Add preliminary disk swapping interface.

Works with Mednafen's disk swapping model.

config.def.h

@@ -515,6 +515,8 @@ static const bool input_autodetect_enable = true;
 #define RETRO_LBL_VOLUME_UP "Volume Up"
 #define RETRO_LBL_VOLUME_DOWN "Volume Down"
 #define RETRO_LBL_OVERLAY_NEXT "Next Overlay"
+#define RETRO_LBL_DISK_EJECT_TOGGLE "Disk Eject Toggle"
+#define RETRO_LBL_DISK_NEXT "Disk Swap Next"
 
 // Player 1
 static const struct retro_keybind retro_keybinds_1[] = {
@@ -583,6 +585,8 @@ static const struct retro_keybind retro_keybinds_1[] = {
    { true, RARCH_VOLUME_UP,                RETRO_LBL_VOLUME_UP,            RETROK_KP_PLUS, NO_BTN,      AXIS_NONE },
    { true, RARCH_VOLUME_DOWN,              RETRO_LBL_VOLUME_DOWN,          RETROK_KP_MINUS,NO_BTN,      AXIS_NONE },
    { true, RARCH_OVERLAY_NEXT,             RETRO_LBL_OVERLAY_NEXT,         RETROK_UNKNOWN, NO_BTN,      AXIS_NONE },
+   { true, RARCH_DISK_EJECT_TOGGLE,        RETRO_LBL_DISK_EJECT_TOGGLE,    RETROK_UNKNOWN, NO_BTN,      AXIS_NONE },
+   { true, RARCH_DISK_NEXT,                RETRO_LBL_DISK_NEXT,            RETROK_UNKNOWN, NO_BTN,      AXIS_NONE },
 };
 
 // Player 2-5

driver.h

@@ -105,6 +105,8 @@ enum // RetroArch specific bind IDs.
    RARCH_VOLUME_UP,
    RARCH_VOLUME_DOWN,
    RARCH_OVERLAY_NEXT,
+   RARCH_DISK_EJECT_TOGGLE,
+   RARCH_DISK_NEXT,
 
 #ifdef RARCH_CONSOLE
    RARCH_CHEAT_INPUT,

dynamic.c

@@ -485,13 +485,17 @@ static bool environment_cb(unsigned cmd, void *data)
       
       case RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK:
       {
+         RARCH_LOG("Environ SET_KEYBOARD_CALLBACK.\n");
          const struct retro_keyboard_callback *info = (const struct retro_keyboard_callback*)data;
-      
          g_extern.system.key_event = info->callback;
-      
          break;
       }
 
+      case RETRO_ENVIRONMENT_SET_DISK_CONTROL_INTERFACE:
+         RARCH_LOG("Environ SET_DISK_CONTROL_INTERFACE.\n");
+         g_extern.system.disk_control = *(const struct retro_disk_control_callback*)data;
+         break;
+
       default:
          RARCH_LOG("Environ UNSUPPORTED (#%u).\n", cmd);
          return false;
@@ -505,7 +509,6 @@ static void set_environment(void)
    pretro_set_environment(environment_cb);
 }
 
-// Assume SNES as defaults.
 static void set_environment_defaults(void)
 {
    char *save;

general.h

@@ -380,6 +380,8 @@ struct global
       char valid_extensions[PATH_MAX];
       
       retro_keyboard_event_t key_event;
+
+      struct retro_disk_control_callback disk_control; 
    } system;
 
    struct

input/input_common.c

@@ -549,6 +549,8 @@ static const struct str_to_bind_map str_to_bind[] = {
    { "volume_up",             RARCH_VOLUME_UP },
    { "volume_down",           RARCH_VOLUME_DOWN },
    { "overlay_next",          RARCH_OVERLAY_NEXT },
+   { "disk_eject_toggle",     RARCH_DISK_EJECT_TOGGLE },
+   { "disk_next",             RARCH_DISK_NEXT },
 };
 
 unsigned input_str_to_bind(const char *str)

libretro.h

@@ -415,6 +415,12 @@ enum retro_mod
 #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).
 
 
 // Callback type passed in RETRO_ENVIRONMENT_SET_KEYBOARD_CALLBACK. Called by the frontend in response to keyboard events.
@@ -429,6 +435,37 @@ struct retro_keyboard_callback
     retro_keyboard_event_t callback;
 };
 
+// Callback 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_set_eject_state_t)(bool ejected);
+// Gets current eject state. The initial state is not ejected.
+typedef bool (*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_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_set_image_index_t)(unsigned index);
+// Gets total number of images which are available to use.
+typedef unsigned (*retro_get_num_images_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;
+};
+
 enum retro_pixel_format
 {
    // 0RGB1555, native endian. 0 bit must be set to 0.

retroarch.c

@@ -2390,6 +2390,77 @@ static void check_cheats(void)
    old_pressed_toggle = pressed_toggle;
 }
 
+static void check_disk(void)
+{
+   const struct retro_disk_control_callback *control = &g_extern.system.disk_control;
+   if (!control->get_num_images)
+      return;
+
+   static bool old_pressed_eject;
+   static bool old_pressed_next;
+
+   bool pressed_eject = input_key_pressed_func(RARCH_DISK_EJECT_TOGGLE);
+   bool pressed_next  = input_key_pressed_func(RARCH_DISK_NEXT);
+   bool error = false;
+   char msg[256];
+   *msg = '\0';
+
+   if (pressed_eject && !old_pressed_eject)
+   {
+      bool new_state = !control->get_eject_state();
+      if (control->set_eject_state(new_state))
+         snprintf(msg, sizeof(msg), "%s virtual disk tray.", new_state ? "Ejected" : "Closed");
+      else
+      {
+         error = true;
+         snprintf(msg, sizeof(msg), "Failed to %s virtual disk tray.", new_state ? "eject" : "close");
+      }
+   }
+   else if (pressed_next && !old_pressed_next)
+   {
+      unsigned num_disks = control->get_num_images();
+      unsigned current   = control->get_image_index();
+      if (num_disks && num_disks != UINT_MAX)
+      {
+         // Use "no disk" state when index == num_disks.
+         unsigned next_index = current >= num_disks ? 0 : ((current + 1) % (num_disks + 1));
+         if (control->set_image_index(next_index))
+         {
+            if (next_index < num_disks)
+               snprintf(msg, sizeof(msg), "Setting disk %u of %u in tray.", next_index + 1, num_disks);
+            else
+               snprintf(msg, sizeof(msg), "Removed disk from tray.");
+         }
+         else
+         {
+            if (next_index < num_disks)
+               snprintf(msg, sizeof(msg), "Failed to set disk %u of %u.", next_index + 1, num_disks);
+            else
+               snprintf(msg, sizeof(msg), "Failed to remove disk from tray.");
+            error = true;
+         }
+      }
+      else
+      {
+         snprintf(msg, sizeof(msg), "Got invalid disk index from libretro.");
+         error = true;
+      }
+   }
+
+   if (*msg)
+   {
+      if (error)
+         RARCH_ERR("%s\n", msg);
+      else
+         RARCH_LOG("%s\n", msg);
+      msg_queue_clear(g_extern.msg_queue);
+      msg_queue_push(g_extern.msg_queue, msg, 1, 180);
+   }
+
+   old_pressed_eject = pressed_eject;
+   old_pressed_next  = pressed_next;
+}
+
 #if defined(HAVE_SCREENSHOTS) && !defined(_XBOX)
 static void check_screenshot(void)
 {
@@ -2562,6 +2633,7 @@ static void do_state_checks(void)
      
       check_shader_dir();
       check_cheats();
+      check_disk();
 
 #ifdef HAVE_DYLIB
       check_dsp_config();

retroarch.cfg

@@ -380,6 +380,13 @@
 # Toggles to next overlay. Wraps around.
 # input_overlay_next =
 
+# Toggles eject for disks. Used for multiple-disk games.
+# input_disk_eject_toggle =
+
+# Cycles through disk images. Use after ejecting.
+# Complete by toggling eject again.
+# input_disk_next =
+
 #### Misc
 
 # Enable rewinding. This will take a performance hit when playing, so it is disabled by default.

settings.c

@@ -825,6 +825,8 @@ static const struct bind_map bind_maps[MAX_PLAYERS][RARCH_BIND_LIST_END_NULL] =
       DECLARE_BIND(volume_up,             RARCH_VOLUME_UP),
       DECLARE_BIND(volume_down,           RARCH_VOLUME_DOWN),
       DECLARE_BIND(overlay_next,          RARCH_OVERLAY_NEXT),
+      DECLARE_BIND(disk_eject_toggle,     RARCH_DISK_EJECT_TOGGLE),
+      DECLARE_BIND(disk_next,             RARCH_DISK_NEXT),
    },
 
    { DECL_PLAYER(2) },