changeset 1687:6c54bb5fe3b3

Hacky WIP libertro implementation
author Michael Pavone <pavone@retrodev.com>
date Sun, 20 Jan 2019 01:03:21 -0800
parents 475e84bfccbb
children 395f684c5379
files Makefile libblastem.c libretro.h
diffstat 3 files changed, 2717 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- a/Makefile	Sun Jan 20 01:02:48 2019 -0800
+++ b/Makefile	Sun Jan 20 01:03:21 2019 -0800
@@ -76,7 +76,11 @@
 
 else
 CFLAGS:=$(shell pkg-config --cflags-only-I $(LIBS)) $(CFLAGS)
+ifeq ($(MAKECMDGOALS),libblastem.so)
+LDFLAGS:=-lm
+else
 LDFLAGS:=-lm $(shell pkg-config --libs $(LIBS))
+endif #libblastem.so
 
 ifeq ($(OS),Darwin)
 LDFLAGS+= -framework OpenGL -framework AppKit
@@ -164,6 +168,10 @@
 MAINOBJS=blastem.o system.o genesis.o debug.o gdb_remote.o vdp.o $(RENDEROBJS) io.o romdb.o hash.o menu.o xband.o \
 	realtec.o i2c.o nor.o sega_mapper.o multi_game.o megawifi.o $(NET) serialize.o $(TERMINAL) $(CONFIGOBJS) gst.o \
 	$(M68KOBJS) $(TRANSOBJS) $(AUDIOOBJS) saves.o zip.o bindings.o jcart.o
+
+LIBOBJS=libblastem.o system.o genesis.o debug.o gdb_remote.o vdp.o io.o romdb.o hash.o menu.o xband.o realtec.o \
+	i2c.o nor.o sega_mapper.o multi_game.o megawifi.o $(NET) serialize.o $(TERMINAL) $(CONFIGOBJS) gst.o \
+	$(M68KOBJS) $(TRANSOBJS) $(AUDIOOBJS) saves.o jcart.o
 	
 ifdef NONUKLEAR
 CFLAGS+= -DDISABLE_NUKLEAR
@@ -187,6 +195,7 @@
 CFLAGS+=-DNO_Z80
 else
 MAINOBJS+= sms.o $(Z80OBJS)
+LIBOBJS+= sms.o $(Z80OBJS)
 endif
 
 ifeq ($(OS),Windows)
@@ -198,8 +207,15 @@
 ALL+= termhelper
 endif
 
+ifeq ($(MAKECMDGOALS),libblastem.so)
+CFLAGS+= -fpic
+endif
+
 all : $(ALL)
 
+libblastem.so : $(LIBOBJS)
+	$(CC) -shared -o $@ $^ $(LDFLAGS)
+
 blastem$(EXE) : $(MAINOBJS)
 	$(CC) -o $@ $^ $(LDFLAGS)
 	$(FIXUP) ./$@
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libblastem.c	Sun Jan 20 01:03:21 2019 -0800
@@ -0,0 +1,358 @@
+#include "libretro.h"
+#include "system.h"
+#include "util.h"
+#include "vdp.h"
+#include "render.h"
+#include "io.h"
+
+static retro_environment_t retro_environment;
+RETRO_API void retro_set_environment(retro_environment_t re)
+{
+	retro_environment = re;
+}
+
+static retro_video_refresh_t retro_video_refresh;
+RETRO_API void retro_set_video_refresh(retro_video_refresh_t rvf)
+{
+	retro_video_refresh = rvf;
+}
+
+static retro_audio_sample_t retro_audio_sample;
+RETRO_API void retro_set_audio_sample(retro_audio_sample_t ras)
+{
+	retro_audio_sample = ras;
+}
+
+RETRO_API void retro_set_audio_sample_batch(retro_audio_sample_batch_t rasb)
+{
+}
+
+static retro_input_poll_t retro_input_poll;
+RETRO_API void retro_set_input_poll(retro_input_poll_t rip)
+{
+	retro_input_poll = rip;
+}
+
+static retro_input_state_t retro_input_state;
+RETRO_API void retro_set_input_state(retro_input_state_t ris)
+{
+	retro_input_state = ris;
+}
+
+int headless = 0;
+int exit_after = 0;
+int z80_enabled = 1;
+char *save_filename;
+tern_node *config;
+uint8_t use_native_states = 1;
+system_header *current_system;
+system_media media;
+
+RETRO_API void retro_init(void)
+{
+}
+
+RETRO_API void retro_deinit(void)
+{
+}
+
+RETRO_API unsigned retro_api_version(void)
+{
+	return RETRO_API_VERSION;
+}
+
+RETRO_API void retro_get_system_info(struct retro_system_info *info)
+{
+	info->library_name = "BlastEm";
+	info->library_version = "0.6.2-pre"; //TODO: share this with blastem.c
+	info->valid_extensions = "md|gen|sms|bin|rom";
+	info->need_fullpath = 0;
+	info->block_extract = 0;
+}
+
+static vid_std video_standard;
+RETRO_API void retro_get_system_av_info(struct retro_system_av_info *info)
+{
+	info->geometry.base_width = info->geometry.max_width = LINEBUF_SIZE;
+	info->geometry.base_height = info->geometry.max_height = video_standard == VID_NTSC ? 243 : 294;
+	info->geometry.aspect_ratio = 0;
+	info->timing.fps = video_standard == VID_NTSC ? 60 : 50;
+	info->timing.sample_rate = 53267; //approximate sample rate of YM2612
+}
+
+RETRO_API void retro_set_controller_port_device(unsigned port, unsigned device)
+{
+}
+
+/* Resets the current game. */
+RETRO_API void retro_reset(void)
+{
+	current_system->soft_reset(current_system);
+}
+
+/* Runs the game for one video frame.
+ * During retro_run(), input_poll callback must be called at least once.
+ *
+ * If a frame is not rendered for reasons where a game "dropped" a frame,
+ * this still counts as a frame, and retro_run() should explicitly dupe
+ * a frame if GET_CAN_DUPE returns true.
+ * In this case, the video callback can take a NULL argument for data.
+ */
+static uint8_t started;
+RETRO_API void retro_run(void)
+{
+	if (started) {
+		current_system->resume_context(current_system);
+	} else {
+		current_system->start_context(current_system, NULL);
+		started = 1;
+	}
+}
+
+/* Returns the amount of data the implementation requires to serialize
+ * internal state (save states).
+ * Between calls to retro_load_game() and retro_unload_game(), the
+ * returned size is never allowed to be larger than a previous returned
+ * value, to ensure that the frontend can allocate a save state buffer once.
+ */
+RETRO_API size_t retro_serialize_size(void)
+{
+	return 0;
+}
+
+/* Serializes internal state. If failed, or size is lower than
+ * retro_serialize_size(), it should return false, true otherwise. */
+RETRO_API bool retro_serialize(void *data, size_t size)
+{
+	return 0;
+}
+
+RETRO_API bool retro_unserialize(const void *data, size_t size)
+{
+	return 0;
+}
+
+RETRO_API void retro_cheat_reset(void)
+{
+}
+
+RETRO_API void retro_cheat_set(unsigned index, bool enabled, const char *code)
+{
+}
+
+/* Loads a game. */
+RETRO_API bool retro_load_game(const struct retro_game_info *game)
+{
+	if (game->path) {
+		media.dir = path_dirname(game->path);
+		media.name = basename_no_extension(game->path);
+		media.extension = path_extension(game->path);
+	}
+	media.buffer = malloc(nearest_pow2(game->size));
+	memcpy(media.buffer, game->data, game->size);
+	media.size = game->size;
+	current_system = alloc_config_system(detect_system_type(&media), &media, 0, 0);
+	
+	unsigned format = RETRO_PIXEL_FORMAT_XRGB8888;
+	retro_environment(RETRO_ENVIRONMENT_SET_PIXEL_FORMAT, &format);
+	return current_system != NULL;
+}
+
+/* Loads a "special" kind of game. Should not be used,
+ * except in extreme cases. */
+RETRO_API bool retro_load_game_special(unsigned game_type, const struct retro_game_info *info, size_t num_info)
+{
+	return retro_load_game(info);
+}
+
+/* Unloads a currently loaded game. */
+RETRO_API void retro_unload_game(void)
+{
+	
+	free(media.dir);
+	free(media.name);
+	free(media.extension);
+	
+}
+
+/* Gets region of game. */
+RETRO_API unsigned retro_get_region(void)
+{
+	return video_standard == VID_NTSC ? RETRO_REGION_NTSC : RETRO_REGION_PAL;
+}
+
+/* Gets region of memory. */
+RETRO_API void *retro_get_memory_data(unsigned id)
+{
+	return NULL;
+}
+
+RETRO_API size_t retro_get_memory_size(unsigned id)
+{
+	return 0;
+}
+
+//blastem render backend API implementation
+uint32_t render_map_color(uint8_t r, uint8_t g, uint8_t b)
+{
+	return r << 16 | g << 8 | b;
+}
+
+uint8_t render_create_window(char *caption, uint32_t width, uint32_t height, window_close_handler close_handler)
+{
+	//not supported in lib build
+	return 0;
+}
+
+void render_destroy_window(uint8_t which)
+{
+	//not supported in lib build
+}
+
+static uint32_t fb[LINEBUF_SIZE * 294 * 2];
+uint32_t *render_get_framebuffer(uint8_t which, int *pitch)
+{
+	*pitch = LINEBUF_SIZE * sizeof(uint32_t);
+	//TODO: deal with interlace
+	return fb;
+}
+
+void render_framebuffer_updated(uint8_t which, int width)
+{
+	//TODO: Deal with 256 px wide modes
+	//TODO: deal with interlace
+	retro_video_refresh(fb, LINEBUF_SIZE, video_standard == VID_NTSC ? 243 : 294, LINEBUF_SIZE * sizeof(uint32_t));
+	current_system->request_exit(current_system);
+}
+
+uint8_t render_get_active_framebuffer(void)
+{
+	return 0;
+}
+
+void render_set_video_standard(vid_std std)
+{
+	video_standard = std;
+}
+
+void process_events()
+{
+	static int16_t prev_state[2][RETRO_DEVICE_ID_JOYPAD_L2];
+	static const uint8_t map[] = {
+		BUTTON_A, BUTTON_X, BUTTON_MODE, BUTTON_START, DPAD_UP, DPAD_DOWN,
+		DPAD_LEFT, DPAD_RIGHT, BUTTON_B, BUTTON_Y, BUTTON_Z, BUTTON_C
+	};
+	//TODO: handle other input device types
+	//TODO: handle more than 2 ports when appropriate
+	retro_input_poll();
+	for (int port = 0; port < 2; port++)
+	{
+		for (int id = RETRO_DEVICE_ID_JOYPAD_B; id < RETRO_DEVICE_ID_JOYPAD_L2; id++)
+		{
+			int16_t new_state = retro_input_state(port, RETRO_DEVICE_JOYPAD, 0, id);
+			if (new_state != prev_state[port][id]) {
+				if (new_state) {
+					current_system->gamepad_down(current_system, port, map[id]);
+				} else {
+					current_system->gamepad_up(current_system, port, map[id]);
+				}
+				prev_state[port][id] = new_state;
+			}
+		}
+	}
+}
+
+void render_errorbox(char *title, char *message)
+{
+}
+void render_warnbox(char *title, char *message)
+{
+}
+void render_infobox(char *title, char *message)
+{
+}
+
+struct audio_source {
+	int32_t freq;
+	int32_t left_accum;
+	int32_t right_accum;
+	int32_t num_samples;
+};
+
+static audio_source *audio_sources[8];
+static uint8_t num_audio_sources;
+audio_source *render_audio_source(uint64_t master_clock, uint64_t sample_divider, uint8_t channels)
+{
+	audio_sources[num_audio_sources] = calloc(1, sizeof(audio_source));
+	return audio_sources[num_audio_sources++];
+}
+
+void render_audio_adjust_clock(audio_source *src, uint64_t master_clock, uint64_t sample_divider)
+{
+}
+
+static void check_put_sample(void)
+{
+	for (int i = 0; i < num_audio_sources; i++)
+	{
+		if (!audio_sources[i]->num_samples) {
+			return;
+		}
+		int32_t effective_freq = audio_sources[i]->freq / audio_sources[i]->num_samples;
+		if (abs(effective_freq - 53267) > 53267) {
+			return;
+		}
+	}
+	int16_t left = 0, right = 0;
+	for (int i = 0; i < num_audio_sources; i++)
+	{
+		left += audio_sources[i]->left_accum / audio_sources[i]->num_samples;
+		right += audio_sources[i]->right_accum / audio_sources[i]->num_samples;
+		audio_sources[i]->left_accum = audio_sources[i]->right_accum = audio_sources[i]->num_samples = 0;
+	}
+	retro_audio_sample(left, right);
+}
+
+void render_put_mono_sample(audio_source *src, int16_t value)
+{
+	src->left_accum += value;
+	src->right_accum += value;
+	src->num_samples++;
+	check_put_sample();
+}
+void render_put_stereo_sample(audio_source *src, int16_t left, int16_t right)
+{
+	src->left_accum += left;
+	src->right_accum += right;
+	src->num_samples++;
+	check_put_sample();
+}
+void render_pause_source(audio_source *src)
+{
+}
+void render_resume_source(audio_source *src)
+{
+}
+void render_free_source(audio_source *src)
+{
+	int index;
+	for (index = 0; index < num_audio_sources; index++)
+	{
+		if (audio_sources[index] == src) {
+			break;
+		}
+	}
+	num_audio_sources--;
+	audio_sources[index] = audio_sources[num_audio_sources];
+	free(src);
+}
+
+void bindings_set_mouse_mode(uint8_t mode)
+{
+}
+void bindings_release_capture(void)
+{
+}
+void bindings_reacquire_capture(void)
+{
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libretro.h	Sun Jan 20 01:03:21 2019 -0800
@@ -0,0 +1,2343 @@
+/* Copyright (C) 2010-2017 The RetroArch team
+ *
+ * ---------------------------------------------------------------------------------------
+ * The following license statement only applies to this libretro API header (libretro.h).
+ * ---------------------------------------------------------------------------------------
+ *
+ * Permission is hereby granted, free of charge,
+ * to any person obtaining a copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef LIBRETRO_H__
+#define LIBRETRO_H__
+
+#include <stdint.h>
+#include <stddef.h>
+#include <limits.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef __cplusplus
+#if defined(_MSC_VER) && _MSC_VER < 1800 && !defined(SN_TARGET_PS3)
+/* Hack applied for MSVC when compiling in C89 mode
+ * as it isn't C99-compliant. */
+#define bool unsigned char
+#define true 1
+#define false 0
+#else
+#include <stdbool.h>
+#endif
+#endif
+
+#ifndef RETRO_CALLCONV
+#  if defined(__GNUC__) && defined(__i386__) && !defined(__x86_64__)
+#    define RETRO_CALLCONV __attribute__((cdecl))
+#  elif defined(_MSC_VER) && defined(_M_X86) && !defined(_M_X64)
+#    define RETRO_CALLCONV __cdecl
+#  else
+#    define RETRO_CALLCONV /* all other platforms only have one calling convention each */
+#  endif
+#endif
+
+#ifndef RETRO_API
+#  if defined(_WIN32) || defined(__CYGWIN__) || defined(__MINGW32__)
+#    ifdef RETRO_IMPORT_SYMBOLS
+#      ifdef __GNUC__
+#        define RETRO_API RETRO_CALLCONV __attribute__((__dllimport__))
+#      else
+#        define RETRO_API RETRO_CALLCONV __declspec(dllimport)
+#      endif
+#    else
+#      ifdef __GNUC__
+#        define RETRO_API RETRO_CALLCONV __attribute__((__dllexport__))
+#      else
+#        define RETRO_API RETRO_CALLCONV __declspec(dllexport)
+#      endif
+#    endif
+#  else
+#      if defined(__GNUC__) && __GNUC__ >= 4 && !defined(__CELLOS_LV2__)
+#        define RETRO_API RETRO_CALLCONV __attribute__((__visibility__("default")))
+#      else
+#        define RETRO_API RETRO_CALLCONV
+#      endif
+#  endif
+#endif
+
+/* Used for checking API/ABI mismatches that can break libretro
+ * implementations.
+ * It is not incremented for compatible changes to the API.
+ */
+#define RETRO_API_VERSION         1
+
+/*
+ * Libretro's fundamental device abstractions.
+ *
+ * Libretro's input system consists of some standardized device types,
+ * such as a joypad (with/without analog), mouse, keyboard, lightgun
+ * and a pointer.
+ *
+ * The functionality of these devices are fixed, and individual cores
+ * map their own concept of a controller to libretro's abstractions.
+ * This makes it possible for frontends to map the abstract types to a
+ * real input device, and not having to worry about binding input
+ * correctly to arbitrary controller layouts.
+ */
+
+#define RETRO_DEVICE_TYPE_SHIFT         8
+#define RETRO_DEVICE_MASK               ((1 << RETRO_DEVICE_TYPE_SHIFT) - 1)
+#define RETRO_DEVICE_SUBCLASS(base, id) (((id + 1) << RETRO_DEVICE_TYPE_SHIFT) | base)
+
+/* Input disabled. */
+#define RETRO_DEVICE_NONE         0
+
+/* The JOYPAD is called RetroPad. It is essentially a Super Nintendo
+ * controller, but with additional L2/R2/L3/R3 buttons, similar to a
+ * PS1 DualShock. */
+#define RETRO_DEVICE_JOYPAD       1
+
+/* The mouse is a simple mouse, similar to Super Nintendo's mouse.
+ * X and Y coordinates are reported relatively to last poll (poll callback).
+ * It is up to the libretro implementation to keep track of where the mouse
+ * pointer is supposed to be on the screen.
+ * The frontend must make sure not to interfere with its own hardware
+ * mouse pointer.
+ */
+#define RETRO_DEVICE_MOUSE        2
+
+/* KEYBOARD device lets one poll for raw key pressed.
+ * It is poll based, so input callback will return with the current
+ * pressed state.
+ * For event/text based keyboard input, see
+ * RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK.
+ */
+#define RETRO_DEVICE_KEYBOARD     3
+
+/* LIGHTGUN device is similar to Guncon-2 for PlayStation 2.
+ * It reports X/Y coordinates in screen space (similar to the pointer)
+ * in the range [-0x8000, 0x7fff] in both axes, with zero being center.
+ * As well as reporting on/off screen state. It features a trigger,
+ * start/select buttons, auxiliary action buttons and a
+ * directional pad. A forced off-screen shot can be requested for
+ * auto-reloading function in some games.
+ */
+#define RETRO_DEVICE_LIGHTGUN     4
+
+/* The ANALOG device is an extension to JOYPAD (RetroPad).
+ * Similar to DualShock2 it adds two analog sticks and all buttons can
+ * be analog. This is treated as a separate device type as it returns
+ * axis values in the full analog range of [-0x8000, 0x7fff].
+ * Positive X axis is right. Positive Y axis is down.
+ * Buttons are returned in the range [0, 0x7fff].
+ * Only use ANALOG type when polling for analog values.
+ */
+#define RETRO_DEVICE_ANALOG       5
+
+/* Abstracts the concept of a pointing mechanism, e.g. touch.
+ * This allows libretro to query in absolute coordinates where on the
+ * screen a mouse (or something similar) is being placed.
+ * For a touch centric device, coordinates reported are the coordinates
+ * of the press.
+ *
+ * Coordinates in X and Y are reported as:
+ * [-0x7fff, 0x7fff]: -0x7fff corresponds to the far left/top of the screen,
+ * and 0x7fff corresponds to the far right/bottom of the screen.
+ * The "screen" is here defined as area that is passed to the frontend and
+ * later displayed on the monitor.
+ *
+ * The frontend is free to scale/resize this screen as it sees fit, however,
+ * (X, Y) = (-0x7fff, -0x7fff) will correspond to the top-left pixel of the
+ * game image, etc.
+ *
+ * To check if the pointer coordinates are valid (e.g. a touch display
+ * actually being touched), PRESSED returns 1 or 0.
+ *
+ * If using a mouse on a desktop, PRESSED will usually correspond to the
+ * left mouse button, but this is a frontend decision.
+ * PRESSED will only return 1 if the pointer is inside the game screen.
+ *
+ * For multi-touch, the index variable can be used to successively query
+ * more presses.
+ * If index = 0 returns true for _PRESSED, coordinates can be extracted
+ * with _X, _Y for index = 0. One can then query _PRESSED, _X, _Y with
+ * index = 1, and so on.
+ * Eventually _PRESSED will return false for an index. No further presses
+ * are registered at this point. */
+#define RETRO_DEVICE_POINTER      6
+
+/* Buttons for the RetroPad (JOYPAD).
+ * The placement of these is equivalent to placements on the
+ * Super Nintendo controller.
+ * L2/R2/L3/R3 buttons correspond to the PS1 DualShock.
+ * Also used as id values for RETRO_DEVICE_INDEX_ANALOG_BUTTON */
+#define RETRO_DEVICE_ID_JOYPAD_B        0
+#define RETRO_DEVICE_ID_JOYPAD_Y        1
+#define RETRO_DEVICE_ID_JOYPAD_SELECT   2
+#define RETRO_DEVICE_ID_JOYPAD_START    3
+#define RETRO_DEVICE_ID_JOYPAD_UP       4
+#define RETRO_DEVICE_ID_JOYPAD_DOWN     5
+#define RETRO_DEVICE_ID_JOYPAD_LEFT     6
+#define RETRO_DEVICE_ID_JOYPAD_RIGHT    7
+#define RETRO_DEVICE_ID_JOYPAD_A        8
+#define RETRO_DEVICE_ID_JOYPAD_X        9
+#define RETRO_DEVICE_ID_JOYPAD_L       10
+#define RETRO_DEVICE_ID_JOYPAD_R       11
+#define RETRO_DEVICE_ID_JOYPAD_L2      12
+#define RETRO_DEVICE_ID_JOYPAD_R2      13
+#define RETRO_DEVICE_ID_JOYPAD_L3      14
+#define RETRO_DEVICE_ID_JOYPAD_R3      15
+
+/* Index / Id values for ANALOG device. */
+#define RETRO_DEVICE_INDEX_ANALOG_LEFT       0
+#define RETRO_DEVICE_INDEX_ANALOG_RIGHT      1
+#define RETRO_DEVICE_INDEX_ANALOG_BUTTON     2
+#define RETRO_DEVICE_ID_ANALOG_X             0
+#define RETRO_DEVICE_ID_ANALOG_Y             1
+
+/* Id values for MOUSE. */
+#define RETRO_DEVICE_ID_MOUSE_X                0
+#define RETRO_DEVICE_ID_MOUSE_Y                1
+#define RETRO_DEVICE_ID_MOUSE_LEFT             2
+#define RETRO_DEVICE_ID_MOUSE_RIGHT            3
+#define RETRO_DEVICE_ID_MOUSE_WHEELUP          4
+#define RETRO_DEVICE_ID_MOUSE_WHEELDOWN        5
+#define RETRO_DEVICE_ID_MOUSE_MIDDLE           6
+#define RETRO_DEVICE_ID_MOUSE_HORIZ_WHEELUP    7
+#define RETRO_DEVICE_ID_MOUSE_HORIZ_WHEELDOWN  8
+#define RETRO_DEVICE_ID_MOUSE_BUTTON_4         9
+#define RETRO_DEVICE_ID_MOUSE_BUTTON_5         10
+
+/* Id values for LIGHTGUN. */
+#define RETRO_DEVICE_ID_LIGHTGUN_SCREEN_X        13 /*Absolute Position*/
+#define RETRO_DEVICE_ID_LIGHTGUN_SCREEN_Y        14 /*Absolute*/
+#define RETRO_DEVICE_ID_LIGHTGUN_IS_OFFSCREEN    15 /*Status Check*/
+#define RETRO_DEVICE_ID_LIGHTGUN_TRIGGER          2
+#define RETRO_DEVICE_ID_LIGHTGUN_RELOAD          16 /*Forced off-screen shot*/
+#define RETRO_DEVICE_ID_LIGHTGUN_AUX_A            3
+#define RETRO_DEVICE_ID_LIGHTGUN_AUX_B            4
+#define RETRO_DEVICE_ID_LIGHTGUN_START            6
+#define RETRO_DEVICE_ID_LIGHTGUN_SELECT           7
+#define RETRO_DEVICE_ID_LIGHTGUN_AUX_C            8
+#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_UP          9
+#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_DOWN       10
+#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_LEFT       11
+#define RETRO_DEVICE_ID_LIGHTGUN_DPAD_RIGHT      12
+/* deprecated */
+#define RETRO_DEVICE_ID_LIGHTGUN_X                0 /*Relative Position*/
+#define RETRO_DEVICE_ID_LIGHTGUN_Y                1 /*Relative*/
+#define RETRO_DEVICE_ID_LIGHTGUN_CURSOR           3 /*Use Aux:A*/
+#define RETRO_DEVICE_ID_LIGHTGUN_TURBO            4 /*Use Aux:B*/
+#define RETRO_DEVICE_ID_LIGHTGUN_PAUSE            5 /*Use Start*/
+
+/* Id values for POINTER. */
+#define RETRO_DEVICE_ID_POINTER_X         0
+#define RETRO_DEVICE_ID_POINTER_Y         1
+#define RETRO_DEVICE_ID_POINTER_PRESSED   2
+
+/* Returned from retro_get_region(). */
+#define RETRO_REGION_NTSC  0
+#define RETRO_REGION_PAL   1
+
+/* Id values for LANGUAGE */
+enum retro_language
+{
+   RETRO_LANGUAGE_ENGLISH             = 0,
+   RETRO_LANGUAGE_JAPANESE            = 1,
+   RETRO_LANGUAGE_FRENCH              = 2,
+   RETRO_LANGUAGE_SPANISH             = 3,
+   RETRO_LANGUAGE_GERMAN              = 4,
+   RETRO_LANGUAGE_ITALIAN             = 5,
+   RETRO_LANGUAGE_DUTCH               = 6,
+   RETRO_LANGUAGE_PORTUGUESE_BRAZIL   = 7,
+   RETRO_LANGUAGE_PORTUGUESE_PORTUGAL = 8,
+   RETRO_LANGUAGE_RUSSIAN             = 9,
+   RETRO_LANGUAGE_KOREAN              = 10,
+   RETRO_LANGUAGE_CHINESE_TRADITIONAL = 11,
+   RETRO_LANGUAGE_CHINESE_SIMPLIFIED  = 12,
+   RETRO_LANGUAGE_ESPERANTO           = 13,
+   RETRO_LANGUAGE_POLISH              = 14,
+   RETRO_LANGUAGE_VIETNAMESE          = 15,
+   RETRO_LANGUAGE_ARABIC              = 16,
+   RETRO_LANGUAGE_LAST,
+
+   /* Ensure sizeof(enum) == sizeof(int) */
+   RETRO_LANGUAGE_DUMMY          = INT_MAX
+};
+
+/* Passed to retro_get_memory_data/size().
+ * If the memory type doesn't apply to the
+ * implementation NULL/0 can be returned.
+ */
+#define RETRO_MEMORY_MASK        0xff
+
+/* Regular save RAM. This RAM is usually found on a game cartridge,
+ * backed up by a battery.
+ * If save game data is too complex for a single memory buffer,
+ * the SAVE_DIRECTORY (preferably) or SYSTEM_DIRECTORY environment
+ * callback can be used. */
+#define RETRO_MEMORY_SAVE_RAM    0
+
+/* Some games have a built-in clock to keep track of time.
+ * This memory is usually just a couple of bytes to keep track of time.
+ */
+#define RETRO_MEMORY_RTC         1
+
+/* System ram lets a frontend peek into a game systems main RAM. */
+#define RETRO_MEMORY_SYSTEM_RAM  2
+
+/* Video ram lets a frontend peek into a game systems video RAM (VRAM). */
+#define RETRO_MEMORY_VIDEO_RAM   3
+
+/* Keysyms used for ID in input state callback when polling RETRO_KEYBOARD. */
+enum retro_key
+{
+   RETROK_UNKNOWN        = 0,
+   RETROK_FIRST          = 0,
+   RETROK_BACKSPACE      = 8,
+   RETROK_TAB            = 9,
+   RETROK_CLEAR          = 12,
+   RETROK_RETURN         = 13,
+   RETROK_PAUSE          = 19,
+   RETROK_ESCAPE         = 27,
+   RETROK_SPACE          = 32,
+   RETROK_EXCLAIM        = 33,
+   RETROK_QUOTEDBL       = 34,
+   RETROK_HASH           = 35,
+   RETROK_DOLLAR         = 36,
+   RETROK_AMPERSAND      = 38,
+   RETROK_QUOTE          = 39,
+   RETROK_LEFTPAREN      = 40,
+   RETROK_RIGHTPAREN     = 41,
+   RETROK_ASTERISK       = 42,
+   RETROK_PLUS           = 43,
+   RETROK_COMMA          = 44,
+   RETROK_MINUS          = 45,
+   RETROK_PERIOD         = 46,
+   RETROK_SLASH          = 47,
+   RETROK_0              = 48,
+   RETROK_1              = 49,
+   RETROK_2              = 50,
+   RETROK_3              = 51,
+   RETROK_4              = 52,
+   RETROK_5              = 53,
+   RETROK_6              = 54,
+   RETROK_7              = 55,
+   RETROK_8              = 56,
+   RETROK_9              = 57,
+   RETROK_COLON          = 58,
+   RETROK_SEMICOLON      = 59,
+   RETROK_LESS           = 60,
+   RETROK_EQUALS         = 61,
+   RETROK_GREATER        = 62,
+   RETROK_QUESTION       = 63,
+   RETROK_AT             = 64,
+   RETROK_LEFTBRACKET    = 91,
+   RETROK_BACKSLASH      = 92,
+   RETROK_RIGHTBRACKET   = 93,
+   RETROK_CARET          = 94,
+   RETROK_UNDERSCORE     = 95,
+   RETROK_BACKQUOTE      = 96,
+   RETROK_a              = 97,
+   RETROK_b              = 98,
+   RETROK_c              = 99,
+   RETROK_d              = 100,
+   RETROK_e              = 101,
+   RETROK_f              = 102,
+   RETROK_g              = 103,
+   RETROK_h              = 104,
+   RETROK_i              = 105,
+   RETROK_j              = 106,
+   RETROK_k              = 107,
+   RETROK_l              = 108,
+   RETROK_m              = 109,
+   RETROK_n              = 110,
+   RETROK_o              = 111,
+   RETROK_p              = 112,
+   RETROK_q              = 113,
+   RETROK_r              = 114,
+   RETROK_s              = 115,
+   RETROK_t              = 116,
+   RETROK_u              = 117,
+   RETROK_v              = 118,
+   RETROK_w              = 119,
+   RETROK_x              = 120,
+   RETROK_y              = 121,
+   RETROK_z              = 122,
+   RETROK_LEFTBRACE      = 123,
+   RETROK_BAR            = 124,
+   RETROK_RIGHTBRACE     = 125,
+   RETROK_TILDE          = 126,
+   RETROK_DELETE         = 127,
+
+   RETROK_KP0            = 256,
+   RETROK_KP1            = 257,
+   RETROK_KP2            = 258,
+   RETROK_KP3            = 259,
+   RETROK_KP4            = 260,
+   RETROK_KP5            = 261,
+   RETROK_KP6            = 262,
+   RETROK_KP7            = 263,
+   RETROK_KP8            = 264,
+   RETROK_KP9            = 265,
+   RETROK_KP_PERIOD      = 266,
+   RETROK_KP_DIVIDE      = 267,
+   RETROK_KP_MULTIPLY    = 268,
+   RETROK_KP_MINUS       = 269,
+   RETROK_KP_PLUS        = 270,
+   RETROK_KP_ENTER       = 271,
+   RETROK_KP_EQUALS      = 272,
+
+   RETROK_UP             = 273,
+   RETROK_DOWN           = 274,
+   RETROK_RIGHT          = 275,
+   RETROK_LEFT           = 276,
+   RETROK_INSERT         = 277,
+   RETROK_HOME           = 278,
+   RETROK_END            = 279,
+   RETROK_PAGEUP         = 280,
+   RETROK_PAGEDOWN       = 281,
+
+   RETROK_F1             = 282,
+   RETROK_F2             = 283,
+   RETROK_F3             = 284,
+   RETROK_F4             = 285,
+   RETROK_F5             = 286,
+   RETROK_F6             = 287,
+   RETROK_F7             = 288,
+   RETROK_F8             = 289,
+   RETROK_F9             = 290,
+   RETROK_F10            = 291,
+   RETROK_F11            = 292,
+   RETROK_F12            = 293,
+   RETROK_F13            = 294,
+   RETROK_F14            = 295,
+   RETROK_F15            = 296,
+
+   RETROK_NUMLOCK        = 300,
+   RETROK_CAPSLOCK       = 301,
+   RETROK_SCROLLOCK      = 302,
+   RETROK_RSHIFT         = 303,
+   RETROK_LSHIFT         = 304,
+   RETROK_RCTRL          = 305,
+   RETROK_LCTRL          = 306,
+   RETROK_RALT           = 307,
+   RETROK_LALT           = 308,
+   RETROK_RMETA          = 309,
+   RETROK_LMETA          = 310,
+   RETROK_LSUPER         = 311,
+   RETROK_RSUPER         = 312,
+   RETROK_MODE           = 313,
+   RETROK_COMPOSE        = 314,
+
+   RETROK_HELP           = 315,
+   RETROK_PRINT          = 316,
+   RETROK_SYSREQ         = 317,
+   RETROK_BREAK          = 318,
+   RETROK_MENU           = 319,
+   RETROK_POWER          = 320,
+   RETROK_EURO           = 321,
+   RETROK_UNDO           = 322,
+
+   RETROK_LAST,
+
+   RETROK_DUMMY          = INT_MAX /* Ensure sizeof(enum) == sizeof(int) */
+};
+
+enum retro_mod
+{
+   RETROKMOD_NONE       = 0x0000,
+
+   RETROKMOD_SHIFT      = 0x01,
+   RETROKMOD_CTRL       = 0x02,
+   RETROKMOD_ALT        = 0x04,
+   RETROKMOD_META       = 0x08,
+
+   RETROKMOD_NUMLOCK    = 0x10,
+   RETROKMOD_CAPSLOCK   = 0x20,
+   RETROKMOD_SCROLLOCK  = 0x40,
+
+   RETROKMOD_DUMMY = INT_MAX /* Ensure sizeof(enum) == sizeof(int) */
+};
+
+/* If set, this call is not part of the public libretro API yet. It can
+ * change or be removed at any time. */
+#define RETRO_ENVIRONMENT_EXPERIMENTAL 0x10000
+/* Environment callback to be used internally in frontend. */
+#define RETRO_ENVIRONMENT_PRIVATE 0x20000
+
+/* Environment commands. */
+#define RETRO_ENVIRONMENT_SET_ROTATION  1  /* const unsigned * --
+                                            * Sets screen rotation of graphics.
+                                            * Is only implemented if rotation can be accelerated by hardware.
+                                            * Valid values are 0, 1, 2, 3, which rotates screen by 0, 90, 180,
+                                            * 270 degrees counter-clockwise respectively.
+                                            */
+#define RETRO_ENVIRONMENT_GET_OVERSCAN  2  /* bool * --
+                                            * Boolean value whether or not the implementation should use overscan,
+                                            * or crop away overscan.
+                                            */
+#define RETRO_ENVIRONMENT_GET_CAN_DUPE  3  /* bool * --
+                                            * Boolean value whether or not frontend supports frame duping,
+                                            * passing NULL to video frame callback.
+                                            */
+
+                                           /* Environ 4, 5 are no longer supported (GET_VARIABLE / SET_VARIABLES),
+                                            * and reserved to avoid possible ABI clash.
+                                            */
+
+#define RETRO_ENVIRONMENT_SET_MESSAGE   6  /* const struct retro_message * --
+                                            * Sets a message to be displayed in implementation-specific manner
+                                            * for a certain amount of 'frames'.
+                                            * Should not be used for trivial messages, which should simply be
+                                            * logged via RETRO_ENVIRONMENT_GET_LOG_INTERFACE (or as a
+                                            * fallback, stderr).
+                                            */
+#define RETRO_ENVIRONMENT_SHUTDOWN      7  /* N/A (NULL) --
+                                            * Requests the frontend to shutdown.
+                                            * Should only be used if game has a specific
+                                            * way to shutdown the game from a menu item or similar.
+                                            */
+#define RETRO_ENVIRONMENT_SET_PERFORMANCE_LEVEL 8
+                                           /* const unsigned * --
+                                            * Gives a hint to the frontend how demanding this implementation
+                                            * is on a system. E.g. reporting a level of 2 means
+                                            * this implementation should run decently on all frontends
+                                            * of level 2 and up.
+                                            *
+                                            * It can be used by the frontend to potentially warn
+                                            * about too demanding implementations.
+                                            *
+                                            * The levels are "floating".
+                                            *
+                                            * This function can be called on a per-game basis,
+                                            * as certain games an implementation can play might be
+                                            * particularly demanding.
+                                            * If called, it should be called in retro_load_game().
+                                            */
+#define RETRO_ENVIRONMENT_GET_SYSTEM_DIRECTORY 9
+                                           /* const char ** --
+                                            * Returns the "system" directory of the frontend.
+                                            * This directory can be used to store system specific
+                                            * content such as BIOSes, configuration data, etc.
+                                            * The returned value can be NULL.
+                                            * If so, no such directory is defined,
+                                            * and it's up to the implementation to find a suitable directory.
+                                            *
+                                            * NOTE: Some cores used this folder also for "save" data such as
+                                            * memory cards, etc, for lack of a better place to put it.
+                                            * This is now discouraged, and if possible, cores should try to
+                                            * use the new GET_SAVE_DIRECTORY.
+                                            */
+#define RETRO_ENVIRONMENT_SET_PIXEL_FORMAT 10
+                                           /* const enum retro_pixel_format * --
+                                            * Sets the internal pixel format used by the implementation.
+                                            * The default pixel format is RETRO_PIXEL_FORMAT_0RGB1555.
+                                            * This pixel format however, is deprecated (see enum retro_pixel_format).
+                                            * If the call returns false, the frontend does not support this pixel
+                                            * format.
+                                            *
+                                            * This function should be called inside retro_load_game() or
+                                            * retro_get_system_av_info().
+                                            */
+#define RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS 11
+                                           /* const struct retro_input_descriptor * --
+                                            * Sets an array of retro_input_descriptors.
+                                            * It is up to the frontend to present this in a usable way.
+                                            * The array is terminated by retro_input_descriptor::description
+                                            * being set to NULL.
+                                            * This function can be called at any time, but it is recommended
+                                            * to call it as early as possible.
+                                            */
+#define RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK 12
+                                           /* const struct retro_keyboard_callback * --
+                                            * Sets a callback function used to notify core about keyboard events.
+                                            */
+#define RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE 13
+                                           /* const struct retro_disk_control_callback * --
+                                            * Sets an interface which frontend can use to eject and insert
+                                            * disk images.
+                                            * This is used for games which consist of multiple images and
+                                            * must be manually swapped out by the user (e.g. PSX).
+                                            */
+#define RETRO_ENVIRONMENT_SET_HW_RENDER 14
+                                           /* struct retro_hw_render_callback * --
+                                            * Sets an interface to let a libretro core render with
+                                            * hardware acceleration.
+                                            * Should be called in retro_load_game().
+                                            * If successful, libretro cores will be able to render to a
+                                            * frontend-provided framebuffer.
+                                            * The size of this framebuffer will be at least as large as
+                                            * max_width/max_height provided in get_av_info().
+                                            * If HW rendering is used, pass only RETRO_HW_FRAME_BUFFER_VALID or
+                                            * NULL to retro_video_refresh_t.
+                                            */
+#define RETRO_ENVIRONMENT_GET_VARIABLE 15
+                                           /* struct retro_variable * --
+                                            * Interface to acquire user-defined information from environment
+                                            * that cannot feasibly be supported in a multi-system way.
+                                            * 'key' should be set to a key which has already been set by
+                                            * SET_VARIABLES.
+                                            * 'data' will be set to a value or NULL.
+                                            */
+#define RETRO_ENVIRONMENT_SET_VARIABLES 16
+                                           /* const struct retro_variable * --
+                                            * Allows an implementation to signal the environment
+                                            * which variables it might want to check for later using
+                                            * GET_VARIABLE.
+                                            * This allows the frontend to present these variables to
+                                            * a user dynamically.
+                                            * This should be called as early as possible (ideally in
+                                            * retro_set_environment).
+                                            *
+                                            * 'data' points to an array of retro_variable structs
+                                            * terminated by a { NULL, NULL } element.
+                                            * retro_variable::key should be namespaced to not collide
+                                            * with other implementations' keys. E.g. A core called
+                                            * 'foo' should use keys named as 'foo_option'.
+                                            * retro_variable::value should contain a human readable
+                                            * description of the key as well as a '|' delimited list
+                                            * of expected values.
+                                            *
+                                            * The number of possible options should be very limited,
+                                            * i.e. it should be feasible to cycle through options
+                                            * without a keyboard.
+                                            *
+                                            * First entry should be treated as a default.
+                                            *
+                                            * Example entry:
+                                            * { "foo_option", "Speed hack coprocessor X; false|true" }
+                                            *
+                                            * Text before first ';' is description. This ';' must be
+                                            * followed by a space, and followed by a list of possible
+                                            * values split up with '|'.
+                                            *
+                                            * Only strings are operated on. The possible values will
+                                            * generally be displayed and stored as-is by the frontend.
+                                            */
+#define RETRO_ENVIRONMENT_GET_VARIABLE_UPDATE 17
+                                           /* bool * --
+                                            * Result is set to true if some variables are updated by
+                                            * frontend since last call to RETRO_ENVIRONMENT_GET_VARIABLE.
+                                            * Variables should be queried with GET_VARIABLE.
+                                            */
+#define RETRO_ENVIRONMENT_SET_SUPPORT_NO_GAME 18
+                                           /* const bool * --
+                                            * If true, the libretro implementation supports calls to
+                                            * retro_load_game() with NULL as argument.
+                                            * Used by cores which can run without particular game data.
+                                            * This should be called within retro_set_environment() only.
+                                            */
+#define RETRO_ENVIRONMENT_GET_LIBRETRO_PATH 19
+                                           /* const char ** --
+                                            * Retrieves the absolute path from where this libretro
+                                            * implementation was loaded.
+                                            * NULL is returned if the libretro was loaded statically
+                                            * (i.e. linked statically to frontend), or if the path cannot be
+                                            * determined.
+                                            * Mostly useful in cooperation with SET_SUPPORT_NO_GAME as assets can
+                                            * be loaded without ugly hacks.
+                                            */
+
+                                           /* Environment 20 was an obsolete version of SET_AUDIO_CALLBACK.
+                                            * It was not used by any known core at the time,
+                                            * and was removed from the API. */
+#define RETRO_ENVIRONMENT_SET_AUDIO_CALLBACK 22
+                                           /* const struct retro_audio_callback * --
+                                            * Sets an interface which is used to notify a libretro core about audio
+                                            * being available for writing.
+                                            * The callback can be called from any thread, so a core using this must
+                                            * have a thread safe audio implementation.
+                                            * It is intended for games where audio and video are completely
+                                            * asynchronous and audio can be generated on the fly.
+                                            * This interface is not recommended for use with emulators which have
+                                            * highly synchronous audio.
+                                            *
+                                            * The callback only notifies about writability; the libretro core still
+                                            * has to call the normal audio callbacks
+                                            * to write audio. The audio callbacks must be called from within the
+                                            * notification callback.
+                                            * The amount of audio data to write is up to the implementation.
+                                            * Generally, the audio callback will be called continously in a loop.
+                                            *
+                                            * Due to thread safety guarantees and lack of sync between audio and
+                                            * video, a frontend  can selectively disallow this interface based on
+                                            * internal configuration. A core using this interface must also
+                                            * implement the "normal" audio interface.
+                                            *
+                                            * A libretro core using SET_AUDIO_CALLBACK should also make use of
+                                            * SET_FRAME_TIME_CALLBACK.
+                                            */
+#define RETRO_ENVIRONMENT_SET_FRAME_TIME_CALLBACK 21
+                                           /* const struct retro_frame_time_callback * --
+                                            * Lets the core know how much time has passed since last
+                                            * invocation of retro_run().
+                                            * The frontend can tamper with the timing to fake fast-forward,
+                                            * slow-motion, frame stepping, etc.
+                                            * In this case the delta time will use the reference value
+                                            * in frame_time_callback..
+                                            */
+#define RETRO_ENVIRONMENT_GET_RUMBLE_INTERFACE 23
+                                           /* struct retro_rumble_interface * --
+                                            * Gets an interface which is used by a libretro core to set
+                                            * state of rumble motors in controllers.
+                                            * A strong and weak motor is supported, and they can be
+                                            * controlled indepedently.
+                                            */
+#define RETRO_ENVIRONMENT_GET_INPUT_DEVICE_CAPABILITIES 24
+                                           /* uint64_t * --
+                                            * Gets a bitmask telling which device type are expected to be
+                                            * handled properly in a call to retro_input_state_t.
+                                            * Devices which are not handled or recognized always return
+                                            * 0 in retro_input_state_t.
+                                            * Example bitmask: caps = (1 << RETRO_DEVICE_JOYPAD) | (1 << RETRO_DEVICE_ANALOG).
+                                            * Should only be called in retro_run().
+                                            */
+#define RETRO_ENVIRONMENT_GET_SENSOR_INTERFACE (25 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* struct retro_sensor_interface * --
+                                            * Gets access to the sensor interface.
+                                            * The purpose of this interface is to allow
+                                            * setting state related to sensors such as polling rate,
+                                            * enabling/disable it entirely, etc.
+                                            * Reading sensor state is done via the normal
+                                            * input_state_callback API.
+                                            */
+#define RETRO_ENVIRONMENT_GET_CAMERA_INTERFACE (26 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* struct retro_camera_callback * --
+                                            * Gets an interface to a video camera driver.
+                                            * A libretro core can use this interface to get access to a
+                                            * video camera.
+                                            * New video frames are delivered in a callback in same
+                                            * thread as retro_run().
+                                            *
+                                            * GET_CAMERA_INTERFACE should be called in retro_load_game().
+                                            *
+                                            * Depending on the camera implementation used, camera frames
+                                            * will be delivered as a raw framebuffer,
+                                            * or as an OpenGL texture directly.
+                                            *
+                                            * The core has to tell the frontend here which types of
+                                            * buffers can be handled properly.
+                                            * An OpenGL texture can only be handled when using a
+                                            * libretro GL core (SET_HW_RENDER).
+                                            * It is recommended to use a libretro GL core when
+                                            * using camera interface.
+                                            *
+                                            * The camera is not started automatically. The retrieved start/stop
+                                            * functions must be used to explicitly
+                                            * start and stop the camera driver.
+                                            */
+#define RETRO_ENVIRONMENT_GET_LOG_INTERFACE 27
+                                           /* struct retro_log_callback * --
+                                            * Gets an interface for logging. This is useful for
+                                            * logging in a cross-platform way
+                                            * as certain platforms cannot use stderr for logging.
+                                            * It also allows the frontend to
+                                            * show logging information in a more suitable way.
+                                            * If this interface is not used, libretro cores should
+                                            * log to stderr as desired.
+                                            */
+#define RETRO_ENVIRONMENT_GET_PERF_INTERFACE 28
+                                           /* struct retro_perf_callback * --
+                                            * Gets an interface for performance counters. This is useful
+                                            * for performance logging in a cross-platform way and for detecting
+                                            * architecture-specific features, such as SIMD support.
+                                            */
+#define RETRO_ENVIRONMENT_GET_LOCATION_INTERFACE 29
+                                           /* struct retro_location_callback * --
+                                            * Gets access to the location interface.
+                                            * The purpose of this interface is to be able to retrieve
+                                            * location-based information from the host device,
+                                            * such as current latitude / longitude.
+                                            */
+#define RETRO_ENVIRONMENT_GET_CONTENT_DIRECTORY 30 /* Old name, kept for compatibility. */
+#define RETRO_ENVIRONMENT_GET_CORE_ASSETS_DIRECTORY 30
+                                           /* const char ** --
+                                            * Returns the "core assets" directory of the frontend.
+                                            * This directory can be used to store specific assets that the
+                                            * core relies upon, such as art assets,
+                                            * input data, etc etc.
+                                            * The returned value can be NULL.
+                                            * If so, no such directory is defined,
+                                            * and it's up to the implementation to find a suitable directory.
+                                            */
+#define RETRO_ENVIRONMENT_GET_SAVE_DIRECTORY 31
+                                           /* const char ** --
+                                            * Returns the "save" directory of the frontend.
+                                            * This directory can be used to store SRAM, memory cards,
+                                            * high scores, etc, if the libretro core
+                                            * cannot use the regular memory interface (retro_get_memory_data()).
+                                            *
+                                            * NOTE: libretro cores used to check GET_SYSTEM_DIRECTORY for
+                                            * similar things before.
+                                            * They should still check GET_SYSTEM_DIRECTORY if they want to
+                                            * be backwards compatible.
+                                            * The path here can be NULL. It should only be non-NULL if the
+                                            * frontend user has set a specific save path.
+                                            */
+#define RETRO_ENVIRONMENT_SET_SYSTEM_AV_INFO 32
+                                           /* const struct retro_system_av_info * --
+                                            * Sets a new av_info structure. This can only be called from
+                                            * within retro_run().
+                                            * This should *only* be used if the core is completely altering the
+                                            * internal resolutions, aspect ratios, timings, sampling rate, etc.
+                                            * Calling this can require a full reinitialization of video/audio
+                                            * drivers in the frontend,
+                                            *
+                                            * so it is important to call it very sparingly, and usually only with
+                                            * the users explicit consent.
+                                            * An eventual driver reinitialize will happen so that video and
+                                            * audio callbacks
+                                            * happening after this call within the same retro_run() call will
+                                            * target the newly initialized driver.
+                                            *
+                                            * This callback makes it possible to support configurable resolutions
+                                            * in games, which can be useful to
+                                            * avoid setting the "worst case" in max_width/max_height.
+                                            *
+                                            * ***HIGHLY RECOMMENDED*** Do not call this callback every time
+                                            * resolution changes in an emulator core if it's
+                                            * expected to be a temporary change, for the reasons of possible
+                                            * driver reinitialization.
+                                            * This call is not a free pass for not trying to provide
+                                            * correct values in retro_get_system_av_info(). If you need to change
+                                            * things like aspect ratio or nominal width/height,
+                                            * use RETRO_ENVIRONMENT_SET_GEOMETRY, which is a softer variant
+                                            * of SET_SYSTEM_AV_INFO.
+                                            *
+                                            * If this returns false, the frontend does not acknowledge a
+                                            * changed av_info struct.
+                                            */
+#define RETRO_ENVIRONMENT_SET_PROC_ADDRESS_CALLBACK 33
+                                           /* const struct retro_get_proc_address_interface * --
+                                            * Allows a libretro core to announce support for the
+                                            * get_proc_address() interface.
+                                            * This interface allows for a standard way to extend libretro where
+                                            * use of environment calls are too indirect,
+                                            * e.g. for cases where the frontend wants to call directly into the core.
+                                            *
+                                            * If a core wants to expose this interface, SET_PROC_ADDRESS_CALLBACK
+                                            * **MUST** be called from within retro_set_environment().
+                                            */
+#define RETRO_ENVIRONMENT_SET_SUBSYSTEM_INFO 34
+                                           /* const struct retro_subsystem_info * --
+                                            * This environment call introduces the concept of libretro "subsystems".
+                                            * A subsystem is a variant of a libretro core which supports
+                                            * different kinds of games.
+                                            * The purpose of this is to support e.g. emulators which might
+                                            * have special needs, e.g. Super Nintendo's Super GameBoy, Sufami Turbo.
+                                            * It can also be used to pick among subsystems in an explicit way
+                                            * if the libretro implementation is a multi-system emulator itself.
+                                            *
+                                            * Loading a game via a subsystem is done with retro_load_game_special(),
+                                            * and this environment call allows a libretro core to expose which
+                                            * subsystems are supported for use with retro_load_game_special().
+                                            * A core passes an array of retro_game_special_info which is terminated
+                                            * with a zeroed out retro_game_special_info struct.
+                                            *
+                                            * If a core wants to use this functionality, SET_SUBSYSTEM_INFO
+                                            * **MUST** be called from within retro_set_environment().
+                                            */
+#define RETRO_ENVIRONMENT_SET_CONTROLLER_INFO 35
+                                           /* const struct retro_controller_info * --
+                                            * This environment call lets a libretro core tell the frontend
+                                            * which controller types are recognized in calls to
+                                            * retro_set_controller_port_device().
+                                            *
+                                            * Some emulators such as Super Nintendo
+                                            * support multiple lightgun types which must be specifically
+                                            * selected from.
+                                            * It is therefore sometimes necessary for a frontend to be able
+                                            * to tell the core about a special kind of input device which is
+                                            * not covered by the libretro input API.
+                                            *
+                                            * In order for a frontend to understand the workings of an input device,
+                                            * it must be a specialized type
+                                            * of the generic device types already defined in the libretro API.
+                                            *
+                                            * Which devices are supported can vary per input port.
+                                            * The core must pass an array of const struct retro_controller_info which
+                                            * is terminated with a blanked out struct. Each element of the struct
+                                            * corresponds to an ascending port index to
+                                            * retro_set_controller_port_device().
+                                            * Even if special device types are set in the libretro core,
+                                            * libretro should only poll input based on the base input device types.
+                                            */
+#define RETRO_ENVIRONMENT_SET_MEMORY_MAPS (36 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* const struct retro_memory_map * --
+                                            * This environment call lets a libretro core tell the frontend
+                                            * about the memory maps this core emulates.
+                                            * This can be used to implement, for example, cheats in a core-agnostic way.
+                                            *
+                                            * Should only be used by emulators; it doesn't make much sense for
+                                            * anything else.
+                                            * It is recommended to expose all relevant pointers through
+                                            * retro_get_memory_* as well.
+                                            *
+                                            * Can be called from retro_init and retro_load_game.
+                                            */
+#define RETRO_ENVIRONMENT_SET_GEOMETRY 37
+                                           /* const struct retro_game_geometry * --
+                                            * This environment call is similar to SET_SYSTEM_AV_INFO for changing
+                                            * video parameters, but provides a guarantee that drivers will not be
+                                            * reinitialized.
+                                            * This can only be called from within retro_run().
+                                            *
+                                            * The purpose of this call is to allow a core to alter nominal
+                                            * width/heights as well as aspect ratios on-the-fly, which can be
+                                            * useful for some emulators to change in run-time.
+                                            *
+                                            * max_width/max_height arguments are ignored and cannot be changed
+                                            * with this call as this could potentially require a reinitialization or a
+                                            * non-constant time operation.
+                                            * If max_width/max_height are to be changed, SET_SYSTEM_AV_INFO is required.
+                                            *
+                                            * A frontend must guarantee that this environment call completes in
+                                            * constant time.
+                                            */
+#define RETRO_ENVIRONMENT_GET_USERNAME 38
+                                           /* const char **
+                                            * Returns the specified username of the frontend, if specified by the user.
+                                            * This username can be used as a nickname for a core that has online facilities
+                                            * or any other mode where personalization of the user is desirable.
+                                            * The returned value can be NULL.
+                                            * If this environ callback is used by a core that requires a valid username,
+                                            * a default username should be specified by the core.
+                                            */
+#define RETRO_ENVIRONMENT_GET_LANGUAGE 39
+                                           /* unsigned * --
+                                            * Returns the specified language of the frontend, if specified by the user.
+                                            * It can be used by the core for localization purposes.
+                                            */
+#define RETRO_ENVIRONMENT_GET_CURRENT_SOFTWARE_FRAMEBUFFER (40 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* struct retro_framebuffer * --
+                                            * Returns a preallocated framebuffer which the core can use for rendering
+                                            * the frame into when not using SET_HW_RENDER.
+                                            * The framebuffer returned from this call must not be used
+                                            * after the current call to retro_run() returns.
+                                            *
+                                            * The goal of this call is to allow zero-copy behavior where a core
+                                            * can render directly into video memory, avoiding extra bandwidth cost by copying
+                                            * memory from core to video memory.
+                                            *
+                                            * If this call succeeds and the core renders into it,
+                                            * the framebuffer pointer and pitch can be passed to retro_video_refresh_t.
+                                            * If the buffer from GET_CURRENT_SOFTWARE_FRAMEBUFFER is to be used,
+                                            * the core must pass the exact
+                                            * same pointer as returned by GET_CURRENT_SOFTWARE_FRAMEBUFFER;
+                                            * i.e. passing a pointer which is offset from the
+                                            * buffer is undefined. The width, height and pitch parameters
+                                            * must also match exactly to the values obtained from GET_CURRENT_SOFTWARE_FRAMEBUFFER.
+                                            *
+                                            * It is possible for a frontend to return a different pixel format
+                                            * than the one used in SET_PIXEL_FORMAT. This can happen if the frontend
+                                            * needs to perform conversion.
+                                            *
+                                            * It is still valid for a core to render to a different buffer
+                                            * even if GET_CURRENT_SOFTWARE_FRAMEBUFFER succeeds.
+                                            *
+                                            * A frontend must make sure that the pointer obtained from this function is
+                                            * writeable (and readable).
+                                            */
+
+#define RETRO_ENVIRONMENT_SET_HW_SHARED_CONTEXT (44 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* N/A (null) * --
+                                            * The frontend will try to use a 'shared' hardware context (mostly applicable
+                                            * to OpenGL) when a hardware context is being set up.
+                                            *
+                                            * Returns true if the frontend supports shared hardware contexts and false
+                                            * if the frontend does not support shared hardware contexts.
+                                            *
+                                            * This will do nothing on its own until SET_HW_RENDER env callbacks are
+                                            * being used.
+                                            */
+
+#define RETRO_ENVIRONMENT_GET_VFS_INTERFACE (45 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* struct retro_vfs_interface_info * --
+                                            * Gets access to the VFS interface.
+                                            * VFS presence needs to be queried prior to load_game or any
+                                            * get_system/save/other_directory being called to let front end know
+                                            * core supports VFS before it starts handing out paths.
+                                            * It is recomended to do so in retro_set_environment */
+
+/* VFS functionality */
+
+/* File paths:
+ * File paths passed as parameters when using this api shall be well formed unix-style,
+ * using "/" (unquoted forward slash) as directory separator regardless of the platform's native separator.
+ * Paths shall also include at least one forward slash ("game.bin" is an invalid path, use "./game.bin" instead).
+ * Other than the directory separator, cores shall not make assumptions about path format:
+ * "C:/path/game.bin", "http://example.com/game.bin", "#game/game.bin", "./game.bin" (without quotes) are all valid paths.
+ * Cores may replace the basename or remove path components from the end, and/or add new components;
+ * however, cores shall not append "./", "../" or multiple consecutive forward slashes ("//") to paths they request to front end.
+ * The frontend is encouraged to make such paths work as well as it can, but is allowed to give up if the core alters paths too much.
+ * Frontends are encouraged, but not required, to support native file system paths (modulo replacing the directory separator, if applicable).
+ * Cores are allowed to try using them, but must remain functional if the front rejects such requests.
+ * Cores are encouraged to use the libretro-common filestream functions for file I/O,
+ * as they seamlessly integrate with VFS, deal with directory separator replacement as appropriate
+ * and provide platform-specific fallbacks in cases where front ends do not support VFS. */
+
+/* Opaque file handle
+ * Introduced in VFS API v1 */
+struct retro_vfs_file_handle;
+
+/* File open flags
+ * Introduced in VFS API v1 */
+#define RETRO_VFS_FILE_ACCESS_READ            (1 << 0) /* Read only mode */
+#define RETRO_VFS_FILE_ACCESS_WRITE           (1 << 1) /* Write only mode, discard contents and overwrites existing file unless RETRO_VFS_FILE_ACCESS_UPDATE is also specified */
+#define RETRO_VFS_FILE_ACCESS_READ_WRITE      (RETRO_VFS_FILE_ACCESS_READ | RETRO_VFS_FILE_ACCESS_WRITE) /* Read-write mode, discard contents and overwrites existing file unless RETRO_VFS_FILE_ACCESS_UPDATE is also specified*/
+#define RETRO_VFS_FILE_ACCESS_UPDATE_EXISTING (1 << 2) /* Prevents discarding content of existing files opened for writing */
+
+/* These are only hints. The frontend may choose to ignore them. Other than RAM/CPU/etc use,
+   and how they react to unlikely external interference (for example someone else writing to that file,
+   or the file's server going down), behavior will not change. */
+#define RETRO_VFS_FILE_ACCESS_HINT_NONE              (0)
+/* Indicate that the file will be accessed many times. The frontend should aggressively cache everything. */
+#define RETRO_VFS_FILE_ACCESS_HINT_FREQUENT_ACCESS   (1 << 0)
+
+/* Seek positions */
+#define RETRO_VFS_SEEK_POSITION_START    0
+#define RETRO_VFS_SEEK_POSITION_CURRENT  1
+#define RETRO_VFS_SEEK_POSITION_END      2
+
+/* Get path from opaque handle. Returns the exact same path passed to file_open when getting the handle
+ * Introduced in VFS API v1 */
+typedef const char *(RETRO_CALLCONV *retro_vfs_get_path_t)(struct retro_vfs_file_handle *stream);
+
+/* Open a file for reading or writing. If path points to a directory, this will
+ * fail. Returns the opaque file handle, or NULL for error.
+ * Introduced in VFS API v1 */
+typedef struct retro_vfs_file_handle *(RETRO_CALLCONV *retro_vfs_open_t)(const char *path, unsigned mode, unsigned hints);
+
+/* Close the file and release its resources. Must be called if open_file returns non-NULL. Returns 0 on succes, -1 on failure.
+ * Whether the call succeeds ot not, the handle passed as parameter becomes invalid and should no longer be used.
+ * Introduced in VFS API v1 */
+typedef int (RETRO_CALLCONV *retro_vfs_close_t)(struct retro_vfs_file_handle *stream);
+
+/* Return the size of the file in bytes, or -1 for error.
+ * Introduced in VFS API v1 */
+typedef int64_t (RETRO_CALLCONV *retro_vfs_size_t)(struct retro_vfs_file_handle *stream);
+
+/* Get the current read / write position for the file. Returns - 1 for error.
+ * Introduced in VFS API v1 */
+typedef int64_t (RETRO_CALLCONV *retro_vfs_tell_t)(struct retro_vfs_file_handle *stream);
+
+/* Set the current read/write position for the file. Returns the new position, -1 for error.
+ * Introduced in VFS API v1 */
+typedef int64_t (RETRO_CALLCONV *retro_vfs_seek_t)(struct retro_vfs_file_handle *stream, int64_t offset, int seek_position);
+
+/* Read data from a file. Returns the number of bytes read, or -1 for error.
+ * Introduced in VFS API v1 */
+typedef int64_t (RETRO_CALLCONV *retro_vfs_read_t)(struct retro_vfs_file_handle *stream, void *s, uint64_t len);
+
+/* Write data to a file. Returns the number of bytes written, or -1 for error.
+ * Introduced in VFS API v1 */
+typedef int64_t (RETRO_CALLCONV *retro_vfs_write_t)(struct retro_vfs_file_handle *stream, const void *s, uint64_t len);
+
+/* Flush pending writes to file, if using buffered IO. Returns 0 on sucess, or -1 on failure.
+ * Introduced in VFS API v1 */
+typedef int (RETRO_CALLCONV *retro_vfs_flush_t)(struct retro_vfs_file_handle *stream);
+
+/* Delete the specified file. Returns 0 on success, -1 on failure
+ * Introduced in VFS API v1 */
+typedef int (RETRO_CALLCONV *retro_vfs_remove_t)(const char *path);
+
+/* Rename the specified file. Returns 0 on success, -1 on failure
+ * Introduced in VFS API v1 */
+typedef int (RETRO_CALLCONV *retro_vfs_rename_t)(const char *old_path, const char *new_path);
+
+struct retro_vfs_interface
+{
+	retro_vfs_get_path_t get_path;
+	retro_vfs_open_t open;
+	retro_vfs_close_t close;
+	retro_vfs_size_t size;
+	retro_vfs_tell_t tell;
+	retro_vfs_seek_t seek;
+	retro_vfs_read_t read;
+	retro_vfs_write_t write;
+	retro_vfs_flush_t flush;
+	retro_vfs_remove_t remove;
+	retro_vfs_rename_t rename;
+};
+
+struct retro_vfs_interface_info
+{
+   /* Set by core: should this be higher than the version the front end supports,
+    * front end will return false in the RETRO_ENVIRONMENT_GET_VFS_INTERFACE call
+    * Introduced in VFS API v1 */
+   uint32_t required_interface_version;
+
+   /* Frontend writes interface pointer here. The frontend also sets the actual
+    * version, must be at least required_interface_version.
+    * Introduced in VFS API v1 */
+   struct retro_vfs_interface *iface;
+};
+
+enum retro_hw_render_interface_type
+{
+   RETRO_HW_RENDER_INTERFACE_VULKAN = 0,
+   RETRO_HW_RENDER_INTERFACE_DUMMY = INT_MAX
+};
+
+/* Base struct. All retro_hw_render_interface_* types
+ * contain at least these fields. */
+struct retro_hw_render_interface
+{
+   enum retro_hw_render_interface_type interface_type;
+   unsigned interface_version;
+};
+
+
+#define RETRO_ENVIRONMENT_GET_LED_INTERFACE (46 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* struct retro_led_interface * --
+                                            * Gets an interface which is used by a libretro core to set 
+                                            * state of LEDs.
+                                            */
+
+typedef void (RETRO_CALLCONV *retro_set_led_state_t)(int led, int state);
+struct retro_led_interface
+{
+    retro_set_led_state_t set_led_state;
+};
+
+
+#define RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE (41 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* const struct retro_hw_render_interface ** --
+                                            * Returns an API specific rendering interface for accessing API specific data.
+                                            * Not all HW rendering APIs support or need this.
+                                            * The contents of the returned pointer is specific to the rendering API
+                                            * being used. See the various headers like libretro_vulkan.h, etc.
+                                            *
+                                            * GET_HW_RENDER_INTERFACE cannot be called before context_reset has been called.
+                                            * Similarly, after context_destroyed callback returns,
+                                            * the contents of the HW_RENDER_INTERFACE are invalidated.
+                                            */
+
+#define RETRO_ENVIRONMENT_SET_SUPPORT_ACHIEVEMENTS (42 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* const bool * --
+                                            * If true, the libretro implementation supports achievements
+                                            * either via memory descriptors set with RETRO_ENVIRONMENT_SET_MEMORY_MAPS
+                                            * or via retro_get_memory_data/retro_get_memory_size.
+                                            *
+                                            * This must be called before the first call to retro_run.
+                                            */
+
+enum retro_hw_render_context_negotiation_interface_type
+{
+   RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_VULKAN = 0,
+   RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_DUMMY = INT_MAX
+};
+
+/* Base struct. All retro_hw_render_context_negotiation_interface_* types
+ * contain at least these fields. */
+struct retro_hw_render_context_negotiation_interface
+{
+   enum retro_hw_render_context_negotiation_interface_type interface_type;
+   unsigned interface_version;
+};
+#define RETRO_ENVIRONMENT_SET_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE (43 | RETRO_ENVIRONMENT_EXPERIMENTAL)
+                                           /* const struct retro_hw_render_context_negotiation_interface * --
+                                            * Sets an interface which lets the libretro core negotiate with frontend how a context is created.
+                                            * The semantics of this interface depends on which API is used in SET_HW_RENDER earlier.
+                                            * This interface will be used when the frontend is trying to create a HW rendering context,
+                                            * so it will be used after SET_HW_RENDER, but before the context_reset callback.
+                                            */
+
+/* Serialized state is incomplete in some way. Set if serialization is
+ * usable in typical end-user cases but should not be relied upon to
+ * implement frame-sensitive frontend features such as netplay or
+ * rerecording. */
+#define RETRO_SERIALIZATION_QUIRK_INCOMPLETE (1 << 0)
+/* The core must spend some time initializing before serialization is
+ * supported. retro_serialize() will initially fail; retro_unserialize()
+ * and retro_serialize_size() may or may not work correctly either. */
+#define RETRO_SERIALIZATION_QUIRK_MUST_INITIALIZE (1 << 1)
+/* Serialization size may change within a session. */
+#define RETRO_SERIALIZATION_QUIRK_CORE_VARIABLE_SIZE (1 << 2)
+/* Set by the frontend to acknowledge that it supports variable-sized
+ * states. */
+#define RETRO_SERIALIZATION_QUIRK_FRONT_VARIABLE_SIZE (1 << 3)
+/* Serialized state can only be loaded during the same session. */
+#define RETRO_SERIALIZATION_QUIRK_SINGLE_SESSION (1 << 4)
+/* Serialized state cannot be loaded on an architecture with a different
+ * endianness from the one it was saved on. */
+#define RETRO_SERIALIZATION_QUIRK_ENDIAN_DEPENDENT (1 << 5)
+/* Serialized state cannot be loaded on a different platform from the one it
+ * was saved on for reasons other than endianness, such as word size
+ * dependence */
+#define RETRO_SERIALIZATION_QUIRK_PLATFORM_DEPENDENT (1 << 6)
+
+#define RETRO_ENVIRONMENT_SET_SERIALIZATION_QUIRKS 44
+                                           /* uint64_t * --
+                                            * Sets quirk flags associated with serialization. The frontend will zero any flags it doesn't
+                                            * recognize or support. Should be set in either retro_init or retro_load_game, but not both.
+                                            */
+
+#define RETRO_MEMDESC_CONST     (1 << 0)   /* The frontend will never change this memory area once retro_load_game has returned. */
+#define RETRO_MEMDESC_BIGENDIAN (1 << 1)   /* The memory area contains big endian data. Default is little endian. */
+#define RETRO_MEMDESC_ALIGN_2   (1 << 16)  /* All memory access in this area is aligned to their own size, or 2, whichever is smaller. */
+#define RETRO_MEMDESC_ALIGN_4   (2 << 16)
+#define RETRO_MEMDESC_ALIGN_8   (3 << 16)
+#define RETRO_MEMDESC_MINSIZE_2 (1 << 24)  /* All memory in this region is accessed at least 2 bytes at the time. */
+#define RETRO_MEMDESC_MINSIZE_4 (2 << 24)
+#define RETRO_MEMDESC_MINSIZE_8 (3 << 24)
+struct retro_memory_descriptor
+{
+   uint64_t flags;
+
+   /* Pointer to the start of the relevant ROM or RAM chip.
+    * It's strongly recommended to use 'offset' if possible, rather than
+    * doing math on the pointer.
+    *
+    * If the same byte is mapped my multiple descriptors, their descriptors
+    * must have the same pointer.
+    * If 'start' does not point to the first byte in the pointer, put the
+    * difference in 'offset' instead.
+    *
+    * May be NULL if there's nothing usable here (e.g. hardware registers and
+    * open bus). No flags should be set if the pointer is NULL.
+    * It's recommended to minimize the number of descriptors if possible,
+    * but not mandatory. */
+   void *ptr;
+   size_t offset;
+
+   /* This is the location in the emulated address space
+    * where the mapping starts. */
+   size_t start;
+
+   /* Which bits must be same as in 'start' for this mapping to apply.
+    * The first memory descriptor to claim a certain byte is the one
+    * that applies.
+    * A bit which is set in 'start' must also be set in this.
+    * Can be zero, in which case each byte is assumed mapped exactly once.
+    * In this case, 'len' must be a power of two. */
+   size_t select;
+
+   /* If this is nonzero, the set bits are assumed not connected to the
+    * memory chip's address pins. */
+   size_t disconnect;
+
+   /* This one tells the size of the current memory area.
+    * If, after start+disconnect are applied, the address is higher than
+    * this, the highest bit of the address is cleared.
+    *
+    * If the address is still too high, the next highest bit is cleared.
+    * Can be zero, in which case it's assumed to be infinite (as limited
+    * by 'select' and 'disconnect'). */
+   size_t len;
+
+   /* To go from emulated address to physical address, the following
+    * order applies:
+    * Subtract 'start', pick off 'disconnect', apply 'len', add 'offset'. */
+
+   /* The address space name must consist of only a-zA-Z0-9_-,
+    * should be as short as feasible (maximum length is 8 plus the NUL),
+    * and may not be any other address space plus one or more 0-9A-F
+    * at the end.
+    * However, multiple memory descriptors for the same address space is
+    * allowed, and the address space name can be empty. NULL is treated
+    * as empty.
+    *
+    * Address space names are case sensitive, but avoid lowercase if possible.
+    * The same pointer may exist in multiple address spaces.
+    *
+    * Examples:
+    * blank+blank - valid (multiple things may be mapped in the same namespace)
+    * 'Sp'+'Sp' - valid (multiple things may be mapped in the same namespace)
+    * 'A'+'B' - valid (neither is a prefix of each other)
+    * 'S'+blank - valid ('S' is not in 0-9A-F)
+    * 'a'+blank - valid ('a' is not in 0-9A-F)
+    * 'a'+'A' - valid (neither is a prefix of each other)
+    * 'AR'+blank - valid ('R' is not in 0-9A-F)
+    * 'ARB'+blank - valid (the B can't be part of the address either, because
+    *                      there is no namespace 'AR')
+    * blank+'B' - not valid, because it's ambigous which address space B1234
+    *             would refer to.
+    * The length can't be used for that purpose; the frontend may want
+    * to append arbitrary data to an address, without a separator. */
+   const char *addrspace;
+
+   /* TODO: When finalizing this one, add a description field, which should be
+    * "WRAM" or something roughly equally long. */
+
+   /* TODO: When finalizing this one, replace 'select' with 'limit', which tells
+    * which bits can vary and still refer to the same address (limit = ~select).
+    * TODO: limit? range? vary? something else? */
+
+   /* TODO: When finalizing this one, if 'len' is above what 'select' (or
+    * 'limit') allows, it's bankswitched. Bankswitched data must have both 'len'
+    * and 'select' != 0, and the mappings don't tell how the system switches the
+    * banks. */
+
+   /* TODO: When finalizing this one, fix the 'len' bit removal order.
+    * For len=0x1800, pointer 0x1C00 should go to 0x1400, not 0x0C00.
+    * Algorithm: Take bits highest to lowest, but if it goes above len, clear
+    * the most recent addition and continue on the next bit.
+    * TODO: Can the above be optimized? Is "remove the lowest bit set in both
+    * pointer and 'len'" equivalent? */
+
+   /* TODO: Some emulators (MAME?) emulate big endian systems by only accessing
+    * the emulated memory in 32-bit chunks, native endian. But that's nothing
+    * compared to Darek Mihocka <http://www.emulators.com/docs/nx07_vm101.htm>
+    * (section Emulation 103 - Nearly Free Byte Reversal) - he flips the ENTIRE
+    * RAM backwards! I'll want to represent both of those, via some flags.
+    *
+    * I suspect MAME either didn't think of that idea, or don't want the #ifdef.
+    * Not sure which, nor do I really care. */
+
+   /* TODO: Some of those flags are unused and/or don't really make sense. Clean
+    * them up. */
+};
+
+/* The frontend may use the largest value of 'start'+'select' in a
+ * certain namespace to infer the size of the address space.
+ *
+ * If the address space is larger than that, a mapping with .ptr=NULL
+ * should be at the end of the array, with .select set to all ones for
+ * as long as the address space is big.
+ *
+ * Sample descriptors (minus .ptr, and RETRO_MEMFLAG_ on the flags):
+ * SNES WRAM:
+ * .start=0x7E0000, .len=0x20000
+ * (Note that this must be mapped before the ROM in most cases; some of the
+ * ROM mappers
+ * try to claim $7E0000, or at least $7E8000.)
+ * SNES SPC700 RAM:
+ * .addrspace="S", .len=0x10000
+ * SNES WRAM mirrors:
+ * .flags=MIRROR, .start=0x000000, .select=0xC0E000, .len=0x2000
+ * .flags=MIRROR, .start=0x800000, .select=0xC0E000, .len=0x2000
+ * SNES WRAM mirrors, alternate equivalent descriptor:
+ * .flags=MIRROR, .select=0x40E000, .disconnect=~0x1FFF
+ * (Various similar constructions can be created by combining parts of
+ * the above two.)
+ * SNES LoROM (512KB, mirrored a couple of times):
+ * .flags=CONST, .start=0x008000, .select=0x408000, .disconnect=0x8000, .len=512*1024
+ * .flags=CONST, .start=0x400000, .select=0x400000, .disconnect=0x8000, .len=512*1024
+ * SNES HiROM (4MB):
+ * .flags=CONST,                 .start=0x400000, .select=0x400000, .len=4*1024*1024
+ * .flags=CONST, .offset=0x8000, .start=0x008000, .select=0x408000, .len=4*1024*1024
+ * SNES ExHiROM (8MB):
+ * .flags=CONST, .offset=0,                  .start=0xC00000, .select=0xC00000, .len=4*1024*1024
+ * .flags=CONST, .offset=4*1024*1024,        .start=0x400000, .select=0xC00000, .len=4*1024*1024
+ * .flags=CONST, .offset=0x8000,             .start=0x808000, .select=0xC08000, .len=4*1024*1024
+ * .flags=CONST, .offset=4*1024*1024+0x8000, .start=0x008000, .select=0xC08000, .len=4*1024*1024
+ * Clarify the size of the address space:
+ * .ptr=NULL, .select=0xFFFFFF
+ * .len can be implied by .select in many of them, but was included for clarity.
+ */
+
+struct retro_memory_map
+{
+   const struct retro_memory_descriptor *descriptors;
+   unsigned num_descriptors;
+};
+
+struct retro_controller_description
+{
+   /* Human-readable description of the controller. Even if using a generic
+    * input device type, this can be set to the particular device type the
+    * core uses. */
+   const char *desc;
+
+   /* Device type passed to retro_set_controller_port_device(). If the device
+    * type is a sub-class of a generic input device type, use the
+    * RETRO_DEVICE_SUBCLASS macro to create an ID.
+    *
+    * E.g. RETRO_DEVICE_SUBCLASS(RETRO_DEVICE_JOYPAD, 1). */
+   unsigned id;
+};
+
+struct retro_controller_info
+{
+   const struct retro_controller_description *types;
+   unsigned num_types;
+};
+
+struct retro_subsystem_memory_info
+{
+   /* The extension associated with a memory type, e.g. "psram". */
+   const char *extension;
+
+   /* The memory type for retro_get_memory(). This should be at
+    * least 0x100 to avoid conflict with standardized
+    * libretro memory types. */
+   unsigned type;
+};
+
+struct retro_subsystem_rom_info
+{
+   /* Describes what the content is (SGB BIOS, GB ROM, etc). */
+   const char *desc;
+
+   /* Same definition as retro_get_system_info(). */
+   const char *valid_extensions;
+
+   /* Same definition as retro_get_system_info(). */
+   bool need_fullpath;
+
+   /* Same definition as retro_get_system_info(). */
+   bool block_extract;
+
+   /* This is set if the content is required to load a game.
+    * If this is set to false, a zeroed-out retro_game_info can be passed. */
+   bool required;
+
+   /* Content can have multiple associated persistent
+    * memory types (retro_get_memory()). */
+   const struct retro_subsystem_memory_info *memory;
+   unsigned num_memory;
+};
+
+struct retro_subsystem_info
+{
+   /* Human-readable string of the subsystem type, e.g. "Super GameBoy" */
+   const char *desc;
+
+   /* A computer friendly short string identifier for the subsystem type.
+    * This name must be [a-z].
+    * E.g. if desc is "Super GameBoy", this can be "sgb".
+    * This identifier can be used for command-line interfaces, etc.
+    */
+   const char *ident;
+
+   /* Infos for each content file. The first entry is assumed to be the
+    * "most significant" content for frontend purposes.
+    * E.g. with Super GameBoy, the first content should be the GameBoy ROM,
+    * as it is the most "significant" content to a user.
+    * If a frontend creates new file paths based on the content used
+    * (e.g. savestates), it should use the path for the first ROM to do so. */
+   const struct retro_subsystem_rom_info *roms;
+
+   /* Number of content files associated with a subsystem. */
+   unsigned num_roms;
+
+   /* The type passed to retro_load_game_special(). */
+   unsigned id;
+};
+
+typedef void (RETRO_CALLCONV *retro_proc_address_t)(void);
+
+/* libretro API extension functions:
+ * (None here so far).
+ *
+ * Get a symbol from a libretro core.
+ * Cores should only return symbols which are actual
+ * extensions to the libretro API.
+ *
+ * Frontends should not use this to obtain symbols to standard
+ * libretro entry points (static linking or dlsym).
+ *
+ * The symbol name must be equal to the function name,
+ * e.g. if void retro_foo(void); exists, the symbol must be called "retro_foo".
+ * The returned function pointer must be cast to the corresponding type.
+ */
+typedef retro_proc_address_t (RETRO_CALLCONV *retro_get_proc_address_t)(const char *sym);
+
+struct retro_get_proc_address_interface
+{
+   retro_get_proc_address_t get_proc_address;
+};
+
+enum retro_log_level
+{
+   RETRO_LOG_DEBUG = 0,
+   RETRO_LOG_INFO,
+   RETRO_LOG_WARN,
+   RETRO_LOG_ERROR,
+
+   RETRO_LOG_DUMMY = INT_MAX
+};
+
+/* Logging function. Takes log level argument as well. */
+typedef void (RETRO_CALLCONV *retro_log_printf_t)(enum retro_log_level level,
+      const char *fmt, ...);
+
+struct retro_log_callback
+{
+   retro_log_printf_t log;
+};
+
+/* Performance related functions */
+
+/* ID values for SIMD CPU features */
+#define RETRO_SIMD_SSE      (1 << 0)
+#define RETRO_SIMD_SSE2     (1 << 1)
+#define RETRO_SIMD_VMX      (1 << 2)
+#define RETRO_SIMD_VMX128   (1 << 3)
+#define RETRO_SIMD_AVX      (1 << 4)
+#define RETRO_SIMD_NEON     (1 << 5)
+#define RETRO_SIMD_SSE3     (1 << 6)
+#define RETRO_SIMD_SSSE3    (1 << 7)
+#define RETRO_SIMD_MMX      (1 << 8)
+#define RETRO_SIMD_MMXEXT   (1 << 9)
+#define RETRO_SIMD_SSE4     (1 << 10)
+#define RETRO_SIMD_SSE42    (1 << 11)
+#define RETRO_SIMD_AVX2     (1 << 12)
+#define RETRO_SIMD_VFPU     (1 << 13)
+#define RETRO_SIMD_PS       (1 << 14)
+#define RETRO_SIMD_AES      (1 << 15)
+#define RETRO_SIMD_VFPV3    (1 << 16)
+#define RETRO_SIMD_VFPV4    (1 << 17)
+#define RETRO_SIMD_POPCNT   (1 << 18)
+#define RETRO_SIMD_MOVBE    (1 << 19)
+#define RETRO_SIMD_CMOV     (1 << 20)
+#define RETRO_SIMD_ASIMD    (1 << 21)
+
+typedef uint64_t retro_perf_tick_t;
+typedef int64_t retro_time_t;
+
+struct retro_perf_counter
+{
+   const char *ident;
+   retro_perf_tick_t start;
+   retro_perf_tick_t total;
+   retro_perf_tick_t call_cnt;
+
+   bool registered;
+};
+
+/* Returns current time in microseconds.
+ * Tries to use the most accurate timer available.
+ */
+typedef retro_time_t (RETRO_CALLCONV *retro_perf_get_time_usec_t)(void);
+
+/* A simple counter. Usually nanoseconds, but can also be CPU cycles.
+ * Can be used directly if desired (when creating a more sophisticated
+ * performance counter system).
+ * */
+typedef retro_perf_tick_t (RETRO_CALLCONV *retro_perf_get_counter_t)(void);
+
+/* Returns a bit-mask of detected CPU features (RETRO_SIMD_*). */
+typedef uint64_t (RETRO_CALLCONV *retro_get_cpu_features_t)(void);
+
+/* Asks frontend to log and/or display the state of performance counters.
+ * Performance counters can always be poked into manually as well.
+ */
+typedef void (RETRO_CALLCONV *retro_perf_log_t)(void);
+
+/* Register a performance counter.
+ * ident field must be set with a discrete value and other values in
+ * retro_perf_counter must be 0.
+ * Registering can be called multiple times. To avoid calling to
+ * frontend redundantly, you can check registered field first. */
+typedef void (RETRO_CALLCONV *retro_perf_register_t)(struct retro_perf_counter *counter);
+
+/* Starts a registered counter. */
+typedef void (RETRO_CALLCONV *retro_perf_start_t)(struct retro_perf_counter *counter);
+
+/* Stops a registered counter. */
+typedef void (RETRO_CALLCONV *retro_perf_stop_t)(struct retro_perf_counter *counter);
+
+/* For convenience it can be useful to wrap register, start and stop in macros.
+ * E.g.:
+ * #ifdef LOG_PERFORMANCE
+ * #define RETRO_PERFORMANCE_INIT(perf_cb, name) static struct retro_perf_counter name = {#name}; if (!name.registered) perf_cb.perf_register(&(name))
+ * #define RETRO_PERFORMANCE_START(perf_cb, name) perf_cb.perf_start(&(name))
+ * #define RETRO_PERFORMANCE_STOP(perf_cb, name) perf_cb.perf_stop(&(name))
+ * #else
+ * ... Blank macros ...
+ * #endif
+ *
+ * These can then be used mid-functions around code snippets.
+ *
+ * extern struct retro_perf_callback perf_cb;  * Somewhere in the core.
+ *
+ * void do_some_heavy_work(void)
+ * {
+ *    RETRO_PERFORMANCE_INIT(cb, work_1;
+ *    RETRO_PERFORMANCE_START(cb, work_1);
+ *    heavy_work_1();
+ *    RETRO_PERFORMANCE_STOP(cb, work_1);
+ *
+ *    RETRO_PERFORMANCE_INIT(cb, work_2);
+ *    RETRO_PERFORMANCE_START(cb, work_2);
+ *    heavy_work_2();
+ *    RETRO_PERFORMANCE_STOP(cb, work_2);
+ * }
+ *
+ * void retro_deinit(void)
+ * {
+ *    perf_cb.perf_log();  * Log all perf counters here for example.
+ * }
+ */
+
+struct retro_perf_callback
+{
+   retro_perf_get_time_usec_t    get_time_usec;
+   retro_get_cpu_features_t      get_cpu_features;
+
+   retro_perf_get_counter_t      get_perf_counter;
+   retro_perf_register_t         perf_register;
+   retro_perf_start_t            perf_start;
+   retro_perf_stop_t             perf_stop;
+   retro_perf_log_t              perf_log;
+};
+
+/* FIXME: Document the sensor API and work out behavior.
+ * It will be marked as experimental until then.
+ */
+enum retro_sensor_action
+{
+   RETRO_SENSOR_ACCELEROMETER_ENABLE = 0,
+   RETRO_SENSOR_ACCELEROMETER_DISABLE,
+
+   RETRO_SENSOR_DUMMY = INT_MAX
+};
+
+/* Id values for SENSOR types. */
+#define RETRO_SENSOR_ACCELEROMETER_X 0
+#define RETRO_SENSOR_ACCELEROMETER_Y 1
+#define RETRO_SENSOR_ACCELEROMETER_Z 2
+
+typedef bool (RETRO_CALLCONV *retro_set_sensor_state_t)(unsigned port,
+      enum retro_sensor_action action, unsigned rate);
+
+typedef float (RETRO_CALLCONV *retro_sensor_get_input_t)(unsigned port, unsigned id);
+
+struct retro_sensor_interface
+{
+   retro_set_sensor_state_t set_sensor_state;
+   retro_sensor_get_input_t get_sensor_input;
+};
+
+enum retro_camera_buffer
+{
+   RETRO_CAMERA_BUFFER_OPENGL_TEXTURE = 0,
+   RETRO_CAMERA_BUFFER_RAW_FRAMEBUFFER,
+
+   RETRO_CAMERA_BUFFER_DUMMY = INT_MAX
+};
+
+/* Starts the camera driver. Can only be called in retro_run(). */
+typedef bool (RETRO_CALLCONV *retro_camera_start_t)(void);
+
+/* Stops the camera driver. Can only be called in retro_run(). */
+typedef void (RETRO_CALLCONV *retro_camera_stop_t)(void);
+
+/* Callback which signals when the camera driver is initialized
+ * and/or deinitialized.
+ * retro_camera_start_t can be called in initialized callback.
+ */
+typedef void (RETRO_CALLCONV *retro_camera_lifetime_status_t)(void);
+
+/* A callback for raw framebuffer data. buffer points to an XRGB8888 buffer.
+ * Width, height and pitch are similar to retro_video_refresh_t.
+ * First pixel is top-left origin.
+ */
+typedef void (RETRO_CALLCONV *retro_camera_frame_raw_framebuffer_t)(const uint32_t *buffer,
+      unsigned width, unsigned height, size_t pitch);
+
+/* A callback for when OpenGL textures are used.
+ *
+ * texture_id is a texture owned by camera driver.
+ * Its state or content should be considered immutable, except for things like
+ * texture filtering and clamping.
+ *
+ * texture_target is the texture target for the GL texture.
+ * These can include e.g. GL_TEXTURE_2D, GL_TEXTURE_RECTANGLE, and possibly
+ * more depending on extensions.
+ *
+ * affine points to a packed 3x3 column-major matrix used to apply an affine
+ * transform to texture coordinates. (affine_matrix * vec3(coord_x, coord_y, 1.0))
+ * After transform, normalized texture coord (0, 0) should be bottom-left
+ * and (1, 1) should be top-right (or (width, height) for RECTANGLE).
+ *
+ * GL-specific typedefs are avoided here to avoid relying on gl.h in
+ * the API definition.
+ */
+typedef void (RETRO_CALLCONV *retro_camera_frame_opengl_texture_t)(unsigned texture_id,
+      unsigned texture_target, const float *affine);
+
+struct retro_camera_callback
+{
+   /* Set by libretro core.
+    * Example bitmask: caps = (1 << RETRO_CAMERA_BUFFER_OPENGL_TEXTURE) | (1 << RETRO_CAMERA_BUFFER_RAW_FRAMEBUFFER).
+    */
+   uint64_t caps;
+
+   /* Desired resolution for camera. Is only used as a hint. */
+   unsigned width;
+   unsigned height;
+
+   /* Set by frontend. */
+   retro_camera_start_t start;
+   retro_camera_stop_t stop;
+
+   /* Set by libretro core if raw framebuffer callbacks will be used. */
+   retro_camera_frame_raw_framebuffer_t frame_raw_framebuffer;
+
+   /* Set by libretro core if OpenGL texture callbacks will be used. */
+   retro_camera_frame_opengl_texture_t frame_opengl_texture;
+
+   /* Set by libretro core. Called after camera driver is initialized and
+    * ready to be started.
+    * Can be NULL, in which this callback is not called.
+    */
+   retro_camera_lifetime_status_t initialized;
+
+   /* Set by libretro core. Called right before camera driver is
+    * deinitialized.
+    * Can be NULL, in which this callback is not called.
+    */
+   retro_camera_lifetime_status_t deinitialized;
+};
+
+/* Sets the interval of time and/or distance at which to update/poll
+ * location-based data.
+ *
+ * To ensure compatibility with all location-based implementations,
+ * values for both interval_ms and interval_distance should be provided.
+ *
+ * interval_ms is the interval expressed in milliseconds.
+ * interval_distance is the distance interval expressed in meters.
+ */
+typedef void (RETRO_CALLCONV *retro_location_set_interval_t)(unsigned interval_ms,
+      unsigned interval_distance);
+
+/* Start location services. The device will start listening for changes to the
+ * current location at regular intervals (which are defined with
+ * retro_location_set_interval_t). */
+typedef bool (RETRO_CALLCONV *retro_location_start_t)(void);
+
+/* Stop location services. The device will stop listening for changes
+ * to the current location. */
+typedef void (RETRO_CALLCONV *retro_location_stop_t)(void);
+
+/* Get the position of the current location. Will set parameters to
+ * 0 if no new  location update has happened since the last time. */
+typedef bool (RETRO_CALLCONV *retro_location_get_position_t)(double *lat, double *lon,
+      double *horiz_accuracy, double *vert_accuracy);
+
+/* Callback which signals when the location driver is initialized
+ * and/or deinitialized.
+ * retro_location_start_t can be called in initialized callback.
+ */
+typedef void (RETRO_CALLCONV *retro_location_lifetime_status_t)(void);
+
+struct retro_location_callback
+{
+   retro_location_start_t         start;
+   retro_location_stop_t          stop;
+   retro_location_get_position_t  get_position;
+   retro_location_set_interval_t  set_interval;
+
+   retro_location_lifetime_status_t initialized;
+   retro_location_lifetime_status_t deinitialized;
+};
+
+enum retro_rumble_effect
+{
+   RETRO_RUMBLE_STRONG = 0,
+   RETRO_RUMBLE_WEAK = 1,
+
+   RETRO_RUMBLE_DUMMY = INT_MAX
+};
+
+/* Sets rumble state for joypad plugged in port 'port'.
+ * Rumble effects are controlled independently,
+ * and setting e.g. strong rumble does not override weak rumble.
+ * Strength has a range of [0, 0xffff].
+ *
+ * Returns true if rumble state request was honored.
+ * Calling this before first retro_run() is likely to return false. */
+typedef bool (RETRO_CALLCONV *retro_set_rumble_state_t)(unsigned port,
+      enum retro_rumble_effect effect, uint16_t strength);
+
+struct retro_rumble_interface
+{
+   retro_set_rumble_state_t set_rumble_state;
+};
+
+/* Notifies libretro that audio data should be written. */
+typedef void (RETRO_CALLCONV *retro_audio_callback_t)(void);
+
+/* True: Audio driver in frontend is active, and callback is
+ * expected to be called regularily.
+ * False: Audio driver in frontend is paused or inactive.
+ * Audio callback will not be called until set_state has been
+ * called with true.
+ * Initial state is false (inactive).
+ */
+typedef void (RETRO_CALLCONV *retro_audio_set_state_callback_t)(bool enabled);
+
+struct retro_audio_callback
+{
+   retro_audio_callback_t callback;
+   retro_audio_set_state_callback_t set_state;
+};
+
+/* Notifies a libretro core of time spent since last invocation
+ * of retro_run() in microseconds.
+ *
+ * It will be called right before retro_run() every frame.
+ * The frontend can tamper with timing to support cases like
+ * fast-forward, slow-motion and framestepping.
+ *
+ * In those scenarios the reference frame time value will be used. */
+typedef int64_t retro_usec_t;
+typedef void (RETRO_CALLCONV *retro_frame_time_callback_t)(retro_usec_t usec);
+struct retro_frame_time_callback
+{
+   retro_frame_time_callback_t callback;
+   /* Represents the time of one frame. It is computed as
+    * 1000000 / fps, but the implementation will resolve the
+    * rounding to ensure that framestepping, etc is exact. */
+   retro_usec_t reference;
+};
+
+/* Pass this to retro_video_refresh_t if rendering to hardware.
+ * Passing NULL to retro_video_refresh_t is still a frame dupe as normal.
+ * */
+#define RETRO_HW_FRAME_BUFFER_VALID ((void*)-1)
+
+/* Invalidates the current HW context.
+ * Any GL state is lost, and must not be deinitialized explicitly.
+ * If explicit deinitialization is desired by the libretro core,
+ * it should implement context_destroy callback.
+ * If called, all GPU resources must be reinitialized.
+ * Usually called when frontend reinits video driver.
+ * Also called first time video driver is initialized,
+ * allowing libretro core to initialize resources.
+ */
+typedef void (RETRO_CALLCONV *retro_hw_context_reset_t)(void);
+
+/* Gets current framebuffer which is to be rendered to.
+ * Could change every frame potentially.
+ */
+typedef uintptr_t (RETRO_CALLCONV *retro_hw_get_current_framebuffer_t)(void);
+
+/* Get a symbol from HW context. */
+typedef retro_proc_address_t (RETRO_CALLCONV *retro_hw_get_proc_address_t)(const char *sym);
+
+enum retro_hw_context_type
+{
+   RETRO_HW_CONTEXT_NONE             = 0,
+   /* OpenGL 2.x. Driver can choose to use latest compatibility context. */
+   RETRO_HW_CONTEXT_OPENGL           = 1,
+   /* OpenGL ES 2.0. */
+   RETRO_HW_CONTEXT_OPENGLES2        = 2,
+   /* Modern desktop core GL context. Use version_major/
+    * version_minor fields to set GL version. */
+   RETRO_HW_CONTEXT_OPENGL_CORE      = 3,
+   /* OpenGL ES 3.0 */
+   RETRO_HW_CONTEXT_OPENGLES3        = 4,
+   /* OpenGL ES 3.1+. Set version_major/version_minor. For GLES2 and GLES3,
+    * use the corresponding enums directly. */
+   RETRO_HW_CONTEXT_OPENGLES_VERSION = 5,
+
+   /* Vulkan, see RETRO_ENVIRONMENT_GET_HW_RENDER_INTERFACE. */
+   RETRO_HW_CONTEXT_VULKAN           = 6,
+
+   RETRO_HW_CONTEXT_DUMMY = INT_MAX
+};
+
+struct retro_hw_render_callback
+{
+   /* Which API to use. Set by libretro core. */
+   enum retro_hw_context_type context_type;
+
+   /* Called when a context has been created or when it has been reset.
+    * An OpenGL context is only valid after context_reset() has been called.
+    *
+    * When context_reset is called, OpenGL resources in the libretro
+    * implementation are guaranteed to be invalid.
+    *
+    * It is possible that context_reset is called multiple times during an
+    * application lifecycle.
+    * If context_reset is called without any notification (context_destroy),
+    * the OpenGL context was lost and resources should just be recreated
+    * without any attempt to "free" old resources.
+    */
+   retro_hw_context_reset_t context_reset;
+
+   /* Set by frontend.
+    * TODO: This is rather obsolete. The frontend should not
+    * be providing preallocated framebuffers. */
+   retro_hw_get_current_framebuffer_t get_current_framebuffer;
+
+   /* Set by frontend.
+    * Can return all relevant functions, including glClear on Windows. */
+   retro_hw_get_proc_address_t get_proc_address;
+
+   /* Set if render buffers should have depth component attached.
+    * TODO: Obsolete. */
+   bool depth;
+
+   /* Set if stencil buffers should be attached.
+    * TODO: Obsolete. */
+   bool stencil;
+
+   /* If depth and stencil are true, a packed 24/8 buffer will be added.
+    * Only attaching stencil is invalid and will be ignored. */
+
+   /* Use conventional bottom-left origin convention. If false,
+    * standard libretro top-left origin semantics are used.
+    * TODO: Move to GL specific interface. */
+   bool bottom_left_origin;
+
+   /* Major version number for core GL context or GLES 3.1+. */
+   unsigned version_major;
+
+   /* Minor version number for core GL context or GLES 3.1+. */
+   unsigned version_minor;
+
+   /* If this is true, the frontend will go very far to avoid
+    * resetting context in scenarios like toggling fullscreen, etc.
+    * TODO: Obsolete? Maybe frontend should just always assume this ...
+    */
+   bool cache_context;
+
+   /* The reset callback might still be called in extreme situations
+    * such as if the context is lost beyond recovery.
+    *
+    * For optimal stability, set this to false, and allow context to be
+    * reset at any time.
+    */
+
+   /* A callback to be called before the context is destroyed in a
+    * controlled way by the frontend. */
+   retro_hw_context_reset_t context_destroy;
+
+   /* OpenGL resources can be deinitialized cleanly at this step.
+    * context_destroy can be set to NULL, in which resources will
+    * just be destroyed without any notification.
+    *
+    * Even when context_destroy is non-NULL, it is possible that
+    * context_reset is called without any destroy notification.
+    * This happens if context is lost by external factors (such as
+    * notified by GL_ARB_robustness).
+    *
+    * In this case, the context is assumed to be already dead,
+    * and the libretro implementation must not try to free any OpenGL
+    * resources in the subsequent context_reset.
+    */
+
+   /* Creates a debug context. */
+   bool debug_context;
+};
+
+/* Callback type passed in RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK.
+ * Called by the frontend in response to keyboard events.
+ * down is set if the key is being pressed, or false if it is being released.
+ * keycode is the RETROK value of the char.
+ * character is the text character of the pressed key. (UTF-32).
+ * key_modifiers is a set of RETROKMOD values or'ed together.
+ *
+ * The pressed/keycode state can be indepedent of the character.
+ * It is also possible that multiple characters are generated from a
+ * single keypress.
+ * Keycode events should be treated separately from character events.
+ * However, when possible, the frontend should try to synchronize these.
+ * If only a character is posted, keycode should be RETROK_UNKNOWN.
+ *
+ * Similarily if only a keycode event is generated with no corresponding
+ * character, character should be 0.
+ */
+typedef void (RETRO_CALLCONV *retro_keyboard_event_t)(bool down, unsigned keycode,
+      uint32_t character, uint16_t key_modifiers);
+
+struct retro_keyboard_callback
+{
+   retro_keyboard_event_t callback;
+};
+
+/* Callbacks for RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE.
+ * Should be set for implementations which can swap out multiple disk
+ * images in runtime.
+ *
+ * If the implementation can do this automatically, it should strive to do so.
+ * However, there are cases where the user must manually do so.
+ *
+ * Overview: To swap a disk image, eject the disk image with
+ * set_eject_state(true).
+ * Set the disk index with set_image_index(index). Insert the disk again
+ * with set_eject_state(false).
+ */
+
+/* If ejected is true, "ejects" the virtual disk tray.
+ * When ejected, the disk image index can be set.
+ */
+typedef bool (RETRO_CALLCONV *retro_set_eject_state_t)(bool ejected);
+
+/* Gets current eject state. The initial state is 'not ejected'. */
+typedef bool (RETRO_CALLCONV *retro_get_eject_state_t)(void);
+
+/* Gets current disk index. First disk is index 0.
+ * If return value is >= get_num_images(), no disk is currently inserted.
+ */
+typedef unsigned (RETRO_CALLCONV *retro_get_image_index_t)(void);
+
+/* Sets image index. Can only be called when disk is ejected.
+ * The implementation supports setting "no disk" by using an
+ * index >= get_num_images().
+ */
+typedef bool (RETRO_CALLCONV *retro_set_image_index_t)(unsigned index);
+
+/* Gets total number of images which are available to use. */
+typedef unsigned (RETRO_CALLCONV *retro_get_num_images_t)(void);
+
+struct retro_game_info;
+
+/* Replaces the disk image associated with index.
+ * Arguments to pass in info have same requirements as retro_load_game().
+ * Virtual disk tray must be ejected when calling this.
+ *
+ * Replacing a disk image with info = NULL will remove the disk image
+ * from the internal list.
+ * As a result, calls to get_image_index() can change.
+ *
+ * E.g. replace_image_index(1, NULL), and previous get_image_index()
+ * returned 4 before.
+ * Index 1 will be removed, and the new index is 3.
+ */
+typedef bool (RETRO_CALLCONV *retro_replace_image_index_t)(unsigned index,
+      const struct retro_game_info *info);
+
+/* Adds a new valid index (get_num_images()) to the internal disk list.
+ * This will increment subsequent return values from get_num_images() by 1.
+ * This image index cannot be used until a disk image has been set
+ * with replace_image_index. */
+typedef bool (RETRO_CALLCONV *retro_add_image_index_t)(void);
+
+struct retro_disk_control_callback
+{
+   retro_set_eject_state_t set_eject_state;
+   retro_get_eject_state_t get_eject_state;
+
+   retro_get_image_index_t get_image_index;
+   retro_set_image_index_t set_image_index;
+   retro_get_num_images_t  get_num_images;
+
+   retro_replace_image_index_t replace_image_index;
+   retro_add_image_index_t add_image_index;
+};
+
+enum retro_pixel_format
+{
+   /* 0RGB1555, native endian.
+    * 0 bit must be set to 0.
+    * This pixel format is default for compatibility concerns only.
+    * If a 15/16-bit pixel format is desired, consider using RGB565. */
+   RETRO_PIXEL_FORMAT_0RGB1555 = 0,
+
+   /* XRGB8888, native endian.
+    * X bits are ignored. */
+   RETRO_PIXEL_FORMAT_XRGB8888 = 1,
+
+   /* RGB565, native endian.
+    * This pixel format is the recommended format to use if a 15/16-bit
+    * format is desired as it is the pixel format that is typically
+    * available on a wide range of low-power devices.
+    *
+    * It is also natively supported in APIs like OpenGL ES. */
+   RETRO_PIXEL_FORMAT_RGB565   = 2,
+
+   /* Ensure sizeof() == sizeof(int). */
+   RETRO_PIXEL_FORMAT_UNKNOWN  = INT_MAX
+};
+
+struct retro_message
+{
+   const char *msg;        /* Message to be displayed. */
+   unsigned    frames;     /* Duration in frames of message. */
+};
+
+/* Describes how the libretro implementation maps a libretro input bind
+ * to its internal input system through a human readable string.
+ * This string can be used to better let a user configure input. */
+struct retro_input_descriptor
+{
+   /* Associates given parameters with a description. */
+   unsigned port;
+   unsigned device;
+   unsigned index;
+   unsigned id;
+
+   /* Human readable description for parameters.
+    * The pointer must remain valid until
+    * retro_unload_game() is called. */
+   const char *description;
+};
+
+struct retro_system_info
+{
+   /* All pointers are owned by libretro implementation, and pointers must
+    * remain valid until retro_deinit() is called. */
+
+   const char *library_name;      /* Descriptive name of library. Should not
+                                   * contain any version numbers, etc. */
+   const char *library_version;   /* Descriptive version of core. */
+
+   const char *valid_extensions;  /* A string listing probably content
+                                   * extensions the core will be able to
+                                   * load, separated with pipe.
+                                   * I.e. "bin|rom|iso".
+                                   * Typically used for a GUI to filter
+                                   * out extensions. */
+
+   /* If true, retro_load_game() is guaranteed to provide a valid pathname
+    * in retro_game_info::path.
+    * ::data and ::size are both invalid.
+    *
+    * If false, ::data and ::size are guaranteed to be valid, but ::path
+    * might not be valid.
+    *
+    * This is typically set to true for libretro implementations that must
+    * load from file.
+    * Implementations should strive for setting this to false, as it allows
+    * the frontend to perform patching, etc. */
+   bool        need_fullpath;
+
+   /* If true, the frontend is not allowed to extract any archives before
+    * loading the real content.
+    * Necessary for certain libretro implementations that load games
+    * from zipped archives. */
+   bool        block_extract;
+};
+
+struct retro_game_geometry
+{
+   unsigned base_width;    /* Nominal video width of game. */
+   unsigned base_height;   /* Nominal video height of game. */
+   unsigned max_width;     /* Maximum possible width of game. */
+   unsigned max_height;    /* Maximum possible height of game. */
+
+   float    aspect_ratio;  /* Nominal aspect ratio of game. If
+                            * aspect_ratio is <= 0.0, an aspect ratio
+                            * of base_width / base_height is assumed.
+                            * A frontend could override this setting,
+                            * if desired. */
+};
+
+struct retro_system_timing
+{
+   double fps;             /* FPS of video content. */
+   double sample_rate;     /* Sampling rate of audio. */
+};
+
+struct retro_system_av_info
+{
+   struct retro_game_geometry geometry;
+   struct retro_system_timing timing;
+};
+
+struct retro_variable
+{
+   /* Variable to query in RETRO_ENVIRONMENT_GET_VARIABLE.
+    * If NULL, obtains the complete environment string if more
+    * complex parsing is necessary.
+    * The environment string is formatted as key-value pairs
+    * delimited by semicolons as so:
+    * "key1=value1;key2=value2;..."
+    */
+   const char *key;
+
+   /* Value to be obtained. If key does not exist, it is set to NULL. */
+   const char *value;
+};
+
+struct retro_game_info
+{
+   const char *path;       /* Path to game, UTF-8 encoded.
+                            * Sometimes used as a reference for building other paths.
+                            * May be NULL if game was loaded from stdin or similar,
+                            * but in this case some cores will be unable to load `data`.
+                            * So, it is preferable to fabricate something here instead
+                            * of passing NULL, which will help more cores to succeed.
+                            * retro_system_info::need_fullpath requires
+                            * that this path is valid. */
+   const void *data;       /* Memory buffer of loaded game. Will be NULL
+                            * if need_fullpath was set. */
+   size_t      size;       /* Size of memory buffer. */
+   const char *meta;       /* String of implementation specific meta-data. */
+};
+
+#define RETRO_MEMORY_ACCESS_WRITE (1 << 0)
+   /* The core will write to the buffer provided by retro_framebuffer::data. */
+#define RETRO_MEMORY_ACCESS_READ (1 << 1)
+   /* The core will read from retro_framebuffer::data. */
+#define RETRO_MEMORY_TYPE_CACHED (1 << 0)
+   /* The memory in data is cached.
+    * If not cached, random writes and/or reading from the buffer is expected to be very slow. */
+struct retro_framebuffer
+{
+   void *data;                      /* The framebuffer which the core can render into.
+                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER.
+                                       The initial contents of data are unspecified. */
+   unsigned width;                  /* The framebuffer width used by the core. Set by core. */
+   unsigned height;                 /* The framebuffer height used by the core. Set by core. */
+   size_t pitch;                    /* The number of bytes between the beginning of a scanline,
+                                       and beginning of the next scanline.
+                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
+   enum retro_pixel_format format;  /* The pixel format the core must use to render into data.
+                                       This format could differ from the format used in
+                                       SET_PIXEL_FORMAT.
+                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
+
+   unsigned access_flags;           /* How the core will access the memory in the framebuffer.
+                                       RETRO_MEMORY_ACCESS_* flags.
+                                       Set by core. */
+   unsigned memory_flags;           /* Flags telling core how the memory has been mapped.
+                                       RETRO_MEMORY_TYPE_* flags.
+                                       Set by frontend in GET_CURRENT_SOFTWARE_FRAMEBUFFER. */
+};
+
+/* Callbacks */
+
+/* Environment callback. Gives implementations a way of performing
+ * uncommon tasks. Extensible. */
+typedef bool (RETRO_CALLCONV *retro_environment_t)(unsigned cmd, void *data);
+
+/* Render a frame. Pixel format is 15-bit 0RGB1555 native endian
+ * unless changed (see RETRO_ENVIRONMENT_SET_PIXEL_FORMAT).
+ *
+ * Width and height specify dimensions of buffer.
+ * Pitch specifices length in bytes between two lines in buffer.
+ *
+ * For performance reasons, it is highly recommended to have a frame
+ * that is packed in memory, i.e. pitch == width * byte_per_pixel.
+ * Certain graphic APIs, such as OpenGL ES, do not like textures
+ * that are not packed in memory.
+ */
+typedef void (RETRO_CALLCONV *retro_video_refresh_t)(const void *data, unsigned width,
+      unsigned height, size_t pitch);
+
+/* Renders a single audio frame. Should only be used if implementation
+ * generates a single sample at a time.
+ * Format is signed 16-bit native endian.
+ */
+typedef void (RETRO_CALLCONV *retro_audio_sample_t)(int16_t left, int16_t right);
+
+/* Renders multiple audio frames in one go.
+ *
+ * One frame is defined as a sample of left and right channels, interleaved.
+ * I.e. int16_t buf[4] = { l, r, l, r }; would be 2 frames.
+ * Only one of the audio callbacks must ever be used.
+ */
+typedef size_t (RETRO_CALLCONV *retro_audio_sample_batch_t)(const int16_t *data,
+      size_t frames);
+
+/* Polls input. */
+typedef void (RETRO_CALLCONV *retro_input_poll_t)(void);
+
+/* Queries for input for player 'port'. device will be masked with
+ * RETRO_DEVICE_MASK.
+ *
+ * Specialization of devices such as RETRO_DEVICE_JOYPAD_MULTITAP that
+ * have been set with retro_set_controller_port_device()
+ * will still use the higher level RETRO_DEVICE_JOYPAD to request input.
+ */
+typedef int16_t (RETRO_CALLCONV *retro_input_state_t)(unsigned port, unsigned device,
+      unsigned index, unsigned id);
+
+/* Sets callbacks. retro_set_environment() is guaranteed to be called
+ * before retro_init().
+ *
+ * The rest of the set_* functions are guaranteed to have been called
+ * before the first call to retro_run() is made. */
+RETRO_API void retro_set_environment(retro_environment_t);
+RETRO_API void retro_set_video_refresh(retro_video_refresh_t);
+RETRO_API void retro_set_audio_sample(retro_audio_sample_t);
+RETRO_API void retro_set_audio_sample_batch(retro_audio_sample_batch_t);
+RETRO_API void retro_set_input_poll(retro_input_poll_t);
+RETRO_API void retro_set_input_state(retro_input_state_t);
+
+/* Library global initialization/deinitialization. */
+RETRO_API void retro_init(void);
+RETRO_API void retro_deinit(void);
+
+/* Must return RETRO_API_VERSION. Used to validate ABI compatibility
+ * when the API is revised. */
+RETRO_API unsigned retro_api_version(void);
+
+/* Gets statically known system info. Pointers provided in *info
+ * must be statically allocated.
+ * Can be called at any time, even before retro_init(). */
+RETRO_API void retro_get_system_info(struct retro_system_info *info);
+
+/* Gets information about system audio/video timings and geometry.
+ * Can be called only after retro_load_game() has successfully completed.
+ * NOTE: The implementation of this function might not initialize every
+ * variable if needed.
+ * E.g. geom.aspect_ratio might not be initialized if core doesn't
+ * desire a particular aspect ratio. */
+RETRO_API void retro_get_system_av_info(struct retro_system_av_info *info);
+
+/* Sets device to be used for player 'port'.
+ * By default, RETRO_DEVICE_JOYPAD is assumed to be plugged into all
+ * available ports.
+ * Setting a particular device type is not a guarantee that libretro cores
+ * will only poll input based on that particular device type. It is only a
+ * hint to the libretro core when a core cannot automatically detect the
+ * appropriate input device type on its own. It is also relevant when a
+ * core can change its behavior depending on device type. */
+RETRO_API void retro_set_controller_port_device(unsigned port, unsigned device);
+
+/* Resets the current game. */
+RETRO_API void retro_reset(void);
+
+/* Runs the game for one video frame.
+ * During retro_run(), input_poll callback must be called at least once.
+ *
+ * If a frame is not rendered for reasons where a game "dropped" a frame,
+ * this still counts as a frame, and retro_run() should explicitly dupe
+ * a frame if GET_CAN_DUPE returns true.
+ * In this case, the video callback can take a NULL argument for data.
+ */
+RETRO_API void retro_run(void);
+
+/* Returns the amount of data the implementation requires to serialize
+ * internal state (save states).
+ * Between calls to retro_load_game() and retro_unload_game(), the
+ * returned size is never allowed to be larger than a previous returned
+ * value, to ensure that the frontend can allocate a save state buffer once.
+ */
+RETRO_API size_t retro_serialize_size(void);
+
+/* Serializes internal state. If failed, or size is lower than
+ * retro_serialize_size(), it should return false, true otherwise. */
+RETRO_API bool retro_serialize(void *data, size_t size);
+RETRO_API bool retro_unserialize(const void *data, size_t size);
+
+RETRO_API void retro_cheat_reset(void);
+RETRO_API void retro_cheat_set(unsigned index, bool enabled, const char *code);
+
+/* Loads a game. */
+RETRO_API bool retro_load_game(const struct retro_game_info *game);
+
+/* Loads a "special" kind of game. Should not be used,
+ * except in extreme cases. */
+RETRO_API bool retro_load_game_special(
+  unsigned game_type,
+  const struct retro_game_info *info, size_t num_info
+);
+
+/* Unloads a currently loaded game. */
+RETRO_API void retro_unload_game(void);
+
+/* Gets region of game. */
+RETRO_API unsigned retro_get_region(void);
+
+/* Gets region of memory. */
+RETRO_API void *retro_get_memory_data(unsigned id);
+RETRO_API size_t retro_get_memory_size(unsigned id);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif