From 0d2b6b8bc98f8c559f50acbc0d019bcd11b5ae90 Mon Sep 17 00:00:00 2001
From: Tal Hayon <talhayon1@gmail.com>
Date: Sat, 7 Jan 2023 08:24:24 +0200
Subject: [PATCH] Match sub_08080278 (by Catobat)

---
 asm/non_matching/scroll/sub_08080278.inc | 120 -----------------------
 src/scroll.c                             |  65 +++++++++++-
 2 files changed, 63 insertions(+), 122 deletions(-)
 delete mode 100644 asm/non_matching/scroll/sub_08080278.inc

diff --git a/asm/non_matching/scroll/sub_08080278.inc b/asm/non_matching/scroll/sub_08080278.inc
deleted file mode 100644
index fb055fc3..00000000
--- a/asm/non_matching/scroll/sub_08080278.inc
+++ /dev/null
@@ -1,120 +0,0 @@
-	.syntax unified
-	push {r4, r5, r6, r7, lr}
-	mov r7, sl
-	mov r6, sb
-	mov r5, r8
-	push {r5, r6, r7}
-	sub sp, #8
-	ldr r0, _08080344 @ =gUnk_02022830
-	mov ip, r0
-	ldr r1, _08080348 @ =gRoomControls
-	ldrh r0, [r1, #0x1e]
-	lsrs r0, r0, #4
-	str r0, [sp]
-	ldrh r0, [r1, #0x20]
-	lsrs r0, r0, #4
-	lsls r0, r0, #6
-	str r0, [sp, #4]
-	movs r5, #0
-	mov sl, r5
-	cmp r5, r0
-	bhs _08080336
-	mov sb, r5
-_080802A2:
-	movs r1, #0
-	mov r8, r1
-	ldr r0, [sp]
-	cmp r8, r0
-	bhs _08080328
-	ldr r4, _0808034C @ =gMapTop+0x0004
-	add r4, sb
-	ldr r7, _08080350 @ =gMapTop+0x3004
-	add r7, sb
-	ldr r3, _08080354 @ =gMapBottom+0x0004
-	add r3, sb
-	ldr r6, _08080358 @ =gMapBottom+0x3004
-	add r6, sb
-_080802BC:
-	mov r2, sl
-	add r2, r8
-	ldrh r0, [r6]
-	ldrh r1, [r3]
-	cmp r0, r1
-	beq _080802EA
-	ldr r0, _0808035C @ =0x00003FFF
-	cmp r1, r0
-	bhi _080802EA
-	adds r0, #1
-	adds r1, r0, #0
-	adds r0, r2, #0
-	orrs r0, r1
-	mov r1, ip
-	strh r0, [r1]
-	ldrh r0, [r3]
-	strh r0, [r1, #2]
-	movs r0, #4
-	add ip, r0
-	adds r5, #1
-	ldr r0, _08080360 @ =0x000005FF
-	cmp r5, r0
-	bhi _08080336
-_080802EA:
-	ldrh r0, [r7]
-	ldrh r1, [r4]
-	cmp r0, r1
-	beq _08080316
-	ldr r0, _0808035C @ =0x00003FFF
-	cmp r1, r0
-	bhi _08080316
-	movs r1, #0x80
-	lsls r1, r1, #8
-	adds r0, r1, #0
-	orrs r2, r0
-	mov r0, ip
-	strh r2, [r0]
-	ldrh r0, [r4]
-	mov r1, ip
-	strh r0, [r1, #2]
-	movs r0, #4
-	add ip, r0
-	adds r5, #1
-	ldr r0, _08080364 @ =0x000007FF
-	cmp r5, r0
-	bhi _08080336
-_08080316:
-	adds r4, #2
-	adds r7, #2
-	adds r3, #2
-	adds r6, #2
-	movs r1, #1
-	add r8, r1
-	ldr r0, [sp]
-	cmp r8, r0
-	blo _080802BC
-_08080328:
-	movs r1, #0x80
-	add sb, r1
-	movs r0, #0x40
-	add sl, r0
-	ldr r1, [sp, #4]
-	cmp sl, r1
-	blo _080802A2
-_08080336:
-	adds r0, r5, #0
-	add sp, #8
-	pop {r3, r4, r5}
-	mov r8, r3
-	mov sb, r4
-	mov sl, r5
-	pop {r4, r5, r6, r7, pc}
-	.align 2, 0
-_08080344: .4byte gUnk_02022830
-_08080348: .4byte gRoomControls
-_0808034C: .4byte gMapTop+0x0004
-_08080350: .4byte gMapTop+0x3004
-_08080354: .4byte gMapBottom+0x0004
-_08080358: .4byte gMapBottom+0x3004
-_0808035C: .4byte 0x00003FFF
-_08080360: .4byte 0x000005FF
-_08080364: .4byte 0x000007FF
-	.syntax divided
diff --git a/src/scroll.c b/src/scroll.c
index 0ae4b91c..3b70936d 100644
--- a/src/scroll.c
+++ b/src/scroll.c
@@ -28,7 +28,7 @@ extern void sub_0805E248();
 extern u8 gUpdateVisibleTiles;
 extern u16 gUnk_0200B640;
 extern u32** gUnk_08109194[];
-extern u8 gUnk_02022830[];
+extern u32 gUnk_02022830[];
 extern u16 gUnk_020246B0[];
 extern u8 gUnk_080B7910[];
 
@@ -418,7 +418,68 @@ void sub_080801BC(RoomControls* controls) {
     }
 }
 
-ASM_FUNC("asm/non_matching/scroll/sub_08080278.inc", u32 sub_08080278())
+u32 sub_08080278(void) {
+    u32 width;
+    u32 height;
+    u32 tilePos;
+    u16* bottomMapDataPtr;
+    u16* topMapDataPtr;
+    u32 result;
+    u16* bottomMapDataClonePtr;
+    u16* topMapDataClonePtr;
+    u32 indexX;
+    FORCE_REGISTER(u32 indexY, r10);
+    int iVar10;
+    u16* ptr1;
+    u32 tmp;
+
+    ptr1 = (u16*)gUnk_02022830;
+    width = gRoomControls.width >> 4;
+    height = (gRoomControls.height >> 4) << 6;
+    result = 0;
+    indexY = 0;
+    if (result < height) {
+        iVar10 = 0;
+        do {
+            indexX = 0;
+            if (indexX < width) {
+                topMapDataPtr = (u16*)((int)gMapTop.mapData + iVar10);
+                topMapDataClonePtr = (u16*)((int)gMapTop.mapDataClone + iVar10);
+                bottomMapDataPtr = (u16*)((int)gMapBottom.mapData + iVar10);
+                bottomMapDataClonePtr = (u16*)((int)gMapBottom.mapDataClone + iVar10);
+                while (indexX < width) {
+                    tilePos = indexY + indexX;
+                    if ((bottomMapDataClonePtr[0] != bottomMapDataPtr[0]) && (bottomMapDataPtr[0] < 0x4000)) {
+                        ptr1[0] = tilePos | 0x4000;
+                        ptr1[1] = bottomMapDataPtr[0];
+                        ptr1 += 2;
+                        result++;
+                        if (result >= 0x600) {
+                            return result;
+                        }
+                    }
+                    if ((topMapDataClonePtr[0] != topMapDataPtr[0]) && (topMapDataPtr[0] < 0x4000)) {
+                        ptr1[0] = tilePos | 0x8000;
+                        ptr1[1] = topMapDataPtr[0];
+                        ptr1 += 2;
+                        result++;
+                        if (result >= 0x800) {
+                            return result;
+                        }
+                    }
+                    topMapDataPtr++;
+                    topMapDataClonePtr++;
+                    bottomMapDataPtr++;
+                    bottomMapDataClonePtr++;
+                    indexX++;
+                }
+            }
+            iVar10 += 0x80;
+            indexY += 0x40;
+        } while (indexY < height);
+    }
+    return result;
+}
 
 void sub_08080368(void) {
     u32 tmp;