084                                            */
   1085#define RETRO_ENVIRONMENT_GET_MIDI_INTERFACE (48 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1086                                           /* struct retro_midi_interface ** --
   1087                                            * Returns a MIDI interface that can be used for raw data I/O.
   1088                                            */
   1089
   1090#define RETRO_ENVIRONMENT_GET_FASTFORWARDING (49 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1091                                            /* bool * --
   1092                                            * Boolean value that indicates whether or not the frontend is in
   1093                                            * fastforwarding mode.
   1094                                            */
   1095
   1096#define RETRO_ENVIRONMENT_GET_TARGET_REFRESH_RATE (50 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1097                                            /* float * --
   1098                                            * Float value that lets us know what target refresh rate
   1099                                            * is curently in use by the frontend.
   1100                                            *
   1101                                            * The core can use the returned value to set an ideal
   1102                                            * refresh rate/framerate.
   1103                                            */
   1104
   1105#define RETRO_ENVIRONMENT_GET_INPUT_BITMASKS (51 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1106                                            /* bool * --
   1107                                            * Boolean value that indicates whether or not the frontend supports
   1108                                            * input bitmasks being returned by retro_input_state_t. The advantage
   1109                                            * of this is that retro_input_state_t has to be only called once to
   1110                                            * grab all button states instead of multiple times.
   1111                                            *
   1112                                            * If it returns true, you can pass RETRO_DEVICE_ID_JOYPAD_MASK as 'id'
   1113                                            * to retro_input_state_t (make sure 'device' is set to RETRO_DEVICE_JOYPAD).
   1114                                            * It will return a bitmask of all the digital buttons.
   1115                                            */
   1116
   1117#define RETRO_ENVIRONMENT_GET_CORE_OPTIONS_VERSION 52
   1118                                           /* unsigned * --
   1119                                            * Unsigned value is the API version number of the core options
   1120                                            * interface supported by the frontend. If callback return false,
   1121                                            * API version is assumed to be 0.
   1122                                            *
   1123                                            * In legacy code, core options are set by passing an array of
   1124                                            * retro_variable structs to RETRO_ENVIRONMENT_SET_VARIABLES.
   1125                                            * This may be still be done regardless of the core options
   1126                                            * interface version.
   1127                                            *
   1128                                            * If version is >= 1 however, core options may instead be set by
   1129                                            * passing an array of retro_core_option_definition structs to
   1130                                            * RETRO_ENVIRONMENT_SET_CORE_OPTIONS, or a 2D array of
   1131                                            * retro_core_option_definition structs to RETRO_ENVIRONMENT_SET_CORE_OPTIONS_INTL.
   1132                                            * This allows the core to additionally set option sublabel information
   1133                                            * and/or provide localisation support.
   1134                                            */
   1135
   1136#define RETRO_ENVIRONMENT_SET_CORE_OPTIONS 53
   1137                                           /* const struct retro_core_option_definition ** --
   1138                                            * Allows an implementation to signal the environment
   1139                                            * which variables it might want to check for later using
   1140                                            * GET_VARIABLE.
   1141                                            * This allows the frontend to present these variables to
   1142                                            * a user dynamically.
   1143                                            * This should only be called if RETRO_ENVIRONMENT_GET_CORE_OPTIONS_VERSION
   1144                                            * returns an API version of >= 1.
   1145                                            * This should be called instead of RETRO_ENVIRONMENT_SET_VARIABLES.
   1146                                            * This should be called the first time as early as
   1147                                            * possible (ideally in retro_set_environment).
   1148                                            * Afterwards it may be called again for the core to communicate
   1149                                            * updated options to the frontend, but the number of core
   1150                                            * options must not change from the number in the initial call.
   1151                                            *
   1152                                            * 'data' points to an array of retro_core_option_definition structs
   1153                                            * terminated by a { NULL, NULL, NULL, {{0}}, NULL } element.
   1154                                            * retro_core_option_definition::key should be namespaced to not collide
   1155                                            * with other implementations' keys. e.g. A core called
   1156                                            * 'foo' should use keys named as 'foo_option'.
   1157                                            * retro_core_option_definition::desc should contain a human readable
   1158                                            * description of the key.
   1159                                            * retro_core_option_definition::info should contain any additional human
   1160                                            * readable information text that a typical user may need to
   1161                                            * understand the functionality of the option.
   1162                                            * retro_core_option_definition::values is an array of retro_core_option_value
   1163                                            * structs terminated by a { NULL, NULL } element.
   1164                                            * > retro_core_option_definition::values[index].value is an expected option
   1165                                            *   value.
   1166                                            * > retro_core_option_definition::values[index].label is a human readable
   1167                                            *   label used when displaying the value on screen. If NULL,
   1168                                            *   the value itself is used.
   1169                                            * retro_core_option_definition::default_value is the default core option
   1170                                            * setting. It must match one of the expected option values in the
   1171                                            * retro_core_option_definition::values array. If it does not, or the
   1172                                            * default value is NULL, the first entry in the
   1173                                            * retro_core_option_definition::values array is treated as the default.
   1174                                            *
   1175                                            * The number of possible options should be very limited,
   1176                                            * and must be less than RETRO_NUM_CORE_OPTION_VALUES_MAX.
   1177                                            * i.e. it should be feasible to cycle through options
   1178                                            * without a keyboard.
   1179                                            *
   1180                                            * Example entry:
   1181                                            * {
   1182                                            *     "foo_option",
   1183                                            *     "Speed hack coprocessor X",
   1184                                            *     "Provides increased performance at the expense of reduced accuracy",
   1185                                            * 	  {
   1186                                            *         { "false",    NULL },
   1187                                            *         { "true",     NULL },
   1188                                            *         { "unstable", "Turbo (Unstable)" },
   1189                                            *         { NULL, NULL },
   1190                                            *     },
   1191                                            *     "false"
   1192                                            * }
   1193                                            *
   1194                                            * Only strings are operated on. The possible values will
   1195                                            * generally be displayed and stored as-is by the frontend.
   1196                                            */
   1197
   1198#define RETRO_ENVIRONMENT_SET_CORE_OPTIONS_INTL 54
   1199                                           /* const struct retro_core_options_intl * --
   1200                                            * Allows an implementation to signal the environment
   1201                                            * which variables it might want to check for later using
   1202                                            * GET_VARIABLE.
   1203                                            * This allows the frontend to present these variables to
   1204                                            * a user dynamically.
   1205                                            * This should only be called if RETRO_ENVIRONMENT_GET_CORE_OPTIONS_VERSION
   1206                                            * returns an API version of >= 1.
   1207                                            * This should be called instead of RETRO_ENVIRONMENT_SET_VARIABLES.
   1208                                            * This should be called the first time as early as
   1209                                            * possible (ideally in retro_set_environment).
   1210                                            * Afterwards it may be called again for the core to communicate
   1211                                            * updated options to the frontend, but the number of core
   1212                                            * options must not change from the number in the initial call.
   1213                                            *
   1214                                            * This is fundamentally the same as RETRO_ENVIRONMENT_SET_CORE_OPTIONS,
   1215                                            * with the addition of localisation support. The description of the
   1216                                            * RETRO_ENVIRONMENT_SET_CORE_OPTIONS callback should be consulted
   1217                                            * for further details.
   1218                                            *
   1219                                            * 'data' points to a retro_core_options_intl struct.
   1220                                            *
   1221                                            * retro_core_options_intl::us is a pointer to an array of
   1222                                            * retro_core_option_definition structs defining the US English
   1223                                            * core options implementation. It must point to a valid array.
   1224                                            *
   1225                                            * retro_core_options_intl::local is a pointer to an array of
   1226                                            * retro_core_option_definition structs defining core options for
   1227                                            * the current frontend language. It may be NULL (in which case
   1228                                            * retro_core_options_intl::us is used by the frontend). Any items
   1229                                            * missing from this array will be read from retro_core_options_intl::us
   1230                                            * instead.
   1231                                            *
   1232                                            * NOTE: Default core option values are always taken from the
   1233                                            * retro_core_options_intl::us array. Any default values in
   1234                                            * retro_core_options_intl::local array will be ignored.
   1235                                            */
   1236
   1237#define RETRO_ENVIRONMENT_SET_CORE_OPTIONS_DISPLAY 55
   1238                                           /* struct retro_core_option_display * --
   1239                                            *
   1240                                            * Allows an implementation to signal the environment to show
   1241                                            * or hide a variable when displaying core options. This is
   1242                                            * considered a *suggestion*. The frontend is free to ignore
   1243                                            * this callback, and its implementation not considered mandatory.
   1244                                            *
   1245                                            * 'data' points to a retro_core_option_display struct
   1246                                            *
   1247                                            * retro_core_option_display::key is a variable identifier
   1248                                            * which has already been set by SET_VARIABLES/SET_CORE_OPTIONS.
   1249                                            *
   1250                                            * retro_core_option_display::visible is a boolean, specifying
   1251                                            * whether variable should be displayed
   1252                                            *
   1253                                            * Note that all core option variables will be set visible by
   1254                                            * default when calling SET_VARIABLES/SET_CORE_OPTIONS.
   1255                                            */
   1256
   1257#define RETRO_ENVIRONMENT_GET_PREFERRED_HW_RENDER 56
   1258                                           /* unsigned * --
   1259                                            *
   1260                                            * Allows an implementation to ask frontend preferred hardware
   1261                                            * context to use. Core should use this information to deal
   1262                                            * with what specific context to request with SET_HW_RENDER.
   1263                                            *
   1264                                            * 'data' points to an unsigned variable
   1265                                            */
   1266
   1267#define RETRO_ENVIRONMENT_GET_DISK_CONTROL_INTERFACE_VERSION 57
   1268                                           /* unsigned * --
   1269                                            * Unsigned value is the API version number of the disk control
   1270                                            * interface supported by the frontend. If callback return false,
   1271                                            * API version is assumed to be 0.
   1272                                            *
   1273                                            * In legacy code, the disk control interface is defined by passing
   1274                                            * a struct of type retro_disk_control_callback to
   1275                                            * RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE.
   1276                                            * This may be still be done regardless of the disk control
   1277                                            * interface version.
   1278                                            *
   1279                                            * If version is >= 1 however, the disk control interface may
   1280                                            * instead be defined by passing a struct of type
   1281                                            * retro_disk_control_ext_callback to
   1282                                            * RETRO_ENVIRONMENT_SET_DISK_CONTROL_EXT_INTERFACE.
   1283                                            * This allows the core to provide additional information about
   1284                                            * disk images to the frontend and/or enables extra
   1285                                            * disk control functionality by the frontend.
   1286                                            */
   1287
   1288#define RETRO_ENVIRONMENT_SET_DISK_CONTROL_EXT_INTERFACE 58
   1289                                           /* const struct retro_disk_control_ext_callback * --
   1290                                            * Sets an interface which frontend can use to eject and insert
   1291                                            * disk images, and also obtain information about individual
   1292                                            * disk image files registered by the core.
   1293                                            * This is used for games which consist of multiple images and
   1294                                            * must be manually swapped out by the user (e.g. PSX, floppy disk
   1295                                            * based systems).
   1296                                            */
   1297
   1298#define RETRO_ENVIRONMENT_GET_MESSAGE_INTERFACE_VERSION 59
   1299                                           /* unsigned * --
   1300                                            * Unsigned value is the API version number of the message
   1301                                            * interface supported by the frontend. If callback returns
   1302                                            * false, API version is assumed to be 0.
   1303                                            *
   1304                                            * In legacy code, messages may be displayed in an
   1305                                            * implementation-specific manner by passing a struct
   1306                                            * of type retro_message to RETRO_ENVIRONMENT_SET_MESSAGE.
   1307                                            * This may be still be done regardless of the message
   1308                                            * interface version.
   1309                                            *
   1310                                            * If version is >= 1 however, messages may instead be
   1311                                            * displayed by passing a struct of type retro_message_ext
   1312                                            * to RETRO_ENVIRONMENT_SET_MESSAGE_EXT. This allows the
   1313                                            * core to specify message logging level, priority and
   1314                                            * destination (OSD, logging interface or both).
   1315                                            */
   1316
   1317#define RETRO_ENVIRONMENT_SET_MESSAGE_EXT 60
   1318                                           /* const struct retro_message_ext * --
   1319                                            * Sets a message to be displayed in an implementation-specific
   1320                                            * manner for a certain amount of 'frames'. Additionally allows
   1321                                            * the core to specify message logging level, priority and
   1322                                            * destination (OSD, logging interface or both).
   1323                                            * Should not be used for trivial messages, which should simply be
   1324                                            * logged via RETRO_ENVIRONMENT_GET_LOG_INTERFACE (or as a
   1325                                            * fallback, stderr).
   1326                                            */
   1327
   1328#define RETRO_ENVIRONMENT_GET_INPUT_MAX_USERS 61
   1329                                           /* unsigned * --
   1330                                            * Unsigned value is the number of active input devices
   1331                                            * provided by the frontend. This may change between
   1332                                            * frames, but will remain constant for the duration
   1333                                            * of each frame.
   1334                                            * If callback returns true, a core need not poll any
   1335                                            * input device with an index greater than or equal to
   1336                                            * the number of active devices.
   1337                                            * If callback returns false, the number of active input
   1338                                            * devices is unknown. In this case, all input devices
   1339                                            * should be considered active.
   1340                                            */
   1341
   1342#define RETRO_ENVIRONMENT_SET_AUDIO_BUFFER_STATUS_CALLBACK 62
   1343                                           /* const struct retro_audio_buffer_status_callback * --
   1344                                            * Lets the core know the occupancy level of the frontend
   1345                                            * audio buffer. Can be used by a core to attempt frame
   1346                                            * skipping in order to avoid buffer under-runs.
   1347                                            * A core may pass NULL to disable buffer status reporting
   1348                                            * in the frontend.
   1349                                            */
   1350
   1351#define RETRO_ENVIRONMENT_SET_MINIMUM_AUDIO_LATENCY 63
   1352                                           /* const unsigned * --
   1353                                            * Sets minimum frontend audio latency in milliseconds.
   1354                                            * Resultant audio latency may be larger than set value,
   1355                                            * or smaller if a hardware limit is encountered. A frontend
   1356                                            * is expected to honour requests up to 512 ms.
   1357                                            *
   1358                                            * - If value is less than current frontend
   1359                                            *   audio latency, callback has no effect
   1360                                            * - If value is zero, default frontend audio
   1361                                            *   latency is set
   1362                                            *
   1363                                            * May be used by a core to increase audio latency and
   1364                                            * therefore decrease the probability of buffer under-runs
   1365                                            * (crackling) when performing 'intensive' operations.
   1366                                            * A core utilising RETRO_ENVIRONMENT_SET_AUDIO_BUFFER_STATUS_CALLBACK
   1367                                            * to implement audio-buffer-based frame skipping may achieve
   1368                                            * optimal results by setting the audio latency to a 'high'
   1369                                            * (typically 6x or 8x) integer multiple of the expected
   1370                                            * frame time.
   1371                                            *
   1372                                            * WARNING: This can only be called from within retro_run().
   1373                                            * Calling this can require a full reinitialization of audio
   1374                                            * drivers in the frontend, so it is important to call it very
   1375                                            * sparingly, and usually only with the users explicit consent.
   1376                                            * An eventual driver reinitialize will happen so that audio
   1377                                            * callbacks happening after this call within the same retro_run()
   1378                                            * call will target the newly initialized driver.
   1379                                            */
   1380
   1381/* VFS functionality */
   1382
   1383/* File paths:
   1384 * File paths passed as parameters when using this API shall be well formed UNIX-style,
   1385 * using "/" (unquoted forward slash) as directory separator regardless of the platform's native separator.
   1386 * Paths shall also include at least one forward slash ("game.bin" is an invalid path, use "./game.bin" instead).
   1387 * Other than the directory separator, cores shall not make assumptions about path format:
   1388 * "C:/path/game.bin", "http://example.com/game.bin", "#game/game.bin", "./game.bin" (without quotes) are all valid paths.
   1389 * Cores may replace the basename or remove path components from the end, and/or add new components;
   1390 * however, cores shall not append "./", "../" or multiple consecutive forward slashes ("//") to paths they request to front end.
   1391 * 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.
   1392 * Frontends are encouraged, but not required, to support native file system paths (modulo replacing the directory separator, if applicable).
   1393 * Cores are allowed to try using them, but must remain functional if the front rejects such requests.
   1394 * Cores are encouraged to use the libretro-common filestream functions for file I/O,
   1395 * as they seamlessly integrate with VFS, deal with directory separator replacement as appropriate
   1396 * and provide platform-specific fallbacks in cases where front ends do not support VFS. */
   1397
   1398/* Opaque file handle
   1399 * Introduced in VFS API v1 */
   1400struct retro_vfs_file_handle;
   1401
   1402/* Opaque directory handle
   1403 * Introduced in VFS API v3 */
   1404struct retro_vfs_dir_handle;
   1405
   1406/* File open flags
   1407 * Introduced in VFS API v1 */
   1408#define RETRO_VFS_FILE_ACCESS_READ            (1 << 0) /* Read only mode */
   1409#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 */
   1410#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*/
   1411#define RETRO_VFS_FILE_ACCESS_UPDATE_EXISTING (1 << 2) /* Prevents discarding content of existing files opened for writing */
   1412
   1413/* These are only hints. The frontend may choose to ignore them. Other than RAM/CPU/etc use,
   1414   and how they react to unlikely external interference (for example someone else writing to that file,
   1415   or the file's server going down), behavior will not change. */
   1416#define RETRO_VFS_FILE_ACCESS_HINT_NONE              (0)
   1417/* Indicate that the file will be accessed many times. The frontend should aggressively cache everything. */
   1418#define RETRO_VFS_FILE_ACCESS_HINT_FREQUENT_ACCESS   (1 << 0)
   1419
   1420/* Seek positions */
   1421#define RETRO_VFS_SEEK_POSITION_START    0
   1422#define RETRO_VFS_SEEK_POSITION_CURRENT  1
   1423#define RETRO_VFS_SEEK_POSITION_END      2
   1424
   1425/* stat() result flags
   1426 * Introduced in VFS API v3 */
   1427#define RETRO_VFS_STAT_IS_VALID               (1 << 0)
   1428#define RETRO_VFS_STAT_IS_DIRECTORY           (1 << 1)
   1429#define RETRO_VFS_STAT_IS_CHARACTER_SPECIAL   (1 << 2)
   1430
   1431/* Get path from opaque handle. Returns the exact same path passed to file_open when getting the handle
   1432 * Introduced in VFS API v1 */
   1433typedef const char *(RETRO_CALLCONV *retro_vfs_get_path_t)(struct retro_vfs_file_handle *stream);
   1434
   1435/* Open a file for reading or writing. If path points to a directory, this will
   1436 * fail. Returns the opaque file handle, or NULL for error.
   1437 * Introduced in VFS API v1 */
   1438typedef struct retro_vfs_file_handle *(RETRO_CALLCONV *retro_vfs_open_t)(const char *path, unsigned mode, unsigned hints);
   1439
   1440/* Close the file and release its resources. Must be called if open_file returns non-NULL. Returns 0 on success, -1 on failure.
   1441 * Whether the call succeeds ot not, the handle passed as parameter becomes invalid and should no longer be used.
   1442 * Introduced in VFS API v1 */
   1443typedef int (RETRO_CALLCONV *retro_vfs_close_t)(struct retro_vfs_file_handle *stream);
   1444
   1445/* Return the size of the file in bytes, or -1 for error.
   1446 * Introduced in VFS API v1 */
   1447typedef int64_t (RETRO_CALLCONV *retro_vfs_size_t)(struct retro_vfs_file_handle *stream);
   1448
   1449/* Truncate file to specified size. Returns 0 on success or -1 on error
   1450 * Introduced in VFS API v2 */
   1451typedef int64_t (RETRO_CALLCONV *retro_vfs_truncate_t)(struct retro_vfs_file_handle *stream, int64_t length);
   1452
   1453/* Get the current read / write position for the file. Returns -1 for error.
   1454 * Introduced in VFS API v1 */
   1455typedef int64_t (RETRO_CALLCONV *retro_vfs_tell_t)(struct retro_vfs_file_handle *stream);
   1456
   1457/* Set the current read/write position for the file. Returns the new position, -1 for error.
   1458 * Introduced in VFS API v1 */
   1459typedef int64_t (RETRO_CALLCONV *retro_vfs_seek_t)(struct retro_vfs_file_handle *stream, int64_t offset, int seek_position);
   1460
   1461/* Read data from a file. Returns the number of bytes read, or -1 for error.
   1462 * Introduced in VFS API v1 */
   1463typedef int64_t (RETRO_CALLCONV *retro_vfs_read_t)(struct retro_vfs_file_handle *stream, void *s, uint64_t len);
   1464
   1465/* Write data to a file. Returns the number of bytes written, or -1 for error.
   1466 * Introduced in VFS API v1 */
   1467typedef int64_t (RETRO_CALLCONV *retro_vfs_write_t)(struct retro_vfs_file_handle *stream, const void *s, uint64_t len);
   1468
   1469/* Flush pending writes to file, if using buffered IO. Returns 0 on sucess, or -1 on failure.
   1470 * Introduced in VFS API v1 */
   1471typedef int (RETRO_CALLCONV *retro_vfs_flush_t)(struct retro_vfs_file_handle *stream);
   1472
   1473/* Delete the specified file. Returns 0 on success, -1 on failure
   1474 * Introduced in VFS API v1 */
   1475typedef int (RETRO_CALLCONV *retro_vfs_remove_t)(const char *path);
   1476
   1477/* Rename the specified file. Returns 0 on success, -1 on failure
   1478 * Introduced in VFS API v1 */
   1479typedef int (RETRO_CALLCONV *retro_vfs_rename_t)(const char *old_path, const char *new_path);
   1480
   1481/* Stat the specified file. Retruns a bitmask of RETRO_VFS_STAT_* flags, none are set if path was not valid.
   1482 * Additionally stores file size in given variable, unless NULL is given.
   1483 * Introduced in VFS API v3 */
   1484typedef int (RETRO_CALLCONV *retro_vfs_stat_t)(const char *path, int32_t *size);
   1485
   1486/* Create the specified directory. Returns 0 on success, -1 on unknown failure, -2 if already exists.
   1487 * Introduced in VFS API v3 */
   1488typedef int (RETRO_CALLCONV *retro_vfs_mkdir_t)(const char *dir);
   1489
   1490/* Open the specified directory for listing. Returns the opaque dir handle, or NULL for error.
   1491 * Support for the include_hidden argument may vary depending on the platform.
   1492 * Introduced in VFS API v3 */
   1493typedef struct retro_vfs_dir_handle *(RETRO_CALLCONV *retro_vfs_opendir_t)(const char *dir, bool include_hidden);
   1494
   1495/* Read the directory entry at the current position, and move the read pointer to the next position.
   1496 * Returns true on success, false if already on the last entry.
   1497 * Introduced in VFS API v3 */
   1498typedef bool (RETRO_CALLCONV *retro_vfs_readdir_t)(struct retro_vfs_dir_handle *dirstream);
   1499
   1500/* Get the name of the last entry read. Returns a string on success, or NULL for error.
   1501 * The returned string pointer is valid until the next call to readdir or closedir.
   1502 * Introduced in VFS API v3 */
   1503typedef const char *(RETRO_CALLCONV *retro_vfs_dirent_get_name_t)(struct retro_vfs_dir_handle *dirstream);
   1504
   1505/* Check if the last entry read was a directory. Returns true if it was, false otherwise (or on error).
   1506 * Introduced in VFS API v3 */
   1507typedef bool (RETRO_CALLCONV *retro_vfs_dirent_is_dir_t)(struct retro_vfs_dir_handle *dirstream);
   1508
   1509/* Close the directory and release its resources. Must be called if opendir returns non-NULL. Returns 0 on success, -1 on failure.
   1510 * Whether the call succeeds ot not, the handle passed as parameter becomes invalid and should no longer be used.
   1511 * Introduced in VFS API v3 */
   1512typedef int (RETRO_CALLCONV *retro_vfs_closedir_t)(struct retro_vfs_dir_handle *dirstream);
   1513
   1514struct retro_vfs_interface
   1515{
   1516   /* VFS API v1 */
   1517	retro_vfs_get_path_t get_path;
   1518	retro_vfs_open_t open;
   1519	retro_vfs_close_t close;
   1520	retro_vfs_size_t size;
   1521	retro_vfs_tell_t tell;
   1522	retro_vfs_seek_t seek;
   1523	retro_vfs_read_t read;
   1524	retro_vfs_write_t write;
   1525	retro_vfs_flush_t flush;
   1526	retro_vfs_remove_t remove;
   1527	retro_vfs_rename_t rename;
   1528   /* VFS API v2 */
   1529   retro_vfs_truncate_t truncate;
   1530   /* VFS API v3 */
   1531   retro_vfs_stat_t stat;
   1532   retro_vfs_mkdir_t mkdir;
   1533   retro_vfs_opendir_t opendir;
   1534   retro_vfs_readdir_t readdir;
   1535   retro_vfs_dirent_get_name_t dirent_get_name;
   1536   retro_vfs_dirent_is_dir_t dirent_is_dir;
   1537   retro_vfs_closedir_t closedir;
   1538};
   1539
   1540struct retro_vfs_interface_info
   1541{
   1542   /* Set by core: should this be higher than the version the front end supports,
   1543    * front end will return false in the RETRO_ENVIRONMENT_GET_VFS_INTERFACE call
   1544    * Introduced in VFS API v1 */
   1545   uint32_t required_interface_version;
   1546
   1547   /* Frontend writes interface pointer here. The frontend also sets the actual
   1548    * version, must be at least required_interface_version.
   1549    * Introduced in VFS API v1 */
   1550   struct retro_vfs_interface *iface;
   1551};
   1552
   1553enum retro_hw_render_interface_type
   1554{
   1555	RETRO_HW_RENDER_INTERFACE_VULKAN = 0,
   1556	RETRO_HW_RENDER_INTERFACE_D3D9   = 1,
   1557	RETRO_HW_RENDER_INTERFACE_D3D10  = 2,
   1558	RETRO_HW_RENDER_INTERFACE_D3D11  = 3,
   1559	RETRO_HW_RENDER_INTERFACE_D3D12  = 4,
   1560   RETRO_HW_RENDER_INTERFACE_GSKIT_PS2  = 5,
   1561   RETRO_HW_RENDER_INTERFACE_DUMMY  = INT_MAX
   1562};
   1563
   1564/* Base struct. All retro_hw_render_interface_* types
   1565 * contain at least these fields. */
   1566struct retro_hw_render_interface
   1567{
   1568   enum retro_hw_render_interface_type interface_type;
   1569   unsigned interface_version;
   1570};
   1571
   1572typedef void (RETRO_CALLCONV *retro_set_led_state_t)(int led, int state);
   1573struct retro_led_interface
   1574{
   1575    retro_set_led_state_t set_led_state;
   1576};
   1577
   1578/* Retrieves the current state of the MIDI input.
   1579 * Returns true if it's enabled, false otherwise. */
   1580typedef bool (RETRO_CALLCONV *retro_midi_input_enabled_t)(void);
   1581
   1582/* Retrieves the current state of the MIDI output.
   1583 * Returns true if it's enabled, false otherwise */
   1584typedef bool (RETRO_CALLCONV *retro_midi_output_enabled_t)(void);
   1585
   1586/* Reads next byte from the input stream.
   1587 * Returns true if byte is read, false otherwise. */
   1588typedef bool (RETRO_CALLCONV *retro_midi_read_t)(uint8_t *byte);
   1589
   1590/* Writes byte to the output stream.
   1591 * 'delta_time' is in microseconds and represent time elapsed since previous write.
   1592 * Returns true if byte is written, false otherwise. */
   1593typedef bool (RETRO_CALLCONV *retro_midi_write_t)(uint8_t byte, uint32_t delta_time);
   1594
   1595/* Flushes previously written data.
   1596 * Returns true if successful, false otherwise. */
   1597typedef bool (RETRO_CALLCONV *retro_midi_flush_t)(void);
   1598
   1599struct retro_midi_interface
   1600{
   1601   retro_midi_input_enabled_t input_enabled;
   1602   retro_midi_output_enabled_t output_enabled;
   1603   retro_midi_read_t read;
   1604   retro_midi_write_t write;
   1605   retro_midi_flush_t flush;
   1606};
   1607
   1608enum retro_hw_render_context_negotiation_interface_type
   1609{
   1610   RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_VULKAN = 0,
   1611   RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_DUMMY = INT_MAX
   1612};
   1613
   1614/* Base struct. All retro_hw_render_context_negotiation_interface_* types
   1615 * contain at least these fields. */
   1616struct retro_hw_render_context_negotiation_interface
   1617{
   1618   enum retro_hw_render_context_negotiation_interface_type interface_type;
   1619   unsigned interface_version;
   1620};
   1621
   1622/* Serialized state is incomplete in some way. Set if serialization is
   1623 * usable in typical end-user cases but should not be relied upon to
   1624 * implement frame-sensitive frontend features such as netplay or
   1625 * rerecording. */
   1626#define RETRO_SERIALIZATION_QUIRK_INCOMPLETE (1 << 0)
   1627/* The core must spend some time initializing before serialization is
   1628 * supported. retro_serialize() will initially fail; retro_unserialize()
   1629 * and retro_serialize_size() may or may not work correctly either. */
   1630#define RETRO_SERIALIZATION_QUIRK_MUST_INITIALIZE (1 << 1)
   1631/* Serialization size may change within a session. */
   1632#define RETRO_SERIALIZATION_QUIRK_CORE_VARIABLE_SIZE (1 << 2)
   1633/* Set by the frontend to acknowledge that it supports variable-sized
   1634 * states. */
   1635#define RETRO_SERIALIZATION_QUIRK_FRONT_VARIABLE_SIZE (1 << 3)
   1636/* Serialized state can only be loaded during the same session. */
   1637#define RETRO_SERIALIZATION_QUIRK_SINGLE_SESSION (1 << 4)
   1638/* Serialized state cannot be loaded on an architecture with a different
   1639 * endianness from the one it was saved on. */
   1640#define RETRO_SERIALIZATION_QUIRK_ENDIAN_DEPENDENT (1 << 5)
   1641/* Serialized state cannot be loaded on a different platform from the one it
   1642 * was saved on for reasons other than endianness, such as word size
   1643 * dependence */
   1644#define RETRO_SERIALIZATION_QUIRK_PLATFORM_DEPENDENT (1 << 6)
   1645
   1646#define RETRO_MEMDESC_CONST      (1 << 0)   /* The frontend will never change this memory area once retro_load_game has returned. */
   1647#define RETRO_MEMDESC_BIGENDIAN  (1 << 1)   /* The memory area contains big endian data. Default is little endian. */
   1648#define RETRO_MEMDESC_SYSTEM_RAM (1 << 2)   /* The memory area is system RAM.  This is main RAM of the gaming system. */
   1649#define RETRO_MEMDESC_SAVE_RAM   (1 << 3)   /* The memory area is save RAM. This RAM is usually found on a game cartridge, backed up by a battery. */
   1650#define RETRO_MEMDESC_VIDEO_RAM  (1 << 4)   /* The memory area is video RAM (VRAM) */
   1651#define RETRO_MEMDESC_ALIGN_2    (1 << 16)  /* All memory access in this area is aligned to their own size, or 2, whichever is smaller. */
   1652#define RETRO_MEMDESC_ALIGN_4    (2 << 16)
   1653#define RETRO_MEMDESC_ALIGN_8    (3 << 16)
   1654#define RETRO_MEMDESC_MINSIZE_2  (1 << 24)  /* All memory in this region is accessed at least 2 bytes at the time. */
   1655#define RETRO_MEMDESC_MINSIZE_4  (2 << 24)
   1656#define RETRO_MEMDESC_MINSIZE_8  (3 << 24)
   1657struct retro_memory_descriptor
   1658{
   1659   uint64_t flags;
   1660
   1661   /* Pointer to the start of the relevant ROM or RAM chip.
   1662    * It's strongly recommended to use 'offset' if possible, rather than
   1663    * doing math on the pointer.
   1664    *
   1665    * If the same byte is mapped my multiple descriptors, their descriptors
   1666    * must have the same pointer.
   1667    * If 'start' does not point to the first byte in the pointer, put the
   1668    * difference in 'offset' instead.
   1669    *
   1670    * May be NULL if there's nothing usable here (e.g. hardware registers and
   1671    * open bus). No flags should be set if the pointer is NULL.
   1672    * It's recommended to minimize the number of descriptors if possible,
   1673    * but not mandatory. */
   1674   void *ptr;
   1675   size_t offset;
   1676
   1677   /* This is the location in the emulated address space
   1678    * where the mapping starts. */
   1679   size_t start;
   1680
   1681   /* Which bits must be same as in 'start' for this mapping to apply.
   1682    * The first memory descriptor to claim a certain byte is the one
   1683    * that applies.
   1684    * A bit which is set in 'start' must also be set in this.
   1685    * Can be zero, in which case each byte is assumed mapped exactly once.
   1686    * In this case, 'len' must be a power of two. */
   1687   size_t select;
   1688
   1689   /* If this is nonzero, the set bits are assumed not connected to the
   1690    * memory chip's address pins. */
   1691   size_t disconnect;
   1692
   1693   /* This one tells the size of the current memory area.
   1694    * If, after start+disconnect are applied, the address is higher than
   1695    * this, the highest bit of the address is cleared.
   1696    *
   1697    * If the address is still too high, the next highest bit is cleared.
   1698    * Can be zero, in which case it's assumed to be infinite (as limited
   1699    * by 'select' and 'disconnect'). */
   1700   size_t len;
   1701
   1702   /* To go from emulated address to physical address, the following
   1703    * order applies:
   1704    * Subtract 'start', pick off 'disconnect', apply 'len', add 'offset'. */
   1705
   1706   /* The address space name must consist of only a-zA-Z0-9_-,
   1707    * should be as short as feasible (maximum length is 8 plus the NUL),
   1708    * and may not be any other address space plus one or more 0-9A-F
   1709    * at the end.
   1710    * However, multiple memory descriptors for the same address space is
   1711    * allowed, and the address space name can be empty. NULL is treated
   1712    * as empty.
   1713    *
   1714    * Address space names are case sensitive, but avoid lowercase if possible.
   1715    * The same pointer may exist in multiple address spaces.
   1716    *
   1717    * Examples:
   1718    * blank+blank - valid (multiple things may be mapped in the same namespace)
   1719    * 'Sp'+'Sp' - valid (multiple things may be mapped in the same namespace)
   1720    * 'A'+'B' - valid (neither is a prefix of each other)
   1721    * 'S'+blank - valid ('S' is not in 0-9A-F)
   1722    * 'a'+blank - valid ('a' is not in 0-9A-F)
   1723    * 'a'+'A' - valid (neither is a prefix of each other)
   1724    * 'AR'+blank - valid ('R' is not in 0-9A-F)
   1725    * 'ARB'+blank - valid (the B can't be part of the address either, because
   1726    *                      there is no namespace 'AR')
   1727    * blank+'B' - not valid, because it's ambigous which address space B1234
   1728    *             would refer to.
   1729    * The length can't be used for that purpose; the frontend may want
   1730    * to append arbitrary data to an address, without a separator. */
   1731   const char *addrspace;
   1732
   1733   /* TODO: When finalizing this one, add a description field, which should be
   1734    * "WRAM" or something roughly equally long. */
   1735
   1736   /* TODO: When finalizing this one, replace 'select' with 'limit', which tells
   1737    * which bits can vary and still refer to the same address (limit = ~select).
   1738    * TODO: limit? range? vary? something else? */
   1739
   1740   /* TODO: When finalizing this one, if 'len' is above what 'select' (or
   1741    * 'limit') allows, it's bankswitched. Bankswitched data must have both 'len'
   1742    * and 'select' != 0, and the mappings don't tell how the system switches the
   1743    * banks. */
   1744
   1745   /* TODO: When finalizing this one, fix the 'len' bit removal order.
   1746    * For len=0x1800, pointer 0x1C00 should go to 0x1400, not 0x0C00.
   1747    * Algorithm: Take bits highest to lowest, but if it goes above len, clear
   1748    * the most recent addition and continue on the next bit.
   1749    * TODO: Can the above be optimized? Is "remove the lowest bit set in both
   1750    * pointer and 'len'" equivalent? */
   1751
   1752   /* TODO: Some emulators (MAME?) emulate big endian systems by only accessing
   1753    * the emulated memory in 32-bit chunks, native endian. But that's nothing
   1754    * compared to Darek Mihocka <http://www.emulators.com/docs/nx07_vm101.htm>
   1755    * (section Emulation 103 - Nearly Free Byte Reversal) - he flips the ENTIRE
   1756    * RAM backwards! I'll want to represent both of those, via some flags.
   1757    *
   1758    * I suspect MAME either didn't think of that idea, or don't want the #ifdef.
   1759    * Not sure which, nor do I really care. */
   1760
   1761   /* TODO: Some of those flags are unused and/or don't really make sense. Clean
   1762    * them up. */
   1763};
   1764
   1765/* The frontend may use the largest value of 'start'+'select' in a
   1766 * certain namespace to infer the size of the address space.
   1767 *
   1768 * If the address space is larger than that, a mapping with .ptr=NULL
   1769 * should be at the end of the array, with .select set to all ones for
   1770 * as long as the address space is big.
   1771 *
   1772 * Sample descriptors (minus .ptr, and RETRO_MEMFLAG_ on the flags):
   1773 * SNES WRAM:
   1774 * .start=0x7E0000, .len=0x20000
   1775 * (Note that this must be mapped before the ROM in most cases; some of the
   1776 * ROM mappers
   1777 * try to claim $7E0000, or at least $7E8000.)
   1778 * SNES SPC700 RAM:
   1779 * .addrspace="S", .len=0x10000
   1780 * SNES WRAM mirrors:
   1781 * .flags=MIRROR, .start=0x000000, .select=0xC0E000, .len=0x2000
   1782 * .flags=MIRROR, .start=0x800000, .select=0xC0E000, .len=0x2000
   1783 * SNES WRAM mirrors, alternate equivalent descriptor:
   1784 * .flags=MIRROR, .select=0x40E000, .disconnect=~0x1FFF
   1785 * (Various similar constructions can be created by combining parts of
   1786 * the above two.)
   1787 * SNES LoROM (512KB, mirrored a couple of times):
   1788 * .flags=CONST, .start=0x008000, .select=0x408000, .disconnect=0x8000, .len=512*1024
   1789 * .flags=CONST, .start=0x400000, .select=0x400000, .disconnect=0x8000, .len=512*1024
   1790 * SNES HiROM (4MB):
   1791 * .flags=CONST,                 .start=0x400000, .select=0x400000, .len=4*1024*1024
   1792 * .flags=CONST, .offset=0x8000, .start=0x008000, .select=0x408000, .len=4*1024*1024
   1793 * SNES ExHiROM (8MB):
   1794 * .flags=CONST, .offset=0,                  .start=0xC00000, .select=0xC00000, .len=4*1024*1024
   1795 * .flags=CONST, .offset=4*1024*1024,        .start=0x400000, .select=0xC00000, .len=4*1024*1024
   1796 * .flags=CONST, .offset=0x8000,             .start=0x808000, .select=0xC08000, .len=4*1024*1024
   1797 * .flags=CONST, .offset=4*1024*1024+0x8000, .start=0x008000, .select=0xC08000, .len=4*1024*1024
   1798 * Clarify the size of the address space:
   1799 * .ptr=NULL, .select=0xFFFFFF
   1800 * .len can be implied by .select in many of them, but was included for clarity.
   1801 */
   1802
   1803struct retro_memory_map
   1804{
   1805   const struct retro_memory_descriptor *descriptors;
   1806   unsigned num_descriptors;
   1807};
   1808
   1809struct retro_controller_description
   1810{
   1811   /* Human-readable description of the controller. Even if using a generic
   1812    * input device type, this can be set to the particular device type the
   1813    * core uses. */
   1814   const char *desc;
   1815
   1816   /* Device type passed to retro_set_controller_port_device(). If the device
   1817    * type is a sub-class of a generic input device type, use the
   1818    * RETRO_DEVICE_SUBCLASS macro to create an ID.
   1819    *
   1820    * E.g. RETRO_DEVICE_SUBCLASS(RETRO_DEVICE_JOYPAD, 1). */
   1821   unsigned id;
   1822};
   1823
   1824struct retro_controller_info
   1825{
   1826   const struct retro_controller_description *types;
   1827   unsigned num_types;
   1828};
   1829
   1830struct retro_subsystem_memory_info
   1831{
   1832   /* The extension associated with a memory type, e.g. "psram". */
   1833   const char *extension;
   1834
   1835   /* The memory type for retro_get_memory(). This should be at
   1836    * least 0x100 to avoid conflict with standardized
   1837    * libretro memory types. */
   1838   unsigned type;
   1839};
   1840
   1841struct retro_subsystem_rom_info
   1842{
   1843   /* Describes what the content is (SGB BIOS, GB ROM, etc). */
   1844   const char *desc;
   1845
   1846   /* Same definition as retro_get_system_info(). */
   1847   const char *valid_extensions;
   1848
   1849   /* Same definition as retro_get_system_info(). */
   1850   bool need_fullpath;
   1851
   1852   /* Same definition as retro_get_system_info(). */
   1853   bool block_extract;
   1854
   1855   /* This is set if the content is required to load a game.
   1856    * If this is set to false, a zeroed-out retro_game_info can be passed. */
   1857   bool required;
   1858
   1859   /* Content can have multiple associated persistent
   1860    * memory types (retro_get_memory()). */
   1861   const struct retro_subsystem_memory_info *memory;
   1862   unsigned num_memory;
   1863};
   1864
   1865struct retro_subsystem_info
   1866{
   1867   /* Human-readable string of the subsystem type, e.g. "Super GameBoy" */
   1868   const char *desc;
   1869
   1870   /* A computer friendly short string identifier for the subsystem type.
   1871    * This name must be [a-z].
   1872    * E.g. if desc is "Super GameBoy", this can be "sgb".
   1873    * This identifier can be used for command-line interfaces, etc.
   1874    */
   1875   const char *ident;
   1876
   1877   /* Infos for each content file. The first entry is assumed to be the
   1878    * "most significant" content for frontend purposes.
   1879    * E.g. with Super GameBoy, the first content should be the GameBoy ROM,
   1880    * as it is the most "significant" content to a user.
   1881    * If a frontend creates new file paths based on the content used
   1882    * (e.g. savestates), it should use the path for the first ROM to do so. */
   1883   const struct retro_subsystem_rom_info *roms;
   1884
   1885   /* Number of content files associated with a subsystem. */
   1886   unsigned num_roms;
   1887
   1888   /* The type passed to retro_load_game_special(). */
   1889   unsigned id;
   1890};
   1891
   1892typedef void (RETRO_CALLCONV *retro_proc_address_t)(void);
   1893
   1894/* libretro API extension functions:
   1895 * (None here so far).
   1896 *
   1897 * Get a symbol from a libretro core.
   1898 * Cores should only return symbols which are actual
   1899 * extensions to the libretro API.
   1900 *
   1901 * Frontends should not use this to obtain symbols to standard
   1902 * libretro entry points (static linking or dlsym).
   1903 *
   1904 * The symbol name must be equal to the function name,
   1905 * e.g. if void retro_foo(void); exists, the symbol must be called "retro_foo".
   1906 * The returned function pointer must be cast to the corresponding type.
   1907 */
   1908typedef retro_proc_address_t (RETRO_CALLCONV *retro_get_proc_address_t)(const char *sym);
   1909
   1910struct retro_get_proc_address_interface
   1911{
   1912   retro_get_proc_address_t get_proc_address;
   1913};
   1914
   1915enum retro_log_level
   1916{
   1917   RETRO_LOG_DEBUG = 0,
   1918   RETRO_LOG_INFO,
   1919   RETRO_LOG_WARN,
   1920   RETRO_LOG_ERROR,
   1921
   1922   RETRO_LOG_DUMMY = INT_MAX
   1923};
   1924
   1925/* Logging function. Takes log level argument as well. */
   1926typedef void (RETRO_CALLCONV *retro_log_printf_t)(enum retro_log_level level,
   1927      const char *fmt, ...);
   1928
   1929struct retro_log_callback
   1930{
   1931   retro_log_printf_t log;
   1932};
   1933
   1934/* Performance related functions */
   1935
   1936/* ID values for SIMD CPU features */
   1937#define RETRO_SIMD_SSE      (1 << 0)
   1938#define RETRO_SIMD_SSE2     (1 << 1)
   1939#define RETRO_SIMD_VMX      (1 << 2)
   1940#define RETRO_SIMD_VMX128   (1 << 3)
   1941#define RETRO_SIMD_AVX      (1 << 4)
   1942#define RETRO_SIMD_NEON     (1 << 5)
   1943#define RETRO_SIMD_SSE3     (1 << 6)
   1944#define RETRO_SIMD_SSSE3    (1 << 7)
   1945#define RETRO_SIMD_MMX      (1 << 8)
   1946#define RETRO_SIMD_MMXEXT   (1 << 9)
   1947#define RETRO_SIMD_SSE4     (1 << 10)
   1948#define RETRO_SIMD_SSE42    (1 << 11)
   1949#define RETRO_SIMD_AVX2     (1 << 12)
   1950#define RETRO_SIMD_VFPU     (1 << 13)
   1951#define RETRO_SIMD_PS       (1 << 14)
   1952#define RETRO_SIMD_AES      (1 << 15)
   1953#define RETRO_SIMD_VFPV3    (1 << 16)
   1954#define RETRO_SIMD_VFPV4    (1 << 17)
   1955#define RETRO_SIMD_POPCNT   (1 << 18)
   1956#define RETRO_SIMD_MOVBE    (1 << 19)
   1957#define RETRO_SIMD_CMOV     (1 << 20)
   1958#define RETRO_SIMD_ASIMD    (1 << 21)
   1959
   1960typedef uint64_t retro_perf_tick_t;
   1961typedef int64_t retro_time_t;
   1962
   1963struct retro_perf_counter
   1964{
   1965   const char *ident;
   1966   retro_perf_tick_t start;
   1967   retro_perf_tick_t total;
   1968   retro_perf_tick_t call_cnt;
   1969
   1970   bool registered;
   1971};
   1972
   1973/* Returns current time in microseconds.
   1974 * Tries to use the most accurate timer available.
   1975 */
   1976typedef retro_time_t (RETRO_CALLCONV *retro_perf_get_time_usec_t)(void);
   1977
   1978/* A simple counter. Usually nanoseconds, but can also be CPU cycles.
   1979 * Can be used directly if desired (when creating a more sophisticated
   1980 * performance counter system).
   1981 * */
   1982typedef retro_perf_tick_t (RETRO_CALLCONV *retro_perf_get_counter_t)(void);
   1983
   1984/* Returns a bit-mask of detected CPU features (RETRO_SIMD_*). */
   1985typedef uint64_t (RETRO_CALLCONV *retro_get_cpu_features_t)(void);
   1986
   1987/* Asks frontend to log and/or display the state of performance counters.
   1988 * Performance counters can always be poked into manually as well.
   1989 */
   1990typedef void (RETRO_CALLCONV *retro_perf_log_t)(void);
   1991
   1992/* Register a performance counter.
   1993 * ident field must be set with a discrete value and other values in
   1994 * retro_perf_counter must be 0.
   1995 * Registering can be called multiple times. To avoid calling to
   1996 * frontend redundantly, you can check registered field first. */
   1997typedef void (RETRO_CALLCONV *retro_perf_register_t)(struct retro_perf_counter *counter);
   1998
   1999/* Starts a registered counter. */
   2000typedef void (RETRO_CALLCONV *retro_perf_start_t)(struct retro_perf_counter *counter);
   2001
   2002/* Stops a registered counter. */
   2003typedef void (RETRO_CALLCONV *retro_perf_stop_t)(struct retro_perf_counter *counter);
   2004
   2005/* For convenience it can be useful to wrap register, start and stop in macros.
   2006 * E.g.:
   2007 * #ifdef LOG_PERFORMANCE
   2008 * #define RETRO_PERFORMANCE_INIT(perf_cb, name) static struct retro_perf_counter name = {#name}; if (!name.registered) perf_cb.perf_register(&(name))
   2009 * #define RETRO_PERFORMANCE_START(perf_cb, name) perf_cb.perf_start(&(name))
   2010 * #define RETRO_PERFORMANCE_STOP(perf_cb, name) perf_cb.perf_stop(&(name))
   2011 * #else
   2012 * ... Blank macros ...
   2013 * #endif
   2014 *
   2015 * These can then be used mid-functions around code snippets.
   2016 *
   2017 * extern struct retro_perf_callback perf_cb;  * Somewhere in the core.
   2018 *
   2019 * void do_some_heavy_work(void)
   2020 * {
   2021 *    RETRO_PERFORMANCE_INIT(cb, work_1;
   2022 *    RETRO_PERFORMANCE_START(cb, work_1);
   2023 *    heavy_work_1();
   2024 *    RETRO_PERFORMANCE_STOP(cb, work_1);
   2025 *
   2026 *    RETRO_PERFORMANCE_INIT(cb, work_2);
   2027 *    RETRO_PERFORMANCE_START(cb, work_2);
   2028 *    heavy_work_2();
   2029 *    RETRO_PERFORMANCE_STOP(cb, work_2);
   2030 * }
   2031 *
   2032 * void retro_deinit(void)
   2033 * {
   2034 *    perf_cb.perf_log();  * Log all perf counters here for example.
   2035 * }
   2036 */
   2037
   2038struct retro_perf_callback
   2039{
   2040   retro_perf_get_time_usec_t    get_time_usec;
   2041   retro_get_cpu_features_t      get_cpu_features;
   2042
   2043   retro_perf_get_counter_t      get_perf_counter;
   2044   retro_perf_register_t         perf_register;
   2045   retro_perf_start_t            perf_start;
   2046   retro_perf_stop_t             perf_stop;
   2047   retro_perf_log_t              perf_log;
   2048};
   2049
   2050/* FIXME: Document the sensor API and work out behavior.
   2051 * It will be marked as experimental until then.
   2052 */
   2053enum retro_sensor_action
   2054{
   2055   RETRO_SENSOR_ACCELEROMETER_ENABLE = 0,
   2056   RETRO_SENSOR_ACCELEROMETER_DISABLE,
   2057   RETRO_SENSOR_GYROSCOPE_ENABLE,
   2058   RETRO_SENSOR_GYROSCOPE_DISABLE,
   2059   RETRO_SENSOR_ILLUMINANCE_ENABLE,
   2060   RETRO_SENSOR_ILLUMINANCE_DISABLE,
   2061
   2062   RETRO_SENSOR_DUMMY = INT_MAX
   2063};
   2064
   2065/* Id values for SENSOR types. */
   2066#define RETRO_SENSOR_ACCELEROMETER_X 0
   2067#define RETRO_SENSOR_ACCELEROMETER_Y 1
   2068#define RETRO_SENSOR_ACCELEROMETER_Z 2
   2069#define RETRO_SENSOR_GYROSCOPE_X 3
   2070#define RETRO_SENSOR_GYROSCOPE_Y 4
   2071#define RETRO_SENSOR_GYROSCOPE_Z 5
   2072#define RETRO_SENSOR_ILLUMINANCE 6
   2073
   2074typedef bool (RETRO_CALLCONV *retro_set_sensor_state_t)(unsigned port,
   2075      enum retro_sensor_action action, unsigned rate);
   2076
   2077typedef float (RETRO_CALLCONV *retro_sensor_get_input_t)(unsigned port, unsigned id);
   2078
   2079struct retro_sensor_interface
   2080{
   2081   retro_set_sensor_state_t set_sensor_state;
   2082   retro_sensor_get_input_t get_sensor_input;
   2083};
   2084
   2085enum retro_camera_buffer
   2086{
   2087   RETRO_CAMERA_BUFFER_OPENGL_TEXTURE = 0,
   2088   RETRO_CAMERA_BUFFER_RAW_FRAMEBUFFER,
   2089
   2090   RETRO_CAMERA_BUFFER_DUMMY = INT_MAX
   2091};
   2092
   2093/* Starts the camera driver. Can only be called in retro_run(). */
   2094typedef bool (RETRO_CALLCONV *retro_camera_start_t)(void);
   2095
   2096/* Stops the camera driver. Can only be called in retro_run(). */
   2097typedef void (RETRO_CALLCONV *retro_camera_stop_t)(void);
   2098
   2099/* Callback which signals when the camera driver is initialized
   2100 * and/or deinitialized.
   2101 * retro_camera_start_t can be called in initialized callback.
   2102 */
   2103typedef void (RETRO_CALLCONV *retro_camera_lifetime_status_t)(void);
   2104
   2105/* A callback for raw framebuffer data. buffer points to an XRGB8888 buffer.
   2106 * Width, height and pitch are similar to retro_video_refresh_t.
   2107 * First pixel is top-left origin.
   2108 */
   2109typedef void (RETRO_CALLCONV *retro_camera_frame_raw_framebuffer_t)(const uint32_t *buffer,
   2110      unsigned width, unsigned height, size_t pitch);
   2111
   2112/* A callback for when OpenGL textures are used.
   2113 *
   2114 * texture_id is a texture owned by camera driver.
   2115 * Its state or content should be considered immutable, except for things like
   2116 * texture filtering and clamping.
   2117 *
   2118 * texture_target is the texture target for the GL texture.
   2119 * These can include e.g. GL_TEXTURE_2D, GL_TEXTURE_RECTANGLE, and possibly
   2120 * more depending on extensions.
   2121 *
   2122 * affine points to a packed 3x3 column-major matrix used to apply an affine
   2123 * transform to texture coordinates. (affine_matrix * vec3(coord_x, coord_y, 1.0))
   2124 * After transform, normalized texture coord (0, 0) should be bottom-left
   2125 * and (1, 1) should be top-right (or (width, height) for RECTANGLE).
   2126 *
   2127 * GL-specific typedefs are avoided here to avoid relying on gl.h in
   2128 * the API definition.
   2129 */
   2130typedef void (RETRO_CALLCONV *retro_camera_frame_opengl_texture_t)(unsigned texture_id,
   2131      unsigned texture_target, const float *affine);
   2132
   2133struct retro_camera_callback
   2134{
   2135   /* Set by libretro core.
   2136    * Example bitmask: caps = (1 << RETRO_CAMERA_BUFFER_OPENGL_TEXTURE) | (1 << RETRO_CAMERA_BUFFER_RAW_FRAMEBUFFER).
   2137    */
   2138   uint64_t caps;
   2139
   2140   /* Desired resolution for camera. Is only used as a hint. */
   2141   unsigned width;
   2142   unsigned height;
   2143
   2144   /* Set by frontend. */
   2145   retro_camera_start_t start;
   2146   retro_camera_stop_t stop;
   2147
   2148   /* Set by libretro core if raw framebuffer callbacks will be used. */
   2149   retro_camera_frame_raw_framebuffer_t frame_raw_framebuffer;
   2150
   2151   /* Set by libretro core if OpenGL texture callbacks will be used. */
   2152   retro_camera_frame_opengl_texture_t frame_opengl_texture;
   2153
   2154   /* Set by libretro core. Called after camera driver is initialized and
   2155    * ready to be started.
   2156    * Can be NULL, in which this callback is not called.
   2157    */
   2158   retro_camera_lifetime_status_t initialized;
   2159
   2160   /* Set by libretro core. Called right before camera driver is
   2161    * deinitialized.
   2162    * Can be NULL, in which this callback is not called.
   2163    */
   2164   retro_camera_lifetime_status_t deinitialized;
   2165};
   2166
   2167/* Sets the interval of time and/or distance at which to update/poll
   2168 * location-based data.
   2169 *
   2170 * To ensure compatibility with all location-based implementations,
   2171 * values for both interval_ms and interval_distance should be provided.
   2172 *
   2173 * interval_ms is the interval expressed in milliseconds.
   2174 * interval_distance is the distance interval expressed in meters.
   2175 */
   2176typedef void (RETRO_CALLCONV *retro_location_set_interval_t)(unsigned interval_ms,
   2177      unsigned interval_distance);
   2178
   2179/* Start location services. The device will start listening for changes to the
   2180 * current location at regular intervals (which are defined with
   2181 * retro_location_set_interval_t). */
   2182typedef bool (RETRO_CALLCONV *retro_location_start_t)(void);
   2183
   2184/* Stop location services. The device will stop listening for changes
   2185 * to the current location. */
   2186typedef void (RETRO_CALLCONV *retro_location_stop_t)(void);
   2187
   2188/* Get the position of the current location. Will set parameters to
   2189 * 0 if no new  location update has happened since the last time. */
   2190typedef bool (RETRO_CALLCONV *retro_location_get_position_t)(double *lat, double *lon,
   2191      double *horiz_accuracy, double *vert_accuracy);
   2192
   2193/* Callback which signals when the location driver is initialized
   2194 * and/or deinitialized.
   2195 * retro_location_start_t can be called in initialized callback.
   2196 */
   2197typedef void (RETRO_CALLCONV *retro_location_lifetime_status_t)(void);
   2198
   2199struct retro_location_callback
   2200{
   2201   retro_location_start_t         start;
   2202   retro_location_stop_t          stop;
   2203   retro_location_get_position_t  get_position;
   2204   retro_location_set_interval_t  set_interval;
   2205
   2206   retro_location_lifetime_status_t initialized;
   2207   retro_location_lifetime_status_t deinitialized;
   2208};
   2209
   2210enum retro_rumble_effect
   2211{
   2212   RETRO_RUMBLE_STRONG = 0,
   2213   RETRO_RUMBLE_WEAK = 1,
   2214
   2215   RETRO_RUMBLE_DUMMY = INT_MAX
   2216};
   2217
   2218/* Sets rumble state for joypad plugged in port 'port'.
   2219 * Rumble effects are controlled independently,
   2220 * and setting e.g. strong rumble does not override weak rumble.
   2221 * Strength has a range of [0, 0xffff].
   2222 *
   2223 * Returns true if rumble state request was honored.
   2224 * Calling this before first retro_run() is likely to return false. */
   2225typedef bool (RETRO_CALLCONV *retro_set_rumble_state_t)(unsigned port,
   2226      enum retro_rumble_effect effect, uint16_t strength);
   2227
   2228struct retro_rumble_interface
   2229{
   2230   retro_set_rumble_state_t set_rumble_state;
   2231};
   2232
   2233/* Notifies libretro that audio data should be written. */
   2234typedef void (RETRO_CALLCONV *retro_audio_callback_t)(void);
   2235
   2236/* True: Audio driver in frontend is active, and callback is
   2237 * expected to be called regularily.
   2238 * False: Audio driver in frontend is paused or inactive.
   2239 * Audio callback will not be called until set_state has been
   2240 * called with true.
   2241 * Initial state is false (inactive).
   2242 */
   2243typedef void (RETRO_CALLCONV *retro_audio_set_state_callback_t)(bool enabled);
   2244
   2245struct retro_audio_callback
   2246{
   2247   retro_audio_callback_t callback;
   2248   retro_audio_set_state_callback_t set_state;
   2249};
   2250
   2251/* Notifies a libretro core of time spent since last invocation
   2252 * of retro_run() in microseconds.
   2253 *
   2254 * It will be called right before retro_run() every frame.
   2255 * The frontend can tamper with timing to support cases like
   2256 * fast-forward, slow-motion and framestepping.
   2257 *
   2258 * In those scenarios the reference frame time value will be used. */
   2259typedef int64_t retro_usec_t;
   2260typedef void (RETRO_CALLCONV *retro_frame_time_callback_t)(retro_usec_t usec);
   2261struct retro_frame_time_callback
   2262{
   2263   retro_frame_time_callback_t callback;
   2264   /* Represents the time of one frame. It is computed as
   2265    * 1000000 / fps, but the implementation will resolve the
   2266    * rounding to ensure that framestepping, etc is exact. */
   2267   retro_usec_t reference;
   2268};
   2269
   2270/* Notifies a libretro core of the current occupancy
   2271 * level of the frontend audio buffer.
   2272 *
   2273 * - active: 'true' if audio buffer is currently
   2274 *           in use. Will be 'false' if audio is
   2275 *           disabled in the frontend
   2276 *
   2277 * - occupancy: Given as a value in the range [0,100],
   2278 *              corresponding to the occupancy percentage
   2279 *              of the audio buffer
   2280 *
   2281 * - underrun_likely: 'true' if the frontend expects an
   2282 *                    audio buffer underrun during the
   2283 *                    next frame (indicates that a core
   2284 *                    should attempt frame skipping)
   2285 *
   2286 * It will be called right before retro_run() every frame. */
   2287typedef void (RETRO_CALLCONV *retro_audio_buffer_status_callback_t)(
   2288      bool active, unsigned occupancy, bool underrun_likely);
   2289struct retro_audio_buffer_status_callback
   2290{
   2291   retro_audio_buffer_status_callback_t callback;
   2292};
   2293
   2294/* Pass this to retro_video_refresh_t if rendering to hardware.
   2295 * Passing NULL to retro_video_refresh_t is still a frame dupe as normal.
   2296 * */
   2297#define RETRO_HW_FRAME_BUFFER_VALID ((void*)-1)
   2298
   2299/* Invalidates the current HW context.
   2300 * Any GL state is lost, and must not be deinitialized explicitly.
   2301 * If explicit deinitialization is desired by the libretro core,
   2302 * it should implement context_destroy callback.
   2303 * If called, all GPU resources must be reinitialized.
   2304 * Usually called when frontend reinits video driver.
   2305 * Also called first time video driver is initialized,
   2306 * allowing libretro core to initialize resources.
   2307 */
   2308typedef void (RETRO_CALLCONV *retro_hw_context_reset_t)(void);
   2309
   2310/* Gets current framebuffer which is to be rendered to.
   2311 * Could change every frame potentially.
   2312 */
   2313typedef uintptr_t (RETRO_CALLCONV *retro_hw_get_current_framebuffer_t)(void);
   2314
   2315/* Get a symbol from HW context. */
   2316typedef retro_proc_address_t (RETRO_CALLCONV *retro_hw_get_proc_address_t)(const char *sym);
   2317
   2318enum retro_hw_context_type
   2319{
   2320   RETRO_HW_CONTEXT_NONE             = 0,
   2321   /* OpenGL 2.x. Driver can choose to use latest compatibility context. */
   2322   RETRO_HW_CONTEXT_OPENGL           = 1,
   2323   /* OpenGL ES 2.0. */
   2324   RETRO_HW_CONTEXT_OPENGLES2        = 2,
   2325   /* Modern desktop core GL context. Use version_major/
   2326    * version_minor fields to set GL version. */
   2327   RETRO_HW_CONTEXT_OPENGL_CORE      = 3,
   2328   /* OpenGL ES 3.0 */
   2329   RETRO_HW_CONTEXT_OPENGLES3        = 4,
   2330   /* OpenGL ES 3.1+. Set version_major/version_minor. For GLES2 and GLES3,
   2331    * use the corresponding enums directly. */
   2332   RETRO_HW_CONTEXT_OPENGLES_VERSION = 5,
   2333
   2334   /* Vulkan, see RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE. */
   2335   RETRO_HW_CONTEXT_VULKAN           = 6,
   2336
   2337   /* Direct3D, set version_major to select the type of interface
   2338    * returned by RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE */
   2339   RETRO_HW_CONTEXT_DIRECT3D         = 7,
   2340
   2341   RETRO_HW_CONTEXT_DUMMY = INT_MAX
   2342};
   2343
   2344struct retro_hw_render_callback
   2345{
   2346   /* Which API to use. Set by libretro core. */
   2347   enum retro_hw_context_type context_type;
   2348
   2349   /* Called when a context has been created or when it has been reset.
   2350    * An OpenGL context is only valid after context_reset() has been called.
   2351    *
   2352    * When context_reset is called, OpenGL resources in the libretro
   2353    * implementation are guaranteed to be invalid.
   2354    *
   2355    * It is possible that context_reset is called multiple times during an
   2356    * application lifecycle.
   2357    * If context_reset is called without any notification (context_destroy),
   2358    * the OpenGL context was lost and resources should just be recreated
   2359    * without any attempt to "free" old resources.
   2360    */
   2361   retro_hw_context_reset_t context_reset;
   2362
   2363   /* Set by frontend.
   2364    * TODO: This is rather obsolete. The frontend should not
   2365    * be providing preallocated framebuffers. */
   2366   retro_hw_get_current_framebuffer_t get_current_framebuffer;
   2367
   2368   /* Set by frontend.
   2369    * Can return all relevant functions, including glClear on Windows. */
   2370   retro_hw_get_proc_address_t get_proc_address;
   2371
   2372   /* Set if render buffers should have depth component attached.
   2373    * TODO: Obsolete. */
   2374   bool depth;
   2375
   2376   /* Set if stencil buffers should be attached.
   2377    * TODO: Obsolete. */
   2378   bool stencil;
   2379
   2380   /* If depth and stencil are true, a packed 24/8 buffer will be added.
   2381    * Only attaching stencil is invalid and will be ignored. */
   2382
   2383   /* Use conventional bottom-left origin convention. If false,
   2384    * standard libretro top-left origin semantics are used.
   2385    * TODO: Move to GL specific interface. */
   2386   bool bottom_left_origin;
   2387
   2388   /* Major version number for core GL context or GLES 3.1+. */
   2389   unsigned version_major;
   2390
   2391   /* Minor version number for core GL context or GLES 3.1+. */
   2392   unsigned version_minor;
   2393
   2394   /* If this is true, the frontend will go very far to avoid
   2395    * resetting context in scenarios like toggling fullscreen, etc.
   2396    * TODO: Obsolete? Maybe frontend should just always assume this ...
   2397    */
   2398   bool cache_context;
   2399
   2400   /* The reset callback might still be called in extreme situations
   2401    * such as if the context is lost beyond recovery.
   2402    *
   2403    * For optimal stability, set this to false, and allow context to be
   2404    * reset at any time.
   2405    */
   2406
   2407   /* A callback to be called before the context is destroyed in a
   2408    * controlled way by the frontend. */
   2409   retro_hw_context_reset_t context_destroy;
   2410
   2411   /* OpenGL resources can be deinitialized cleanly at this step.
   2412    * context_destroy can be set to NULL, in which resources will
   2413    * just be destroyed without any notification.
   2414    *
   2415    * Even when context_destroy is non-NULL, it is possible that
   2416    * context_reset is called without any destroy notification.
   2417    * This happens if context is lost by external factors (such as
   2418    * notified by GL_ARB_robustness).
   2419    *
   2420    * In this case, the context is assumed to be already dead,
   2421    * and the libretro implementation must not try to free any OpenGL
   2422    * resources in the subsequent context_reset.
   2423    */
   2424
   2425   /* Creates a debug context. */
   2426   bool debug_context;
   2427};
   2428
   2429/* Callback type passed in RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK.
   2430 * Called by the frontend in response to keyboard events.
   2431 * down is set if the key is being pressed, or false if it is being released.
   2432 * keycode is the RETROK value of the char.
   2433 * character is the text character of the pressed key. (UTF-32).
   2434 * key_modifiers is a set of RETROKMOD values or'ed together.
   2435 *
   2436 * The pressed/keycode state can be indepedent of the character.
   2437 * It is also possible that multiple characters are generated from a
   2438 * single keypress.
   2439 * Keycode events should be treated separately from character events.
   2440 * However, when possible, the frontend should try to synchronize these.
   2441 * If only a character is posted, keycode should be RETROK_UNKNOWN.
   2442 *
   2443 * Similarily if only a keycode event is generated with no corresponding
   2444 * character, character should be 0.
   2445 */
   2446typedef void (RETRO_CALLCONV *retro_keyboard_event_t)(bool down, unsigned keycode,
   2447      uint32_t character, uint16_t key_modifiers);
   2448
   2449struct retro_keyboard_callback
   2450{
   2451   retro_keyboard_event_t callback;
   2452};
   2453
   2454/* Callbacks for RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE &
   2455 * RETRO_ENVIRONMENT_SET_DISK_CONTROL_EXT_INTERFACE.
   2456 * Should be set for implementations which can swap out multiple disk
   2457 * images in runtime.
   2458 *
   2459 * If the implementation can do this automatically, it should strive to do so.
   2460 * However, there are cases where the user must manually do so.
   2461 *
   2462 * Overview: To swap a disk image, eject the disk image with
   2463 * set_eject_state(true).
   2464 * Set the disk index with set_image_index(index). Insert the disk again
   2465 * with set_eject_state(false).
   2466 */
   2467
   2468/* If ejected is true, "ejects" the virtual disk tray.
   2469 * When ejected, the disk image index can be set.
   2470 */
   2471typedef bool (RETRO_CALLCONV *retro_set_eject_state_t)(bool ejected);
   2472
   2473/* Gets current eject state. The initial state is 'not ejected'. */
   2474typedef bool (RETRO_CALLCONV *retro_get_eject_state_t)(void);
   2475
   2476/* Gets current disk index. First disk is index 0.
   2477 * If return value is >= get_num_images(), no disk is currently inserted.
   2478 */
   2479typedef unsigned (RETRO_CALLCONV *retro_get_image_index_t)(void);
   2480
   2481/* Sets image index. Can only be called when disk is ejected.
   2482 * The implementation supports setting "no disk" by using an
   2483 * index >= get_num_images().
   2484 */
   2485typedef bool (RETRO_CALLCONV *retro_set_image_index_t)(unsigned index);
   2486
   2487/* Gets total number of images which are available to use. */
   2488typedef unsigned (RETRO_CALLCONV *retro_get_num_images_t)(void);
   2489
   2490struct retro_game_info;
   2491
   2492/* Replaces the disk image associated with index.
   2493 * Arguments to pass in info have same requirements as retro_load_game().
   2494 * Virtual disk tray must be ejected when calling this.
   2495 *
   2496 * Replacing a disk image with info = NULL will remove the disk image
   2497 * from the internal list.
   2498 * As a result, calls to get_image_index() can change.
   2499 *
   2500 * E.g. replace_image_index(1, NULL), and previous get_image_index()
   2501 * returned 4 before.
   2502 * Index 1 will be removed, and the new index is 3.
   2503 */
   2504typedef bool (RETRO_CALLCONV *retro_replace_image_index_t)(unsigned index,
   2505      const struct retro_game_info *info);
   2506
   2507/* Adds a new valid index (get_num_images()) to the internal disk list.
   2508 * This will increment subsequent return values from get_num_images() by 1.
   2509 * This image index cannot be used until a disk image has been set
   2510 * with replace_image_index. */
   2511typedef bool (RETRO_CALLCONV *retro_add_image_index_t)(void);
   2512
   2513/* Sets initial image to insert in drive when calling
   2514 * core_load_game().
   2515 * Since we cannot pass the initial index when loading
   2516 * content (this would require a major API change), this
   2517 * is set by the frontend *before* calling the core's
   2518 * retro_load_game()/retro_load_game_special() implementation.
   2519 * A core should therefore cache the index/path values and handle
   2520 * them inside retro_load_game()/retro_load_game_special().
   2521 * - If 'index' is invalid (index >= get_num_images()), the
   2522 *   core should ignore the set value and instead use 0
   2523 * - 'path' is used purely for error checking - i.e. when
   2524 *   content is loaded, the core should verify that the
   2525 *   disk specified by 'index' has the specified file path.
   2526 *   This is to guard against auto selecting the wrong image
   2527 *   if (for example) the user should modify an existing M3U
   2528 *   playlist. We have to let the core handle this because
   2529 *   set_initial_image() must be called before loading content,
   2530 *   i.e. the frontend cannot access image paths in advance
   2531 *   and thus cannot perform the error check itself.
   2532 *   If set path and content path do not match, the core should
   2533 *   ignore the set 'index' value and instead use 0
   2534 * Returns 'false' if index or 'path' are invalid, or core
   2535 * does not support this functionality
   2536 */
   2537typedef bool (RETRO_CALLCONV *retro_set_initial_image_t)(unsigned index, const char *path);
   2538
   2539/* Fetches the path of the specified disk image file.
   2540 * Returns 'false' if index is invalid (index >= get_num_images())
   2541 * or path is otherwise unavailable.
   2542 */
   2543typedef bool (RETRO_CALLCONV *retro_get_image_path_t)(unsigned index, char *path, size_t len);
   2544
   2545/* Fetches a core-provided 'label' for the specified disk
   2546 * image file. In the simplest case this may be a file name
   2547 * (without extension), but for cores with more complex
   2548 * content requirements information may be provided to
   2549 * facilitate user disk swapping - for example, a core
   2550 * running floppy-disk-based content may uniquely label
   2551 * save disks, data disks, level disks, etc. with names
   2552 * corresponding to in-game disk change prompts (so the
   2553 * frontend can provide better user guidance than a 'dumb'
   2554 * disk index value).
   2555 * Returns 'false' if index is invalid (index >= get_num_images())
   2556 * or label is otherwise unavailable.
   2557 */
   2558typedef bool (RETRO_CALLCONV *retro_get_image_label_t)(unsigned index, char *label, size_t len);
   2559
   2560struct retro_disk_control_callback
   2561{
   2562   retro_set_eject_state_t set_eject_state;
   2563   retro_get_eject_state_t get_eject_state;
   2564
   2565   retro_get_image_index_t get_image_index;
   2566   retro_set_image_index_t set_image_index;
   2567   retro_get_num_images_t  get_num_images;
   2568
   2569   retro_replace_image_index_t replace_image_index;
   2570   retro_add_image_index_t add_image_index;
   2571};
   2572
   2573struct retro_disk_control_ext_callback
   2574{
   2575   retro_set_eject_state_t set_eject_state;
   2576   retro_get_eject_state_t get_eject_state;
   2577
   2578   retro_get_image_index_t get_image_index;
   2579   retro_set_image_index_t set_image_index;
   2580   retro_get_num_images_t  get_num_images;
   2581
   2582   retro_replace_image_index_t replace_image_index;
   2583   retro_add_image_index_t add_image_index;
   2584
   2585   /* NOTE: Frontend will only attempt to record/restore
   2586    * last used disk index if both set_initial_image()
   2587    * and get_image_path() are implemented */
   2588   retro_set_initial_image_t set_initial_image; /* Optional - may be NULL */
   2589
   2590   retro_get_image_path_t get_image_path;       /* Optional - may be NULL */
   2591   retro_get_image_label_t get_image_label;     /* Optional - may be NULL */
   2592};
   2593
   2594enum retro_pixel_format
   2595{
   2596   /* 0RGB1555, native endian.
   2597    * 0 bit must be set to 0.
   2598    * This pixel format is default for compatibility concerns only.
   2599    * If a 15/16-bit pixel format is desired, consider using RGB565. */
   2600   RETRO_PIXEL_FORMAT_0RGB1555 = 0,
   2601
   2602   /* XRGB8888, native endian.
   2603    * X bits are ignored. */
   2604   RETRO_PIXEL_FORMAT_XRGB8888 = 1,
   2605
   2606   /* RGB565, native endian.
   2607    * This pixel format is the recommended format to use if a 15/16-bit
   2608    * format is desired as it is the pixel format that is typically
   2609    * available on a wide range of low-power devices.
   2610    *
   2611    * It is also natively supported in APIs like OpenGL ES. */
   2612   RETRO_PIXEL_FORMAT_RGB565   = 2,
   2613
   2614   /* Ensure sizeof() == sizeof(int). */
   2615   RETRO_PIXEL_FORMAT_UNKNOWN  = INT_MAX
   2616};
   2617
   2618struct retro_message
   2619{
   2620   const char *msg;        /* Message to be displayed. */
   2621   unsigned    frames;     /* Duration in frames of message. */
   2622};
   2623
   2624enum retro_message_target
   2625{
   2626   RETRO_MESSAGE_TARGET_ALL = 0,
   2627   RETRO_MESSAGE_TARGET_OSD,
   2628   RETRO_MESSAGE_TARGET_LOG
   2629};
   2630
   2631enum retro_message_type
   2632{
   2633   RETRO_MESSAGE_TYPE_NOTIFICATION = 0,
   2634   RETRO_MESSAGE_TYPE_NOTIFICATION_ALT,
   2635   RETRO_MESSAGE_TYPE_STATUS,
   2636   RETRO_MESSAGE_TYPE_PROGRESS
   2637};
   2638
   2639struct retro_message_ext
   2640{
   2641   /* Message string to be displayed/logged */
   2642   const char *msg;
   2643   /* Duration (in ms) of message when targeting the OSD */
   2644   unsigned duration;
   2645   /* Message priority when targeting the OSD
   2646    * > When multiple concurrent messages are sent to
   2647    *   the frontend and the frontend does not have the
   2648    *   capacity to display them all, messages with the
   2649    *   *highest* priority value should be shown
   2650    * > There is no upper limit to a message priority
   2651    *   value (within the bounds of the unsigned data type)
   2652    * > In the reference frontend (RetroArch), the same
   2653    *   priority values are used for frontend-generated
   2654    *   notifications, which are typically assigned values
   2655    *   between 0 and 3 depending upon importance */
   2656   unsigned priority;
   2657   /* Message logging level (info, warn, error, etc.) */
   2658   enum retro_log_level level;
   2659   /* Message destination: OSD, logging interface or both */
   2660   enum retro_message_target target;
   2661   /* Message 'type' when targeting the OSD
   2662    * > RETRO_MESSAGE_TYPE_NOTIFICATION: Specifies that a
   2663    *   message should be handled in identical fashion to
   2664    *   a standard frontend-generated notification
   2665    * > RETRO_MESSAGE_TYPE_NOTIFICATION_ALT: Specifies that
   2666    *   message is a notification that requires user attention
   2667    *   or action, but that it should be displayed in a manner
   2668    *   that differs from standard frontend-generated notifications.
   2669    *   This would typically correspond to messages that should be
   2670    *   displayed immediately (independently from any internal
   2671    *   frontend message queue), and/or which should be visually
   2672    *   distinguishable from frontend-generated notifications.
   2673    *   For example, a core may wish to inform the user of
   2674    *   information related to a disk-change event. It is
   2675    *   expected that the frontend itself may provide a
   2676    *   notification in this case; if the core sends a
   2677    *   message of type RETRO_MESSAGE_TYPE_NOTIFICATION, an
   2678    *   uncomfortable 'double-notification' may occur. A message
   2679    *   of RETRO_MESSAGE_TYPE_NOTIFICATION_ALT should therefore
   2680    *   be presented such that visual conflict with regular
   2681    *   notifications does not occur
   2682    * > RETRO_MESSAGE_TYPE_STATUS: Indicates that message
   2683    *   is not a standard notification. This typically
   2684    *   corresponds to 'status' indicators, such as a core's
   2685    *   internal FPS, which are intended to be displayed
   2686    *   either permanently while a core is running, or in
   2687    *   a manner that does not suggest user attention or action
   2688    *   is required. 'Status' type messages should therefore be
   2689    *   displayed in a different on-screen location and in a manner
   2690    *   easily distinguishable from both standard frontend-generated
   2691    *   notifications and messages of type RETRO_MESSAGE_TYPE_NOTIFICATION_ALT
   2692    * > RETRO_MESSAGE_TYPE_PROGRESS: Indicates that message reports
   2693    *   the progress of an internal core task. For example, in cases
   2694    *   where a core itself handles the loading of content from a file,
   2695    *   this may correspond to the percentage of the file that has been
   2696    *   read. Alternatively, an audio/video playback core may use a
   2697    *   message of type RETRO_MESSAGE_TYPE_PROGRESS to display the current
   2698    *   playback position as a percentage of the runtime. 'Progress' type
   2699    *   messages should therefore be displayed as a literal progress bar,
   2700    *   where:
   2701    *   - 'retro_message_ext.msg' is the progress bar title/label
   2702    *   - 'retro_message_ext.progress' determines the length of
   2703    *     the progress bar
   2704    * NOTE: Message type is a *hint*, and may be ignored
   2705    * by the frontend. If a frontend lacks support for
   2706    * displaying messages via alternate means than standard
   2707    * frontend-generated notifications, it will treat *all*
   2708    * messages as having the type RETRO_MESSAGE_TYPE_NOTIFICATION */
   2709   enum retro_message_type type;
   2710   /* Task progress when targeting the OSD and message is
   2711    * of type RETRO_MESSAGE_TYPE_PROGRESS
   2712    * > -1:    Unmetered/indeterminate
   2713    * > 0-100: Current progress percentage
   2714    * NOTE: Since message type is a hint, a frontend may ignore
   2715    * progress values. Where relevant, a core should therefore
   2716    * include progress percentage within the message string,
   2717    * such that the message intent remains clear when displayed
   2718    * as a standard frontend-generated notification */
   2719   int8_t progress;
   2720};
   2721
   2722/* Describes how the libretro implementation maps a libretro input bind
   2723 * to its internal input system through a human readable string.
   2724 * This string can be used to better let a user configure input. */
   2725struct retro_input_descriptor
   2726{
   2727   /* Associates given parameters with a description. */
   2728   unsigned port;
   2729   unsigned device;
   2730   unsigned index;
   2731   unsigned id;
   2732
   2733   /* Human readable description for parameters.
   2734    * The pointer must remain valid until
   2735    * retro_unload_game() is called. */
   2736   const char *description;
   2737};
   2738
   2739struct retro_system_info
   2740{
   2741   /* All pointers are owned by libretro implementation, and pointers must
   2742    * remain valid until it is unloaded. */
   2743
   2744   const char *library_name;      /* Descriptive name of library. Should not
   2745                                   * contain any version numbers, etc. */
   2746   const char *library_version;   /* Descriptive version of core. */
   2747
   2748   const char *valid_extensions;  /* A string listing probably content
   2749                                   * extensions the core will be able to
   2750                                   * load, separated with pipe.
   2751                                   * I.e. "bin|rom|iso".
   2752                                   * Typically used for a GUI to filter
   2753                                   * out extensions. */
   2754
   2755   /* Libretro cores that need to have direct access to their content
   2756    * files, including cores which use the path of the content files to
   2757    * determine the paths of other files, should set need_fullpath to true.
   2758    *
   2759    * Cores should strive for setting need_fullpath to false,
   2760    * as it allows the frontend to perform patching, etc.
   2761    *
   2762    * If need_fullpath is true and retro_load_game() is called:
   2763    *    - retro_game_info::path is guaranteed to have a valid path
   2764    *    - retro_game_info::data and retro_game_info::size are invalid
   2765    *
   2766    * If need_fullpath is false and retro_load_game() is called:
   2767    *    - retro_game_info::path may be NULL
   2768    *    - retro_game_info::data and retro_game_info::size are guaranteed
   2769    *      to be valid
   2770    *
   2771    * See also:
   2772    *    - RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY
   2773    *    - RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY
   2774    */
   2775   bool        need_fullpath;
   2776
   2777   /* If true, the frontend is not allowed to extract any archives before
   2778    * loading the real content.
   2779    * Necessary for certain libretro implementations that load games
   2780    * from zipped archives. */
   2781   bool        block_extract;
   2782};
   2783
   2784struct retro_game_geometry
   2785{
   2786   unsigned base_width;    /* Nominal video width of game. */
   2787   unsigned base_height;   /* Nominal video height of game. */
   2788   unsigned max_width;     /* Maximum possible width of game. */
   2789   unsigned max_height;    /* Maximum possible height of game. */
   2790
   2791   float    aspect_ratio;  /* Nominal aspect ratio of game. If
   2792                            * aspect_ratio is <= 0.0, an aspect ratio
   2793                            * of base_width / base_height is assumed.
   2794                            * A frontend could override this setting,
   2795                            * if desired. */
   2796};
   2797
   2798struct retro_system_timing
   2799{
   2800   double fps;             /* FPS of video content. */
   2801   double sample_rate;     /* Sampling rate of audio. */
   2802};
   2803
   2804struct retro_system_av_info
   2805{
   2806   struct retro_game_geometry geometry;
   2807   struct retro_system_timing timing;
   2808};
   2809
   2810struct retro_variable
   2811{
   2812   /* Variable to query in RETRO_ENVIRONMENT_GET_VARIABLE.
   2813    * If NULL, obtains the complete environment string if more
   2814    * complex parsing is necessary.
   2815    * The environment string is formatted as key-value pairs
   2816    * delimited by semicolons as so:
   2817    * "key1=value1;key2=value2;..."
   2818    */
   2819   const char *key;
   2820
   2821   /* Value to be obtained. If key does not exist, it is set to NULL. */
   2822   const char *value;
   2823};
   2824
   2825struct retro_core_option_display
   2826{
   2827   /* Variable to configure in RETRO_ENVIRONMENT_SET_CORE_OPTIONS_DISPLAY */
   2828   const char *key;
   2829
   2830   /* Specifies whether variable should be displayed
   2831    * when presenting core options to the user */
   2832   bool visible;
   2833};
   2834
   2835/* Maximum number of values permitted for a core option
   2836 * > Note: We have to set a maximum value due the limitations
   2837 *   of the C language - i.e. it is not possible to create an
   2838 *   array of structs each containing a variable sized array,
   2839 *   so the retro_core_option_definition values array must
   2840 *   have a fixed size. The size limit of 128 is a balancing
   2841 *   act - it needs to be large enough to support all 'sane'
   2842 *   core options, but setting it too large may impact low memory
   2843 *   platforms. In practise, if a core option has more than
   2844 *   128 values then the implementation is likely flawed.
   2845 *   To quote the above API reference:
   2846 *      "The number of possible options should be very limited
   2847 *       i.e. it should be feasible to cycle through options
   2848 *       without a keyboard."
   2849 */
   2850#define RETRO_NUM_CORE_OPTION_VALUES_MAX 128
   2851
   2852struct retro_core_option_value
   2853{
   2854   /* Expected option value */
   2855   const char *value;
   2856
   2857   /* Human-readable value label. If NULL, value itself
   2858    * will be displayed by the frontend */
   2859   const char *label;
   2860};
   2861
   2862struct retro_core_option_definition
   2863{
   2864   /* Variable to query in RETRO_ENVIRONMENT_GET_VARIABLE. */
   2865   const char *key;
   2866
   2867   /* Human-readable core option description (used as menu label) */
   2868   const char *desc;
   2869
   2870   /* Human-readable core option information (used as menu sublabel) */
   2871   const char *info;
   2872
   2873   /* Array of retro_core_option_value structs, terminated by NULL */
   2874   struct retro_core_option_value values[RETRO_NUM_CORE_OPTION_VALUES_MAX];
   2875
   2876   /* Default core option value. Must match one of the values
   2877    * in the retro_core_option_value array, otherwise will be
   2878    * ignored */
   2879   const char *default_value;
   2880};
   2881
   2882struct retro_core_options_intl
   2883{
   2884   /* Pointer to an array of retro_core_option_definition structs
   2885    * - US English implementation
   2886    * - Must point to a valid array */
   2887   struct retro_core_option_definition *us;
   2888
   2889   /* Pointer to an array of retro_core_option_definition structs
   2890    * - Implementation for current frontend language
   2891    * - May be NULL */
   2892   struct retro_core_option_definition *local;
   2893};
   2894
   2895struct retro_game_info
   2896{
   2897   const char *path;       /* Path to game, UTF-8 encoded.
   2898                            * Sometimes used as a reference for building other paths.
   2899                            * May be NULL if game was loaded from stdin or similar,
   2900                            * but in this case some cores will be unable to load `data`.
   2901                            * So, it is preferable to fabricate something here instead
   2902                            * of passing NULL, which will help more cores to succeed.
   2903                            * retro_system_info::need_fullpath requires
   2904                            * that this path is valid. */
   2905   const void *data;       /* Memory buffer of loaded game. Will be NULL
   2906                            * if need_fullpath was set. */
   2907   size_t      size;       /* Size of memory buffer. */
   2908   const char *meta;       /* String of implementation specific meta-data. */
   2909};
   2910
   2911#define RETRO_MEMORY_ACCESS_WRITE (1 << 0)
   2912   /* The core will write to the buffer provided by retro_framebuffer::data. */
   2913#define RETRO_MEMORY_ACCESS_READ (1 << 1)
   2914   /* The core will read from retro_framebuffer::data. */
   2915#define RETRO_MEMORY_TYPE_CACHED (1 << 0)
   2916   /* The memory in data is cached.
   2917    * If not cached, random writes and/or reading from the buffer is expected to be very slow. */
   2918struct retro_framebuffer
   2919{
   2920   void *data;                      /* The framebuffer which the core can render into.
   2921                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER.
   2922                                       The initial contents of data are unspecified. */
   2923   unsigned width;                  /* The framebuffer width used by the core. Set by core. */
   2924   unsigned height;                 /* The framebuffer height used by the core. Set by core. */
   2925   size_t pitch;                    /* The number of bytes between the beginning of a scanline,
   2926                                       and beginning of the next scanline.
   2927                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
   2928   enum retro_pixel_format format;  /* The pixel format the core must use to render into data.
   2929                                       This format could differ from the format used in
   2930                                       SET_PIXEL_FORMAT.
   2931                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
   2932
   2933   unsigned access_flags;           /* How the core will access the memory in the framebuffer.
   2934                                       RETRO_MEMORY_ACCESS_* flags.
   2935                                       Set by core. */
   2936   unsigned memory_flags;           /* Flags telling core how the memory has been mapped.
   2937                                       RETRO_MEMORY_TYPE_* flags.
   2938                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
   2939};
   2940
   2941/* Callbacks */
   2942
   2943/* Environment callback. Gives implementations a way of performing
   2944 * uncommon tasks. Extensible. */
   2945typedef bool (RETRO_CALLCONV *retro_environment_t)(unsigned cmd, void *data);
   2946
   2947/* Render a frame. Pixel format is 15-bit 0RGB1555 native endian
   2948 * unless changed (see RETRO_ENVIRONMENT_SET_PIXEL_FORMAT).
   2949 *
   2950 * Width and height specify dimensions of buffer.
   2951 * Pitch specifices length in bytes between two lines in buffer.
   2952 *
   2953 * For performance reasons, it is highly recommended to have a frame
   2954 * that is packed in memory, i.e. pitch == width * byte_per_pixel.
   2955 * Certain graphic APIs, such as OpenGL ES, do not like textures
   2956 * that are not packed in memory.
   2957 */
   2958typedef void (RETRO_CALLCONV *retro_video_refresh_t)(const void *data, unsigned width,
   2959      unsigned height, size_t pitch);
   2960
   2961/* Renders a single audio frame. Should only be used if implementation
   2962 * generates a single sample at a time.
   2963 * Format is signed 16-bit native endian.
   2964 */
   2965typedef void (RETRO_CALLCONV *retro_audio_sample_t)(int16_t left, int16_t right);
   2966
   2967/* Renders multiple audio frames in one go.
   2968 *
   2969 * One frame is defined as a sample of left and right channels, interleaved.
   2970 * I.e. int16_t buf[4] = { l, r, l, r }; would be 2 frames.
   2971 * Only one of the audio callbacks must ever be used.
   2972 */
   2973typedef size_t (RETRO_CALLCONV *retro_audio_sample_batch_t)(const int16_t *data,
   2974      size_t frames);
   2975
   2976/* Polls input. */
   2977typedef void (RETRO_CALLCONV *retro_input_poll_t)(void);
   2978
   2979/* Queries for input for player 'port'. device will be masked with
   2980 * RETRO_DEVICE_MASK.
   2981 *
   2982 * Specialization of devices such as RETRO_DEVICE_JOYPAD_MULTITAP that
   2983 * have been set with retro_set_controller_port_device()
   2984 * will still use the higher level RETRO_DEVICE_JOYPAD to request input.
   2985 */
   2986typedef int16_t (RETRO_CALLCONV *retro_input_state_t)(unsigned port, unsigned device,
   2987      unsigned index, unsigned id);
   2988
   2989/* Sets callbacks. retro_set_environment() is guaranteed to be called
   2990 * before retro_init().
   2991 *
   2992 * The rest of the set_* functions are guaranteed to have been called
   2993 * before the first call to retro_run() is made. */
   2994RETRO_API void retro_set_environment(retro_environment_t);
   2995RETRO_API void retro_set_video_refresh(retro_video_refresh_t);
   2996RETRO_API void retro_set_audio_sample(retro_audio_sample_t);
   2997RETRO_API void retro_set_audio_sample_batch(retro_audio_sample_batch_t);
   2998RETRO_API void retro_set_input_poll(retro_input_poll_t);
   2999RETRO_API void retro_set_input_state(retro_input_state_t);
   3000
   3001/* Library global initialization/deinitialization. */
   3002RETRO_API void retro_init(void);
   3003RETRO_API void retro_deinit(void);
   3004
   3005/* Must return RETRO_API_VERSION. Used to validate ABI compatibility
   3006 * when the API is revised. */
   3007RETRO_API unsigned retro_api_version(void);
   3008
   3009/* Gets statically known system info. Pointers provided in *info
   3010 * must be statically allocated.
   3011 * Can be called at any time, even before retro_init(). */
   3012RETRO_API void retro_get_system_info(struct retro_system_info *info);
   3013
   3014/* Gets information about system audio/video timings and geometry.
   3015 * Can be called only after retro_load_game() has successfully completed.
   3016 * NOTE: The implementation of this function might not initialize every
   3017 * variable if needed.
   3018 * E.g. geom.aspect_ratio might not be initialized if core doesn't
   3019 * desire a particular aspect ratio. */
   3020RETRO_API void retro_get_system_av_info(struct retro_system_av_info *info);
   3021
   3022/* Sets device to be used for player 'port'.
   3023 * By default, RETRO_DEVICE_JOYPAD is assumed to be plugged into all
   3024 * available ports.
   3025 * Setting a particular device type is not a guarantee that libretro cores
   3026 * will only poll input based on that particular device type. It is only a
   3027 * hint to the libretro core when a core cannot automatically detect the
   3028 * appropriate input device type on its own. It is also relevant when a
   3029 * core can change its behavior depending on device type.
   3030 *
   3031 * As part of the core's implementation of retro_set_controller_port_device,
   3032 * the core should call RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS to notify the
   3033 * frontend if the descriptions for any controls have changed as a
   3034 * result of changing the device type.
   3035 */
   3036RETRO_API void retro_set_controller_port_device(unsigned port, unsigned device);
   3037
   3038/* Resets the current game. */
   3039RETRO_API void retro_reset(void);
   3040
   3041/* Runs the game for one video frame.
   3042 * During retro_run(), input_poll callback must be called at least once.
   3043 *
   3044 * If a frame is not rendered for reasons where a game "dropped" a frame,
   3045 * this still counts as a frame, and retro_run() should explicitly dupe
   3046 * a frame if GET_CAN_DUPE returns true.
   3047 * In this case, the video callback can take a NULL argument for data.
   3048 */
   3049RETRO_API void retro_run(void);
   3050
   3051/* Returns the amount of data the implementation requires to serialize
   3052 * internal state (save states).
   3053 * Between calls to retro_load_game() and retro_unload_game(), the
   3054 * returned size is never allowed to be larger than a previous returned
   3055 * value, to ensure that the frontend can allocate a save state buffer once.
   3056 */
   3057RETRO_API size_t retro_serialize_size(void);
   3058
   3059/* Serializes internal state. If failed, or size is lower than
   3060 * retro_serialize_size(), it should return false, true otherwise. */
   3061RETRO_API bool retro_serialize(void *data, size_t size);
   3062RETRO_API bool retro_unserialize(const void *data, size_t size);
   3063
   3064RETRO_API void retro_cheat_reset(void);
   3065RETRO_API void retro_cheat_set(unsigned index, bool enabled, const char *code);
   3066
   3067/* Loads a game.
   3068 * Return true to indicate successful loading and false to indicate load failure.
   3069 */
   3070RETRO_API bool retro_load_game(const struct retro_game_info *game);
   3071
   3072/* Loads a "special" kind of game. Should not be used,
   3073 * except in extreme cases. */
   3074RETRO_API bool retro_load_game_special(
   3075  unsigned game_type,
   3076  const struct retro_game_info *info, size_t num_info
   3077);
   3078
   3079/* Unloads the currently loaded game. Called before retro_deinit(void). */
   3080RETRO_API void retro_unload_game(void);
   3081
   3082/* Gets region of game. */
   3083RETRO_API unsigned retro_get_region(void);
   3084
   3085/* Gets region of memory. */
   3086RETRO_API void *retro_get_memory_data(unsigned id);
   3087RETRO_API size_t retro_get_memory_size(unsigned id);
   3088
   3089#ifdef __cplusplus
   3090}
   3091#endif
   3092
   3093#endif