Add ability to manually set default core option values when using the new v1 core options interface

libretro-common/include/libretro.h

@@ -1142,7 +1142,7 @@ enum retro_mod
                                             * options must not change from the number in the initial call.
                                             *
                                             * 'data' points to an array of retro_core_option_definition structs
-                                            * terminated by a { NULL, NULL, NULL, {{0}} } element.
+                                            * terminated by a { NULL, NULL, NULL, {{0}}, NULL } element.
                                             * retro_core_option_definition::key should be namespaced to not collide
                                             * with other implementations' keys. e.g. A core called
                                             * 'foo' should use keys named as 'foo_option'.
@@ -1151,13 +1151,18 @@ enum retro_mod
                                             * retro_core_option_definition::info should contain any additional human
                                             * readable information text that a typical user may need to
                                             * understand the functionality of the option.
-                                            * retro_variable::values is an array of retro_core_option_value
+                                            * retro_core_option_definition::values is an array of retro_core_option_value
                                             * structs terminated by a { NULL, NULL } element.
-                                            * > retro_variable::values[index].value is an expected option
+                                            * > retro_core_option_definition::values[index].value is an expected option
                                             *   value.
-                                            * > retro_variable::values[index].label is a human readable
+                                            * > retro_core_option_definition::values[index].label is a human readable
                                             *   label used when displaying the value on screen. If NULL,
                                             *   the value itself is used.
+                                            * retro_core_option_definition::default_value is the default core option
+                                            * setting. It must match one of the expected option values in the
+                                            * retro_core_option_definition::values array. If it does not, or the
+                                            * default value is NULL, the first entry in the
+                                            * retro_core_option_definition::values array is treated as the default.
                                             *
                                             * The number of possible options should be very limited,
                                             * and must be less than RETRO_NUM_CORE_OPTION_VALUES_MAX.
@@ -1176,7 +1181,8 @@ enum retro_mod
                                             *         { "true",     NULL },
                                             *         { "unstable", "Turbo (Unstable)" },
                                             *         { NULL, NULL },
-                                            *     }
+                                            *     },
+                                            *     "false"
                                             * }
                                             *
                                             * Only strings are operated on. The possible values will
@@ -1216,6 +1222,10 @@ enum retro_mod
                                             * retro_core_options_intl::us is used by the frontend). Any items
                                             * missing from this array will be read from retro_core_options_intl::us
                                             * instead.
+                                            *
+                                            * NOTE: Default core option values are always taken from the
+                                            * retro_core_options_intl::us array. Any default values in
+                                            * retro_core_options_intl::local array will be ignored.
                                             */
 
 #define RETRO_ENVIRONMENT_SET_CORE_OPTIONS_DISPLAY 55
@@ -2521,6 +2531,11 @@ struct retro_core_option_definition
 
    /* Array of retro_core_option_value structs, terminated by NULL */
    struct retro_core_option_value values[RETRO_NUM_CORE_OPTION_VALUES_MAX];
+
+   /* Default core option value. Must match one of the values
+    * in the retro_core_option_value array, otherwise will be
+    * ignored */
+   const char *default_value;
 };
 
 struct retro_core_options_intl

managers/core_option_manager.h

@@ -34,6 +34,7 @@ struct core_option
    char *key;
    struct string_list *vals;
    struct string_list *val_labels;
+   size_t default_index;
    size_t index;
    bool visible;
 };

retroarch.c

@@ -1725,6 +1725,11 @@ static bool core_option_manager_parse_variable(
    if (!option->val_labels)
       goto error;
 
+   /* Legacy core option interface always uses first
+    * defined value as the default */
+   option->default_index = 0;
+   option->index         = 0;
+
    if (config_get_string(opt->conf, option->key, &config_val))
    {
       size_t i;
@@ -1793,6 +1798,10 @@ static bool core_option_manager_parse_option(
    if (!option->vals || !option->val_labels)
       return false;
 
+   /* Initialse default value */
+   option->default_index = 0;
+   option->index         = 0;
+
    /* Extract value/label pairs */
    for (i = 0; i < num_vals; i++)
    {
@@ -1804,6 +1813,16 @@ static bool core_option_manager_parse_option(
          string_list_append(option->val_labels, values[i].label, attr);
       else
          string_list_append(option->val_labels, values[i].value, attr);
+
+      /* Check whether this value is the default setting */
+      if (!string_is_empty(option_def->default_value))
+      {
+         if (string_is_equal(option_def->default_value, values[i].value))
+         {
+            option->default_index = i;
+            option->index         = i;
+         }
+      }
    }
 
    /* Set current config value */
@@ -2189,7 +2208,7 @@ void core_option_manager_set_default(core_option_manager_t *opt, size_t idx)
    if (idx >= opt->size)
       return;
 
-   opt->opts[idx].index = 0;
+   opt->opts[idx].index = opt->opts[idx].default_index;
    opt->updated         = true;
 }
 
@@ -2246,6 +2265,9 @@ static struct retro_core_option_definition *core_option_manager_get_definitions(
       /* Key is always taken from us english defs */
       option_defs[i].key = key;
 
+      /* Default value is always taken from us english defs */
+      option_defs[i].default_value = option_defs_us[i].default_value;
+
       /* Try to find corresponding entry in local defs array */
       if (option_defs_local)
       {