Document some faraway_island code

2 files changed, 68 insertions, 67 deletions

diff --git a/src/event_object_movement.c b/src/event_object_movement.c
index 30dffd8d7..6a3527bc1 100644
--- a/src/event_object_movement.c
+++ b/src/event_object_movement.c
@@ -4414,8 +4414,8 @@ bool8 CopyablePlayerMovement_GoSpeed0(struct EventObject *eventObject, struct Sp
     direction = playerDirection;
     if (EventObjectIsFarawayIslandMew(eventObject))
     {
-        direction = sub_81D427C();
-        if (direction == 0)
+        direction = GetMewMoveDirection();
+        if (direction == DIR_NONE)
         {
             direction = playerDirection;
             direction = state_to_direction(gInitialMovementTypeFacingDirections[eventObject->movementType], eventObject->directionSequenceIndex, direction);
diff --git a/src/faraway_island.c b/src/faraway_island.c
index 1c8dff14e..6a835a02b 100755
--- a/src/faraway_island.c
+++ b/src/faraway_island.c
@@ -17,12 +17,13 @@ static u8 sub_81D4C9C(struct EventObject*, u8);
 static u8 sub_81D4C58(struct EventObject*, u8);
 static u8 sub_81D4CE0(struct EventObject*, u8);
 static u8 sub_81D4D24(u8);
-static bool8 sub_81D4834(s16, s16);
+static bool8 CanMewWalkToCoords(s16, s16);
 
-extern u8 gUnknown_0203CF50;
-extern s16 gUnknown_030012F8;
-extern s16 gUnknown_030012FA;
-extern u8 gUnknown_030012FC[4];
+static EWRAM_DATA u8 sUnknown_0203CF50 = 0;
+
+static s16 sPlayerToMewDeltaX;
+static s16 sPlayerToMewDeltaY;
+static u8 sMewDirectionCandidates[4];
 
 extern const struct SpritePalette gFieldEffectObjectPaletteInfo1;
 extern const struct SpriteTemplate *const gFieldEffectObjectTemplatePointers[];
@@ -35,23 +36,23 @@ static const s16 sFarawayIslandRockCoords[4][2] =
     {20, 20},
 };
 
-static u8 sub_81D4258(void)
+static u8 GetMewEventObjectId(void)
 {
     u8 eventObjectId;
     TryGetEventObjectIdByLocalIdAndMap(1, gSaveBlock1Ptr->location.mapNum, gSaveBlock1Ptr->location.mapGroup, &eventObjectId);
     return eventObjectId;
 }
 
-u32 sub_81D427C(void)
+u32 GetMewMoveDirection(void)
 {
     u8 i;
     int skip;
-    struct EventObject *mew = &gEventObjects[sub_81D4258()];
+    struct EventObject *mew = &gEventObjects[GetMewEventObjectId()];
 
-    gUnknown_030012F8 = gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x - mew->currentCoords.x;
-    gUnknown_030012FA = gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y - mew->currentCoords.y;
-    for (i = 0; i < ARRAY_COUNT(gUnknown_030012FC); i++)
-        gUnknown_030012FC[i] = DIR_NONE;
+    sPlayerToMewDeltaX = gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x - mew->currentCoords.x;
+    sPlayerToMewDeltaY = gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y - mew->currentCoords.y;
+    for (i = 0; i < ARRAY_COUNT(sMewDirectionCandidates); i++)
+        sMewDirectionCandidates[i] = DIR_NONE;
 
     if (gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x == gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.x
      && gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y == gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.y)
@@ -85,33 +86,33 @@ u32 sub_81D427C(void)
 
             if (!skip)
             {
-                if (gUnknown_030012F8 > 0)
+                if (sPlayerToMewDeltaX > 0)
                 {
                     if (mew->currentCoords.x + 1 == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x)
                     {
-                        if (sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y))
+                        if (CanMewWalkToCoords(mew->currentCoords.x + 1, mew->currentCoords.y))
                             return DIR_EAST;
                     }
                 }
-                else if (gUnknown_030012F8 < 0)
+                else if (sPlayerToMewDeltaX < 0)
                 {
                     if (mew->currentCoords.x - 1 == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x)
                     {
-                        if (sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y))
+                        if (CanMewWalkToCoords(mew->currentCoords.x - 1, mew->currentCoords.y))
                             return DIR_WEST;
                     }
                 }
 
                 if (mew->currentCoords.x == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x)
                 {
-                    if (gUnknown_030012FA > 0)
+                    if (sPlayerToMewDeltaY > 0)
                     {
-                        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1))
+                        if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y - 1))
                             return DIR_NORTH;
                     }
                     else
                     {
-                        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1))
+                        if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y + 1))
                             return DIR_SOUTH;
                     }
                 }
@@ -134,33 +135,33 @@ u32 sub_81D427C(void)
 
             if (!skip)
             {
-                if (gUnknown_030012FA > 0)
+                if (sPlayerToMewDeltaY > 0)
                 {
                     if (mew->currentCoords.y + 1 == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y)
                     {
-                        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1))
+                        if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y + 1))
                             return DIR_SOUTH;
                     }
                 }
-                else if (gUnknown_030012FA < 0)
+                else if (sPlayerToMewDeltaY < 0)
                 {
                     if (mew->currentCoords.y - 1 == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y)
                     {
-                        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1))
+                        if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y - 1))
                             return DIR_NORTH;
                     }
                 }
 
                 if (mew->currentCoords.y == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y)
                 {
-                    if (gUnknown_030012F8 > 0)
+                    if (sPlayerToMewDeltaX > 0)
                     {
-                        if (sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y))
+                        if (CanMewWalkToCoords(mew->currentCoords.x - 1, mew->currentCoords.y))
                             return DIR_WEST;
                     }
                     else
                     {
-                        if (sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y))
+                        if (CanMewWalkToCoords(mew->currentCoords.x + 1, mew->currentCoords.y))
                             return DIR_EAST;
                     }
                 }
@@ -208,52 +209,52 @@ u32 sub_81D427C(void)
             return DIR_WEST;
     }
 
-    if (gUnknown_030012FA == 0)
+    if (sPlayerToMewDeltaY == 0)
     {
         if (gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.y > mew->currentCoords.y)
         {
-            if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1))
+            if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y - 1))
                 return DIR_NORTH;
         }
 
         if (gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.y < mew->currentCoords.y)
         {
-            if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1))
+            if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y + 1))
                 return DIR_SOUTH;
         }
 
-        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1))
+        if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y - 1))
             return DIR_NORTH;
 
-        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1))
+        if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y + 1))
             return DIR_SOUTH;
     }
 
-    if (gUnknown_030012F8 == 0)
+    if (sPlayerToMewDeltaX == 0)
     {
         if (gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.x > mew->currentCoords.x)
         {
-            if (sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y))
+            if (CanMewWalkToCoords(mew->currentCoords.x - 1, mew->currentCoords.y))
                 return DIR_WEST;
         }
 
         if (gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.x < mew->currentCoords.x)
         {
-            if (sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y))
+            if (CanMewWalkToCoords(mew->currentCoords.x + 1, mew->currentCoords.y))
                 return DIR_EAST;
         }
 
-        if (sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y))
+        if (CanMewWalkToCoords(mew->currentCoords.x + 1, mew->currentCoords.y))
             return DIR_EAST;
 
-        if (sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y))
+        if (CanMewWalkToCoords(mew->currentCoords.x - 1, mew->currentCoords.y))
             return DIR_WEST;
     }
 
     return sub_81D4890(DIR_NONE);
 }
 
-static bool8 sub_81D4834(s16 x, s16 y)
+static bool8 CanMewWalkToCoords(s16 x, s16 y)
 {
     if (gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.x == x
      && gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.y == y)
@@ -268,39 +269,39 @@ static u8 sub_81D4890(u8 ignoredDir)
 {
     u8 i;
     u8 count = 0;
-    struct EventObject *mew = &gEventObjects[sub_81D4258()];
+    struct EventObject *mew = &gEventObjects[GetMewEventObjectId()];
 
-    for (i = 0; i < ARRAY_COUNT(gUnknown_030012FC); i++)
-        gUnknown_030012FC[i] = DIR_NONE;
+    for (i = 0; i < ARRAY_COUNT(sMewDirectionCandidates); i++)
+        sMewDirectionCandidates[i] = DIR_NONE;
 
-    if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1) == TRUE && ignoredDir != DIR_NORTH)
+    if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y - 1) == TRUE && ignoredDir != DIR_NORTH)
     {
-        gUnknown_030012FC[count] = DIR_NORTH;
+        sMewDirectionCandidates[count] = DIR_NORTH;
         count++;
     }
 
-    if (sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y) == TRUE && ignoredDir != DIR_EAST)
+    if (CanMewWalkToCoords(mew->currentCoords.x + 1, mew->currentCoords.y) == TRUE && ignoredDir != DIR_EAST)
     {
-        gUnknown_030012FC[count] = DIR_EAST;
+        sMewDirectionCandidates[count] = DIR_EAST;
         count++;
     }
 
-    if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1) == TRUE && ignoredDir != DIR_SOUTH)
+    if (CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y + 1) == TRUE && ignoredDir != DIR_SOUTH)
     {
-        gUnknown_030012FC[count] = DIR_SOUTH;
+        sMewDirectionCandidates[count] = DIR_SOUTH;
         count++;
     }
 
-    if (sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y) == TRUE && ignoredDir != DIR_WEST)
+    if (CanMewWalkToCoords(mew->currentCoords.x - 1, mew->currentCoords.y) == TRUE && ignoredDir != DIR_WEST)
     {
-        gUnknown_030012FC[count] = DIR_WEST;
+        sMewDirectionCandidates[count] = DIR_WEST;
         count++;
     }
 
     if (count > 1)
-        return gUnknown_030012FC[VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) % count];
+        return sMewDirectionCandidates[VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) % count];
     else
-        return gUnknown_030012FC[0];
+        return sMewDirectionCandidates[0];
 }
 
 void UpdateFarawayIslandStepCounter(void)
@@ -355,7 +356,7 @@ void sub_81D4A90(void)
     s16 x;
     s16 y;
     u8 spriteId;
-    struct EventObject *mew = &gEventObjects[sub_81D4258()];
+    struct EventObject *mew = &gEventObjects[GetMewEventObjectId()];
 
     mew->invisible = 0;
     if (gSpecialVar_0x8004 == 1)
@@ -378,10 +379,10 @@ void sub_81D4A90(void)
         x = mew->currentCoords.x;
         y = mew->currentCoords.y;
         sub_80930E0(&x, &y, 8, 8);
-        gUnknown_0203CF50 = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[15], x, y, gSprites[mew->spriteId].subpriority - 1);
-        if (gUnknown_0203CF50 != MAX_SPRITES)
+        sUnknown_0203CF50 = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[15], x, y, gSprites[mew->spriteId].subpriority - 1);
+        if (sUnknown_0203CF50 != MAX_SPRITES)
         {
-            struct Sprite *sprite = &gSprites[gUnknown_0203CF50];
+            struct Sprite *sprite = &gSprites[sUnknown_0203CF50];
             sprite->coordOffsetEnabled = 1;
             sprite->oam.priority = 2;
             sprite->callback = SpriteCallbackDummy;
@@ -391,15 +392,15 @@ void sub_81D4A90(void)
 
 void sub_81D4BEC(void)
 {
-    if (gUnknown_0203CF50 != MAX_SPRITES)
-        DestroySprite(&gSprites[gUnknown_0203CF50]);
+    if (sUnknown_0203CF50 != MAX_SPRITES)
+        DestroySprite(&gSprites[sUnknown_0203CF50]);
 }
 
 static bool8 sub_81D4C14(struct EventObject *mew, u8 index)
 {
-    if (gUnknown_030012FA > 0 && sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1))
+    if (sPlayerToMewDeltaY > 0 && CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y - 1))
     {
-        gUnknown_030012FC[index] = DIR_NORTH;
+        sMewDirectionCandidates[index] = DIR_NORTH;
         return TRUE;
     }
 
@@ -408,9 +409,9 @@ static bool8 sub_81D4C14(struct EventObject *mew, u8 index)
 
 static u8 sub_81D4C58(struct EventObject *mew, u8 index)
 {
-    if (gUnknown_030012F8 < 0 && sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y))
+    if (sPlayerToMewDeltaX < 0 && CanMewWalkToCoords(mew->currentCoords.x + 1, mew->currentCoords.y))
     {
-        gUnknown_030012FC[index] = DIR_EAST;
+        sMewDirectionCandidates[index] = DIR_EAST;
         return TRUE;
     }
 
@@ -419,9 +420,9 @@ static u8 sub_81D4C58(struct EventObject *mew, u8 index)
 
 static u8 sub_81D4C9C(struct EventObject *mew, u8 index)
 {
-    if (gUnknown_030012FA < 0 && sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1))
+    if (sPlayerToMewDeltaY < 0 && CanMewWalkToCoords(mew->currentCoords.x, mew->currentCoords.y + 1))
     {
-        gUnknown_030012FC[index] = DIR_SOUTH;
+        sMewDirectionCandidates[index] = DIR_SOUTH;
         return TRUE;
     }
 
@@ -430,9 +431,9 @@ static u8 sub_81D4C9C(struct EventObject *mew, u8 index)
 
 static u8 sub_81D4CE0(struct EventObject *mew, u8 index)
 {
-    if (gUnknown_030012F8 > 0 && sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y))
+    if (sPlayerToMewDeltaX > 0 && CanMewWalkToCoords(mew->currentCoords.x - 1, mew->currentCoords.y))
     {
-        gUnknown_030012FC[index] = DIR_WEST;
+        sMewDirectionCandidates[index] = DIR_WEST;
         return TRUE;
     }
 
@@ -441,5 +442,5 @@ static u8 sub_81D4CE0(struct EventObject *mew, u8 index)
 
 static u8 sub_81D4D24(u8 mod)
 {
-    return gUnknown_030012FC[VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) % mod];
+    return sMewDirectionCandidates[VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) % mod];
 }