+#define RETRO_ENVIRONMENT_GET_PREFERRED_HW_RENDER 56
+ /* unsigned * --
+ *
+ * Allows an implementation to ask frontend preferred hardware
+ * context to use. Core should use this information to deal
+ * with what specific context to request with SET_HW_RENDER.
+ *
+ * 'data' points to an unsigned variable
+ */
+
+#define RETRO_ENVIRONMENT_GET_DISK_CONTROL_INTERFACE_VERSION 57
+ /* unsigned * --
+ * Unsigned value is the API version number of the disk control
+ * interface supported by the frontend. If callback return false,
+ * API version is assumed to be 0.
+ *
+ * In legacy code, the disk control interface is defined by passing
+ * a struct of type retro_disk_control_callback to
+ * RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE.
+ * This may be still be done regardless of the disk control
+ * interface version.
+ *
+ * If version is >= 1 however, the disk control interface may
+ * instead be defined by passing a struct of type
+ * retro_disk_control_ext_callback to
+ * RETRO_ENVIRONMENT_SET_DISK_CONTROL_EXT_INTERFACE.
+ * This allows the core to provide additional information about
+ * disk images to the frontend and/or enables extra
+ * disk control functionality by the frontend.
+ */
+
+#define RETRO_ENVIRONMENT_SET_DISK_CONTROL_EXT_INTERFACE 58
+ /* const struct retro_disk_control_ext_callback * --
+ * Sets an interface which frontend can use to eject and insert
+ * disk images, and also obtain information about individual
+ * disk image files registered by the core.
+ * This is used for games which consist of multiple images and
+ * must be manually swapped out by the user (e.g. PSX, floppy disk
+ * based systems).
+ */
+
+#define RETRO_ENVIRONMENT_GET_MESSAGE_INTERFACE_VERSION 59
+ /* unsigned * --
+ * Unsigned value is the API version number of the message
+ * interface supported by the frontend. If callback returns
+ * false, API version is assumed to be 0.
+ *
+ * In legacy code, messages may be displayed in an
+ * implementation-specific manner by passing a struct
+ * of type retro_message to RETRO_ENVIRONMENT_SET_MESSAGE.
+ * This may be still be done regardless of the message
+ * interface version.
+ *
+ * If version is >= 1 however, messages may instead be
+ * displayed by passing a struct of type retro_message_ext
+ * to RETRO_ENVIRONMENT_SET_MESSAGE_EXT. This allows the
+ * core to specify message logging level, priority and
+ * destination (OSD, logging interface or both).
+ */
+
+#define RETRO_ENVIRONMENT_SET_MESSAGE_EXT 60
+ /* const struct retro_message_ext * --
+ * Sets a message to be displayed in an implementation-specific
+ * manner for a certain amount of 'frames'. Additionally allows
+ * the core to specify message logging level, priority and
+ * destination (OSD, logging interface or both).
+ * 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_GET_INPUT_MAX_USERS 61
+ /* unsigned * --
+ * Unsigned value is the number of active input devices
+ * provided by the frontend. This may change between
+ * frames, but will remain constant for the duration
+ * of each frame.
+ * If callback returns true, a core need not poll any
+ * input device with an index greater than or equal to
+ * the number of active devices.
+ * If callback returns false, the number of active input
+ * devices is unknown. In this case, all input devices
+ * should be considered active.
+ */
+
+#define RETRO_ENVIRONMENT_SET_AUDIO_BUFFER_STATUS_CALLBACK 62
+ /* const struct retro_audio_buffer_status_callback * --
+ * Lets the core know the occupancy level of the frontend
+ * audio buffer. Can be used by a core to attempt frame
+ * skipping in order to avoid buffer under-runs.
+ * A core may pass NULL to disable buffer status reporting
+ * in the frontend.
+ */
+
+#define RETRO_ENVIRONMENT_SET_MINIMUM_AUDIO_LATENCY 63
+ /* const unsigned * --
+ * Sets minimum frontend audio latency in milliseconds.
+ * Resultant audio latency may be larger than set value,
+ * or smaller if a hardware limit is encountered. A frontend
+ * is expected to honour requests up to 512 ms.
+ *
+ * - If value is less than current frontend
+ * audio latency, callback has no effect
+ * - If value is zero, default frontend audio
+ * latency is set
+ *
+ * May be used by a core to increase audio latency and
+ * therefore decrease the probability of buffer under-runs
+ * (crackling) when performing 'intensive' operations.
+ * A core utilising RETRO_ENVIRONMENT_SET_AUDIO_BUFFER_STATUS_CALLBACK
+ * to implement audio-buffer-based frame skipping may achieve
+ * optimal results by setting the audio latency to a 'high'
+ * (typically 6x or 8x) integer multiple of the expected
+ * frame time.
+ *
+ * WARNING: This can only be called from within retro_run().
+ * Calling this can require a full reinitialization of 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 audio
+ * callbacks happening after this call within the same retro_run()
+ * call will target the newly initialized driver.
+ */
+