From cd99d80e424afdc312ad960835811254c8adea02 Mon Sep 17 00:00:00 2001
From: profi200 <fd3194@gmx.de>
Date: Mon, 15 Jun 2020 18:59:09 +0200
Subject: [PATCH] Detect homebrew and force SRAM save type. Bug fixes.

---
 include/types.h             |  1 +
 source/arm11/hardware/lgy.c | 22 +++++++++++++++-------
 source/arm9/hardware/lgy.c  |  2 +-
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/include/types.h b/include/types.h
index a16bf8a..0380364 100644
--- a/include/types.h
+++ b/include/types.h
@@ -30,6 +30,7 @@
 
 #define ALIGN(a)      __attribute__((aligned(a))) // Use alignas() instead.
 #define NAKED         __attribute__((naked))
+#define NOINLINE      __attribute__((noinline))
 #define PACKED        __attribute__((packed))
 #define TARGET_ARM    __attribute__((target("arm")))
 #define TARGET_THUMB  __attribute__((target("thumb")))
diff --git a/source/arm11/hardware/lgy.c b/source/arm11/hardware/lgy.c
index b0f39e4..39d40cb 100644
--- a/source/arm11/hardware/lgy.c
+++ b/source/arm11/hardware/lgy.c
@@ -39,7 +39,7 @@ static void lgySleepIrqHandler(u32 intSource)
 	}
 }
 
-static Result loadRom(const char *const path, u32 *const rsOut)
+static Result loadGbaRom(const char *const path, u32 *const rsOut)
 {
 	Result res;
 	FHandle f;
@@ -57,7 +57,7 @@ static Result loadRom(const char *const path, u32 *const rsOut)
 			{
 				*rsOut = romSize;
 				// Pad ROM area with "open bus" value.
-				memset((void*)(ROM_LOC + romSize), 0xFFFFFFFFu, romSize);
+				memset((void*)(ROM_LOC + romSize), 0xFFFFFFFFu, MAX_ROM_SIZE - romSize);
 			}
 		}
 		else res = RES_ROM_TOO_BIG;
@@ -71,9 +71,15 @@ static Result loadRom(const char *const path, u32 *const rsOut)
 // Code based on: https://github.com/Gericom/GBARunner2/blob/master/arm9/source/save/Save.vram.cpp
 static u16 tryDetectSaveType(u32 romSize)
 {
-	// TODO: Homebrew detection (always SRAM).
+	const u32 *romPtr = (u32*)ROM_LOC;
+	if(romPtr[0xAC / 4] == 0) // If Game Code all zeros --> Homebrew.
+	{
+		debug_printf("Detected homebrew. Using SRAM save type.\n");
+		return SAVE_TYPE_SRAM_256k;
+	}
+
+	romPtr += 0xE4 / 4; // Skip headers.
 	u16 saveType = SAVE_TYPE_NONE;
-	const u32 *romPtr = (u32*)(ROM_LOC + 0xE4u); // Skip headers.
 	for(; romPtr < (u32*)(ROM_LOC + romSize); romPtr++)
 	{
 		u32 tmp = *romPtr;
@@ -129,14 +135,16 @@ static u16 tryDetectSaveType(u32 romSize)
 
 				if(memcmp(romPtr, str, strlen(str)) == 0)
 				{
-					debug_printf("Detected save type '%s'.\n", str);
 					saveType = tmpSaveType;
-					break;
+					debug_printf("Detected save type '%s'.\n", str);
+					goto saveTypeFound;
 				}
 			}
 		}
 	}
 
+saveTypeFound:
+
 	return saveType;
 }
 
@@ -156,7 +164,7 @@ Result LGY_prepareGbaMode(bool gbaBios, const char *const romPath, const char *c
 {
 	// Load the ROM image.
 	u32 romSize;
-	Result res = loadRom(romPath, &romSize);
+	Result res = loadGbaRom(romPath, &romSize);
 	if(res != RES_OK) return res;
 
 	// Try to detect the save type.
diff --git a/source/arm9/hardware/lgy.c b/source/arm9/hardware/lgy.c
index 1625280..b87a822 100644
--- a/source/arm9/hardware/lgy.c
+++ b/source/arm9/hardware/lgy.c
@@ -49,7 +49,7 @@ static void setupBiosOverlay(bool gbaBios)
 	iomemcpy(REGs_LGY_A7_VECTOR, (u32*)_overlay_stub, (u32)_overlay_stub_size);
 
 	NDMA_copy((u32*)ARM7_STUB_LOC9, _arm7_stub_start, (u32)_arm7_stub_size);
-	// Patch swi 0x10 (RegisterRamReset) to swi 0x26 (HardReset).
+	// Patch swi 0x01 (RegisterRamReset) to swi 0x26 (HardReset).
 	if(gbaBios) *((u8*)_arm7_stub_swi) = 0x26;
 }