Merge pull request #622 from huderlem/ereader

Finish decompiling ereader and faraway island code

7 files changed, 920 insertions, 23 deletions

diff --git a/src/ereader.c b/src/ereader_helpers.c
index 053f82381..6c92b676f 100755
--- a/src/ereader.c
+++ b/src/ereader_helpers.c
@@ -1,16 +1,15 @@
 #include "global.h"
 #include "alloc.h"
-#include "event_object_movement.h"
+#include "decompress.h"
+#include "ereader_helpers.h"
 #include "link.h"
+#include "main.h"
+#include "rom_8011DC0.h"
 #include "save.h"
+#include "sprite.h"
+#include "task.h"
 #include "util.h"
 
-struct Unk81D38FC
-{
-    u8 unk0[0x270];
-    int checksum;
-};
-
 struct Unknown030012C8
 {
     u8 unk0[8];
@@ -20,10 +19,7 @@ struct Unknown030012C8
     int unk14;
 };
 
-void sub_81D41A0(void);
 static void sub_81D4170(void);
-int sub_81D3D70(u8, u32, u32*, u32*);
-void sub_81D41F4(void);
 static u16 sub_81D3EE8(u8);
 static void sub_81D413C(void);
 static void sub_81D414C(void);
@@ -555,10 +551,3 @@ void sub_81D4238(void)
 {
     CpuFill32(0, &gUnknown_030012C8, sizeof(struct Unknown030012C8));
 }
-
-u8 sub_81D4258(void)
-{
-    u8 eventObjectId;
-    TryGetEventObjectIdByLocalIdAndMap(1, gSaveBlock1Ptr->location.mapNum, gSaveBlock1Ptr->location.mapGroup, &eventObjectId);
-    return eventObjectId;
-}
diff --git a/src/ereader_screen.c b/src/ereader_screen.c
new file mode 100755
index 000000000..b15c1fd0c
--- /dev/null
+++ b/src/ereader_screen.c
@@ -0,0 +1,464 @@
+#include "global.h"
+#include "alloc.h"
+#include "decompress.h"
+#include "ereader_helpers.h"
+#include "link.h"
+#include "main.h"
+#include "rom_8011DC0.h"
+#include "save.h"
+#include "sound.h"
+#include "sprite.h"
+#include "task.h"
+#include "strings.h"
+#include "util.h"
+#include "constants/songs.h"
+
+struct Unk81D5014
+{
+    u16 unk0;
+    u16 unk2;
+    u16 unk4;
+    u16 unk6;
+    u8 unk8;
+    u8 unk9;
+    u8 unkA;
+    u8 unkB;
+    u8 unkC;
+    u8 unkD;
+    u8 unkE;
+    u8 *unk10;
+};
+
+struct Unk03006370
+{
+    u16 unk0;
+    u32 unk4;
+    u32 *unk8;
+};
+
+static void sub_81D5084(u8);
+
+extern struct Unk03006370 gUnknown_03006370;
+
+extern const u8 gUnknown_089A3470[];
+extern const u8 gMultiBootProgram_BerryGlitchFix_Start[];
+
+static void sub_81D4D50(struct Unk03006370 *arg0, int arg1, u32 *arg2)
+{
+    volatile u16 backupIME = REG_IME;
+    REG_IME = 0;
+    gIntrTable[1] = sub_81D3FAC;
+    gIntrTable[2] = sub_81D3F9C;
+    sub_81D41A0();
+    sub_81D4238();
+    REG_IE |= INTR_FLAG_VCOUNT;
+    REG_IME = backupIME;
+    arg0->unk0 = 0;
+    arg0->unk4 = arg1;
+    arg0->unk8 = arg2;
+}
+
+static void sub_81D4DB8(struct Unk03006370 *arg0)
+{
+    volatile u16 backupIME = REG_IME;
+    REG_IME = 0;
+    sub_81D4238();
+    sub_81D41F4();
+    RestoreSerialTimer3IntrHandlers();
+    REG_IME = backupIME;
+}
+
+static u8 sub_81D4DE8(struct Unk03006370 *arg0)
+{
+    u8 var0 = 0;
+    arg0->unk0 = sub_81D3D70(1, arg0->unk4, arg0->unk8, NULL);
+    if ((arg0->unk0 & 0x13) == 0x10)
+        var0 = 1;
+
+    if (arg0->unk0 & 0x8)
+        var0 = 2;
+
+    if (arg0->unk0 & 0x4)
+        var0 = 3;
+
+    gShouldAdvanceLinkState = 0;
+    return var0;
+}
+
+static void sub_81D4E30(void)
+{
+    memset(gDecompressionBuffer, 0, 0x2000);
+    gLinkType = 0x5503;
+    OpenLink();
+    SetSuppressLinkErrorMessage(TRUE);
+}
+
+static bool32 sub_81D4E60(void)
+{
+    volatile u16 backupIME;
+    u16 sp4[4];
+
+    backupIME = REG_IME;
+    REG_IME = 0;
+    *(u64 *)sp4 = *(u64 *)gLink.tempRecvBuffer;
+    REG_IME = backupIME;
+    if (sp4[0] == 0xB9A0 && sp4[1] == 0xCCD0
+     && sp4[2] == 0xFFFF && sp4[3] == 0xFFFF)
+    {
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+static bool32 sub_81D4EC0(void)
+{
+    if (IsLinkMaster() && GetLinkPlayerCount_2() == 2)
+        return TRUE;
+
+    return FALSE;
+}
+
+static u32 sub_81D4EE4(u8 *arg0, u16 *arg1)
+{
+    u8 var0;
+
+    var0 = *arg0 - 3;
+    if (var0 < 3 && HasLinkErrorOccurred())
+    {
+        *arg0 = 0;
+        return 3;
+    }
+
+    switch (*arg0)
+    {
+    case 0:
+        if (IsLinkMaster() && GetLinkPlayerCount_2() > 1)
+        {
+            *arg0 = 1;
+        }
+        else if (gMain.newKeys & B_BUTTON)
+        {
+            *arg0 = 0;
+            return 1;
+        }
+        break;
+    case 1:
+        if (++(*arg1) > 5)
+        {
+            *arg1 = 0;
+            *arg0 = 2;
+        }
+        break;
+    case 2:
+        if (GetLinkPlayerCount_2() == 2)
+        {
+            PlaySE(SE_PINPON);
+            CheckShouldAdvanceLinkState();
+            *arg1 = 0;
+            *arg0 = 3;
+        }
+        else if (gMain.newKeys & B_BUTTON)
+        {
+            *arg0 = 0;
+            return 1;
+        }
+        break;
+    case 3:
+        if (++(*arg1) > 30)
+        {
+            *arg0 = 0;
+            return 5;
+        }
+
+        if (IsLinkConnectionEstablished())
+        {
+            if (gReceivedRemoteLinkPlayers)
+            {
+                if (IsLinkPlayerDataExchangeComplete())
+                {
+                    *arg0 = 0;
+                    return 2;
+                }
+                else
+                {
+                    *arg0 = 4;
+                }
+            }
+            else
+            {
+                *arg0 = 3;
+            }
+        }
+        break;
+    case 4:
+        sub_800ABF4(0);
+        *arg0 = 5;
+        break;
+    case 5:
+        if (!gReceivedRemoteLinkPlayers)
+        {
+            *arg0 = 0;
+            return 4;
+        }
+        break;
+    default:
+        return 0;
+    }
+
+    return 0;
+}
+
+void sub_81D5014(void)
+{
+    int value;
+    struct Unk81D5014 *data;
+    u8 taskId = CreateTask(sub_81D5084, 0);
+    data = (struct Unk81D5014 *)gTasks[taskId].data;
+    data->unk8 = 0;
+    data->unk9 = 0;
+    data->unkA = 0;
+    data->unkB = 0;
+    data->unkC = 0;
+    data->unkD = 0;
+    data->unk0 = 0;
+    data->unk2 = 0;
+    data->unk4 = 0;
+    data->unk6 = 0;
+    data->unkE = 0;
+    data->unk10 = AllocZeroed(0x40);
+}
+
+static void sub_81D505C(u16 *arg0)
+{
+    *arg0 = 0;
+}
+
+static bool32 sub_81D5064(u16 *arg0, u16 arg1)
+{
+    if (++(*arg0) > arg1)
+    {
+        *arg0 = 0;
+        return TRUE;
+    }
+    
+    return FALSE;
+}
+
+static void sub_81D5084(u8 taskId)
+{
+    struct Unk81D5014 *data = (struct Unk81D5014 *)gTasks[taskId].data;
+    switch (data->unk8)
+    {
+    case 0:
+        if (mevent_0814257C(&data->unk9, gUnknown_085EDFD6))
+            data->unk8 = 1;
+        break;
+    case 1:
+        sub_81D4E30();
+        sub_81D505C(&data->unk0);
+        data->unk8 = 2;
+        break;
+    case 2:
+        if (sub_81D5064(&data->unk0, 10))
+            data->unk8 = 3;
+        break;
+    case 3:
+        if (!sub_81D4EC0())
+        {
+            CloseLink();
+            data->unk8 = 4;
+        }
+        else
+        {
+            data->unk8 = 13;
+        }
+        break;
+    case 4:
+        if (mevent_0814257C(&data->unk9, gUnknown_085EDFF5))
+        {
+            sub_8018884(gUnknown_085EE014);
+            sub_81D505C(&data->unk0);
+            data->unk8 = 5;
+        }
+        break;
+    case 5:
+        if (sub_81D5064(&data->unk0, 90))
+        {
+            sub_81D4E30();
+            data->unk8 = 6;
+        }
+        else if (gMain.newKeys & B_BUTTON)
+        {
+            sub_81D505C(&data->unk0);
+            PlaySE(SE_SELECT);
+            data->unk8 = 23;
+        }
+        break;
+    case 6:
+        if (gMain.newKeys & B_BUTTON)
+        {
+            PlaySE(SE_SELECT);
+            CloseLink();
+            sub_81D505C(&data->unk0);
+            data->unk8 = 23;
+        }
+        else if (GetLinkPlayerCount_2() > 1)
+        {
+            sub_81D505C(&data->unk0);
+            CloseLink();
+            data->unk8 = 7;
+        }
+        else if (sub_81D4E60())
+        {
+            PlaySE(SE_SELECT);
+            CloseLink();
+            sub_81D505C(&data->unk0);
+            data->unk8 = 8;
+        }
+        else if (sub_81D5064(&data->unk0, 10))
+        {
+            CloseLink();
+            sub_81D4E30();
+            sub_81D505C(&data->unk0);
+        }
+        break;
+    case 7:
+        if (mevent_0814257C(&data->unk9, gUnknown_085EE05C))
+            data->unk8 = 4;
+        break;
+    case 8:
+        sub_8018884(gUnknown_085EE097);
+        // XXX: This (u32*) cast is discarding the const qualifier from gUnknown_089A3470
+        sub_81D4D50(&gUnknown_03006370, gMultiBootProgram_BerryGlitchFix_Start - gUnknown_089A3470, (u32*)gUnknown_089A3470);
+        data->unk8 = 9;
+        break;
+    case 9:
+        data->unkE = sub_81D4DE8(&gUnknown_03006370);
+        if (data->unkE)
+            data->unk8 = 10;
+        break;
+    case 10:
+        sub_81D4DB8(&gUnknown_03006370);
+        if (data->unkE == 3)
+        {
+            data->unk8 = 20;
+        }
+        else if (data->unkE == 1)
+        {
+            sub_81D505C(&data->unk0);
+            sub_8018884(gUnknown_085EE120);
+            data->unk8 = 11;
+        }
+        else
+        {
+            data->unk8 = 0;
+        }
+        break;
+    case 11:
+        if (sub_81D5064(&data->unk0, 840))
+            data->unk8 = 12;
+        break;
+    case 12:
+        sub_81D4E30();
+        sub_8018884(gUnknown_085EE0DC);
+        data->unk8 = 13;
+        break;
+    case 13:
+        switch (sub_81D4EE4(&data->unk9, &data->unk0))
+        {
+            case 0:
+                break;
+            case 2:
+                sub_8018884(gUnknown_085EE097);
+                data->unk8 = 14;
+                break;
+            case 1:
+                PlaySE(SE_SELECT);
+                CloseLink();
+                data->unk8 = 23;
+                break;
+            case 5:
+                CloseLink();
+                data->unk8 = 21;
+                break;
+            case 3:
+            case 4:
+                CloseLink();
+                data->unk8 = 20;
+                break;
+        }
+        break;
+    case 14:
+        if (HasLinkErrorOccurred())
+        {
+            CloseLink();
+            data->unk8 = 20;
+        }
+        else if (GetBlockReceivedStatus())
+        {
+            ResetBlockReceivedFlags();
+            data->unk8 = 15;
+        }
+        break;
+    case 15:
+        data->unkE = sub_81D3920(gDecompressionBuffer);
+        sub_800ABF4(data->unkE);
+        data->unk8 = 16;
+        break;
+    case 16:
+        if (!gReceivedRemoteLinkPlayers)
+        {
+            if (data->unkE == 1)
+                data->unk8 = 17;
+            else
+                data->unk8 = 20;
+        }
+        break;
+    case 17:
+        if (sub_81D3AB0((struct Unk81D38FC *)&gDecompressionBuffer))
+        {
+            sub_8018884(gUnknown_085EE0FA);
+            sub_81D505C(&data->unk0);
+            data->unk8 = 18;
+        }
+        else
+        {
+            data->unk8 = 22;
+        }
+        break;
+    case 18:
+        if (sub_81D5064(&data->unk0, 120))
+        {
+            sub_8018884(gUnknown_085EE107);
+            PlayFanfare(MUS_FANFA4);
+            data->unk8 = 19;
+        }
+        break;
+    case 19:
+        if (IsFanfareTaskInactive() && (gMain.newKeys & (A_BUTTON | B_BUTTON)))
+            data->unk8 = 26;
+        break;
+    case 23:
+        if (mevent_0814257C(&data->unk9,gUnknown_085EE06B))
+            data->unk8 = 26;
+        break;
+    case 20:
+        if (mevent_0814257C(&data->unk9, gUnknown_085EE0A3))
+            data->unk8 = 0;
+        break;
+    case 21:
+        if (mevent_0814257C(&data->unk9, gUnknown_085EE0BF))
+            data->unk8 = 0;
+        break;
+    case 22:
+        if (mevent_0814257C(&data->unk9, gUnknown_085EE12D))
+            data->unk8 = 0;
+        break;
+    case 26:
+        Free(data->unk10);
+        DestroyTask(taskId);
+        SetMainCallback2(sub_80186A4);
+        break;
+    }
+}
diff --git a/src/event_object_movement.c b/src/event_object_movement.c
index 8ebdd883f..30dffd8d7 100644
--- a/src/event_object_movement.c
+++ b/src/event_object_movement.c
@@ -3,10 +3,10 @@
 #include "battle_pyramid.h"
 #include "berry.h"
 #include "decoration.h"
-#include "ereader.h"
 #include "event_data.h"
 #include "event_object_movement.h"
 #include "event_scripts.h"
+#include "faraway_island.h"
 #include "field_camera.h"
 #include "field_effect.h"
 #include "field_effect_helpers.h"
diff --git a/src/faraway_island.c b/src/faraway_island.c
new file mode 100755
index 000000000..1c8dff14e
--- /dev/null
+++ b/src/faraway_island.c
@@ -0,0 +1,445 @@
+#include "global.h"
+#include "event_data.h"
+#include "event_object_movement.h"
+#include "field_weather.h"
+#include "fieldmap.h"
+#include "metatile_behavior.h"
+#include "sprite.h"
+#include "constants/event_objects.h"
+#include "constants/flags.h"
+#include "constants/maps.h"
+#include "constants/metatile_behaviors.h"
+#include "constants/vars.h"
+
+static u8 sub_81D4890(u8);
+static bool8 sub_81D4C14(struct EventObject*, u8);
+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);
+
+extern u8 gUnknown_0203CF50;
+extern s16 gUnknown_030012F8;
+extern s16 gUnknown_030012FA;
+extern u8 gUnknown_030012FC[4];
+
+extern const struct SpritePalette gFieldEffectObjectPaletteInfo1;
+extern const struct SpriteTemplate *const gFieldEffectObjectTemplatePointers[];
+
+static const s16 sFarawayIslandRockCoords[4][2] =
+{
+    {21, 16},
+    {25, 16},
+    {16, 17},
+    {20, 20},
+};
+
+static u8 sub_81D4258(void)
+{
+    u8 eventObjectId;
+    TryGetEventObjectIdByLocalIdAndMap(1, gSaveBlock1Ptr->location.mapNum, gSaveBlock1Ptr->location.mapGroup, &eventObjectId);
+    return eventObjectId;
+}
+
+u32 sub_81D427C(void)
+{
+    u8 i;
+    int skip;
+    struct EventObject *mew = &gEventObjects[sub_81D4258()];
+
+    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;
+
+    if (gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x == gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.x
+     && gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y == gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.y)
+    {
+        return DIR_NONE;
+    }
+
+    if (VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) % 8 == 0)
+        mew->invisible = 0;
+    else
+        mew->invisible = 1;
+
+    if (VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) % 9 == 0)
+        return DIR_NONE;
+
+    for (i = 0; i < ARRAY_COUNT(sFarawayIslandRockCoords); i++)
+    {
+        if (gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x == sFarawayIslandRockCoords[i][0])
+        {
+            skip = 0;
+            if (gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y < sFarawayIslandRockCoords[i][1])
+            {
+                if (mew->currentCoords.y <= sFarawayIslandRockCoords[i][1])
+                    skip = 1;
+            }
+            else
+            {
+                if (mew->currentCoords.y >= sFarawayIslandRockCoords[i][1])
+                    skip = 1;
+            }
+
+            if (!skip)
+            {
+                if (gUnknown_030012F8 > 0)
+                {
+                    if (mew->currentCoords.x + 1 == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x)
+                    {
+                        if (sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y))
+                            return DIR_EAST;
+                    }
+                }
+                else if (gUnknown_030012F8 < 0)
+                {
+                    if (mew->currentCoords.x - 1 == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x)
+                    {
+                        if (sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y))
+                            return DIR_WEST;
+                    }
+                }
+
+                if (mew->currentCoords.x == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x)
+                {
+                    if (gUnknown_030012FA > 0)
+                    {
+                        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1))
+                            return DIR_NORTH;
+                    }
+                    else
+                    {
+                        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1))
+                            return DIR_SOUTH;
+                    }
+                }
+            }
+        }
+
+        if (gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y == sFarawayIslandRockCoords[i][1])
+        {
+            skip = 0;
+            if (gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.x < sFarawayIslandRockCoords[i][0])
+            {
+                if (mew->currentCoords.x <= sFarawayIslandRockCoords[i][0])
+                    skip = 1;
+            }
+            else
+            {
+                if (mew->currentCoords.x >= sFarawayIslandRockCoords[i][0])
+                    skip = 1;
+            }
+
+            if (!skip)
+            {
+                if (gUnknown_030012FA > 0)
+                {
+                    if (mew->currentCoords.y + 1 == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y)
+                    {
+                        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1))
+                            return DIR_SOUTH;
+                    }
+                }
+                else if (gUnknown_030012FA < 0)
+                {
+                    if (mew->currentCoords.y - 1 == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y)
+                    {
+                        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1))
+                            return DIR_NORTH;
+                    }
+                }
+
+                if (mew->currentCoords.y == gEventObjects[gPlayerAvatar.eventObjectId].previousCoords.y)
+                {
+                    if (gUnknown_030012F8 > 0)
+                    {
+                        if (sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y))
+                            return DIR_WEST;
+                    }
+                    else
+                    {
+                        if (sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y))
+                            return DIR_EAST;
+                    }
+                }
+            }
+        }
+    }
+
+    if (sub_81D4C14(mew, 0))
+    {
+        if (sub_81D4C58(mew, 1))
+            return sub_81D4D24(2);
+        else if (sub_81D4CE0(mew, 1))
+            return sub_81D4D24(2);
+        else
+            return DIR_NORTH;
+    }
+
+    if (sub_81D4C9C(mew, 0))
+    {
+        if (sub_81D4C58(mew, 1))
+            return sub_81D4D24(2);
+        else if (sub_81D4CE0(mew, 1))
+            return sub_81D4D24(2);
+        else
+            return DIR_SOUTH;
+    }
+
+    if (sub_81D4C58(mew, 0))
+    {
+        if (sub_81D4C14(mew, 1))
+            return sub_81D4D24(2);
+        else if (sub_81D4C9C(mew, 1))
+            return sub_81D4D24(2);
+        else
+            return DIR_EAST;
+    }
+
+    if (sub_81D4CE0(mew, 0))
+    {
+        if (sub_81D4C14(mew, 1))
+            return sub_81D4D24(2);
+        else if (sub_81D4C9C(mew, 1))
+            return sub_81D4D24(2);
+        else
+            return DIR_WEST;
+    }
+
+    if (gUnknown_030012FA == 0)
+    {
+        if (gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.y > mew->currentCoords.y)
+        {
+            if (sub_81D4834(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))
+                return DIR_SOUTH;
+        }
+
+        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1))
+            return DIR_NORTH;
+
+        if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1))
+            return DIR_SOUTH;
+    }
+
+    if (gUnknown_030012F8 == 0)
+    {
+        if (gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.x > mew->currentCoords.x)
+        {
+            if (sub_81D4834(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))
+                return DIR_EAST;
+        }
+
+        if (sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y))
+            return DIR_EAST;
+
+        if (sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y))
+            return DIR_WEST;
+    }
+
+    return sub_81D4890(DIR_NONE);
+}
+
+static bool8 sub_81D4834(s16 x, s16 y)
+{
+    if (gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.x == x
+     && gEventObjects[gPlayerAvatar.eventObjectId].currentCoords.y == y)
+    {
+        return FALSE;
+    }
+
+    return MetatileBehavior_IsPokeGrass(MapGridGetMetatileBehaviorAt(x, y));
+}
+
+static u8 sub_81D4890(u8 ignoredDir)
+{
+    u8 i;
+    u8 count = 0;
+    struct EventObject *mew = &gEventObjects[sub_81D4258()];
+
+    for (i = 0; i < ARRAY_COUNT(gUnknown_030012FC); i++)
+        gUnknown_030012FC[i] = DIR_NONE;
+
+    if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1) == TRUE && ignoredDir != DIR_NORTH)
+    {
+        gUnknown_030012FC[count] = DIR_NORTH;
+        count++;
+    }
+
+    if (sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y) == TRUE && ignoredDir != DIR_EAST)
+    {
+        gUnknown_030012FC[count] = DIR_EAST;
+        count++;
+    }
+
+    if (sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1) == TRUE && ignoredDir != DIR_SOUTH)
+    {
+        gUnknown_030012FC[count] = DIR_SOUTH;
+        count++;
+    }
+
+    if (sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y) == TRUE && ignoredDir != DIR_WEST)
+    {
+        gUnknown_030012FC[count] = DIR_WEST;
+        count++;
+    }
+
+    if (count > 1)
+        return gUnknown_030012FC[VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) % count];
+    else
+        return gUnknown_030012FC[0];
+}
+
+void UpdateFarawayIslandStepCounter(void)
+{
+    u16 steps = VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER);
+    if (gSaveBlock1Ptr->location.mapNum == MAP_NUM(FARAWAY_ISLAND_INTERIOR)
+     && gSaveBlock1Ptr->location.mapGroup == MAP_GROUP(FARAWAY_ISLAND_INTERIOR))
+    {
+        steps++;
+        if (steps >= 9999)
+            VarSet(VAR_FARAWAY_ISLAND_STEP_COUNTER, 0);
+        else
+            VarSet(VAR_FARAWAY_ISLAND_STEP_COUNTER, steps);
+    }
+}
+
+bool8 EventObjectIsFarawayIslandMew(struct EventObject *eventObject)
+{
+    if (gSaveBlock1Ptr->location.mapNum == MAP_NUM(FARAWAY_ISLAND_INTERIOR)
+     && gSaveBlock1Ptr->location.mapGroup == MAP_GROUP(FARAWAY_ISLAND_INTERIOR))
+    {
+        if (eventObject->graphicsId == EVENT_OBJ_GFX_MEW)
+            return TRUE;
+    }
+
+    return FALSE;
+}
+
+bool8 IsMewPlayingHideAndSeek(void)
+{
+    if (gSaveBlock1Ptr->location.mapNum == MAP_NUM(FARAWAY_ISLAND_INTERIOR)
+     && gSaveBlock1Ptr->location.mapGroup == MAP_GROUP(FARAWAY_ISLAND_INTERIOR))
+    {
+        if (FlagGet(FLAG_CAUGHT_MEW) != TRUE && FlagGet(FLAG_HIDE_MEW) != TRUE)
+            return TRUE;
+    }
+
+    return FALSE;
+}
+
+bool8 sub_81D4A58(struct EventObject *eventObject)
+{
+    if (VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) != 0xFFFF
+     && VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) % 4 == 0)
+        return TRUE;
+
+    return FALSE;
+}
+
+void sub_81D4A90(void)
+{
+    s16 x;
+    s16 y;
+    u8 spriteId;
+    struct EventObject *mew = &gEventObjects[sub_81D4258()];
+
+    mew->invisible = 0;
+    if (gSpecialVar_0x8004 == 1)
+    {
+        mew->fixedPriority = 1;
+        gSprites[mew->spriteId].subspriteMode = SUBSPRITES_IGNORE_PRIORITY;
+        gSprites[mew->spriteId].subpriority = 1;
+    }
+    else
+    {
+        VarSet(VAR_FARAWAY_ISLAND_STEP_COUNTER, 0xFFFF);
+        mew->fixedPriority = 1;
+        gSprites[mew->spriteId].subspriteMode = SUBSPRITES_IGNORE_PRIORITY;
+        if (gSpecialVar_Facing != DIR_NORTH)
+            gSprites[mew->spriteId].subpriority = 1;
+
+        LoadSpritePalette(&gFieldEffectObjectPaletteInfo1);
+        UpdateSpritePaletteWithWeather(IndexOfSpritePaletteTag(gFieldEffectObjectPaletteInfo1.tag));
+
+        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)
+        {
+            struct Sprite *sprite = &gSprites[gUnknown_0203CF50];
+            sprite->coordOffsetEnabled = 1;
+            sprite->oam.priority = 2;
+            sprite->callback = SpriteCallbackDummy;
+        }
+    }
+}
+
+void sub_81D4BEC(void)
+{
+    if (gUnknown_0203CF50 != MAX_SPRITES)
+        DestroySprite(&gSprites[gUnknown_0203CF50]);
+}
+
+static bool8 sub_81D4C14(struct EventObject *mew, u8 index)
+{
+    if (gUnknown_030012FA > 0 && sub_81D4834(mew->currentCoords.x, mew->currentCoords.y - 1))
+    {
+        gUnknown_030012FC[index] = DIR_NORTH;
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+static u8 sub_81D4C58(struct EventObject *mew, u8 index)
+{
+    if (gUnknown_030012F8 < 0 && sub_81D4834(mew->currentCoords.x + 1, mew->currentCoords.y))
+    {
+        gUnknown_030012FC[index] = DIR_EAST;
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+static u8 sub_81D4C9C(struct EventObject *mew, u8 index)
+{
+    if (gUnknown_030012FA < 0 && sub_81D4834(mew->currentCoords.x, mew->currentCoords.y + 1))
+    {
+        gUnknown_030012FC[index] = DIR_SOUTH;
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+static u8 sub_81D4CE0(struct EventObject *mew, u8 index)
+{
+    if (gUnknown_030012F8 > 0 && sub_81D4834(mew->currentCoords.x - 1, mew->currentCoords.y))
+    {
+        gUnknown_030012FC[index] = DIR_WEST;
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+static u8 sub_81D4D24(u8 mod)
+{
+    return gUnknown_030012FC[VarGet(VAR_FARAWAY_ISLAND_STEP_COUNTER) % mod];
+}
diff --git a/src/field_control_avatar.c b/src/field_control_avatar.c
index 680191bb3..6735df3a0 100644
--- a/src/field_control_avatar.c
+++ b/src/field_control_avatar.c
@@ -3,6 +3,7 @@
 #include "bike.h"
 #include "coord_event_weather.h"
 #include "daycare.h"
+#include "faraway_island.h"
 #include "event_data.h"
 #include "event_object_movement.h"
 #include "event_scripts.h"
@@ -18,7 +19,6 @@
 #include "metatile_behavior.h"
 #include "overworld.h"
 #include "pokemon.h"
-#include "pokenav.h"
 #include "safari_zone.h"
 #include "script.h"
 #include "secret_base.h"
@@ -541,7 +541,7 @@ static bool8 TryStartStepCountScript(u16 metatileBehavior)
 
     IncrementRematchStepCounter();
     UpdateHappinessStepCounter();
-    sub_81D4998();
+    UpdateFarawayIslandStepCounter();
 
     if (!(gPlayerAvatar.flags & PLAYER_AVATAR_FLAG_6) && !MetatileBehavior_IsForcedMovementTile(metatileBehavior))
     {
diff --git a/src/fldeff_cut.c b/src/fldeff_cut.c
index b1f4a6368..3da1a9217 100644
--- a/src/fldeff_cut.c
+++ b/src/fldeff_cut.c
@@ -1,6 +1,7 @@
 #include "global.h"
 #include "event_obj_lock.h"
 #include "event_object_movement.h"
+#include "faraway_island.h"
 #include "field_camera.h"
 #include "field_effect.h"
 #include "field_player_avatar.h"
@@ -20,8 +21,6 @@
 #include "constants/field_effects.h"
 #include "constants/songs.h"
 
-extern bool8 IsMewPlayingHideAndSeek(void);
-
 extern struct MapPosition gPlayerFacingPosition;
 
 extern const u8 Route103_EventScript_290705[];
diff --git a/src/trainer_hill.c b/src/trainer_hill.c
index 7bb1b997a..eafd1eb3d 100644
--- a/src/trainer_hill.c
+++ b/src/trainer_hill.c
@@ -3,7 +3,7 @@
 #include "battle.h"
 #include "battle_tower.h"
 #include "battle_setup.h"
-#include "ereader.h"
+#include "ereader_helpers.h"
 #include "event_data.h"
 #include "event_scripts.h"
 #include "fieldmap.h"