Decompile no0 func_us_801D0718 + func_us_801D0898 (#1930)

Couple of smaller Diplo functions and a little bit of clean up for the
earlier function I did

`func_us_801D0718`
PSX: https://decomp.me/scratch/NkB3j
PSP: https://decomp.me/scratch/xz0Oi

`func_us_801D0898`
PSX: https://decomp.me/scratch/7GFMG
PSP: https://decomp.me/scratch/aHDvP

include/entity.h

@@ -2113,17 +2113,21 @@ typedef struct {
 } ET_Skelerang;
 
 typedef struct {
-    /* 0x7C */ s32 : 32;
-    /* 0x80 */ s32 : 32;
+    /* 0x7C */ struct Entity* parent;
+    /* 0x80 */ struct Entity* entity;
     /* 0x84 */ s32 : 32;
     /* 0x88 */ s32 : 32;
     /* 0x8C */ s32 : 32;
-    /* 0x90 */ s32 : 32;
+    /* 0x90 */ Point32* unk90;
     /* 0x94 */ s32 : 32;
-    /* 0x98 */ u32 velocityY;
+    /* 0x98 */ s32 velocityY;
     /* 0x9C */ s16 : 16;
     /* 0x9E */ u8 unk9E;
     /* 0x9F */ u8 unk9F;
+    /* 0xA0 */ u32 : 32;
+    /* 0xA4 */ s32 posX;
+    /* 0xA8 */ s32 posY;
+    /* 0xAC */ s32 unkAC;
 } ET_Diplocephalus;
 
 typedef struct {

src/st/no0/e_diplocephalus.c

@@ -68,7 +68,7 @@ void EntityDiplocephalusFoot(Entity* self) {
             self->animCurFrame++;
             if (self->ext.diplocephalus.unk9E < 3) {
                 if (g_CurrentEntity->facingLeft ^
-                    (LOHU(self->ext.prim->x3) % 2)) {
+                    (self->ext.diplocephalus.parent->step % 2)) {
                     EntityGreyPuffSpawner(self, 6, 3, 6, 16, 0, -4);
                 } else {
                     EntityGreyPuffSpawner(self, 6, 3, -6, 16, 0, 4);
@@ -86,15 +86,75 @@ void EntityDiplocephalusFoot(Entity* self) {
 
 INCLUDE_ASM("st/no0/nonmatchings/e_diplocephalus", func_us_801CF910);
 
+// Main entity?
 INCLUDE_ASM("st/no0/nonmatchings/e_diplocephalus", func_us_801CFBE8);
 
-INCLUDE_ASM("st/no0/nonmatchings/e_diplocephalus", func_us_801D0718);
+// Likely the torso entity that player can stand on top of
+void func_us_801D0718(Entity* self) {
+    Entity* parent;
+    Entity* player;
+    s32 step;
+    s32 collision;
+    s32 posX;
+    s32 posY;
+
+    if (!self->step) {
+        InitializeEntity(g_EInitInteractable);
+        self->ext.diplocephalus.posX = self->posX.i.hi + g_Tilemap.scrollX.i.hi;
+        self->ext.diplocephalus.posY = self->posY.i.hi + g_Tilemap.scrollY.i.hi;
+    }
+
+    player = &PLAYER;
+    parent = self->ext.diplocephalus.parent;
+    self->posX.i.hi = parent->posX.i.hi;
+    self->posY.i.hi = parent->posY.i.hi;
+    posX =
+        self->posX.i.hi + g_Tilemap.scrollX.i.hi - self->ext.diplocephalus.posX;
+    posY =
+        self->posY.i.hi + g_Tilemap.scrollY.i.hi - self->ext.diplocephalus.posY;
+    collision = 0;
+    step = parent->step;
+    if (step < 13) {
+        collision = GetPlayerCollisionWith(self, 8, 18, 4) & 0xFF;
+        if (collision) {
+            player->posX.i.hi += posX;
+            player->posY.i.hi += 2;
+            D_80097488.x.i.hi += posX;
+            D_80097488.y.i.hi += 2;
+        }
+    }
+    self->ext.diplocephalus.posX = self->posX.i.hi + g_Tilemap.scrollX.i.hi;
+    self->ext.diplocephalus.posY = self->posY.i.hi + g_Tilemap.scrollY.i.hi;
+
+    // Parent is func_us_801CFBE8 (self - 1)
+    if (parent->entityId != 0x21) {
+        DestroyEntity(self);
+    }
+}
 
 // Death explosion
-INCLUDE_ASM("st/no0/nonmatchings/e_diplocephalus", func_us_801D0898);
+void func_us_801D0898(Entity* self, s32 count) {
+    Entity* newEntity;
+    s32 i;
+    s8 randomX;
+    s8 randomY;
+
+    for (i = 0; i < count; i++) {
+        randomX = (Random() & 0x3F) - 0x20;
+        randomY = (Random() & 0x1F) - 0xF;
+        newEntity = AllocEntity(&g_Entities[160], &g_Entities[192]);
+        if (newEntity != NULL) {
+            CreateEntityFromEntity(E_EXPLOSION, self, newEntity);
+            newEntity->params = 1;
+            newEntity->posX.i.hi += randomX;
+            newEntity->posY.i.hi += randomY;
+            newEntity->zPriority = self->zPriority + 2;
+        }
+    }
+}
 
 // Fireball
 INCLUDE_ASM("st/no0/nonmatchings/e_diplocephalus", func_us_801D0990);
 
-// Main entity?
+// Tail entity
 INCLUDE_ASM("st/no0/nonmatchings/e_diplocephalus", func_us_801D0E7C);