From e708b51d6d80ce5c273817c5a0aa8df3b7f7eda7 Mon Sep 17 00:00:00 2001
From: RocketRobz <bobesh8@gmail.com>
Date: Thu, 20 Aug 2020 08:07:00 -0600
Subject: [PATCH] DS(i): Improve emulator check

DS header is now grabbed from GBA slot by ARM7, to avoid crashes.

Also mount NitroFS in order of how fast data is accessible.
---
 nds/arm7/source/main.c    |  6 ++++-
 nds/arm9/source/gfx.cpp   |  2 +-
 nds/arm9/source/nitrofs.c | 55 +++++++++++++++++++++------------------
 3 files changed, 35 insertions(+), 28 deletions(-)

diff --git a/nds/arm7/source/main.c b/nds/arm7/source/main.c
index 38c996a..5e0e6f6 100644
--- a/nds/arm7/source/main.c
+++ b/nds/arm7/source/main.c
@@ -55,7 +55,11 @@ void powerButtonCB() {
 int main() {
 //---------------------------------------------------------------------------------
     // nocashMessage("ARM7 main.c main");
-	
+
+	// Grab from DS header in GBA slot
+	*(u16*)0x02FFFC36 = *(u16*)0x0800015E;	// Header CRC16
+	*(u32*)0x02FFFC38 = *(u32*)0x0800000C;	// Game Code
+
 	// clear sound registers
 	dmaFillWords(0, (void*)0x04000400, 0x100);
 
diff --git a/nds/arm9/source/gfx.cpp b/nds/arm9/source/gfx.cpp
index bff52d4..bda38d0 100644
--- a/nds/arm9/source/gfx.cpp
+++ b/nds/arm9/source/gfx.cpp
@@ -63,7 +63,7 @@ extern int characterLimit;
 
 void GFX::loadSheets() {
 	if (!isDSiMode()) {
-		sysSetCartOwner (BUS_OWNER_ARM9);	// Allow arm9 to access GBA ROM (or in this case, the DS Memory Expansion Pak)
+		//sysSetCartOwner (BUS_OWNER_ARM9);	// Allow arm9 to access GBA ROM (or in this case, the DS Memory Expansion Pak)
 		*(vu32*)(0x08240000) = 1;
 		if (*(vu32*)(0x08240000) == 1) {
 			charSpriteMem3 = (u16*)0x09000000;
diff --git a/nds/arm9/source/nitrofs.c b/nds/arm9/source/nitrofs.c
index 920c81f..b52a0c8 100644
--- a/nds/arm9/source/nitrofs.c
+++ b/nds/arm9/source/nitrofs.c
@@ -137,6 +137,35 @@ nitroFSInit(const char *ndsfile)
     chdirpathid = NITROROOT;
     ndsFileLastpos = 0;
     ndsFile = NULL;
+	bool noLoader = ((strncmp((const char *)0x02FFFC38, __NDSHeader->gameCode, 4) == 0)
+	              && (*(u16*)0x02FFFC36 == __NDSHeader->headerCRC16));
+	if (!isDSiMode() || noLoader)
+	{
+		sysSetCartOwner (BUS_OWNER_ARM9); //give us gba slot ownership
+		if ((strncmp(((const char *)GBAROM) + LOADERSTROFFSET, LOADERSTR, strlen(LOADERSTR)) == 0) || noLoader)
+		{ // We has gba rahm
+			//printf("yes i think this is GBA?!\n");
+			if ((strncmp(((const char *)GBAROM) + 0x20C, __NDSHeader->gameCode, 4) == 0)
+			 && (*(u16*)0x0800035E == __NDSHeader->headerCRC16))
+			{ //Look for second magic string, if found its a sc.nds or nds.gba
+				//printf("sc/gba\n");
+				fntOffset = ((u32) * (u32 *)(((const char *)GBAROM) + FNTOFFSET + LOADEROFFSET)) + LOADEROFFSET;
+				fatOffset = ((u32) * (u32 *)(((const char *)GBAROM) + FATOFFSET + LOADEROFFSET)) + LOADEROFFSET;
+				hasLoader = true;
+				AddDevice(&nitroFSdevoptab);
+				return (1);
+			}
+			else
+			{ //Ok, its not a .gba build, so must be emulator
+				//printf("gba, must be emu\n");
+				fntOffset = ((u32) * (u32 *)(((const char *)GBAROM) + FNTOFFSET));
+				fatOffset = ((u32) * (u32 *)(((const char *)GBAROM) + FATOFFSET));
+				hasLoader = false;
+				AddDevice(&nitroFSdevoptab);
+				return (1);
+			}
+		}
+	}
     if (ndsfile != NULL)
     {
         if ((ndsFile = fopen(ndsfile, "rb")))
@@ -165,32 +194,6 @@ nitroFSInit(const char *ndsfile)
             return (1);
         }
     }
-	if (!isDSiMode() || PersonalData->name[0]==0 /* Regular NO$GBA */ || strncmp((const char*)0x4FFFA00, "no$gba", 6) == 0) {
-		sysSetCartOwner (BUS_OWNER_ARM9); //give us gba slot ownership
-		if ((strncmp(((const char *)GBAROM) + LOADERSTROFFSET, LOADERSTR, strlen(LOADERSTR)) == 0)
-		 || (strncmp(((const char *)GBAROM) + 0xC, __NDSHeader->gameCode, 4) == 0))
-		{ // We has gba rahm
-			//printf("yes i think this is GBA?!\n");
-			if (strncmp(((const char *)GBAROM) + LOADERSTROFFSET + LOADEROFFSET, LOADERSTR, strlen(LOADERSTR)) == 0)
-			{ //Look for second magic string, if found its a sc.nds or nds.gba
-				//printf("sc/gba\n");
-				fntOffset = ((u32) * (u32 *)(((const char *)GBAROM) + FNTOFFSET + LOADEROFFSET)) + LOADEROFFSET;
-				fatOffset = ((u32) * (u32 *)(((const char *)GBAROM) + FATOFFSET + LOADEROFFSET)) + LOADEROFFSET;
-				hasLoader = true;
-				AddDevice(&nitroFSdevoptab);
-				return (1);
-			}
-			else
-			{ //Ok, its not a .gba build, so must be emulator
-				//printf("gba, must be emu\n");
-				fntOffset = ((u32) * (u32 *)(((const char *)GBAROM) + FNTOFFSET));
-				fatOffset = ((u32) * (u32 *)(((const char *)GBAROM) + FATOFFSET));
-				hasLoader = false;
-				AddDevice(&nitroFSdevoptab);
-				return (1);
-			}
-		}
-	}
     return (0);
 }