Add RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS.

dynamic.c

@@ -352,6 +352,49 @@ static bool environment_cb(unsigned cmd, void *data)
          break;
       }
 
+      case RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS:
+      {
+         memset(g_extern.system.input_desc_btn, 0, sizeof(g_extern.system.input_desc_btn));
+
+         const struct retro_input_descriptor *desc = (const struct retro_input_descriptor*)data;
+         for (; desc->description; desc++)
+         {
+            if (desc->port >= MAX_PLAYERS)
+               continue;
+
+            if (desc->device != RETRO_DEVICE_JOYPAD) // Ignore all others for now.
+               continue;
+
+            if (desc->id >= RARCH_FIRST_ANALOG_BIND)
+               continue;
+
+            g_extern.system.input_desc_btn[desc->port][desc->id] = desc->description;
+         }
+
+         static const char *libretro_btn_desc[] = {
+            "B (bottom)", "Y (left)", "Select", "Start",
+            "D-Pad Up", "D-Pad Down", "D-Pad Left", "D-Pad Right",
+            "A (right)", "X (up)",
+            "L", "R", "L2", "R2", "L3", "R3",
+         };
+
+         RARCH_LOG("Environ SET_INPUT_DESCRIPTORS:\n");
+         for (unsigned p = 0; p < MAX_PLAYERS; p++)
+         {
+            for (unsigned id = 0; id < RARCH_FIRST_ANALOG_BIND; id++)
+            {
+               const char *desc = g_extern.system.input_desc_btn[p][id];
+               if (desc)
+               {
+                  RARCH_LOG("\tRetroPad, Player %u, Button \"%s\" => \"%s\"\n",
+                        p + 1, libretro_btn_desc[id], desc);
+               }
+            }
+         }
+
+         break;
+      }
+
       default:
          RARCH_LOG("Environ UNSUPPORTED (#%u).\n", cmd);
          return false;

general.h

@@ -344,6 +344,8 @@ struct global
       bool rgb32;
 
       bool force_nonblock;
+
+      const char *input_desc_btn[MAX_PLAYERS][RARCH_FIRST_ANALOG_BIND];
    } system;
 
    struct

libretro-test/libretro-test.c

@@ -170,6 +170,16 @@ void retro_run(void)
 
 bool retro_load_game(const struct retro_game_info *info)
 {
+   struct retro_input_descriptor desc[] = {
+      { .port = 0, .device = RETRO_DEVICE_JOYPAD, .index = 0, .id = RETRO_DEVICE_ID_JOYPAD_LEFT,  .description = "Left" },
+      { .port = 0, .device = RETRO_DEVICE_JOYPAD, .index = 0, .id = RETRO_DEVICE_ID_JOYPAD_UP,    .description = "Up" },
+      { .port = 0, .device = RETRO_DEVICE_JOYPAD, .index = 0, .id = RETRO_DEVICE_ID_JOYPAD_DOWN,  .description = "Down" },
+      { .port = 0, .device = RETRO_DEVICE_JOYPAD, .index = 0, .id = RETRO_DEVICE_ID_JOYPAD_RIGHT, .description = "Right" },
+      { 0 },
+   };
+
+   environ_cb(RETRO_ENVIRONMENT_SET_INPUT_DESCRIPTORS, desc);
+
    (void)info;
    return true;
 }

libretro.h

@@ -357,6 +357,14 @@ enum retro_key
                                            // The default pixel format is RETRO_PIXEL_FORMAT_0RGB1555.
                                            // 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.
+
 
 enum retro_pixel_format
 {
@@ -370,8 +378,25 @@ struct retro_message
    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;
+
+   const char *description; // Human readable description for parameters.
+                            // The pointer must remain valid until retro_unload_game() is called.
+};
+
 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.