From f6a55433a2d93898b03e3ee3a65a2061ceda6a9a Mon Sep 17 00:00:00 2001
From: PikalaxALT <pikalaxalt@gmail.com>
Date: Mon, 30 Oct 2017 08:46:36 -0400
Subject: [PATCH] through sub_81237B4

---
 asm/region_map.s     | 75 --------------------------------------------
 include/region_map.h |  2 +-
 src/region_map.c     | 32 ++++++++++++++++---
 3 files changed, 29 insertions(+), 80 deletions(-)

diff --git a/asm/region_map.s b/asm/region_map.s
index a50279692..892cf338c 100644
--- a/asm/region_map.s
+++ b/asm/region_map.s
@@ -5,81 +5,6 @@
 
 	.text
 
-	thumb_func_start sub_812378C
-sub_812378C: @ 812378C
-	ldr r2, =gRegionMap
-	ldr r2, [r2]
-	lsls r0, 16
-	asrs r0, 8
-	movs r3, 0xE0
-	lsls r3, 5
-	adds r0, r3
-	str r0, [r2, 0x24]
-	lsls r1, 16
-	asrs r1, 8
-	movs r0, 0x90
-	lsls r0, 6
-	adds r1, r0
-	str r1, [r2, 0x28]
-	adds r2, 0x7D
-	movs r0, 0x1
-	strb r0, [r2]
-	bx lr
-	.pool
-	thumb_func_end sub_812378C
-
-	thumb_func_start sub_81237B4
-sub_81237B4: @ 81237B4
-	push {r4,lr}
-	ldr r4, =gRegionMap
-	ldr r1, [r4]
-	adds r0, r1, 0
-	adds r0, 0x7D
-	ldrb r0, [r0]
-	cmp r0, 0
-	beq _0812381A
-	ldrh r1, [r1, 0x2C]
-	movs r0, 0x20
-	bl SetGpuReg
-	ldr r0, [r4]
-	ldrh r1, [r0, 0x34]
-	movs r0, 0x22
-	bl SetGpuReg
-	ldr r0, [r4]
-	ldrh r1, [r0, 0x30]
-	movs r0, 0x24
-	bl SetGpuReg
-	ldr r0, [r4]
-	ldrh r1, [r0, 0x38]
-	movs r0, 0x26
-	bl SetGpuReg
-	ldr r0, [r4]
-	ldrh r1, [r0, 0x24]
-	movs r0, 0x28
-	bl SetGpuReg
-	ldr r0, [r4]
-	ldrh r1, [r0, 0x26]
-	movs r0, 0x2A
-	bl SetGpuReg
-	ldr r0, [r4]
-	ldrh r1, [r0, 0x28]
-	movs r0, 0x2C
-	bl SetGpuReg
-	ldr r0, [r4]
-	ldrh r1, [r0, 0x2A]
-	movs r0, 0x2E
-	bl SetGpuReg
-	ldr r0, [r4]
-	adds r0, 0x7D
-	movs r1, 0
-	strb r1, [r0]
-_0812381A:
-	pop {r4}
-	pop {r0}
-	bx r0
-	.pool
-	thumb_func_end sub_81237B4
-
 	thumb_func_start sub_8123824
 sub_8123824: @ 8123824
 	push {r4,r5,lr}
diff --git a/include/region_map.h b/include/region_map.h
index 92bf0946e..eb8bb3222 100644
--- a/include/region_map.h
+++ b/include/region_map.h
@@ -232,8 +232,8 @@ struct RegionMap {
     /*0x024*/ s32 bg2x;
     /*0x028*/ s32 bg2y;
     /*0x02c*/ u32 bg2pa;
-    /*0x030*/ u32 bg2pb;
     /*0x034*/ u32 bg2pc;
+    /*0x030*/ u32 bg2pb;
     /*0x038*/ u32 bg2pd;
     /*0x03c*/ s32 unk_03c;
     /*0x040*/ s32 unk_040;
diff --git a/src/region_map.c b/src/region_map.c
index c4d15a8ac..0a2da354a 100644
--- a/src/region_map.c
+++ b/src/region_map.c
@@ -3,6 +3,7 @@
 #include "global.h"
 #include "main.h"
 #include "menu.h"
+#include "gpu_regs.h"
 #include "palette.h"
 #include "trig.h"
 #include "region_map.h"
@@ -454,17 +455,40 @@ void CalcZoomScrollParams(s16 scrollX, s16 scrollY, s16 c, s16 d, u16 e, u16 f,
     s32 var4;
 
     gRegionMap->bg2pa = e * gSineTable[rotation + 64] >> 8;
-    gRegionMap->bg2pb = e * -gSineTable[rotation] >> 8;
-    gRegionMap->bg2pc = f * gSineTable[rotation] >> 8;
+    gRegionMap->bg2pc = e * -gSineTable[rotation] >> 8;
+    gRegionMap->bg2pb = f * gSineTable[rotation] >> 8;
     gRegionMap->bg2pd = f * gSineTable[rotation + 64] >> 8;
 
     var1 = (scrollX << 8) + (c << 8);
-    var2 = d * gRegionMap->bg2pc + gRegionMap->bg2pa * c;
+    var2 = d * gRegionMap->bg2pb + gRegionMap->bg2pa * c;
     gRegionMap->bg2x = var1 - var2;
 
     var3 = (scrollY << 8) + (d << 8);
-    var4 = gRegionMap->bg2pd * d + gRegionMap->bg2pb * c;
+    var4 = gRegionMap->bg2pd * d + gRegionMap->bg2pc * c;
     gRegionMap->bg2y = var3 - var4;
 
     gRegionMap->needUpdateVideoRegs = TRUE;
 }
+
+void sub_812378C(s16 x, s16 y)
+{
+    gRegionMap->bg2x = (x << 8) + 0x1c00;
+    gRegionMap->bg2y = (y << 8) + 0x2400;
+    gRegionMap->needUpdateVideoRegs = TRUE;
+}
+
+void sub_81237B4(void)
+{
+    if (gRegionMap->needUpdateVideoRegs)
+    {
+        SetGpuReg(REG_OFFSET_BG2PA, gRegionMap->bg2pa);
+        SetGpuReg(REG_OFFSET_BG2PB, gRegionMap->bg2pb);
+        SetGpuReg(REG_OFFSET_BG2PC, gRegionMap->bg2pc);
+        SetGpuReg(REG_OFFSET_BG2PD, gRegionMap->bg2pd);
+        SetGpuReg(REG_OFFSET_BG2X_L, gRegionMap->bg2x);
+        SetGpuReg(REG_OFFSET_BG2X_H, gRegionMap->bg2x >> 16);
+        SetGpuReg(REG_OFFSET_BG2Y_L, gRegionMap->bg2y);
+        SetGpuReg(REG_OFFSET_BG2Y_H, gRegionMap->bg2y >> 16);
+        gRegionMap->needUpdateVideoRegs = FALSE;
+    }
+}