Undo PokeCodec's PRs

This commit undoes most of PokeCodec's PRs after the debate in chat. Some
harmless or completely superseded PRs have been left alone, as there is not
much benefit in attempting to undo them.

Reverts #1104, #1108, #1115, #1118, #1119, #1124, #1126, #1127, #1132, #1136,
#1137, #1139, #1140, #1144, #1148, #1149, #1150, #1153, #1155, #1177, #1179,
#1180, #1181, #1182 and #1183.

src/trainer_hill.c

@@ -356,7 +356,7 @@ static void SetUpDataStruct(void)
 {
     if (sHillData == NULL)
     {
-        sHillData = AllocZeroed(sizeof(struct TrHillStruct2));
+        sHillData = AllocZeroed(sizeof(*sHillData));
         sHillData->floorId = gMapHeader.mapLayoutId - LAYOUT_TRAINER_HILL_1F;
         CpuCopy32(sDataPerTag[gSaveBlock1Ptr->trainerHill.tag], &sHillData->tag, sizeof(sHillData->tag) + 4 * sizeof(struct TrHillFloor));
         nullsub_2();
@@ -672,18 +672,70 @@ bool32 LoadTrainerHillFloorObjectEventScripts(void)
     return TRUE;
 }
 
-static u16 sub_81D5F58(u8 floorId, u32 bit, u32 arg2, u32 arg3)
+// Functionally equivalent.
+#ifdef NONMATCHING
+static u32 sub_81D5F58(u8 floorId, u32 bit, u32 arg2, u32 arg3)
 {
-    u8 var0;
-    u16 var1;
-    u16 var2;
+    u32 var0, var1, var2, var3;
 
-    var0 = (sHillData->floors[floorId].display.unk3A0[arg2] >> (15 - bit) & 1);
-    var1 = sHillData->floors[floorId].display.data[arg3 * arg2 + bit] + 0x200;
+    var0 = (sHillData->floors[floorId].display.unk3A0[arg2] >> (15 - bit)) & 1;
+    var1 = sHillData->floors[floorId].display.data[arg2 * arg3 + bit];
+    var3 = 0x200;
     var2 = 0x3000;
 
-    return (((var0 << 10) & 0xc00) | var2) | (var1 & 0x3ff);
+    return ((var0 << 10) | var2) | (var1 | var3);
 }
+#else
+NAKED
+static u32 sub_81D5F58(u8 floorId, u32 bit, u32 arg2, u32 arg3)
+{
+    asm_unified("\n\
+    push {r4,r5,lr}\n\
+	lsls r0, 24\n\
+	lsrs r0, 24\n\
+	ldr r4, =sHillData\n\
+	ldr r4, [r4]\n\
+	mov r12, r4\n\
+	lsls r4, r2, 1\n\
+	lsls r5, r0, 4\n\
+	subs r5, r0\n\
+	lsls r5, 3\n\
+	subs r5, r0\n\
+	lsls r5, 3\n\
+	adds r4, r5\n\
+	movs r0, 0xE8\n\
+	lsls r0, 2\n\
+	add r0, r12\n\
+	adds r0, r4\n\
+	ldrh r0, [r0]\n\
+	movs r4, 0xF\n\
+	subs r4, r1\n\
+	asrs r0, r4\n\
+	movs r4, 0x1\n\
+	ands r0, r4\n\
+	muls r2, r3\n\
+	adds r2, r1\n\
+	adds r2, r5\n\
+	movs r1, 0xA8\n\
+	lsls r1, 2\n\
+	add r1, r12\n\
+	adds r1, r2\n\
+	ldrb r1, [r1]\n\
+	movs r2, 0x80\n\
+	lsls r2, 2\n\
+	adds r3, r2, 0\n\
+	movs r2, 0xC0\n\
+	lsls r2, 6\n\
+	lsls r0, 10\n\
+	orrs r0, r2\n\
+	orrs r1, r3\n\
+	orrs r0, r1\n\
+	pop {r4,r5}\n\
+	pop {r1}\n\
+	bx r1\n\
+	.pool");
+}
+#endif // NONMATCHING
 
 void GenerateTrainerHillFloorLayout(u16 *mapArg)
 {