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SameBoy

Accurate GB/GBC emulator
download: https://git.y1.nz/archives/sameboy.tar.gz
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libretro/libretro.h

      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
     31 extern "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 */
    260 enum 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. */
    317 enum 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 
    472 enum 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 #define RETRO_ENVIRONMENT_SET_FASTFORWARDING_OVERRIDE 64
   1382                                            /* const struct retro_fastforwarding_override * --
   1383                                             * Used by a libretro core to override the current
   1384                                             * fastforwarding mode of the frontend.
   1385                                             * If NULL is passed to this function, the frontend
   1386                                             * will return true if fastforwarding override
   1387                                             * functionality is supported (no change in
   1388                                             * fastforwarding state will occur in this case).
   1389                                             */
   1390 
   1391 #define RETRO_ENVIRONMENT_SET_CONTENT_INFO_OVERRIDE 65
   1392                                            /* const struct retro_system_content_info_override * --
   1393                                             * Allows an implementation to override 'global' content
   1394                                             * info parameters reported by retro_get_system_info().
   1395                                             * Overrides also affect subsystem content info parameters
   1396                                             * set via RETRO_ENVIRONMENT_SET_SUBSYSTEM_INFO.
   1397                                             * This function must be called inside retro_set_environment().
   1398                                             * If callback returns false, content info overrides
   1399                                             * are unsupported by the frontend, and will be ignored.
   1400                                             * If callback returns true, extended game info may be
   1401                                             * retrieved by calling RETRO_ENVIRONMENT_GET_GAME_INFO_EXT
   1402                                             * in retro_load_game() or retro_load_game_special().
   1403                                             *
   1404                                             * 'data' points to an array of retro_system_content_info_override
   1405                                             * structs terminated by a { NULL, false, false } element.
   1406                                             * If 'data' is NULL, no changes will be made to the frontend;
   1407                                             * a core may therefore pass NULL in order to test whether
   1408                                             * the RETRO_ENVIRONMENT_SET_CONTENT_INFO_OVERRIDE and
   1409                                             * RETRO_ENVIRONMENT_GET_GAME_INFO_EXT callbacks are supported
   1410                                             * by the frontend.
   1411                                             *
   1412                                             * For struct member descriptions, see the definition of
   1413                                             * struct retro_system_content_info_override.
   1414                                             *
   1415                                             * Example:
   1416                                             *
   1417                                             * - struct retro_system_info:
   1418                                             * {
   1419                                             *    "My Core",                      // library_name
   1420                                             *    "v1.0",                         // library_version
   1421                                             *    "m3u|md|cue|iso|chd|sms|gg|sg", // valid_extensions
   1422                                             *    true,                           // need_fullpath
   1423                                             *    false                           // block_extract
   1424                                             * }
   1425                                             *
   1426                                             * - Array of struct retro_system_content_info_override:
   1427                                             * {
   1428                                             *    {
   1429                                             *       "md|sms|gg", // extensions
   1430                                             *       false,       // need_fullpath
   1431                                             *       true         // persistent_data
   1432                                             *    },
   1433                                             *    {
   1434                                             *       "sg",        // extensions
   1435                                             *       false,       // need_fullpath
   1436                                             *       false        // persistent_data
   1437                                             *    },
   1438                                             *    { NULL, false, false }
   1439                                             * }
   1440                                             *
   1441                                             * Result:
   1442                                             * - Files of type m3u, cue, iso, chd will not be
   1443                                             *   loaded by the frontend. Frontend will pass a
   1444                                             *   valid path to the core, and core will handle
   1445                                             *   loading internally
   1446                                             * - Files of type md, sms, gg will be loaded by
   1447                                             *   the frontend. A valid memory buffer will be
   1448                                             *   passed to the core. This memory buffer will
   1449                                             *   remain valid until retro_deinit() returns
   1450                                             * - Files of type sg will be loaded by the frontend.
   1451                                             *   A valid memory buffer will be passed to the core.
   1452                                             *   This memory buffer will remain valid until
   1453                                             *   retro_load_game() (or retro_load_game_special())
   1454                                             *   returns
   1455                                             *
   1456                                             * NOTE: If an extension is listed multiple times in
   1457                                             * an array of retro_system_content_info_override
   1458                                             * structs, only the first instance will be registered
   1459                                             */
   1460 
   1461 #define RETRO_ENVIRONMENT_GET_GAME_INFO_EXT 66
   1462                                            /* const struct retro_game_info_ext ** --
   1463                                             * Allows an implementation to fetch extended game
   1464                                             * information, providing additional content path
   1465                                             * and memory buffer status details.
   1466                                             * This function may only be called inside
   1467                                             * retro_load_game() or retro_load_game_special().
   1468                                             * If callback returns false, extended game information
   1469                                             * is unsupported by the frontend. In this case, only
   1470                                             * regular retro_game_info will be available.
   1471                                             * RETRO_ENVIRONMENT_GET_GAME_INFO_EXT is guaranteed
   1472                                             * to return true if RETRO_ENVIRONMENT_SET_CONTENT_INFO_OVERRIDE
   1473                                             * returns true.
   1474                                             *
   1475                                             * 'data' points to an array of retro_game_info_ext structs.
   1476                                             *
   1477                                             * For struct member descriptions, see the definition of
   1478                                             * struct retro_game_info_ext.
   1479                                             *
   1480                                             * - If function is called inside retro_load_game(),
   1481                                             *   the retro_game_info_ext array is guaranteed to
   1482                                             *   have a size of 1 - i.e. the returned pointer may
   1483                                             *   be used to access directly the members of the
   1484                                             *   first retro_game_info_ext struct, for example:
   1485                                             *
   1486                                             *      struct retro_game_info_ext *game_info_ext;
   1487                                             *      if (environ_cb(RETRO_ENVIRONMENT_GET_GAME_INFO_EXT, &game_info_ext))
   1488                                             *         printf("Content Directory: %s\n", game_info_ext->dir);
   1489                                             *
   1490                                             * - If the function is called inside retro_load_game_special(),
   1491                                             *   the retro_game_info_ext array is guaranteed to have a
   1492                                             *   size equal to the num_info argument passed to
   1493                                             *   retro_load_game_special()
   1494                                             */
   1495 
   1496 #define RETRO_ENVIRONMENT_SET_CORE_OPTIONS_V2 67
   1497                                            /* const struct retro_core_options_v2 * --
   1498                                             * Allows an implementation to signal the environment
   1499                                             * which variables it might want to check for later using
   1500                                             * GET_VARIABLE.
   1501                                             * This allows the frontend to present these variables to
   1502                                             * a user dynamically.
   1503                                             * This should only be called if RETRO_ENVIRONMENT_GET_CORE_OPTIONS_VERSION
   1504                                             * returns an API version of >= 2.
   1505                                             * This should be called instead of RETRO_ENVIRONMENT_SET_VARIABLES.
   1506                                             * This should be called instead of RETRO_ENVIRONMENT_SET_CORE_OPTIONS.
   1507                                             * This should be called the first time as early as
   1508                                             * possible (ideally in retro_set_environment).
   1509                                             * Afterwards it may be called again for the core to communicate
   1510                                             * updated options to the frontend, but the number of core
   1511                                             * options must not change from the number in the initial call.
   1512                                             * If RETRO_ENVIRONMENT_GET_CORE_OPTIONS_VERSION returns an API
   1513                                             * version of >= 2, this callback is guaranteed to succeed
   1514                                             * (i.e. callback return value does not indicate success)
   1515                                             * If callback returns true, frontend has core option category
   1516                                             * support.
   1517                                             * If callback returns false, frontend does not have core option
   1518                                             * category support.
   1519                                             *
   1520                                             * 'data' points to a retro_core_options_v2 struct, containing
   1521                                             * of two pointers:
   1522                                             * - retro_core_options_v2::categories is an array of
   1523                                             *   retro_core_option_v2_category structs terminated by a
   1524                                             *   { NULL, NULL, NULL } element. If retro_core_options_v2::categories
   1525                                             *   is NULL, all core options will have no category and will be shown
   1526                                             *   at the top level of the frontend core option interface. If frontend
   1527                                             *   does not have core option category support, categories array will
   1528                                             *   be ignored.
   1529                                             * - retro_core_options_v2::definitions is an array of
   1530                                             *   retro_core_option_v2_definition structs terminated by a
   1531                                             *   { NULL, NULL, NULL, NULL, NULL, NULL, {{0}}, NULL }
   1532                                             *   element.
   1533                                             *
   1534                                             * >> retro_core_option_v2_category notes:
   1535                                             *
   1536                                             * - retro_core_option_v2_category::key should contain string
   1537                                             *   that uniquely identifies the core option category. Valid
   1538                                             *   key characters are [a-z, A-Z, 0-9, _, -]
   1539                                             *   Namespace collisions with other implementations' category
   1540                                             *   keys are permitted.
   1541                                             * - retro_core_option_v2_category::desc should contain a human
   1542                                             *   readable description of the category key.
   1543                                             * - retro_core_option_v2_category::info should contain any
   1544                                             *   additional human readable information text that a typical
   1545                                             *   user may need to understand the nature of the core option
   1546                                             *   category.
   1547                                             *
   1548                                             * Example entry:
   1549                                             * {
   1550                                             *     "advanced_settings",
   1551                                             *     "Advanced",
   1552                                             *     "Options affecting low-level emulation performance and accuracy."
   1553                                             * }
   1554                                             *
   1555                                             * >> retro_core_option_v2_definition notes:
   1556                                             *
   1557                                             * - retro_core_option_v2_definition::key should be namespaced to not
   1558                                             *   collide with other implementations' keys. e.g. A core called
   1559                                             *   'foo' should use keys named as 'foo_option'. Valid key characters
   1560                                             *   are [a-z, A-Z, 0-9, _, -].
   1561                                             * - retro_core_option_v2_definition::desc should contain a human readable
   1562                                             *   description of the key. Will be used when the frontend does not
   1563                                             *   have core option category support. Examples: "Aspect Ratio" or
   1564                                             *   "Video > Aspect Ratio".
   1565                                             * - retro_core_option_v2_definition::desc_categorized should contain a
   1566                                             *   human readable description of the key, which will be used when
   1567                                             *   frontend has core option category support. Example: "Aspect Ratio",
   1568                                             *   where associated retro_core_option_v2_category::desc is "Video".
   1569                                             *   If empty or NULL, the string specified by
   1570                                             *   retro_core_option_v2_definition::desc will be used instead.
   1571                                             *   retro_core_option_v2_definition::desc_categorized will be ignored
   1572                                             *   if retro_core_option_v2_definition::category_key is empty or NULL.
   1573                                             * - retro_core_option_v2_definition::info should contain any additional
   1574                                             *   human readable information text that a typical user may need to
   1575                                             *   understand the functionality of the option.
   1576                                             * - retro_core_option_v2_definition::info_categorized should contain
   1577                                             *   any additional human readable information text that a typical user
   1578                                             *   may need to understand the functionality of the option, and will be
   1579                                             *   used when frontend has core option category support. This is provided
   1580                                             *   to accommodate the case where info text references an option by
   1581                                             *   name/desc, and the desc/desc_categorized text for that option differ.
   1582                                             *   If empty or NULL, the string specified by
   1583                                             *   retro_core_option_v2_definition::info will be used instead.
   1584                                             *   retro_core_option_v2_definition::info_categorized will be ignored
   1585                                             *   if retro_core_option_v2_definition::category_key is empty or NULL.
   1586                                             * - retro_core_option_v2_definition::category_key should contain a
   1587                                             *   category identifier (e.g. "video" or "audio") that will be
   1588                                             *   assigned to the core option if frontend has core option category
   1589                                             *   support. A categorized option will be shown in a subsection/
   1590                                             *   submenu of the frontend core option interface. If key is empty
   1591                                             *   or NULL, or if key does not match one of the
   1592                                             *   retro_core_option_v2_category::key values in the associated
   1593                                             *   retro_core_option_v2_category array, option will have no category
   1594                                             *   and will be shown at the top level of the frontend core option
   1595                                             *   interface.
   1596                                             * - retro_core_option_v2_definition::values is an array of
   1597                                             *   retro_core_option_value structs terminated by a { NULL, NULL }
   1598                                             *   element.
   1599                                             * --> retro_core_option_v2_definition::values[index].value is an
   1600                                             *     expected option value.
   1601                                             * --> retro_core_option_v2_definition::values[index].label is a
   1602                                             *     human readable label used when displaying the value on screen.
   1603                                             *     If NULL, the value itself is used.
   1604                                             * - retro_core_option_v2_definition::default_value is the default
   1605                                             *   core option setting. It must match one of the expected option
   1606                                             *   values in the retro_core_option_v2_definition::values array. If
   1607                                             *   it does not, or the default value is NULL, the first entry in the
   1608                                             *   retro_core_option_v2_definition::values array is treated as the
   1609                                             *   default.
   1610                                             *
   1611                                             * The number of possible option values should be very limited,
   1612                                             * and must be less than RETRO_NUM_CORE_OPTION_VALUES_MAX.
   1613                                             * i.e. it should be feasible to cycle through options
   1614                                             * without a keyboard.
   1615                                             *
   1616                                             * Example entries:
   1617                                             *
   1618                                             * - Uncategorized:
   1619                                             *
   1620                                             * {
   1621                                             *     "foo_option",
   1622                                             *     "Speed hack coprocessor X",
   1623                                             *     NULL,
   1624                                             *     "Provides increased performance at the expense of reduced accuracy.",
   1625                                             *     NULL,
   1626                                             *     NULL,
   1627                                             * 	  {
   1628                                             *         { "false",    NULL },
   1629                                             *         { "true",     NULL },
   1630                                             *         { "unstable", "Turbo (Unstable)" },
   1631                                             *         { NULL, NULL },
   1632                                             *     },
   1633                                             *     "false"
   1634                                             * }
   1635                                             *
   1636                                             * - Categorized:
   1637                                             *
   1638                                             * {
   1639                                             *     "foo_option",
   1640                                             *     "Advanced > Speed hack coprocessor X",
   1641                                             *     "Speed hack coprocessor X",
   1642                                             *     "Setting 'Advanced > Speed hack coprocessor X' to 'true' or 'Turbo' provides increased performance at the expense of reduced accuracy",
   1643                                             *     "Setting 'Speed hack coprocessor X' to 'true' or 'Turbo' provides increased performance at the expense of reduced accuracy",
   1644                                             *     "advanced_settings",
   1645                                             * 	  {
   1646                                             *         { "false",    NULL },
   1647                                             *         { "true",     NULL },
   1648                                             *         { "unstable", "Turbo (Unstable)" },
   1649                                             *         { NULL, NULL },
   1650                                             *     },
   1651                                             *     "false"
   1652                                             * }
   1653                                             *
   1654                                             * Only strings are operated on. The possible values will
   1655                                             * generally be displayed and stored as-is by the frontend.
   1656                                             */
   1657 
   1658 #define RETRO_ENVIRONMENT_SET_CORE_OPTIONS_V2_INTL 68
   1659                                            /* const struct retro_core_options_v2_intl * --
   1660                                             * Allows an implementation to signal the environment
   1661                                             * which variables it might want to check for later using
   1662                                             * GET_VARIABLE.
   1663                                             * This allows the frontend to present these variables to
   1664                                             * a user dynamically.
   1665                                             * This should only be called if RETRO_ENVIRONMENT_GET_CORE_OPTIONS_VERSION
   1666                                             * returns an API version of >= 2.
   1667                                             * This should be called instead of RETRO_ENVIRONMENT_SET_VARIABLES.
   1668                                             * This should be called instead of RETRO_ENVIRONMENT_SET_CORE_OPTIONS.
   1669                                             * This should be called instead of RETRO_ENVIRONMENT_SET_CORE_OPTIONS_INTL.
   1670                                             * This should be called instead of RETRO_ENVIRONMENT_SET_CORE_OPTIONS_V2.
   1671                                             * This should be called the first time as early as
   1672                                             * possible (ideally in retro_set_environment).
   1673                                             * Afterwards it may be called again for the core to communicate
   1674                                             * updated options to the frontend, but the number of core
   1675                                             * options must not change from the number in the initial call.
   1676                                             * If RETRO_ENVIRONMENT_GET_CORE_OPTIONS_VERSION returns an API
   1677                                             * version of >= 2, this callback is guaranteed to succeed
   1678                                             * (i.e. callback return value does not indicate success)
   1679                                             * If callback returns true, frontend has core option category
   1680                                             * support.
   1681                                             * If callback returns false, frontend does not have core option
   1682                                             * category support.
   1683                                             *
   1684                                             * This is fundamentally the same as RETRO_ENVIRONMENT_SET_CORE_OPTIONS_V2,
   1685                                             * with the addition of localisation support. The description of the
   1686                                             * RETRO_ENVIRONMENT_SET_CORE_OPTIONS_V2 callback should be consulted
   1687                                             * for further details.
   1688                                             *
   1689                                             * 'data' points to a retro_core_options_v2_intl struct.
   1690                                             *
   1691                                             * - retro_core_options_v2_intl::us is a pointer to a
   1692                                             *   retro_core_options_v2 struct defining the US English
   1693                                             *   core options implementation. It must point to a valid struct.
   1694                                             *
   1695                                             * - retro_core_options_v2_intl::local is a pointer to a
   1696                                             *   retro_core_options_v2 struct defining core options for
   1697                                             *   the current frontend language. It may be NULL (in which case
   1698                                             *   retro_core_options_v2_intl::us is used by the frontend). Any items
   1699                                             *   missing from this struct will be read from
   1700                                             *   retro_core_options_v2_intl::us instead.
   1701                                             *
   1702                                             * NOTE: Default core option values are always taken from the
   1703                                             * retro_core_options_v2_intl::us struct. Any default values in
   1704                                             * the retro_core_options_v2_intl::local struct will be ignored.
   1705                                             */
   1706 
   1707 #define RETRO_ENVIRONMENT_SET_CORE_OPTIONS_UPDATE_DISPLAY_CALLBACK 69
   1708                                            /* const struct retro_core_options_update_display_callback * --
   1709                                             * Allows a frontend to signal that a core must update
   1710                                             * the visibility of any dynamically hidden core options,
   1711                                             * and enables the frontend to detect visibility changes.
   1712                                             * Used by the frontend to update the menu display status
   1713                                             * of core options without requiring a call of retro_run().
   1714                                             * Must be called in retro_set_environment().
   1715                                             */
   1716 
   1717 #define RETRO_ENVIRONMENT_SET_VARIABLE 70
   1718                                            /* const struct retro_variable * --
   1719                                             * Allows an implementation to notify the frontend
   1720                                             * that a core option value has changed.
   1721                                             *
   1722                                             * retro_variable::key and retro_variable::value
   1723                                             * must match strings that have been set previously
   1724                                             * via one of the following:
   1725                                             *
   1726                                             * - RETRO_ENVIRONMENT_SET_VARIABLES
   1727                                             * - RETRO_ENVIRONMENT_SET_CORE_OPTIONS
   1728                                             * - RETRO_ENVIRONMENT_SET_CORE_OPTIONS_INTL
   1729                                             * - RETRO_ENVIRONMENT_SET_CORE_OPTIONS_V2
   1730                                             * - RETRO_ENVIRONMENT_SET_CORE_OPTIONS_V2_INTL
   1731                                             *
   1732                                             * After changing a core option value via this
   1733                                             * callback, RETRO_ENVIRONMENT_GET_VARIABLE_UPDATE
   1734                                             * will return true.
   1735                                             *
   1736                                             * If data is NULL, no changes will be registered
   1737                                             * and the callback will return true; an
   1738                                             * implementation may therefore pass NULL in order
   1739                                             * to test whether the callback is supported.
   1740                                             */
   1741 
   1742 #define RETRO_ENVIRONMENT_GET_THROTTLE_STATE (71 | RETRO_ENVIRONMENT_EXPERIMENTAL)
   1743                                            /* struct retro_throttle_state * --
   1744                                             * Allows an implementation to get details on the actual rate
   1745                                             * the frontend is attempting to call retro_run().
   1746                                             */
   1747 
   1748 /* VFS functionality */
   1749 
   1750 /* File paths:
   1751  * File paths passed as parameters when using this API shall be well formed UNIX-style,
   1752  * using "/" (unquoted forward slash) as directory separator regardless of the platform's native separator.
   1753  * Paths shall also include at least one forward slash ("game.bin" is an invalid path, use "./game.bin" instead).
   1754  * Other than the directory separator, cores shall not make assumptions about path format:
   1755  * "C:/path/game.bin", "http://example.com/game.bin", "#game/game.bin", "./game.bin" (without quotes) are all valid paths.
   1756  * Cores may replace the basename or remove path components from the end, and/or add new components;
   1757  * however, cores shall not append "./", "../" or multiple consecutive forward slashes ("//") to paths they request to front end.
   1758  * 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.
   1759  * Frontends are encouraged, but not required, to support native file system paths (modulo replacing the directory separator, if applicable).
   1760  * Cores are allowed to try using them, but must remain functional if the front rejects such requests.
   1761  * Cores are encouraged to use the libretro-common filestream functions for file I/O,
   1762  * as they seamlessly integrate with VFS, deal with directory separator replacement as appropriate
   1763  * and provide platform-specific fallbacks in cases where front ends do not support VFS. */
   1764 
   1765 /* Opaque file handle
   1766  * Introduced in VFS API v1 */
   1767 struct retro_vfs_file_handle;
   1768 
   1769 /* Opaque directory handle
   1770  * Introduced in VFS API v3 */
   1771 struct retro_vfs_dir_handle;
   1772 
   1773 /* File open flags
   1774  * Introduced in VFS API v1 */
   1775 #define RETRO_VFS_FILE_ACCESS_READ            (1 << 0) /* Read only mode */
   1776 #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 */
   1777 #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*/
   1778 #define RETRO_VFS_FILE_ACCESS_UPDATE_EXISTING (1 << 2) /* Prevents discarding content of existing files opened for writing */
   1779 
   1780 /* These are only hints. The frontend may choose to ignore them. Other than RAM/CPU/etc use,
   1781    and how they react to unlikely external interference (for example someone else writing to that file,
   1782    or the file's server going down), behavior will not change. */
   1783 #define RETRO_VFS_FILE_ACCESS_HINT_NONE              (0)
   1784 /* Indicate that the file will be accessed many times. The frontend should aggressively cache everything. */
   1785 #define RETRO_VFS_FILE_ACCESS_HINT_FREQUENT_ACCESS   (1 << 0)
   1786 
   1787 /* Seek positions */
   1788 #define RETRO_VFS_SEEK_POSITION_START    0
   1789 #define RETRO_VFS_SEEK_POSITION_CURRENT  1
   1790 #define RETRO_VFS_SEEK_POSITION_END      2
   1791 
   1792 /* stat() result flags
   1793  * Introduced in VFS API v3 */
   1794 #define RETRO_VFS_STAT_IS_VALID               (1 << 0)
   1795 #define RETRO_VFS_STAT_IS_DIRECTORY           (1 << 1)
   1796 #define RETRO_VFS_STAT_IS_CHARACTER_SPECIAL   (1 << 2)
   1797 
   1798 /* Get path from opaque handle. Returns the exact same path passed to file_open when getting the handle
   1799  * Introduced in VFS API v1 */
   1800 typedef const char *(RETRO_CALLCONV *retro_vfs_get_path_t)(struct retro_vfs_file_handle *stream);
   1801 
   1802 /* Open a file for reading or writing. If path points to a directory, this will
   1803  * fail. Returns the opaque file handle, or NULL for error.
   1804  * Introduced in VFS API v1 */
   1805 typedef struct retro_vfs_file_handle *(RETRO_CALLCONV *retro_vfs_open_t)(const char *path, unsigned mode, unsigned hints);
   1806 
   1807 /* Close the file and release its resources. Must be called if open_file returns non-NULL. Returns 0 on success, -1 on failure.
   1808  * Whether the call succeeds ot not, the handle passed as parameter becomes invalid and should no longer be used.
   1809  * Introduced in VFS API v1 */
   1810 typedef int (RETRO_CALLCONV *retro_vfs_close_t)(struct retro_vfs_file_handle *stream);
   1811 
   1812 /* Return the size of the file in bytes, or -1 for error.
   1813  * Introduced in VFS API v1 */
   1814 typedef int64_t (RETRO_CALLCONV *retro_vfs_size_t)(struct retro_vfs_file_handle *stream);
   1815 
   1816 /* Truncate file to specified size. Returns 0 on success or -1 on error
   1817  * Introduced in VFS API v2 */
   1818 typedef int64_t (RETRO_CALLCONV *retro_vfs_truncate_t)(struct retro_vfs_file_handle *stream, int64_t length);
   1819 
   1820 /* Get the current read / write position for the file. Returns -1 for error.
   1821  * Introduced in VFS API v1 */
   1822 typedef int64_t (RETRO_CALLCONV *retro_vfs_tell_t)(struct retro_vfs_file_handle *stream);
   1823 
   1824 /* Set the current read/write position for the file. Returns the new position, -1 for error.
   1825  * Introduced in VFS API v1 */
   1826 typedef int64_t (RETRO_CALLCONV *retro_vfs_seek_t)(struct retro_vfs_file_handle *stream, int64_t offset, int seek_position);
   1827 
   1828 /* Read data from a file. Returns the number of bytes read, or -1 for error.
   1829  * Introduced in VFS API v1 */
   1830 typedef int64_t (RETRO_CALLCONV *retro_vfs_read_t)(struct retro_vfs_file_handle *stream, void *s, uint64_t len);
   1831 
   1832 /* Write data to a file. Returns the number of bytes written, or -1 for error.
   1833  * Introduced in VFS API v1 */
   1834 typedef int64_t (RETRO_CALLCONV *retro_vfs_write_t)(struct retro_vfs_file_handle *stream, const void *s, uint64_t len);
   1835 
   1836 /* Flush pending writes to file, if using buffered IO. Returns 0 on sucess, or -1 on failure.
   1837  * Introduced in VFS API v1 */
   1838 typedef int (RETRO_CALLCONV *retro_vfs_flush_t)(struct retro_vfs_file_handle *stream);
   1839 
   1840 /* Delete the specified file. Returns 0 on success, -1 on failure
   1841  * Introduced in VFS API v1 */
   1842 typedef int (RETRO_CALLCONV *retro_vfs_remove_t)(const char *path);
   1843 
   1844 /* Rename the specified file. Returns 0 on success, -1 on failure
   1845  * Introduced in VFS API v1 */
   1846 typedef int (RETRO_CALLCONV *retro_vfs_rename_t)(const char *old_path, const char *new_path);
   1847 
   1848 /* Stat the specified file. Retruns a bitmask of RETRO_VFS_STAT_* flags, none are set if path was not valid.
   1849  * Additionally stores file size in given variable, unless NULL is given.
   1850  * Introduced in VFS API v3 */
   1851 typedef int (RETRO_CALLCONV *retro_vfs_stat_t)(const char *path, int32_t *size);
   1852 
   1853 /* Create the specified directory. Returns 0 on success, -1 on unknown failure, -2 if already exists.
   1854  * Introduced in VFS API v3 */
   1855 typedef int (RETRO_CALLCONV *retro_vfs_mkdir_t)(const char *dir);
   1856 
   1857 /* Open the specified directory for listing. Returns the opaque dir handle, or NULL for error.
   1858  * Support for the include_hidden argument may vary depending on the platform.
   1859  * Introduced in VFS API v3 */
   1860 typedef struct retro_vfs_dir_handle *(RETRO_CALLCONV *retro_vfs_opendir_t)(const char *dir, bool include_hidden);
   1861 
   1862 /* Read the directory entry at the current position, and move the read pointer to the next position.
   1863  * Returns true on success, false if already on the last entry.
   1864  * Introduced in VFS API v3 */
   1865 typedef bool (RETRO_CALLCONV *retro_vfs_readdir_t)(struct retro_vfs_dir_handle *dirstream);
   1866 
   1867 /* Get the name of the last entry read. Returns a string on success, or NULL for error.
   1868  * The returned string pointer is valid until the next call to readdir or closedir.
   1869  * Introduced in VFS API v3 */
   1870 typedef const char *(RETRO_CALLCONV *retro_vfs_dirent_get_name_t)(struct retro_vfs_dir_handle *dirstream);
   1871 
   1872 /* Check if the last entry read was a directory. Returns true if it was, false otherwise (or on error).
   1873  * Introduced in VFS API v3 */
   1874 typedef bool (RETRO_CALLCONV *retro_vfs_dirent_is_dir_t)(struct retro_vfs_dir_handle *dirstream);
   1875 
   1876 /* Close the directory and release its resources. Must be called if opendir returns non-NULL. Returns 0 on success, -1 on failure.
   1877  * Whether the call succeeds ot not, the handle passed as parameter becomes invalid and should no longer be used.
   1878  * Introduced in VFS API v3 */
   1879 typedef int (RETRO_CALLCONV *retro_vfs_closedir_t)(struct retro_vfs_dir_handle *dirstream);
   1880 
   1881 struct retro_vfs_interface
   1882 {
   1883     /* VFS API v1 */
   1884     retro_vfs_get_path_t get_path;
   1885     retro_vfs_open_t open;
   1886     retro_vfs_close_t close;
   1887     retro_vfs_size_t size;
   1888     retro_vfs_tell_t tell;
   1889     retro_vfs_seek_t seek;
   1890     retro_vfs_read_t read;
   1891     retro_vfs_write_t write;
   1892     retro_vfs_flush_t flush;
   1893     retro_vfs_remove_t remove;
   1894     retro_vfs_rename_t rename;
   1895     /* VFS API v2 */
   1896     retro_vfs_truncate_t truncate;
   1897     /* VFS API v3 */
   1898     retro_vfs_stat_t stat;
   1899     retro_vfs_mkdir_t mkdir;
   1900     retro_vfs_opendir_t opendir;
   1901     retro_vfs_readdir_t readdir;
   1902     retro_vfs_dirent_get_name_t dirent_get_name;
   1903     retro_vfs_dirent_is_dir_t dirent_is_dir;
   1904     retro_vfs_closedir_t closedir;
   1905 };
   1906 
   1907 struct retro_vfs_interface_info
   1908 {
   1909    /* Set by core: should this be higher than the version the front end supports,
   1910     * front end will return false in the RETRO_ENVIRONMENT_GET_VFS_INTERFACE call
   1911     * Introduced in VFS API v1 */
   1912    uint32_t required_interface_version;
   1913 
   1914    /* Frontend writes interface pointer here. The frontend also sets the actual
   1915     * version, must be at least required_interface_version.
   1916     * Introduced in VFS API v1 */
   1917    struct retro_vfs_interface *iface;
   1918 };
   1919 
   1920 enum retro_hw_render_interface_type
   1921 {
   1922     RETRO_HW_RENDER_INTERFACE_VULKAN = 0,
   1923     RETRO_HW_RENDER_INTERFACE_D3D9   = 1,
   1924     RETRO_HW_RENDER_INTERFACE_D3D10  = 2,
   1925     RETRO_HW_RENDER_INTERFACE_D3D11  = 3,
   1926     RETRO_HW_RENDER_INTERFACE_D3D12  = 4,
   1927     RETRO_HW_RENDER_INTERFACE_GSKIT_PS2  = 5,
   1928     RETRO_HW_RENDER_INTERFACE_DUMMY  = INT_MAX
   1929 };
   1930 
   1931 /* Base struct. All retro_hw_render_interface_* types
   1932  * contain at least these fields. */
   1933 struct retro_hw_render_interface
   1934 {
   1935    enum retro_hw_render_interface_type interface_type;
   1936    unsigned interface_version;
   1937 };
   1938 
   1939 typedef void (RETRO_CALLCONV *retro_set_led_state_t)(int led, int state);
   1940 struct retro_led_interface
   1941 {
   1942     retro_set_led_state_t set_led_state;
   1943 };
   1944 
   1945 /* Retrieves the current state of the MIDI input.
   1946  * Returns true if it's enabled, false otherwise. */
   1947 typedef bool (RETRO_CALLCONV *retro_midi_input_enabled_t)(void);
   1948 
   1949 /* Retrieves the current state of the MIDI output.
   1950  * Returns true if it's enabled, false otherwise */
   1951 typedef bool (RETRO_CALLCONV *retro_midi_output_enabled_t)(void);
   1952 
   1953 /* Reads next byte from the input stream.
   1954  * Returns true if byte is read, false otherwise. */
   1955 typedef bool (RETRO_CALLCONV *retro_midi_read_t)(uint8_t *byte);
   1956 
   1957 /* Writes byte to the output stream.
   1958  * 'delta_time' is in microseconds and represent time elapsed since previous write.
   1959  * Returns true if byte is written, false otherwise. */
   1960 typedef bool (RETRO_CALLCONV *retro_midi_write_t)(uint8_t byte, uint32_t delta_time);
   1961 
   1962 /* Flushes previously written data.
   1963  * Returns true if successful, false otherwise. */
   1964 typedef bool (RETRO_CALLCONV *retro_midi_flush_t)(void);
   1965 
   1966 struct retro_midi_interface
   1967 {
   1968    retro_midi_input_enabled_t input_enabled;
   1969    retro_midi_output_enabled_t output_enabled;
   1970    retro_midi_read_t read;
   1971    retro_midi_write_t write;
   1972    retro_midi_flush_t flush;
   1973 };
   1974 
   1975 enum retro_hw_render_context_negotiation_interface_type
   1976 {
   1977    RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_VULKAN = 0,
   1978    RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_DUMMY = INT_MAX
   1979 };
   1980 
   1981 /* Base struct. All retro_hw_render_context_negotiation_interface_* types
   1982  * contain at least these fields. */
   1983 struct retro_hw_render_context_negotiation_interface
   1984 {
   1985    enum retro_hw_render_context_negotiation_interface_type interface_type;
   1986    unsigned interface_version;
   1987 };
   1988 
   1989 /* Serialized state is incomplete in some way. Set if serialization is
   1990  * usable in typical end-user cases but should not be relied upon to
   1991  * implement frame-sensitive frontend features such as netplay or
   1992  * rerecording. */
   1993 #define RETRO_SERIALIZATION_QUIRK_INCOMPLETE (1 << 0)
   1994 /* The core must spend some time initializing before serialization is
   1995  * supported. retro_serialize() will initially fail; retro_unserialize()
   1996  * and retro_serialize_size() may or may not work correctly either. */
   1997 #define RETRO_SERIALIZATION_QUIRK_MUST_INITIALIZE (1 << 1)
   1998 /* Serialization size may change within a session. */
   1999 #define RETRO_SERIALIZATION_QUIRK_CORE_VARIABLE_SIZE (1 << 2)
   2000 /* Set by the frontend to acknowledge that it supports variable-sized
   2001  * states. */
   2002 #define RETRO_SERIALIZATION_QUIRK_FRONT_VARIABLE_SIZE (1 << 3)
   2003 /* Serialized state can only be loaded during the same session. */
   2004 #define RETRO_SERIALIZATION_QUIRK_SINGLE_SESSION (1 << 4)
   2005 /* Serialized state cannot be loaded on an architecture with a different
   2006  * endianness from the one it was saved on. */
   2007 #define RETRO_SERIALIZATION_QUIRK_ENDIAN_DEPENDENT (1 << 5)
   2008 /* Serialized state cannot be loaded on a different platform from the one it
   2009  * was saved on for reasons other than endianness, such as word size
   2010  * dependence */
   2011 #define RETRO_SERIALIZATION_QUIRK_PLATFORM_DEPENDENT (1 << 6)
   2012 
   2013 #define RETRO_MEMDESC_CONST      (1 << 0)   /* The frontend will never change this memory area once retro_load_game has returned. */
   2014 #define RETRO_MEMDESC_BIGENDIAN  (1 << 1)   /* The memory area contains big endian data. Default is little endian. */
   2015 #define RETRO_MEMDESC_SYSTEM_RAM (1 << 2)   /* The memory area is system RAM.  This is main RAM of the gaming system. */
   2016 #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. */
   2017 #define RETRO_MEMDESC_VIDEO_RAM  (1 << 4)   /* The memory area is video RAM (VRAM) */
   2018 #define RETRO_MEMDESC_ALIGN_2    (1 << 16)  /* All memory access in this area is aligned to their own size, or 2, whichever is smaller. */
   2019 #define RETRO_MEMDESC_ALIGN_4    (2 << 16)
   2020 #define RETRO_MEMDESC_ALIGN_8    (3 << 16)
   2021 #define RETRO_MEMDESC_MINSIZE_2  (1 << 24)  /* All memory in this region is accessed at least 2 bytes at the time. */
   2022 #define RETRO_MEMDESC_MINSIZE_4  (2 << 24)
   2023 #define RETRO_MEMDESC_MINSIZE_8  (3 << 24)
   2024 struct retro_memory_descriptor
   2025 {
   2026    uint64_t flags;
   2027 
   2028    /* Pointer to the start of the relevant ROM or RAM chip.
   2029     * It's strongly recommended to use 'offset' if possible, rather than
   2030     * doing math on the pointer.
   2031     *
   2032     * If the same byte is mapped my multiple descriptors, their descriptors
   2033     * must have the same pointer.
   2034     * If 'start' does not point to the first byte in the pointer, put the
   2035     * difference in 'offset' instead.
   2036     *
   2037     * May be NULL if there's nothing usable here (e.g. hardware registers and
   2038     * open bus). No flags should be set if the pointer is NULL.
   2039     * It's recommended to minimize the number of descriptors if possible,
   2040     * but not mandatory. */
   2041    void *ptr;
   2042    size_t offset;
   2043 
   2044    /* This is the location in the emulated address space
   2045     * where the mapping starts. */
   2046    size_t start;
   2047 
   2048    /* Which bits must be same as in 'start' for this mapping to apply.
   2049     * The first memory descriptor to claim a certain byte is the one
   2050     * that applies.
   2051     * A bit which is set in 'start' must also be set in this.
   2052     * Can be zero, in which case each byte is assumed mapped exactly once.
   2053     * In this case, 'len' must be a power of two. */
   2054    size_t select;
   2055 
   2056    /* If this is nonzero, the set bits are assumed not connected to the
   2057     * memory chip's address pins. */
   2058    size_t disconnect;
   2059 
   2060    /* This one tells the size of the current memory area.
   2061     * If, after start+disconnect are applied, the address is higher than
   2062     * this, the highest bit of the address is cleared.
   2063     *
   2064     * If the address is still too high, the next highest bit is cleared.
   2065     * Can be zero, in which case it's assumed to be infinite (as limited
   2066     * by 'select' and 'disconnect'). */
   2067    size_t len;
   2068 
   2069    /* To go from emulated address to physical address, the following
   2070     * order applies:
   2071     * Subtract 'start', pick off 'disconnect', apply 'len', add 'offset'. */
   2072 
   2073    /* The address space name must consist of only a-zA-Z0-9_-,
   2074     * should be as short as feasible (maximum length is 8 plus the NUL),
   2075     * and may not be any other address space plus one or more 0-9A-F
   2076     * at the end.
   2077     * However, multiple memory descriptors for the same address space is
   2078     * allowed, and the address space name can be empty. NULL is treated
   2079     * as empty.
   2080     *
   2081     * Address space names are case sensitive, but avoid lowercase if possible.
   2082     * The same pointer may exist in multiple address spaces.
   2083     *
   2084     * Examples:
   2085     * blank+blank - valid (multiple things may be mapped in the same namespace)
   2086     * 'Sp'+'Sp' - valid (multiple things may be mapped in the same namespace)
   2087     * 'A'+'B' - valid (neither is a prefix of each other)
   2088     * 'S'+blank - valid ('S' is not in 0-9A-F)
   2089     * 'a'+blank - valid ('a' is not in 0-9A-F)
   2090     * 'a'+'A' - valid (neither is a prefix of each other)
   2091     * 'AR'+blank - valid ('R' is not in 0-9A-F)
   2092     * 'ARB'+blank - valid (the B can't be part of the address either, because
   2093     *                      there is no namespace 'AR')
   2094     * blank+'B' - not valid, because it's ambigous which address space B1234
   2095     *             would refer to.
   2096     * The length can't be used for that purpose; the frontend may want
   2097     * to append arbitrary data to an address, without a separator. */
   2098    const char *addrspace;
   2099 
   2100    /* TODO: When finalizing this one, add a description field, which should be
   2101     * "WRAM" or something roughly equally long. */
   2102 
   2103    /* TODO: When finalizing this one, replace 'select' with 'limit', which tells
   2104     * which bits can vary and still refer to the same address (limit = ~select).
   2105     * TODO: limit? range? vary? something else? */
   2106 
   2107    /* TODO: When finalizing this one, if 'len' is above what 'select' (or
   2108     * 'limit') allows, it's bankswitched. Bankswitched data must have both 'len'
   2109     * and 'select' != 0, and the mappings don't tell how the system switches the
   2110     * banks. */
   2111 
   2112    /* TODO: When finalizing this one, fix the 'len' bit removal order.
   2113     * For len=0x1800, pointer 0x1C00 should go to 0x1400, not 0x0C00.
   2114     * Algorithm: Take bits highest to lowest, but if it goes above len, clear
   2115     * the most recent addition and continue on the next bit.
   2116     * TODO: Can the above be optimized? Is "remove the lowest bit set in both
   2117     * pointer and 'len'" equivalent? */
   2118 
   2119    /* TODO: Some emulators (MAME?) emulate big endian systems by only accessing
   2120     * the emulated memory in 32-bit chunks, native endian. But that's nothing
   2121     * compared to Darek Mihocka <http://www.emulators.com/docs/nx07_vm101.htm>
   2122     * (section Emulation 103 - Nearly Free Byte Reversal) - he flips the ENTIRE
   2123     * RAM backwards! I'll want to represent both of those, via some flags.
   2124     *
   2125     * I suspect MAME either didn't think of that idea, or don't want the #ifdef.
   2126     * Not sure which, nor do I really care. */
   2127 
   2128    /* TODO: Some of those flags are unused and/or don't really make sense. Clean
   2129     * them up. */
   2130 };
   2131 
   2132 /* The frontend may use the largest value of 'start'+'select' in a
   2133  * certain namespace to infer the size of the address space.
   2134  *
   2135  * If the address space is larger than that, a mapping with .ptr=NULL
   2136  * should be at the end of the array, with .select set to all ones for
   2137  * as long as the address space is big.
   2138  *
   2139  * Sample descriptors (minus .ptr, and RETRO_MEMFLAG_ on the flags):
   2140  * SNES WRAM:
   2141  * .start=0x7E0000, .len=0x20000
   2142  * (Note that this must be mapped before the ROM in most cases; some of the
   2143  * ROM mappers
   2144  * try to claim $7E0000, or at least $7E8000.)
   2145  * SNES SPC700 RAM:
   2146  * .addrspace="S", .len=0x10000
   2147  * SNES WRAM mirrors:
   2148  * .flags=MIRROR, .start=0x000000, .select=0xC0E000, .len=0x2000
   2149  * .flags=MIRROR, .start=0x800000, .select=0xC0E000, .len=0x2000
   2150  * SNES WRAM mirrors, alternate equivalent descriptor:
   2151  * .flags=MIRROR, .select=0x40E000, .disconnect=~0x1FFF
   2152  * (Various similar constructions can be created by combining parts of
   2153  * the above two.)
   2154  * SNES LoROM (512KB, mirrored a couple of times):
   2155  * .flags=CONST, .start=0x008000, .select=0x408000, .disconnect=0x8000, .len=512*1024
   2156  * .flags=CONST, .start=0x400000, .select=0x400000, .disconnect=0x8000, .len=512*1024
   2157  * SNES HiROM (4MB):
   2158  * .flags=CONST,                 .start=0x400000, .select=0x400000, .len=4*1024*1024
   2159  * .flags=CONST, .offset=0x8000, .start=0x008000, .select=0x408000, .len=4*1024*1024
   2160  * SNES ExHiROM (8MB):
   2161  * .flags=CONST, .offset=0,                  .start=0xC00000, .select=0xC00000, .len=4*1024*1024
   2162  * .flags=CONST, .offset=4*1024*1024,        .start=0x400000, .select=0xC00000, .len=4*1024*1024
   2163  * .flags=CONST, .offset=0x8000,             .start=0x808000, .select=0xC08000, .len=4*1024*1024
   2164  * .flags=CONST, .offset=4*1024*1024+0x8000, .start=0x008000, .select=0xC08000, .len=4*1024*1024
   2165  * Clarify the size of the address space:
   2166  * .ptr=NULL, .select=0xFFFFFF
   2167  * .len can be implied by .select in many of them, but was included for clarity.
   2168  */
   2169 
   2170 struct retro_memory_map
   2171 {
   2172    const struct retro_memory_descriptor *descriptors;
   2173    unsigned num_descriptors;
   2174 };
   2175 
   2176 struct retro_controller_description
   2177 {
   2178    /* Human-readable description of the controller. Even if using a generic
   2179     * input device type, this can be set to the particular device type the
   2180     * core uses. */
   2181    const char *desc;
   2182 
   2183    /* Device type passed to retro_set_controller_port_device(). If the device
   2184     * type is a sub-class of a generic input device type, use the
   2185     * RETRO_DEVICE_SUBCLASS macro to create an ID.
   2186     *
   2187     * E.g. RETRO_DEVICE_SUBCLASS(RETRO_DEVICE_JOYPAD, 1). */
   2188    unsigned id;
   2189 };
   2190 
   2191 struct retro_controller_info
   2192 {
   2193    const struct retro_controller_description *types;
   2194    unsigned num_types;
   2195 };
   2196 
   2197 struct retro_subsystem_memory_info
   2198 {
   2199    /* The extension associated with a memory type, e.g. "psram". */
   2200    const char *extension;
   2201 
   2202    /* The memory type for retro_get_memory(). This should be at
   2203     * least 0x100 to avoid conflict with standardized
   2204     * libretro memory types. */
   2205    unsigned type;
   2206 };
   2207 
   2208 struct retro_subsystem_rom_info
   2209 {
   2210    /* Describes what the content is (SGB BIOS, GB ROM, etc). */
   2211    const char *desc;
   2212 
   2213    /* Same definition as retro_get_system_info(). */
   2214    const char *valid_extensions;
   2215 
   2216    /* Same definition as retro_get_system_info(). */
   2217    bool need_fullpath;
   2218 
   2219    /* Same definition as retro_get_system_info(). */
   2220    bool block_extract;
   2221 
   2222    /* This is set if the content is required to load a game.
   2223     * If this is set to false, a zeroed-out retro_game_info can be passed. */
   2224    bool required;
   2225 
   2226    /* Content can have multiple associated persistent
   2227     * memory types (retro_get_memory()). */
   2228    const struct retro_subsystem_memory_info *memory;
   2229    unsigned num_memory;
   2230 };
   2231 
   2232 struct retro_subsystem_info
   2233 {
   2234    /* Human-readable string of the subsystem type, e.g. "Super GameBoy" */
   2235    const char *desc;
   2236 
   2237    /* A computer friendly short string identifier for the subsystem type.
   2238     * This name must be [a-z].
   2239     * E.g. if desc is "Super GameBoy", this can be "sgb".
   2240     * This identifier can be used for command-line interfaces, etc.
   2241     */
   2242    const char *ident;
   2243 
   2244    /* Infos for each content file. The first entry is assumed to be the
   2245     * "most significant" content for frontend purposes.
   2246     * E.g. with Super GameBoy, the first content should be the GameBoy ROM,
   2247     * as it is the most "significant" content to a user.
   2248     * If a frontend creates new file paths based on the content used
   2249     * (e.g. savestates), it should use the path for the first ROM to do so. */
   2250    const struct retro_subsystem_rom_info *roms;
   2251 
   2252    /* Number of content files associated with a subsystem. */
   2253    unsigned num_roms;
   2254 
   2255    /* The type passed to retro_load_game_special(). */
   2256    unsigned id;
   2257 };
   2258 
   2259 typedef void (RETRO_CALLCONV *retro_proc_address_t)(void);
   2260 
   2261 /* libretro API extension functions:
   2262  * (None here so far).
   2263  *
   2264  * Get a symbol from a libretro core.
   2265  * Cores should only return symbols which are actual
   2266  * extensions to the libretro API.
   2267  *
   2268  * Frontends should not use this to obtain symbols to standard
   2269  * libretro entry points (static linking or dlsym).
   2270  *
   2271  * The symbol name must be equal to the function name,
   2272  * e.g. if void retro_foo(void); exists, the symbol must be called "retro_foo".
   2273  * The returned function pointer must be cast to the corresponding type.
   2274  */
   2275 typedef retro_proc_address_t (RETRO_CALLCONV *retro_get_proc_address_t)(const char *sym);
   2276 
   2277 struct retro_get_proc_address_interface
   2278 {
   2279    retro_get_proc_address_t get_proc_address;
   2280 };
   2281 
   2282 enum retro_log_level
   2283 {
   2284    RETRO_LOG_DEBUG = 0,
   2285    RETRO_LOG_INFO,
   2286    RETRO_LOG_WARN,
   2287    RETRO_LOG_ERROR,
   2288 
   2289    RETRO_LOG_DUMMY = INT_MAX
   2290 };
   2291 
   2292 /* Logging function. Takes log level argument as well. */
   2293 typedef void (RETRO_CALLCONV *retro_log_printf_t)(enum retro_log_level level,
   2294       const char *fmt, ...);
   2295 
   2296 struct retro_log_callback
   2297 {
   2298    retro_log_printf_t log;
   2299 };
   2300 
   2301 /* Performance related functions */
   2302 
   2303 /* ID values for SIMD CPU features */
   2304 #define RETRO_SIMD_SSE      (1 << 0)
   2305 #define RETRO_SIMD_SSE2     (1 << 1)
   2306 #define RETRO_SIMD_VMX      (1 << 2)
   2307 #define RETRO_SIMD_VMX128   (1 << 3)
   2308 #define RETRO_SIMD_AVX      (1 << 4)
   2309 #define RETRO_SIMD_NEON     (1 << 5)
   2310 #define RETRO_SIMD_SSE3     (1 << 6)
   2311 #define RETRO_SIMD_SSSE3    (1 << 7)
   2312 #define RETRO_SIMD_MMX      (1 << 8)
   2313 #define RETRO_SIMD_MMXEXT   (1 << 9)
   2314 #define RETRO_SIMD_SSE4     (1 << 10)
   2315 #define RETRO_SIMD_SSE42    (1 << 11)
   2316 #define RETRO_SIMD_AVX2     (1 << 12)
   2317 #define RETRO_SIMD_VFPU     (1 << 13)
   2318 #define RETRO_SIMD_PS       (1 << 14)
   2319 #define RETRO_SIMD_AES      (1 << 15)
   2320 #define RETRO_SIMD_VFPV3    (1 << 16)
   2321 #define RETRO_SIMD_VFPV4    (1 << 17)
   2322 #define RETRO_SIMD_POPCNT   (1 << 18)
   2323 #define RETRO_SIMD_MOVBE    (1 << 19)
   2324 #define RETRO_SIMD_CMOV     (1 << 20)
   2325 #define RETRO_SIMD_ASIMD    (1 << 21)
   2326 
   2327 typedef uint64_t retro_perf_tick_t;
   2328 typedef int64_t retro_time_t;
   2329 
   2330 struct retro_perf_counter
   2331 {
   2332    const char *ident;
   2333    retro_perf_tick_t start;
   2334    retro_perf_tick_t total;
   2335    retro_perf_tick_t call_cnt;
   2336 
   2337    bool registered;
   2338 };
   2339 
   2340 /* Returns current time in microseconds.
   2341  * Tries to use the most accurate timer available.
   2342  */
   2343 typedef retro_time_t (RETRO_CALLCONV *retro_perf_get_time_usec_t)(void);
   2344 
   2345 /* A simple counter. Usually nanoseconds, but can also be CPU cycles.
   2346  * Can be used directly if desired (when creating a more sophisticated
   2347  * performance counter system).
   2348  * */
   2349 typedef retro_perf_tick_t (RETRO_CALLCONV *retro_perf_get_counter_t)(void);
   2350 
   2351 /* Returns a bit-mask of detected CPU features (RETRO_SIMD_*). */
   2352 typedef uint64_t (RETRO_CALLCONV *retro_get_cpu_features_t)(void);
   2353 
   2354 /* Asks frontend to log and/or display the state of performance counters.
   2355  * Performance counters can always be poked into manually as well.
   2356  */
   2357 typedef void (RETRO_CALLCONV *retro_perf_log_t)(void);
   2358 
   2359 /* Register a performance counter.
   2360  * ident field must be set with a discrete value and other values in
   2361  * retro_perf_counter must be 0.
   2362  * Registering can be called multiple times. To avoid calling to
   2363  * frontend redundantly, you can check registered field first. */
   2364 typedef void (RETRO_CALLCONV *retro_perf_register_t)(struct retro_perf_counter *counter);
   2365 
   2366 /* Starts a registered counter. */
   2367 typedef void (RETRO_CALLCONV *retro_perf_start_t)(struct retro_perf_counter *counter);
   2368 
   2369 /* Stops a registered counter. */
   2370 typedef void (RETRO_CALLCONV *retro_perf_stop_t)(struct retro_perf_counter *counter);
   2371 
   2372 /* For convenience it can be useful to wrap register, start and stop in macros.
   2373  * E.g.:
   2374  * #ifdef LOG_PERFORMANCE
   2375  * #define RETRO_PERFORMANCE_INIT(perf_cb, name) static struct retro_perf_counter name = {#name}; if (!name.registered) perf_cb.perf_register(&(name))
   2376  * #define RETRO_PERFORMANCE_START(perf_cb, name) perf_cb.perf_start(&(name))
   2377  * #define RETRO_PERFORMANCE_STOP(perf_cb, name) perf_cb.perf_stop(&(name))
   2378  * #else
   2379  * ... Blank macros ...
   2380  * #endif
   2381  *
   2382  * These can then be used mid-functions around code snippets.
   2383  *
   2384  * extern struct retro_perf_callback perf_cb;  * Somewhere in the core.
   2385  *
   2386  * void do_some_heavy_work(void)
   2387  * {
   2388  *    RETRO_PERFORMANCE_INIT(cb, work_1;
   2389  *    RETRO_PERFORMANCE_START(cb, work_1);
   2390  *    heavy_work_1();
   2391  *    RETRO_PERFORMANCE_STOP(cb, work_1);
   2392  *
   2393  *    RETRO_PERFORMANCE_INIT(cb, work_2);
   2394  *    RETRO_PERFORMANCE_START(cb, work_2);
   2395  *    heavy_work_2();
   2396  *    RETRO_PERFORMANCE_STOP(cb, work_2);
   2397  * }
   2398  *
   2399  * void retro_deinit(void)
   2400  * {
   2401  *    perf_cb.perf_log();  * Log all perf counters here for example.
   2402  * }
   2403  */
   2404 
   2405 struct retro_perf_callback
   2406 {
   2407    retro_perf_get_time_usec_t    get_time_usec;
   2408    retro_get_cpu_features_t      get_cpu_features;
   2409 
   2410    retro_perf_get_counter_t      get_perf_counter;
   2411    retro_perf_register_t         perf_register;
   2412    retro_perf_start_t            perf_start;
   2413    retro_perf_stop_t             perf_stop;
   2414    retro_perf_log_t              perf_log;
   2415 };
   2416 
   2417 /* FIXME: Document the sensor API and work out behavior.
   2418  * It will be marked as experimental until then.
   2419  */
   2420 enum retro_sensor_action
   2421 {
   2422    RETRO_SENSOR_ACCELEROMETER_ENABLE = 0,
   2423    RETRO_SENSOR_ACCELEROMETER_DISABLE,
   2424    RETRO_SENSOR_GYROSCOPE_ENABLE,
   2425    RETRO_SENSOR_GYROSCOPE_DISABLE,
   2426    RETRO_SENSOR_ILLUMINANCE_ENABLE,
   2427    RETRO_SENSOR_ILLUMINANCE_DISABLE,
   2428 
   2429    RETRO_SENSOR_DUMMY = INT_MAX
   2430 };
   2431 
   2432 /* Id values for SENSOR types. */
   2433 #define RETRO_SENSOR_ACCELEROMETER_X 0
   2434 #define RETRO_SENSOR_ACCELEROMETER_Y 1
   2435 #define RETRO_SENSOR_ACCELEROMETER_Z 2
   2436 #define RETRO_SENSOR_GYROSCOPE_X 3
   2437 #define RETRO_SENSOR_GYROSCOPE_Y 4
   2438 #define RETRO_SENSOR_GYROSCOPE_Z 5
   2439 #define RETRO_SENSOR_ILLUMINANCE 6
   2440 
   2441 typedef bool (RETRO_CALLCONV *retro_set_sensor_state_t)(unsigned port,
   2442       enum retro_sensor_action action, unsigned rate);
   2443 
   2444 typedef float (RETRO_CALLCONV *retro_sensor_get_input_t)(unsigned port, unsigned id);
   2445 
   2446 struct retro_sensor_interface
   2447 {
   2448    retro_set_sensor_state_t set_sensor_state;
   2449    retro_sensor_get_input_t get_sensor_input;
   2450 };
   2451 
   2452 enum retro_camera_buffer
   2453 {
   2454    RETRO_CAMERA_BUFFER_OPENGL_TEXTURE = 0,
   2455    RETRO_CAMERA_BUFFER_RAW_FRAMEBUFFER,
   2456 
   2457    RETRO_CAMERA_BUFFER_DUMMY = INT_MAX
   2458 };
   2459 
   2460 /* Starts the camera driver. Can only be called in retro_run(). */
   2461 typedef bool (RETRO_CALLCONV *retro_camera_start_t)(void);
   2462 
   2463 /* Stops the camera driver. Can only be called in retro_run(). */
   2464 typedef void (RETRO_CALLCONV *retro_camera_stop_t)(void);
   2465 
   2466 /* Callback which signals when the camera driver is initialized
   2467  * and/or deinitialized.
   2468  * retro_camera_start_t can be called in initialized callback.
   2469  */
   2470 typedef void (RETRO_CALLCONV *retro_camera_lifetime_status_t)(void);
   2471 
   2472 /* A callback for raw framebuffer data. buffer points to an XRGB8888 buffer.
   2473  * Width, height and pitch are similar to retro_video_refresh_t.
   2474  * First pixel is top-left origin.
   2475  */
   2476 typedef void (RETRO_CALLCONV *retro_camera_frame_raw_framebuffer_t)(const uint32_t *buffer,
   2477       unsigned width, unsigned height, size_t pitch);
   2478 
   2479 /* A callback for when OpenGL textures are used.
   2480  *
   2481  * texture_id is a texture owned by camera driver.
   2482  * Its state or content should be considered immutable, except for things like
   2483  * texture filtering and clamping.
   2484  *
   2485  * texture_target is the texture target for the GL texture.
   2486  * These can include e.g. GL_TEXTURE_2D, GL_TEXTURE_RECTANGLE, and possibly
   2487  * more depending on extensions.
   2488  *
   2489  * affine points to a packed 3x3 column-major matrix used to apply an affine
   2490  * transform to texture coordinates. (affine_matrix * vec3(coord_x, coord_y, 1.0))
   2491  * After transform, normalized texture coord (0, 0) should be bottom-left
   2492  * and (1, 1) should be top-right (or (width, height) for RECTANGLE).
   2493  *
   2494  * GL-specific typedefs are avoided here to avoid relying on gl.h in
   2495  * the API definition.
   2496  */
   2497 typedef void (RETRO_CALLCONV *retro_camera_frame_opengl_texture_t)(unsigned texture_id,
   2498       unsigned texture_target, const float *affine);
   2499 
   2500 struct retro_camera_callback
   2501 {
   2502    /* Set by libretro core.
   2503     * Example bitmask: caps = (1 << RETRO_CAMERA_BUFFER_OPENGL_TEXTURE) | (1 << RETRO_CAMERA_BUFFER_RAW_FRAMEBUFFER).
   2504     */
   2505    uint64_t caps;
   2506 
   2507    /* Desired resolution for camera. Is only used as a hint. */
   2508    unsigned width;
   2509    unsigned height;
   2510 
   2511    /* Set by frontend. */
   2512    retro_camera_start_t start;
   2513    retro_camera_stop_t stop;
   2514 
   2515    /* Set by libretro core if raw framebuffer callbacks will be used. */
   2516    retro_camera_frame_raw_framebuffer_t frame_raw_framebuffer;
   2517 
   2518    /* Set by libretro core if OpenGL texture callbacks will be used. */
   2519    retro_camera_frame_opengl_texture_t frame_opengl_texture;
   2520 
   2521    /* Set by libretro core. Called after camera driver is initialized and
   2522     * ready to be started.
   2523     * Can be NULL, in which this callback is not called.
   2524     */
   2525    retro_camera_lifetime_status_t initialized;
   2526 
   2527    /* Set by libretro core. Called right before camera driver is
   2528     * deinitialized.
   2529     * Can be NULL, in which this callback is not called.
   2530     */
   2531    retro_camera_lifetime_status_t deinitialized;
   2532 };
   2533 
   2534 /* Sets the interval of time and/or distance at which to update/poll
   2535  * location-based data.
   2536  *
   2537  * To ensure compatibility with all location-based implementations,
   2538  * values for both interval_ms and interval_distance should be provided.
   2539  *
   2540  * interval_ms is the interval expressed in milliseconds.
   2541  * interval_distance is the distance interval expressed in meters.
   2542  */
   2543 typedef void (RETRO_CALLCONV *retro_location_set_interval_t)(unsigned interval_ms,
   2544       unsigned interval_distance);
   2545 
   2546 /* Start location services. The device will start listening for changes to the
   2547  * current location at regular intervals (which are defined with
   2548  * retro_location_set_interval_t). */
   2549 typedef bool (RETRO_CALLCONV *retro_location_start_t)(void);
   2550 
   2551 /* Stop location services. The device will stop listening for changes
   2552  * to the current location. */
   2553 typedef void (RETRO_CALLCONV *retro_location_stop_t)(void);
   2554 
   2555 /* Get the position of the current location. Will set parameters to
   2556  * 0 if no new  location update has happened since the last time. */
   2557 typedef bool (RETRO_CALLCONV *retro_location_get_position_t)(double *lat, double *lon,
   2558       double *horiz_accuracy, double *vert_accuracy);
   2559 
   2560 /* Callback which signals when the location driver is initialized
   2561  * and/or deinitialized.
   2562  * retro_location_start_t can be called in initialized callback.
   2563  */
   2564 typedef void (RETRO_CALLCONV *retro_location_lifetime_status_t)(void);
   2565 
   2566 struct retro_location_callback
   2567 {
   2568    retro_location_start_t         start;
   2569    retro_location_stop_t          stop;
   2570    retro_location_get_position_t  get_position;
   2571    retro_location_set_interval_t  set_interval;
   2572 
   2573    retro_location_lifetime_status_t initialized;
   2574    retro_location_lifetime_status_t deinitialized;
   2575 };
   2576 
   2577 enum retro_rumble_effect
   2578 {
   2579    RETRO_RUMBLE_STRONG = 0,
   2580    RETRO_RUMBLE_WEAK = 1,
   2581 
   2582    RETRO_RUMBLE_DUMMY = INT_MAX
   2583 };
   2584 
   2585 /* Sets rumble state for joypad plugged in port 'port'.
   2586  * Rumble effects are controlled independently,
   2587  * and setting e.g. strong rumble does not override weak rumble.
   2588  * Strength has a range of [0, 0xffff].
   2589  *
   2590  * Returns true if rumble state request was honored.
   2591  * Calling this before first retro_run() is likely to return false. */
   2592 typedef bool (RETRO_CALLCONV *retro_set_rumble_state_t)(unsigned port,
   2593       enum retro_rumble_effect effect, uint16_t strength);
   2594 
   2595 struct retro_rumble_interface
   2596 {
   2597    retro_set_rumble_state_t set_rumble_state;
   2598 };
   2599 
   2600 /* Notifies libretro that audio data should be written. */
   2601 typedef void (RETRO_CALLCONV *retro_audio_callback_t)(void);
   2602 
   2603 /* True: Audio driver in frontend is active, and callback is
   2604  * expected to be called regularily.
   2605  * False: Audio driver in frontend is paused or inactive.
   2606  * Audio callback will not be called until set_state has been
   2607  * called with true.
   2608  * Initial state is false (inactive).
   2609  */
   2610 typedef void (RETRO_CALLCONV *retro_audio_set_state_callback_t)(bool enabled);
   2611 
   2612 struct retro_audio_callback
   2613 {
   2614    retro_audio_callback_t callback;
   2615    retro_audio_set_state_callback_t set_state;
   2616 };
   2617 
   2618 /* Notifies a libretro core of time spent since last invocation
   2619  * of retro_run() in microseconds.
   2620  *
   2621  * It will be called right before retro_run() every frame.
   2622  * The frontend can tamper with timing to support cases like
   2623  * fast-forward, slow-motion and framestepping.
   2624  *
   2625  * In those scenarios the reference frame time value will be used. */
   2626 typedef int64_t retro_usec_t;
   2627 typedef void (RETRO_CALLCONV *retro_frame_time_callback_t)(retro_usec_t usec);
   2628 struct retro_frame_time_callback
   2629 {
   2630    retro_frame_time_callback_t callback;
   2631    /* Represents the time of one frame. It is computed as
   2632     * 1000000 / fps, but the implementation will resolve the
   2633     * rounding to ensure that framestepping, etc is exact. */
   2634    retro_usec_t reference;
   2635 };
   2636 
   2637 /* Notifies a libretro core of the current occupancy
   2638  * level of the frontend audio buffer.
   2639  *
   2640  * - active: 'true' if audio buffer is currently
   2641  *           in use. Will be 'false' if audio is
   2642  *           disabled in the frontend
   2643  *
   2644  * - occupancy: Given as a value in the range [0,100],
   2645  *              corresponding to the occupancy percentage
   2646  *              of the audio buffer
   2647  *
   2648  * - underrun_likely: 'true' if the frontend expects an
   2649  *                    audio buffer underrun during the
   2650  *                    next frame (indicates that a core
   2651  *                    should attempt frame skipping)
   2652  *
   2653  * It will be called right before retro_run() every frame. */
   2654 typedef void (RETRO_CALLCONV *retro_audio_buffer_status_callback_t)(
   2655       bool active, unsigned occupancy, bool underrun_likely);
   2656 struct retro_audio_buffer_status_callback
   2657 {
   2658    retro_audio_buffer_status_callback_t callback;
   2659 };
   2660 
   2661 /* Pass this to retro_video_refresh_t if rendering to hardware.
   2662  * Passing NULL to retro_video_refresh_t is still a frame dupe as normal.
   2663  * */
   2664 #define RETRO_HW_FRAME_BUFFER_VALID ((void*)-1)
   2665 
   2666 /* Invalidates the current HW context.
   2667  * Any GL state is lost, and must not be deinitialized explicitly.
   2668  * If explicit deinitialization is desired by the libretro core,
   2669  * it should implement context_destroy callback.
   2670  * If called, all GPU resources must be reinitialized.
   2671  * Usually called when frontend reinits video driver.
   2672  * Also called first time video driver is initialized,
   2673  * allowing libretro core to initialize resources.
   2674  */
   2675 typedef void (RETRO_CALLCONV *retro_hw_context_reset_t)(void);
   2676 
   2677 /* Gets current framebuffer which is to be rendered to.
   2678  * Could change every frame potentially.
   2679  */
   2680 typedef uintptr_t (RETRO_CALLCONV *retro_hw_get_current_framebuffer_t)(void);
   2681 
   2682 /* Get a symbol from HW context. */
   2683 typedef retro_proc_address_t (RETRO_CALLCONV *retro_hw_get_proc_address_t)(const char *sym);
   2684 
   2685 enum retro_hw_context_type
   2686 {
   2687    RETRO_HW_CONTEXT_NONE             = 0,
   2688    /* OpenGL 2.x. Driver can choose to use latest compatibility context. */
   2689    RETRO_HW_CONTEXT_OPENGL           = 1,
   2690    /* OpenGL ES 2.0. */
   2691    RETRO_HW_CONTEXT_OPENGLES2        = 2,
   2692    /* Modern desktop core GL context. Use version_major/
   2693     * version_minor fields to set GL version. */
   2694    RETRO_HW_CONTEXT_OPENGL_CORE      = 3,
   2695    /* OpenGL ES 3.0 */
   2696    RETRO_HW_CONTEXT_OPENGLES3        = 4,
   2697    /* OpenGL ES 3.1+. Set version_major/version_minor. For GLES2 and GLES3,
   2698     * use the corresponding enums directly. */
   2699    RETRO_HW_CONTEXT_OPENGLES_VERSION = 5,
   2700 
   2701    /* Vulkan, see RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE. */
   2702    RETRO_HW_CONTEXT_VULKAN           = 6,
   2703 
   2704    /* Direct3D, set version_major to select the type of interface
   2705     * returned by RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE */
   2706    RETRO_HW_CONTEXT_DIRECT3D         = 7,
   2707 
   2708    RETRO_HW_CONTEXT_DUMMY = INT_MAX
   2709 };
   2710 
   2711 struct retro_hw_render_callback
   2712 {
   2713    /* Which API to use. Set by libretro core. */
   2714    enum retro_hw_context_type context_type;
   2715 
   2716    /* Called when a context has been created or when it has been reset.
   2717     * An OpenGL context is only valid after context_reset() has been called.
   2718     *
   2719     * When context_reset is called, OpenGL resources in the libretro
   2720     * implementation are guaranteed to be invalid.
   2721     *
   2722     * It is possible that context_reset is called multiple times during an
   2723     * application lifecycle.
   2724     * If context_reset is called without any notification (context_destroy),
   2725     * the OpenGL context was lost and resources should just be recreated
   2726     * without any attempt to "free" old resources.
   2727     */
   2728    retro_hw_context_reset_t context_reset;
   2729 
   2730    /* Set by frontend.
   2731     * TODO: This is rather obsolete. The frontend should not
   2732     * be providing preallocated framebuffers. */
   2733    retro_hw_get_current_framebuffer_t get_current_framebuffer;
   2734 
   2735    /* Set by frontend.
   2736     * Can return all relevant functions, including glClear on Windows. */
   2737    retro_hw_get_proc_address_t get_proc_address;
   2738 
   2739    /* Set if render buffers should have depth component attached.
   2740     * TODO: Obsolete. */
   2741    bool depth;
   2742 
   2743    /* Set if stencil buffers should be attached.
   2744     * TODO: Obsolete. */
   2745    bool stencil;
   2746 
   2747    /* If depth and stencil are true, a packed 24/8 buffer will be added.
   2748     * Only attaching stencil is invalid and will be ignored. */
   2749 
   2750    /* Use conventional bottom-left origin convention. If false,
   2751     * standard libretro top-left origin semantics are used.
   2752     * TODO: Move to GL specific interface. */
   2753    bool bottom_left_origin;
   2754 
   2755    /* Major version number for core GL context or GLES 3.1+. */
   2756    unsigned version_major;
   2757 
   2758    /* Minor version number for core GL context or GLES 3.1+. */
   2759    unsigned version_minor;
   2760 
   2761    /* If this is true, the frontend will go very far to avoid
   2762     * resetting context in scenarios like toggling fullscreen, etc.
   2763     * TODO: Obsolete? Maybe frontend should just always assume this ...
   2764     */
   2765    bool cache_context;
   2766 
   2767    /* The reset callback might still be called in extreme situations
   2768     * such as if the context is lost beyond recovery.
   2769     *
   2770     * For optimal stability, set this to false, and allow context to be
   2771     * reset at any time.
   2772     */
   2773 
   2774    /* A callback to be called before the context is destroyed in a
   2775     * controlled way by the frontend. */
   2776    retro_hw_context_reset_t context_destroy;
   2777 
   2778    /* OpenGL resources can be deinitialized cleanly at this step.
   2779     * context_destroy can be set to NULL, in which resources will
   2780     * just be destroyed without any notification.
   2781     *
   2782     * Even when context_destroy is non-NULL, it is possible that
   2783     * context_reset is called without any destroy notification.
   2784     * This happens if context is lost by external factors (such as
   2785     * notified by GL_ARB_robustness).
   2786     *
   2787     * In this case, the context is assumed to be already dead,
   2788     * and the libretro implementation must not try to free any OpenGL
   2789     * resources in the subsequent context_reset.
   2790     */
   2791 
   2792    /* Creates a debug context. */
   2793    bool debug_context;
   2794 };
   2795 
   2796 /* Callback type passed in RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK.
   2797  * Called by the frontend in response to keyboard events.
   2798  * down is set if the key is being pressed, or false if it is being released.
   2799  * keycode is the RETROK value of the char.
   2800  * character is the text character of the pressed key. (UTF-32).
   2801  * key_modifiers is a set of RETROKMOD values or'ed together.
   2802  *
   2803  * The pressed/keycode state can be indepedent of the character.
   2804  * It is also possible that multiple characters are generated from a
   2805  * single keypress.
   2806  * Keycode events should be treated separately from character events.
   2807  * However, when possible, the frontend should try to synchronize these.
   2808  * If only a character is posted, keycode should be RETROK_UNKNOWN.
   2809  *
   2810  * Similarily if only a keycode event is generated with no corresponding
   2811  * character, character should be 0.
   2812  */
   2813 typedef void (RETRO_CALLCONV *retro_keyboard_event_t)(bool down, unsigned keycode,
   2814       uint32_t character, uint16_t key_modifiers);
   2815 
   2816 struct retro_keyboard_callback
   2817 {
   2818    retro_keyboard_event_t callback;
   2819 };
   2820 
   2821 /* Callbacks for RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE &
   2822  * RETRO_ENVIRONMENT_SET_DISK_CONTROL_EXT_INTERFACE.
   2823  * Should be set for implementations which can swap out multiple disk
   2824  * images in runtime.
   2825  *
   2826  * If the implementation can do this automatically, it should strive to do so.
   2827  * However, there are cases where the user must manually do so.
   2828  *
   2829  * Overview: To swap a disk image, eject the disk image with
   2830  * set_eject_state(true).
   2831  * Set the disk index with set_image_index(index). Insert the disk again
   2832  * with set_eject_state(false).
   2833  */
   2834 
   2835 /* If ejected is true, "ejects" the virtual disk tray.
   2836  * When ejected, the disk image index can be set.
   2837  */
   2838 typedef bool (RETRO_CALLCONV *retro_set_eject_state_t)(bool ejected);
   2839 
   2840 /* Gets current eject state. The initial state is 'not ejected'. */
   2841 typedef bool (RETRO_CALLCONV *retro_get_eject_state_t)(void);
   2842 
   2843 /* Gets current disk index. First disk is index 0.
   2844  * If return value is >= get_num_images(), no disk is currently inserted.
   2845  */
   2846 typedef unsigned (RETRO_CALLCONV *retro_get_image_index_t)(void);
   2847 
   2848 /* Sets image index. Can only be called when disk is ejected.
   2849  * The implementation supports setting "no disk" by using an
   2850  * index >= get_num_images().
   2851  */
   2852 typedef bool (RETRO_CALLCONV *retro_set_image_index_t)(unsigned index);
   2853 
   2854 /* Gets total number of images which are available to use. */
   2855 typedef unsigned (RETRO_CALLCONV *retro_get_num_images_t)(void);
   2856 
   2857 struct retro_game_info;
   2858 
   2859 /* Replaces the disk image associated with index.
   2860  * Arguments to pass in info have same requirements as retro_load_game().
   2861  * Virtual disk tray must be ejected when calling this.
   2862  *
   2863  * Replacing a disk image with info = NULL will remove the disk image
   2864  * from the internal list.
   2865  * As a result, calls to get_image_index() can change.
   2866  *
   2867  * E.g. replace_image_index(1, NULL), and previous get_image_index()
   2868  * returned 4 before.
   2869  * Index 1 will be removed, and the new index is 3.
   2870  */
   2871 typedef bool (RETRO_CALLCONV *retro_replace_image_index_t)(unsigned index,
   2872       const struct retro_game_info *info);
   2873 
   2874 /* Adds a new valid index (get_num_images()) to the internal disk list.
   2875  * This will increment subsequent return values from get_num_images() by 1.
   2876  * This image index cannot be used until a disk image has been set
   2877  * with replace_image_index. */
   2878 typedef bool (RETRO_CALLCONV *retro_add_image_index_t)(void);
   2879 
   2880 /* Sets initial image to insert in drive when calling
   2881  * core_load_game().
   2882  * Since we cannot pass the initial index when loading
   2883  * content (this would require a major API change), this
   2884  * is set by the frontend *before* calling the core's
   2885  * retro_load_game()/retro_load_game_special() implementation.
   2886  * A core should therefore cache the index/path values and handle
   2887  * them inside retro_load_game()/retro_load_game_special().
   2888  * - If 'index' is invalid (index >= get_num_images()), the
   2889  *   core should ignore the set value and instead use 0
   2890  * - 'path' is used purely for error checking - i.e. when
   2891  *   content is loaded, the core should verify that the
   2892  *   disk specified by 'index' has the specified file path.
   2893  *   This is to guard against auto selecting the wrong image
   2894  *   if (for example) the user should modify an existing M3U
   2895  *   playlist. We have to let the core handle this because
   2896  *   set_initial_image() must be called before loading content,
   2897  *   i.e. the frontend cannot access image paths in advance
   2898  *   and thus cannot perform the error check itself.
   2899  *   If set path and content path do not match, the core should
   2900  *   ignore the set 'index' value and instead use 0
   2901  * Returns 'false' if index or 'path' are invalid, or core
   2902  * does not support this functionality
   2903  */
   2904 typedef bool (RETRO_CALLCONV *retro_set_initial_image_t)(unsigned index, const char *path);
   2905 
   2906 /* Fetches the path of the specified disk image file.
   2907  * Returns 'false' if index is invalid (index >= get_num_images())
   2908  * or path is otherwise unavailable.
   2909  */
   2910 typedef bool (RETRO_CALLCONV *retro_get_image_path_t)(unsigned index, char *path, size_t len);
   2911 
   2912 /* Fetches a core-provided 'label' for the specified disk
   2913  * image file. In the simplest case this may be a file name
   2914  * (without extension), but for cores with more complex
   2915  * content requirements information may be provided to
   2916  * facilitate user disk swapping - for example, a core
   2917  * running floppy-disk-based content may uniquely label
   2918  * save disks, data disks, level disks, etc. with names
   2919  * corresponding to in-game disk change prompts (so the
   2920  * frontend can provide better user guidance than a 'dumb'
   2921  * disk index value).
   2922  * Returns 'false' if index is invalid (index >= get_num_images())
   2923  * or label is otherwise unavailable.
   2924  */
   2925 typedef bool (RETRO_CALLCONV *retro_get_image_label_t)(unsigned index, char *label, size_t len);
   2926 
   2927 struct retro_disk_control_callback
   2928 {
   2929    retro_set_eject_state_t set_eject_state;
   2930    retro_get_eject_state_t get_eject_state;
   2931 
   2932    retro_get_image_index_t get_image_index;
   2933    retro_set_image_index_t set_image_index;
   2934    retro_get_num_images_t  get_num_images;
   2935 
   2936    retro_replace_image_index_t replace_image_index;
   2937    retro_add_image_index_t add_image_index;
   2938 };
   2939 
   2940 struct retro_disk_control_ext_callback
   2941 {
   2942    retro_set_eject_state_t set_eject_state;
   2943    retro_get_eject_state_t get_eject_state;
   2944 
   2945    retro_get_image_index_t get_image_index;
   2946    retro_set_image_index_t set_image_index;
   2947    retro_get_num_images_t  get_num_images;
   2948 
   2949    retro_replace_image_index_t replace_image_index;
   2950    retro_add_image_index_t add_image_index;
   2951 
   2952    /* NOTE: Frontend will only attempt to record/restore
   2953     * last used disk index if both set_initial_image()
   2954     * and get_image_path() are implemented */
   2955    retro_set_initial_image_t set_initial_image; /* Optional - may be NULL */
   2956 
   2957    retro_get_image_path_t get_image_path;       /* Optional - may be NULL */
   2958    retro_get_image_label_t get_image_label;     /* Optional - may be NULL */
   2959 };
   2960 
   2961 enum retro_pixel_format
   2962 {
   2963    /* 0RGB1555, native endian.
   2964     * 0 bit must be set to 0.
   2965     * This pixel format is default for compatibility concerns only.
   2966     * If a 15/16-bit pixel format is desired, consider using RGB565. */
   2967    RETRO_PIXEL_FORMAT_0RGB1555 = 0,
   2968 
   2969    /* XRGB8888, native endian.
   2970     * X bits are ignored. */
   2971    RETRO_PIXEL_FORMAT_XRGB8888 = 1,
   2972 
   2973    /* RGB565, native endian.
   2974     * This pixel format is the recommended format to use if a 15/16-bit
   2975     * format is desired as it is the pixel format that is typically
   2976     * available on a wide range of low-power devices.
   2977     *
   2978     * It is also natively supported in APIs like OpenGL ES. */
   2979    RETRO_PIXEL_FORMAT_RGB565   = 2,
   2980 
   2981    /* Ensure sizeof() == sizeof(int). */
   2982    RETRO_PIXEL_FORMAT_UNKNOWN  = INT_MAX
   2983 };
   2984 
   2985 struct retro_message
   2986 {
   2987    const char *msg;        /* Message to be displayed. */
   2988    unsigned    frames;     /* Duration in frames of message. */
   2989 };
   2990 
   2991 enum retro_message_target
   2992 {
   2993    RETRO_MESSAGE_TARGET_ALL = 0,
   2994    RETRO_MESSAGE_TARGET_OSD,
   2995    RETRO_MESSAGE_TARGET_LOG
   2996 };
   2997 
   2998 enum retro_message_type
   2999 {
   3000    RETRO_MESSAGE_TYPE_NOTIFICATION = 0,
   3001    RETRO_MESSAGE_TYPE_NOTIFICATION_ALT,
   3002    RETRO_MESSAGE_TYPE_STATUS,
   3003    RETRO_MESSAGE_TYPE_PROGRESS
   3004 };
   3005 
   3006 struct retro_message_ext
   3007 {
   3008    /* Message string to be displayed/logged */
   3009    const char *msg;
   3010    /* Duration (in ms) of message when targeting the OSD */
   3011    unsigned duration;
   3012    /* Message priority when targeting the OSD
   3013     * > When multiple concurrent messages are sent to
   3014     *   the frontend and the frontend does not have the
   3015     *   capacity to display them all, messages with the
   3016     *   *highest* priority value should be shown
   3017     * > There is no upper limit to a message priority
   3018     *   value (within the bounds of the unsigned data type)
   3019     * > In the reference frontend (RetroArch), the same
   3020     *   priority values are used for frontend-generated
   3021     *   notifications, which are typically assigned values
   3022     *   between 0 and 3 depending upon importance */
   3023    unsigned priority;
   3024    /* Message logging level (info, warn, error, etc.) */
   3025    enum retro_log_level level;
   3026    /* Message destination: OSD, logging interface or both */
   3027    enum retro_message_target target;
   3028    /* Message 'type' when targeting the OSD
   3029     * > RETRO_MESSAGE_TYPE_NOTIFICATION: Specifies that a
   3030     *   message should be handled in identical fashion to
   3031     *   a standard frontend-generated notification
   3032     * > RETRO_MESSAGE_TYPE_NOTIFICATION_ALT: Specifies that
   3033     *   message is a notification that requires user attention
   3034     *   or action, but that it should be displayed in a manner
   3035     *   that differs from standard frontend-generated notifications.
   3036     *   This would typically correspond to messages that should be
   3037     *   displayed immediately (independently from any internal
   3038     *   frontend message queue), and/or which should be visually
   3039     *   distinguishable from frontend-generated notifications.
   3040     *   For example, a core may wish to inform the user of
   3041     *   information related to a disk-change event. It is
   3042     *   expected that the frontend itself may provide a
   3043     *   notification in this case; if the core sends a
   3044     *   message of type RETRO_MESSAGE_TYPE_NOTIFICATION, an
   3045     *   uncomfortable 'double-notification' may occur. A message
   3046     *   of RETRO_MESSAGE_TYPE_NOTIFICATION_ALT should therefore
   3047     *   be presented such that visual conflict with regular
   3048     *   notifications does not occur
   3049     * > RETRO_MESSAGE_TYPE_STATUS: Indicates that message
   3050     *   is not a standard notification. This typically
   3051     *   corresponds to 'status' indicators, such as a core's
   3052     *   internal FPS, which are intended to be displayed
   3053     *   either permanently while a core is running, or in
   3054     *   a manner that does not suggest user attention or action
   3055     *   is required. 'Status' type messages should therefore be
   3056     *   displayed in a different on-screen location and in a manner
   3057     *   easily distinguishable from both standard frontend-generated
   3058     *   notifications and messages of type RETRO_MESSAGE_TYPE_NOTIFICATION_ALT
   3059     * > RETRO_MESSAGE_TYPE_PROGRESS: Indicates that message reports
   3060     *   the progress of an internal core task. For example, in cases
   3061     *   where a core itself handles the loading of content from a file,
   3062     *   this may correspond to the percentage of the file that has been
   3063     *   read. Alternatively, an audio/video playback core may use a
   3064     *   message of type RETRO_MESSAGE_TYPE_PROGRESS to display the current
   3065     *   playback position as a percentage of the runtime. 'Progress' type
   3066     *   messages should therefore be displayed as a literal progress bar,
   3067     *   where:
   3068     *   - 'retro_message_ext.msg' is the progress bar title/label
   3069     *   - 'retro_message_ext.progress' determines the length of
   3070     *     the progress bar
   3071     * NOTE: Message type is a *hint*, and may be ignored
   3072     * by the frontend. If a frontend lacks support for
   3073     * displaying messages via alternate means than standard
   3074     * frontend-generated notifications, it will treat *all*
   3075     * messages as having the type RETRO_MESSAGE_TYPE_NOTIFICATION */
   3076    enum retro_message_type type;
   3077    /* Task progress when targeting the OSD and message is
   3078     * of type RETRO_MESSAGE_TYPE_PROGRESS
   3079     * > -1:    Unmetered/indeterminate
   3080     * > 0-100: Current progress percentage
   3081     * NOTE: Since message type is a hint, a frontend may ignore
   3082     * progress values. Where relevant, a core should therefore
   3083     * include progress percentage within the message string,
   3084     * such that the message intent remains clear when displayed
   3085     * as a standard frontend-generated notification */
   3086    int8_t progress;
   3087 };
   3088 
   3089 /* Describes how the libretro implementation maps a libretro input bind
   3090  * to its internal input system through a human readable string.
   3091  * This string can be used to better let a user configure input. */
   3092 struct retro_input_descriptor
   3093 {
   3094    /* Associates given parameters with a description. */
   3095    unsigned port;
   3096    unsigned device;
   3097    unsigned index;
   3098    unsigned id;
   3099 
   3100    /* Human readable description for parameters.
   3101     * The pointer must remain valid until
   3102     * retro_unload_game() is called. */
   3103    const char *description;
   3104 };
   3105 
   3106 struct retro_system_info
   3107 {
   3108    /* All pointers are owned by libretro implementation, and pointers must
   3109     * remain valid until it is unloaded. */
   3110 
   3111    const char *library_name;      /* Descriptive name of library. Should not
   3112                                    * contain any version numbers, etc. */
   3113    const char *library_version;   /* Descriptive version of core. */
   3114 
   3115    const char *valid_extensions;  /* A string listing probably content
   3116                                    * extensions the core will be able to
   3117                                    * load, separated with pipe.
   3118                                    * I.e. "bin|rom|iso".
   3119                                    * Typically used for a GUI to filter
   3120                                    * out extensions. */
   3121 
   3122    /* Libretro cores that need to have direct access to their content
   3123     * files, including cores which use the path of the content files to
   3124     * determine the paths of other files, should set need_fullpath to true.
   3125     *
   3126     * Cores should strive for setting need_fullpath to false,
   3127     * as it allows the frontend to perform patching, etc.
   3128     *
   3129     * If need_fullpath is true and retro_load_game() is called:
   3130     *    - retro_game_info::path is guaranteed to have a valid path
   3131     *    - retro_game_info::data and retro_game_info::size are invalid
   3132     *
   3133     * If need_fullpath is false and retro_load_game() is called:
   3134     *    - retro_game_info::path may be NULL
   3135     *    - retro_game_info::data and retro_game_info::size are guaranteed
   3136     *      to be valid
   3137     *
   3138     * See also:
   3139     *    - RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY
   3140     *    - RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY
   3141     */
   3142    bool        need_fullpath;
   3143 
   3144    /* If true, the frontend is not allowed to extract any archives before
   3145     * loading the real content.
   3146     * Necessary for certain libretro implementations that load games
   3147     * from zipped archives. */
   3148    bool        block_extract;
   3149 };
   3150 
   3151 struct retro_game_geometry
   3152 {
   3153    unsigned base_width;    /* Nominal video width of game. */
   3154    unsigned base_height;   /* Nominal video height of game. */
   3155    unsigned max_width;     /* Maximum possible width of game. */
   3156    unsigned max_height;    /* Maximum possible height of game. */
   3157 
   3158    float    aspect_ratio;  /* Nominal aspect ratio of game. If
   3159                             * aspect_ratio is <= 0.0, an aspect ratio
   3160                             * of base_width / base_height is assumed.
   3161                             * A frontend could override this setting,
   3162                             * if desired. */
   3163 };
   3164 
   3165 struct retro_system_timing
   3166 {
   3167    double fps;             /* FPS of video content. */
   3168    double sample_rate;     /* Sampling rate of audio. */
   3169 };
   3170 
   3171 struct retro_system_av_info
   3172 {
   3173    struct retro_game_geometry geometry;
   3174    struct retro_system_timing timing;
   3175 };
   3176 
   3177 struct retro_variable
   3178 {
   3179    /* Variable to query in RETRO_ENVIRONMENT_GET_VARIABLE.
   3180     * If NULL, obtains the complete environment string if more
   3181     * complex parsing is necessary.
   3182     * The environment string is formatted as key-value pairs
   3183     * delimited by semicolons as so:
   3184     * "key1=value1;key2=value2;..."
   3185     */
   3186    const char *key;
   3187 
   3188    /* Value to be obtained. If key does not exist, it is set to NULL. */
   3189    const char *value;
   3190 };
   3191 
   3192 struct retro_core_option_display
   3193 {
   3194    /* Variable to configure in RETRO_ENVIRONMENT_SET_CORE_OPTIONS_DISPLAY */
   3195    const char *key;
   3196 
   3197    /* Specifies whether variable should be displayed
   3198     * when presenting core options to the user */
   3199    bool visible;
   3200 };
   3201 
   3202 /* Maximum number of values permitted for a core option
   3203  * > Note: We have to set a maximum value due the limitations
   3204  *   of the C language - i.e. it is not possible to create an
   3205  *   array of structs each containing a variable sized array,
   3206  *   so the retro_core_option_definition values array must
   3207  *   have a fixed size. The size limit of 128 is a balancing
   3208  *   act - it needs to be large enough to support all 'sane'
   3209  *   core options, but setting it too large may impact low memory
   3210  *   platforms. In practise, if a core option has more than
   3211  *   128 values then the implementation is likely flawed.
   3212  *   To quote the above API reference:
   3213  *      "The number of possible options should be very limited
   3214  *       i.e. it should be feasible to cycle through options
   3215  *       without a keyboard."
   3216  */
   3217 #define RETRO_NUM_CORE_OPTION_VALUES_MAX 128
   3218 
   3219 struct retro_core_option_value
   3220 {
   3221    /* Expected option value */
   3222    const char *value;
   3223 
   3224    /* Human-readable value label. If NULL, value itself
   3225     * will be displayed by the frontend */
   3226    const char *label;
   3227 };
   3228 
   3229 struct retro_core_option_definition
   3230 {
   3231    /* Variable to query in RETRO_ENVIRONMENT_GET_VARIABLE. */
   3232    const char *key;
   3233 
   3234    /* Human-readable core option description (used as menu label) */
   3235    const char *desc;
   3236 
   3237    /* Human-readable core option information (used as menu sublabel) */
   3238    const char *info;
   3239 
   3240    /* Array of retro_core_option_value structs, terminated by NULL */
   3241    struct retro_core_option_value values[RETRO_NUM_CORE_OPTION_VALUES_MAX];
   3242 
   3243    /* Default core option value. Must match one of the values
   3244     * in the retro_core_option_value array, otherwise will be
   3245     * ignored */
   3246    const char *default_value;
   3247 };
   3248 
   3249 struct retro_core_options_intl
   3250 {
   3251    /* Pointer to an array of retro_core_option_definition structs
   3252     * - US English implementation
   3253     * - Must point to a valid array */
   3254    struct retro_core_option_definition *us;
   3255 
   3256    /* Pointer to an array of retro_core_option_definition structs
   3257     * - Implementation for current frontend language
   3258     * - May be NULL */
   3259    struct retro_core_option_definition *local;
   3260 };
   3261 
   3262 struct retro_core_option_v2_category
   3263 {
   3264    /* Variable uniquely identifying the
   3265     * option category. Valid key characters
   3266     * are [a-z, A-Z, 0-9, _, -] */
   3267    const char *key;
   3268 
   3269    /* Human-readable category description
   3270     * > Used as category menu label when
   3271     *   frontend has core option category
   3272     *   support */
   3273    const char *desc;
   3274 
   3275    /* Human-readable category information
   3276     * > Used as category menu sublabel when
   3277     *   frontend has core option category
   3278     *   support
   3279     * > Optional (may be NULL or an empty
   3280     *   string) */
   3281    const char *info;
   3282 };
   3283 
   3284 struct retro_core_option_v2_definition
   3285 {
   3286    /* Variable to query in RETRO_ENVIRONMENT_GET_VARIABLE.
   3287     * Valid key characters are [a-z, A-Z, 0-9, _, -] */
   3288    const char *key;
   3289 
   3290    /* Human-readable core option description
   3291     * > Used as menu label when frontend does
   3292     *   not have core option category support
   3293     *   e.g. "Video > Aspect Ratio" */
   3294    const char *desc;
   3295 
   3296    /* Human-readable core option description
   3297     * > Used as menu label when frontend has
   3298     *   core option category support
   3299     *   e.g. "Aspect Ratio", where associated
   3300     *   retro_core_option_v2_category::desc
   3301     *   is "Video"
   3302     * > If empty or NULL, the string specified by
   3303     *   desc will be used as the menu label
   3304     * > Will be ignored (and may be set to NULL)
   3305     *   if category_key is empty or NULL */
   3306    const char *desc_categorized;
   3307 
   3308    /* Human-readable core option information
   3309     * > Used as menu sublabel */
   3310    const char *info;
   3311 
   3312    /* Human-readable core option information
   3313     * > Used as menu sublabel when frontend
   3314     *   has core option category support
   3315     *   (e.g. may be required when info text
   3316     *   references an option by name/desc,
   3317     *   and the desc/desc_categorized text
   3318     *   for that option differ)
   3319     * > If empty or NULL, the string specified by
   3320     *   info will be used as the menu sublabel
   3321     * > Will be ignored (and may be set to NULL)
   3322     *   if category_key is empty or NULL */
   3323    const char *info_categorized;
   3324 
   3325    /* Variable specifying category (e.g. "video",
   3326     * "audio") that will be assigned to the option
   3327     * if frontend has core option category support.
   3328     * > Categorized options will be displayed in a
   3329     *   subsection/submenu of the frontend core
   3330     *   option interface
   3331     * > Specified string must match one of the
   3332     *   retro_core_option_v2_category::key values
   3333     *   in the associated retro_core_option_v2_category
   3334     *   array; If no match is not found, specified
   3335     *   string will be considered as NULL
   3336     * > If specified string is empty or NULL, option will
   3337     *   have no category and will be shown at the top
   3338     *   level of the frontend core option interface */
   3339    const char *category_key;
   3340 
   3341    /* Array of retro_core_option_value structs, terminated by NULL */
   3342    struct retro_core_option_value values[RETRO_NUM_CORE_OPTION_VALUES_MAX];
   3343 
   3344    /* Default core option value. Must match one of the values
   3345     * in the retro_core_option_value array, otherwise will be
   3346     * ignored */
   3347    const char *default_value;
   3348 };
   3349 
   3350 struct retro_core_options_v2
   3351 {
   3352    /* Array of retro_core_option_v2_category structs,
   3353     * terminated by NULL
   3354     * > If NULL, all entries in definitions array
   3355     *   will have no category and will be shown at
   3356     *   the top level of the frontend core option
   3357     *   interface
   3358     * > Will be ignored if frontend does not have
   3359     *   core option category support */
   3360    struct retro_core_option_v2_category *categories;
   3361 
   3362    /* Array of retro_core_option_v2_definition structs,
   3363     * terminated by NULL */
   3364    struct retro_core_option_v2_definition *definitions;
   3365 };
   3366 
   3367 struct retro_core_options_v2_intl
   3368 {
   3369    /* Pointer to a retro_core_options_v2 struct
   3370     * > US English implementation
   3371     * > Must point to a valid struct */
   3372    struct retro_core_options_v2 *us;
   3373 
   3374    /* Pointer to a retro_core_options_v2 struct
   3375     * - Implementation for current frontend language
   3376     * - May be NULL */
   3377    struct retro_core_options_v2 *local;
   3378 };
   3379 
   3380 /* Used by the frontend to monitor changes in core option
   3381  * visibility. May be called each time any core option
   3382  * value is set via the frontend.
   3383  * - On each invocation, the core must update the visibility
   3384  *   of any dynamically hidden options using the
   3385  *   RETRO_ENVIRONMENT_SET_CORE_OPTIONS_DISPLAY environment
   3386  *   callback.
   3387  * - On the first invocation, returns 'true' if the visibility
   3388  *   of any core option has changed since the last call of
   3389  *   retro_load_game() or retro_load_game_special().
   3390  * - On each subsequent invocation, returns 'true' if the
   3391  *   visibility of any core option has changed since the last
   3392  *   time the function was called. */
   3393 typedef bool (RETRO_CALLCONV *retro_core_options_update_display_callback_t)(void);
   3394 struct retro_core_options_update_display_callback
   3395 {
   3396    retro_core_options_update_display_callback_t callback;
   3397 };
   3398 
   3399 struct retro_game_info
   3400 {
   3401    const char *path;       /* Path to game, UTF-8 encoded.
   3402                             * Sometimes used as a reference for building other paths.
   3403                             * May be NULL if game was loaded from stdin or similar,
   3404                             * but in this case some cores will be unable to load `data`.
   3405                             * So, it is preferable to fabricate something here instead
   3406                             * of passing NULL, which will help more cores to succeed.
   3407                             * retro_system_info::need_fullpath requires
   3408                             * that this path is valid. */
   3409    const void *data;       /* Memory buffer of loaded game. Will be NULL
   3410                             * if need_fullpath was set. */
   3411    size_t      size;       /* Size of memory buffer. */
   3412    const char *meta;       /* String of implementation specific meta-data. */
   3413 };
   3414 
   3415 #define RETRO_MEMORY_ACCESS_WRITE (1 << 0)
   3416    /* The core will write to the buffer provided by retro_framebuffer::data. */
   3417 #define RETRO_MEMORY_ACCESS_READ (1 << 1)
   3418    /* The core will read from retro_framebuffer::data. */
   3419 #define RETRO_MEMORY_TYPE_CACHED (1 << 0)
   3420    /* The memory in data is cached.
   3421     * If not cached, random writes and/or reading from the buffer is expected to be very slow. */
   3422 struct retro_framebuffer
   3423 {
   3424    void *data;                      /* The framebuffer which the core can render into.
   3425                                        Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER.
   3426                                        The initial contents of data are unspecified. */
   3427    unsigned width;                  /* The framebuffer width used by the core. Set by core. */
   3428    unsigned height;                 /* The framebuffer height used by the core. Set by core. */
   3429    size_t pitch;                    /* The number of bytes between the beginning of a scanline,
   3430                                        and beginning of the next scanline.
   3431                                        Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
   3432    enum retro_pixel_format format;  /* The pixel format the core must use to render into data.
   3433                                        This format could differ from the format used in
   3434                                        SET_PIXEL_FORMAT.
   3435                                        Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
   3436 
   3437    unsigned access_flags;           /* How the core will access the memory in the framebuffer.
   3438                                        RETRO_MEMORY_ACCESS_* flags.
   3439                                        Set by core. */
   3440    unsigned memory_flags;           /* Flags telling core how the memory has been mapped.
   3441                                        RETRO_MEMORY_TYPE_* flags.
   3442                                        Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
   3443 };
   3444 
   3445 /* Used by a libretro core to override the current
   3446  * fastforwarding mode of the frontend */
   3447 struct retro_fastforwarding_override
   3448 {
   3449    /* Specifies the runtime speed multiplier that
   3450     * will be applied when 'fastforward' is true.
   3451     * For example, a value of 5.0 when running 60 FPS
   3452     * content will cap the fast-forward rate at 300 FPS.
   3453     * Note that the target multiplier may not be achieved
   3454     * if the host hardware has insufficient processing
   3455     * power.
   3456     * Setting a value of 0.0 (or greater than 0.0 but
   3457     * less than 1.0) will result in an uncapped
   3458     * fast-forward rate (limited only by hardware
   3459     * capacity).
   3460     * If the value is negative, it will be ignored
   3461     * (i.e. the frontend will use a runtime speed
   3462     * multiplier of its own choosing) */
   3463    float ratio;
   3464 
   3465    /* If true, fastforwarding mode will be enabled.
   3466     * If false, fastforwarding mode will be disabled. */
   3467    bool fastforward;
   3468 
   3469    /* If true, and if supported by the frontend, an
   3470     * on-screen notification will be displayed while
   3471     * 'fastforward' is true.
   3472     * If false, and if supported by the frontend, any
   3473     * on-screen fast-forward notifications will be
   3474     * suppressed */
   3475    bool notification;
   3476 
   3477    /* If true, the core will have sole control over
   3478     * when fastforwarding mode is enabled/disabled;
   3479     * the frontend will not be able to change the
   3480     * state set by 'fastforward' until either
   3481     * 'inhibit_toggle' is set to false, or the core
   3482     * is unloaded */
   3483    bool inhibit_toggle;
   3484 };
   3485 
   3486 /* Callbacks */
   3487 
   3488 /* Environment callback. Gives implementations a way of performing
   3489  * uncommon tasks. Extensible. */
   3490 typedef bool (RETRO_CALLCONV *retro_environment_t)(unsigned cmd, void *data);
   3491 
   3492 /* Render a frame. Pixel format is 15-bit 0RGB1555 native endian
   3493  * unless changed (see RETRO_ENVIRONMENT_SET_PIXEL_FORMAT).
   3494  *
   3495  * Width and height specify dimensions of buffer.
   3496  * Pitch specifices length in bytes between two lines in buffer.
   3497  *
   3498  * For performance reasons, it is highly recommended to have a frame
   3499  * that is packed in memory, i.e. pitch == width * byte_per_pixel.
   3500  * Certain graphic APIs, such as OpenGL ES, do not like textures
   3501  * that are not packed in memory.
   3502  */
   3503 typedef void (RETRO_CALLCONV *retro_video_refresh_t)(const void *data, unsigned width,
   3504       unsigned height, size_t pitch);
   3505 
   3506 /* Renders a single audio frame. Should only be used if implementation
   3507  * generates a single sample at a time.
   3508  * Format is signed 16-bit native endian.
   3509  */
   3510 typedef void (RETRO_CALLCONV *retro_audio_sample_t)(int16_t left, int16_t right);
   3511 
   3512 /* Renders multiple audio frames in one go.
   3513  *
   3514  * One frame is defined as a sample of left and right channels, interleaved.
   3515  * I.e. int16_t buf[4] = { l, r, l, r }; would be 2 frames.
   3516  * Only one of the audio callbacks must ever be used.
   3517  */
   3518 typedef size_t (RETRO_CALLCONV *retro_audio_sample_batch_t)(const int16_t *data,
   3519       size_t frames);
   3520 
   3521 /* Polls input. */
   3522 typedef void (RETRO_CALLCONV *retro_input_poll_t)(void);
   3523 
   3524 /* Queries for input for player 'port'. device will be masked with
   3525  * RETRO_DEVICE_MASK.
   3526  *
   3527  * Specialization of devices such as RETRO_DEVICE_JOYPAD_MULTITAP that
   3528  * have been set with retro_set_controller_port_device()
   3529  * will still use the higher level RETRO_DEVICE_JOYPAD to request input.
   3530  */
   3531 typedef int16_t (RETRO_CALLCONV *retro_input_state_t)(unsigned port, unsigned device,
   3532       unsigned index, unsigned id);
   3533 
   3534 /* Sets callbacks. retro_set_environment() is guaranteed to be called
   3535  * before retro_init().
   3536  *
   3537  * The rest of the set_* functions are guaranteed to have been called
   3538  * before the first call to retro_run() is made. */
   3539 RETRO_API void retro_set_environment(retro_environment_t);
   3540 RETRO_API void retro_set_video_refresh(retro_video_refresh_t);
   3541 RETRO_API void retro_set_audio_sample(retro_audio_sample_t);
   3542 RETRO_API void retro_set_audio_sample_batch(retro_audio_sample_batch_t);
   3543 RETRO_API void retro_set_input_poll(retro_input_poll_t);
   3544 RETRO_API void retro_set_input_state(retro_input_state_t);
   3545 
   3546 /* Library global initialization/deinitialization. */
   3547 RETRO_API void retro_init(void);
   3548 RETRO_API void retro_deinit(void);
   3549 
   3550 /* Must return RETRO_API_VERSION. Used to validate ABI compatibility
   3551  * when the API is revised. */
   3552 RETRO_API unsigned retro_api_version(void);
   3553 
   3554 /* Gets statically known system info. Pointers provided in *info
   3555  * must be statically allocated.
   3556  * Can be called at any time, even before retro_init(). */
   3557 RETRO_API void retro_get_system_info(struct retro_system_info *info);
   3558 
   3559 /* Gets information about system audio/video timings and geometry.
   3560  * Can be called only after retro_load_game() has successfully completed.
   3561  * NOTE: The implementation of this function might not initialize every
   3562  * variable if needed.
   3563  * E.g. geom.aspect_ratio might not be initialized if core doesn't
   3564  * desire a particular aspect ratio. */
   3565 RETRO_API void retro_get_system_av_info(struct retro_system_av_info *info);
   3566 
   3567 /* Sets device to be used for player 'port'.
   3568  * By default, RETRO_DEVICE_JOYPAD is assumed to be plugged into all
   3569  * available ports.
   3570  * Setting a particular device type is not a guarantee that libretro cores
   3571  * will only poll input based on that particular device type. It is only a
   3572  * hint to the libretro core when a core cannot automatically detect the
   3573  * appropriate input device type on its own. It is also relevant when a
   3574  * core can change its behavior depending on device type.
   3575  *
   3576  * As part of the core's implementation of retro_set_controller_port_device,
   3577  * the core should call RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS to notify the
   3578  * frontend if the descriptions for any controls have changed as a
   3579  * result of changing the device type.
   3580  */
   3581 RETRO_API void retro_set_controller_port_device(unsigned port, unsigned device);
   3582 
   3583 /* Resets the current game. */
   3584 RETRO_API void retro_reset(void);
   3585 
   3586 /* Runs the game for one video frame.
   3587  * During retro_run(), input_poll callback must be called at least once.
   3588  *
   3589  * If a frame is not rendered for reasons where a game "dropped" a frame,
   3590  * this still counts as a frame, and retro_run() should explicitly dupe
   3591  * a frame if GET_CAN_DUPE returns true.
   3592  * In this case, the video callback can take a NULL argument for data.
   3593  */
   3594 RETRO_API void retro_run(void);
   3595 
   3596 /* Returns the amount of data the implementation requires to serialize
   3597  * internal state (save states).
   3598  * Between calls to retro_load_game() and retro_unload_game(), the
   3599  * returned size is never allowed to be larger than a previous returned
   3600  * value, to ensure that the frontend can allocate a save state buffer once.
   3601  */
   3602 RETRO_API size_t retro_serialize_size(void);
   3603 
   3604 /* Serializes internal state. If failed, or size is lower than
   3605  * retro_serialize_size(), it should return false, true otherwise. */
   3606 RETRO_API bool retro_serialize(void *data, size_t size);
   3607 RETRO_API bool retro_unserialize(const void *data, size_t size);
   3608 
   3609 RETRO_API void retro_cheat_reset(void);
   3610 RETRO_API void retro_cheat_set(unsigned index, bool enabled, const char *code);
   3611 
   3612 /* Loads a game.
   3613  * Return true to indicate successful loading and false to indicate load failure.
   3614  */
   3615 RETRO_API bool retro_load_game(const struct retro_game_info *game);
   3616 
   3617 /* Loads a "special" kind of game. Should not be used,
   3618  * except in extreme cases. */
   3619 RETRO_API bool retro_load_game_special(
   3620   unsigned game_type,
   3621   const struct retro_game_info *info, size_t num_info
   3622 );
   3623 
   3624 /* Unloads the currently loaded game. Called before retro_deinit(void). */
   3625 RETRO_API void retro_unload_game(void);
   3626 
   3627 /* Gets region of game. */
   3628 RETRO_API unsigned retro_get_region(void);
   3629 
   3630 /* Gets region of memory. */
   3631 RETRO_API void *retro_get_memory_data(unsigned id);
   3632 RETRO_API size_t retro_get_memory_size(unsigned id);
   3633 
   3634 #ifdef __cplusplus
   3635 }
   3636 #endif
   3637 
   3638 #endif

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